Bulletin of the Geological Society of Malaysia

Transcription

ISSN 0126–6187
PP3279/05/2013 (032783)
PERSATUAN GEOLOGI MALAYSIA
KANDUNGAN / CONTENTS
1 – 7
The geological heritage values and potential geotourism development of the beaches in Northern Sabah, Malaysia
Joanes Muda
9 – 12
ASEAN Mineral Resources Information System using FOSS and OGC-based standards
Joel Bandibas, Koji Wakita & Tetsuji Ohno
13 – 17 Geoheritage values of the Dong Van Karst Plateau Geopark: A quantitative geomorphological and topographic
analysis
Pham Viet Ha, Tran Tan Van, Quach Duc Tin, Ho Huu Hieu, Nguyen Dinh Tuan & Nguyen Quang Hưng
19 – 26 Geological interpretation based on satelite imagery: Updating geological maps of Indonesia to 1:50,000 map scale
Jamal, Sidarto, Ipranto & Sonny Mawardi
27 – 32 Global Heritage Stone Resource
Hirokazu Kato
33 – 38 Middle Permian Radiolarians from the siliceous mudstone block near Pos Blau, Ulu Kelantan and their significance
Basir Jasin, Atilia Bashardin & Zaiton Harun
39 – 45 Beberapa fitur dan tapak bernilai warisan geologi di Pulau Sibu, Mersing, Johor (Geological heritage values of
several features and sites of Pulau Sibu, Mersing, Johor)
Mohd. Fauzi Rajimin @ Jeman, Kamal Roslan Mohamad & Che Aziz Ali
47 – 51 Sedimentologi Lapisan Perantaraan Formasi Kubang Pasu dan Formasi Chuping, Beseri, Perlis (Sedimentology of
the Passage beds between the Kubang Pasu Formation and Chuping Formation, Berseri, Perlis)
Noorhashima Adenan, Che Aziz Ali & Kamal Roslan Mohamed
53 – 58 Sumber permineralan emas dan bijih timah di Jalur Barat Semenanjung Malaysia: Bukti dari kajian geokimia dan
mineral berat (Sources of gold and tin mineralization in the Western Belt of Peninsular Malaysia: Evidence from
geochemical and heavy mineral studies)
Mahat Hj Sibon, Habibah Jamil, Mohd Rozi Umor & Wan Fuad Wan Hassan
59 – 66 Microfacies and diagenesis in the Setul Limestone in Langkawi and Perlis
Che Aziz Ali & Kamal Roslan Mohamed
67 – 72 Evidence of Holocene and historical changes of sea level in the Langkawi Islands
H.D. Tjia
73 – 84 Input geologi untuk Sistem Sokongan Membuat Keputusan dalam pengurusan risiko bencana: Kajian kes
Universiti Kebangsaan Malaysia (Geological input for Decision Support System to manage the risk of disasters: A
case study of Universiti Kebangsaan Malaysia)
Nurfashareena Muhamad, Choun-Sian Lim, Mohammad Imam Hasan Reza & Joy Jacqueline Pereira
85 – 91 Chert blocks in Bentong-Raub Suture Zone: A heritage of Palaeo-Tethys
Basir Jasin
93 – 99 Discovery of Late Devonian (Frasnian) conodonts from the “Sanai limestone”, Guar Jentik, Perlis, Malaysia
Aye Ko Aung, Meor Hakif Amir Hassan & Ng Tham Fatt
101 – 107 Geological landscape and public perception: A case for Dataran Lang viewpoint, Langkawi
Tanot Unjah, Mohd Shafeea Leman & Ibrahim Komoo
Editors: Antony J. Reedman, Nguyen Thi Minh Ngoc, C.S. Lim & T.F. Ng
Bulletin
of the
GEOLOGICAL SOCIETY OF MALAYSIA
NOVEMBER 2013
No. 59
Buletin Persatuan
Geologi Malaysia
Bulletin of the Geological
Society of Malaysia
Geological Society of Malaysia
Editor-in-Chief
Ng Tham Fatt (University of Malaya)
Council 2013/2014
Managing Editor
President :
Prof. Dr. Joy Jacqueline Pereira
Vice President : Dr. Mazlan Madon
Secretary :
Mr. Ling Nan Ley
Assistant Secretary : Mr. Lim Choun Sian
Treasurer : Mr. Ahmad Nizam Hasan
Editor : Assoc. Prof. Dr. Ng Tham Fatt
Immediate Past President : Dato’ Yunus Abdul Razak
Councillors :
Assoc. Prof. Askury Abd Kadir
Dr. Meor Hakif Amir Hassan
Mr. Nicholas Jacob
Dr. Nur Iskandar Taib
Mr. Robert Wong
Dr. Samsudin Hj Taib
Mr. Tan Boon Kong
Dr. Tanot Unjah
Ralph L. Kugler (University of Malaya)
Editorial Board
Prof. Dr. Abdul Rahim Samsudin
(Universiti Kebangsaan Malaysia)
Prof. Dr. Azman A. Ghani
(University of Malaya)
Prof. Dr. Basir Jasin
Assoc. Prof. Dr. Chow Weng Sum
(Universiti Teknologi Petronas)
Prof. Dr. Felix Tongkul
(Universiti Malaysia Sabah)
Prof. Emeritus Dr. H.D. Tjia
Prof. Dato' Dr. Ibrahim Komoo
(Universiti Malaysia Terengganu)
Prof. Dr. J.J. Pereira
The Geological Society of Malaysia was founded in
1967 with the aim of promoting the advancement of
geoscience, particularly in Malaysia and Southeast
Asia. The Society has a membership of about 600
local and international geoscientists.
The Bulletin is the official journal of the Geological
Society of Malaysia. The Bulletin welcomes
submission of original articles of basic, applied and
multidisciplinary geosciences, as well as case studies
and review articles. Please refer to the instruction to
authors on the inner back page. Manuscript should
be submitted to:
The Editor
c/o Department of Geology,
University of Malaya,
50603 Kuala Lumpur, Malaysia
Tel: 603-79577036 Fax: 603-79563900
Email: geologicalsociety@gmail.com
Prof. Dr. John K. Raj
Prof. Dr. Lee Chai Peng
Prof. Dr. Mohd Shafeea Leman
Mr. Tan Boon Kong
(Consultant)
Prof. Dr. Teh Guan Hoe
(Consultant)
Prof. Dr. Wan Hasiah Abdullah
Dato' Yunus Abdul Razak
(Minerals & Geoscience Department
Malaysia)
Secretariat
Anna Lim
ISSN 0126–6187
PP3279/05/2013 (032783)
BULETIN
KANDUNGAN / CONTENTS
1 – 7
The geological heritage values and potential geotourism development of the beaches in Northern Sabah, Malaysia
Joanes Muda
9 – 12
ASEAN Mineral Resources Information System using FOSS and OGC-based standards
13 – 17 Geoheritage values of the Dong Van Karst Plateau Geopark: A quantitative geomorphological and topographic
analysis
19 – 26 Geological interpretation based on satelite imagery: Updating geological maps of Indonesia to 1:50,000 map scale
27 – 32 Global Heritage Stone Resource
Hirokazu Kato
33 – 38 Middle Permian Radiolarians from the siliceous mudstone block near Pos Blau, Ulu Kelantan and their significance
39 – 45 Beberapa fitur dan tapak bernilai warisan geologi di Pulau Sibu, Mersing, Johor (Geological heritage values of
several features and sites of Pulau Sibu, Mersing, Johor)
47 – 51 Sedimentologi Lapisan Perantaraan Formasi Kubang Pasu dan Formasi Chuping, Beseri, Perlis (Sedimentology of
the Passage beds between the Kubang Pasu Formation and Chuping Formation, Berseri, Perlis)
53 – 58 Sumber permineralan emas dan bijih timah di Jalur Barat Semenanjung Malaysia: Bukti dari kajian geokimia dan
mineral berat (Sources of gold and tin mineralization in the Western Belt of Peninsular Malaysia: Evidence from
geochemical and heavy mineral studies)
59 – 66 Microfacies and diagenesis in the Setul Limestone in Langkawi and Perlis
67 – 72 Evidence of Holocene and historical changes of sea level in the Langkawi Islands
H.D. Tjia
73 – 84 Input geologi untuk Sistem Sokongan Membuat Keputusan dalam pengurusan risiko bencana: Kajian kes
Universiti Kebangsaan Malaysia (Geological input for Decision Support System to manage the risk of disasters: A
case study of Universiti Kebangsaan Malaysia)
Nurfashareena Muhamad, Choun-Sian Lim, Mohammad Imam Hasan Reza & Joy Jacqueline Pereira
85 – 91 Chert blocks in Bentong-Raub Suture Zone: A heritage of Palaeo-Tethys
Basir Jasin
93 – 99 Discovery of Late Devonian (Frasnian) conodonts from the “Sanai limestone”, Guar Jentik, Perlis, Malaysia
101 – 107 Geological landscape and public perception: A case for Dataran Lang viewpoint, Langkawi
Editors: Antony J. Reedman, Nguyen Thi Minh Ngoc, C.S. Lim & T.F. Ng
Bulletin
of the
GEOLOGICAL SOCIETY OF MALAYSIA
NOVEMBER 2013
No. 59
Copyright: Geological Society of Malaysia, 2013
All rights reserved. No part of this publication may be reproduced,
stored in a retrieval system, or transmitted, in any form or by any means,
without the prior permission in writing of Geological Society of Malaysia.
This publication
is financed by the
Society’s Publication Fund
Published by
c/o Department of Geology, University of Malaya, 50603 Kuala Lumpur
Tel: 603-79577036 Fax: 603-79563900
Email: geologicalsociety@gmail.com
http://www.gsm.org.my/
Printed by
Art Printing Works Sdn. Bhd.
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PREFACE
Since its establishment in 1967, the Geological Society of Malaysia has been a major contributor to
the advancement of knowledge in geoscience at national and regional levels.
Bulletin 59 is a collection of 15 papers based on basic, applied and policy research on geoscience.
The first five articles are thematic papers presented at the 48th CCOP Annual Session held from 5-8 November
2012 in Langkawi, Malaysia and the other papers were papers presented at the National Geoscience Conference
and the Petroleum Geology Conference and Exhibition.
I would like to thank guest editors, Dr. Antony J. Reedman & Dr. Nguyen Thi Minh Ngoc for editing
the CCOP manuscripts. I am also grateful to all the authors for their contributions, the reviewers for making
time to improve the contributions and the organising committee of the conferences for facilitating publication
of the papers.
T.F. Ng
Editor
iii
GLOSSARY
Barat
B
west
Baratdaya
BD
southwest
Baratlaut
BL
northwest
Batustone
Batuanrock
Besarlarge
Bukit
Bthill
Genting
Gtgpass
Gunung Gmountain
Jalan
Jln
road, street
Kampung Kgvillage
Kecilsmall
Kuala
K
mouth of river
Lautsea
Permatang
Ptg
sandy ridge along coast
Pulau
Pisland
Selatstrait
Selatan Ssouth
Semenanjung
peninsula
Sungai
S, Sg
river
Tanjung Tgcape
Tasiklake
Teluk
T, Tlk
bay
Tenggara TGsoutheast
Timur
Teast
Timurlaut
TL
southwest
Utara
Unorth
iv
Bulletin of the Geological Society of Malaysia, Volume 59, November 2013, pp. 1 – 7
The geological heritage values and potential geotourism
development of the beaches in Northern Sabah, Malaysia
Joanes Muda
Minerals and Geoscience Department Malaysia, Sarawak
Jalan Wan Abdul Rahman, Kenyalang Park, P.O. Box 560, 93712 Kuching, Sarawak, Malaysia
Email address: joannes@jmg.gov.my
Abstract: A study was carried out on 13 beaches in Northern Sabah, Malaysia to identify their geological heritage values
and geotourism potential. Northern Sabah has some of the finest beaches in Sabah and most of them are still undisturbed
and in pristine condition. However, with the increasing demand for tourism facilities, considerable development is currently
being undertaken in the coastal areas and the impact upon the beaches is considerable. The natural geomorphologic
processes may be disrupted and the beaches in the area might be degraded and damaged. The main attractions of the
beaches are their beautiful landscape. The geological heritage values usually go unnoticed and unappreciated due to lack
of awareness and information. By unraveling and explaining their hidden natural qualities, the attractions of the beaches
could be enhanced. This study has identified the scientific values of the beaches such as the composition, morphology
and sources of the beach sediments. Black sand comprising mainly chromite was found at Marasimsim Beach and pink
sand comprising mainly garnet was found at a pocket beach in Tanjung Simpang Mengayau. The study also revealed
that several of the beaches in the area have aesthetic and cultural value as well as their obvious recreational value. Such
aspects could be explained to visitors so that they can appreciate the importance of conservation. Geotourism could be
developed and promoted on some of the beaches together with steps to ensure the sustainability and to protect these
beach environments. The promotion of beach geotourism could be carried out together with other potential geotourism
sites in Northern Sabah. The study on beaches for geotourism development is an innovative way to add-value to their
existing aesthetic attractions and to enhance and sustain the tourism industry in the State.
Keywords: geological heritage, geotourism, beach, Sabah
INTRODUCTION
Beaches are one of the most important landscape assets
for the tourism industry in Sabah. For instance, nearly all the
highly rated hotels in Sabah are built near beaches such as
the Nexus Karambunai Resort, Shangri-La Rasa Ria Resort
and Shangri-La Tanjung Aru Resort.
Northern Sabah has some of the finest beaches in
Sabah, especially in the western part of the Kudat Peninsula.
The beaches in this area stretch from Teringkai, located
south of the Kudat Peninsula to Kosuhui just south of
Tanjung Simpang Mengayau (popularly known as the Tip
of Borneo). Beaches can also be found at the eastern side
of the Kudat Peninsula and at the western part of the
Bengkoka Peninsula.
Beaches are formed where there is a sufficient supply
of sediment and suitable sites for accumulation. Beaches
are often associated with fishing, recreation and scientific
research such as studies on geomorphology, coastal
environmental and global sea level change. Beaches lure
visitors because of their sandy nature and beautiful landscape.
By unraveling more of their hidden natural qualities, the
attractions could be enhanced. Most of the beaches in the
study area are still undisturbed and in pristine condition.
However, with the increasing demand for tourism facilities,
developments is now being carried in the coastal areas and
the impact upon the beaches are greater now than ever. The
natural geomorphologic processes could be disrupted and
Presented at 48th CCOP Annual Session
the beaches in the area might be degraded and damaged.
The main attraction of a beach is because of its sandy
nature. Visitors naturally shun muddy or rocky beaches. The
supplies of sand to a beach area are from various sources
such as from the hinterland, coastal rocky outcrops and
from the seabed. Disruption at the source or of the transport
medium could alter the nature of a beach. Therefore, this
study is timely and the outcome of this study could
be used as a guide for sustainable development along
coastal areas in Northern Sabah.
Each beach has its own heritage value. The value which
is usually appreciated by the public is the aesthetic value
while the other values such as the scientific values usually
go unnoticed and unappreciated due to lack of awareness
and information. The scientific values of beaches could be
conveyed to the general public so that they can appreciate
its importance. Visitors to beaches could thereby gain some
knowledge concerning the history of the formation of these
important landscapes of the earth.
Beach landscape is one of the youngest landscapes
compared to many other types of landscape. The coastal
areas are very dynamic and among the factors that form
beach landscapes are sea level changes, tides, wave actions,
rock types and geological structures. Visitors have to be
made aware of the geomorphologic processes and geological
features that shape and control the formation of beaches so
that they can appreciate and protect them.
Joanes Muda
LOCATION OF STUDY AREA
The study area is located mainly in the Kudat
Peninsula, Northern Sabah. A total of thirteen beaches
were involved in the study (Figure 1). They are Kampung
Kuala Tajau, Sampaping, Tanjung Simpang Mengayau,
Kosuhui, Pongugadan, Bawang Jamal, Kulambu, Loro
Kecil, Kamihang, Sikuati, Torongkongan, Teluk Agal and
Marasimsim Beach (Figures 2 and 3).
OBJECTIVES AND METHODOLOGY
The objectives of the study are to identify the geological
heritage values and the geotourism potential of the beaches
in Northern Sabah. This includes the study of the physical
characteristics and composition of the beach sand and the
beach landscape itself.
Beach sediment samples were collected for grain size,
compositional and morphological analyses. Two types of
samples were collected at each sampling site, one which
is nearer to the sea (foreshore) and the other nearer to the
land (backshore). Samples were also collected whenever
coloured sediments were encountered. The beach sand
samples were collected up to 10 cm deep using a small
plastic scope and the amount of sample collected was at least
300 g. A duplicate sample was collected at each beach for
quality control of the sampling procedure. All samples were
washed with fresh water, air-dried and thoroughly dispersed
before sieving. The amount of sample used for dry sieving
was about 250 g. A mechanical riffle splitter was used to
split samples before sieving. Sieve with sizes of 2.0, 1.0,
0.5, 0.25, 0.125 and 0.0625 mm were used and set up in
order of decreasing mesh size. The results obtained from
the sieve analysis were treated statistically using the Folk
and Ward (1957) method.
The statistical parameters calculated in phi (Φ) units
were mean particle size, standard deviation (sorting),
skewness and kurtosis. Semi-quantitative estimation (QME)
analysis was also carried out on selected beach sediment
samples. The characteristics of the beach and its surrounding
landscapes such as the profile, slope, width, rock outcrops,
erosional features and vegetation were also recorded.
GEOLOGICAL SETTING
The oldest rocks in Northern Sabah, the basement
rocks are consist of ophiolite and associated sedimentary
rocks such as sandstone, mudstone and chert. These are
overlain by sedimentary rocks comprising the Crocker,
Kudat, South Banggi and Bongaya Formations together
with minor mélange and Quaternary deposits of alluvium,
terrace sand and gravel. The geological map of Northern
Sabah is shown in Figure 4.
RESULTS
Two types of beach are observed in the study area; the
linear type and pocket type respectively. Linear beaches are
generally straight or slightly curved while pocket beaches are
small interruptions of rocky shores. For the purpose of this
study, pocket beaches are those less than 500 m in length.
The characteristics of the beach sediments in the study area
range from fine to coarse grained and poorly sorted to very
well sorted. The summary of the landscapes and physical
characteristics of the beach sediments in Northern Sabah
is shown in Table 1.
According to King (1972), fine-grained sediments
form beaches with a smooth profile. The beaches with
fine-grained and well-sorted sediments are Kampung Kuala
Tajau, Kosuhui, Bawang Jamal, Kulambu, Loro Kecil,
Figure 2: The Kulambu Beach.
Figure 1: Location of study area and beaches in Northern Sabah.
Figure 3: The Loro Kecil pocket beach.
Bulletin of the Geological Society of Malaysia, Volume 59, November 2013
2
The
geological heritage values and potential geotourism development of the beaches in
Northern Sabah, Malaysia
Figure 5: Black sand at the Marasimsim Beach, Northern Sabah. The
black sand comprises mainly chromite derived from the hinterland.
Figure 4: Geological map of Northern Sabah, Malaysia.
Kamihang, Sikuati, Teluk Agal and Torongkongan. The
ccurrence of black sand was found at Marasimsim Beach
and Torongkongan Beach (Figure 5). The black sand at
the Marasimsim Beach comprises mainly chromite (3983%) which originated from the ultrabasic rocks in the
hinterland. The patches of black sand at the Torongkongan
Beach comprise mainly zircon (39%) and chromite (35%)
which probably derived from the ultrabasic rocks and
basalt at Tanjung Bangau located just north of the Sikuati
Beach (Figure 6). Pink sand was found at Tanjung Simpang
Mengayau pocket beach (Figure 7). The QME analysis
carried out on the pink sand shows it consists mostly of
garnet (73%) with minor amounts of ilmenite, chromite,
pyroxene, iron oxide, zircon, rutile, leucoxene and other
minerals. The garnet sand is medium grained and moderately
well sorted. The colour of the garnet is various shades of
pink (Figure 8). The grains are subangular to rounded and
mostly spherical in shape due to attrition. The source of
the garnet is not known with certainty but probably was
derived from the reworking of older sediments.
EVALUATION OF THE GEOLOGICAL HERITAGE
OF BEACHES
The evaluation of the geological heritage of beaches
is carried out based on scientific, aesthetic, recreational,
Figure 6: Zircon (zr) and rutile (ru) grains in the black sand of the
Torongkongan Beach.
cultural and ecological values (Table 2). The geological
heritage values that are present in beaches usually go
unnoticed and unappreciated by visitors. These values should
be conveyed to the beach users and the general public so
that they can appreciate their importance. Based on the
evaluation, several beaches such as the Kosuhui, Kulambu,
Loro Kecil, Torongkongan and Marasimsim Beach have
scientific, aesthetic, recreational and cultural values.
GEOTOURISM POTENTIAL
The target groups identified for geotourism development
include amateur and professional geoscientists, school and
university students, academics and teachers, ecotourism
participants, landscape photographers, artists, historians,
those interested in the physical natural wonders of the
earth and ordinary tourists (Joyce, 2006). With these in
mind, the geotourism potential of beaches is evaluated as
based on research, educational and recreational activities.
The geotourism potential of the beaches in Northern
Sabah is shown in Table 3. Beaches such as the Tanjung
Simpang Mengayau, Kulambu, Loro Kecil, Torongkongan
and Marasimsim Beach have research, educational and
recreational values and therefore have high potential for
geotourism.
3
Joanes Muda
Figure 7: A patch of pink beach sand at Tanjung Simpang Mengayau
comprising mainly garnet.
Figure 8: Garnet grains of various shades of pink that give the pink
colour to the beach sand at Tanjung Simpang Mengayau.
Table 1: Summary of the landscape and physical characteristics of the beach sediments in Northern Sabah, Malaysia.
No.
Name of Beach
Type of Beach/Other
Features Near Beach
Beach Sediment Analysis
Grain Size and Sorting
Colour/
Composition
Very light grey/Quartz
(95%).
1
Kampung Kuala
Tajau
Linear
Sandy sediment (fine-grained,
moderately sorted to well-sorted).
2
Sampaping
Linear/Remnant cliffs
Sandy sediment (fine- to coarse-grained, Yellowish grey/Quartz
moderately sorted to poorly sorted).
(60-70%).
3
Tanjung Simpang
Mengayau
4
Kosuhui
5
6
Pongugadan
Bawang Jamal
7
Kulambu
8
Loro Kecil
9
Kamihang
10
Sikuati
11
12
13
4
Torongkongan
Teluk Agal
Marasimsim
Sandy to pebbly sediment (coarsePocket/Cliffs, faults, sea
grained, moderately well-sorted), pink
caves
sand (garnet).
Sandy sediment (fine- to mediumExtensive linear
grained, moderately well-sorted to
well- sorted).
Sandy sediment (medium- to very
Pocket/Cliffs, karrencoarse-grained, moderately well- sorted
like feature
to poorly sorted).
Sandy sediment (fine- to mediumLinear
grained, moderately well-sorted to very
well-sorted).
Linear/Remnant cliff,
Sandy sediment (fine-grained,
remnant island (Pulau
moderately well- sorted to well- sorted).
Kulambu), tombolo
Sandy sediment (fine- to very fineEmbayed pocket/Cliffs grained, moderately well-sorted to
well- sorted).
Sandy sediment (fine- to very fineEmbayed pocket
grained, well-sorted to poorly sorted).
Sandy sediment (fine- to mediumExtensive linear/Terrace
beach
well-sorted).
Sandy sediment (fine- to mediumExtensive linear/
grained, moderately sorted to
Remnant cliffs, rocky
moderately well-sorted). Black sandy
shore
patch (chromite, zircon).
Sandy sediment (fine- to mediumEmbayed pocket/
Cliffs
well-sorted).
Linear
Sandy to pebbly sediment (medium- to
very coarse-grained, poorly sorted),
black sand (chromite).
Grain Morphology
Subrounded to rounded
Angular to subrounded
Light grey/Quartz (7080%). Garnet (73%) in
pink sand.
Subangular to
subrounded
Light grey/Quartz (7580%).
Subangular to
subrounded
Yellowish grey/Quartz
(85%).
Subangular to
subrounded
Light-yellowish grey/
Quartz (65-75%).
Subangular to
subrounded
Light grey/Quartz
(70%).
Subangular to rounded
Light brownish grey/
Quartz (75%).
Subangular to
subrounded
Dark grey/Quartz (7580%).
Subangular to
subrounded
Light grey/Quartz (9095%).
Subrounded to rounded
(80-85%). Chromite
Subangular to rounded
(35%) and zircon (39%)
in black sand.
(55-65%).
Subangular to
subrounded
Brownish to dark
yellowish grey/Quartz
(65-75%). Chromite in
black sand (39-83%).
Subangular to
subrounded
The
Table 2: The evaluation of the geological heritage of the beaches in Northern Sabah, Malaysia.
Name of
Beach
Kampung
Kuala Tajau
Sampaping
Tanjung
Simpang
Mengayau
Kosuhui
Pongugadan
Bawang
Jamal
Kulambu
Loro Kecil
Kamihang
Sikuati
Torongkongan
Teluk Agal
Marasimsim
Evaluation of Geological Heritage Values
Main Geological Heritage
Resources
Scientific
Linear beach, sandy sediment
(fine-grained, moderately sorted
to well-sorted).
(fine- to coarse-grained,
moderately sorted to poorly
sorted), remnant cliffs.
Pocket beach, sandy to pebbly
sediment (coarse-grained,
moderately well-sorted), cliffs,
faults, sea caves.
Depositional history,
coastal processes and
source of beach sediment.
Depositional and erosional
history, coastal processes
and source of beach
sediment.
history, coastal processes
and source of pink
sediment.
Linear beach, extensive sandy
sediment (fine- to mediumgrained, moderately well-sorted
to well-sorted).
Pocket beach, sandy sediment
(medium- to very coarse-grained,
moderately well-sorted to
poorly sorted), cliffs, karren-like
feature.
(fine- to medium-grained,
moderately well-sorted to very
well-sorted).
(fine-grained, moderately wellsorted to well-sorted), remnant
cliff, remnant island (Pulau
Kulambu), tombolo, pocket
beach.
Embayed pocket beach, sandy
sediment (fine- to very finegrained, moderately well-sorted
to well-sorted), cliff.
sediment (fine- to very finegrained, well-sorted to poorly
sorted).
to very well-sorted), terrace
beach.
sediment (fine- to mediumgrained, moderately sorted to
moderately well-sorted), black
sandy patch (chromite, zircon),
remnant cliff, rocky shore.
to very well-sorted), cliff.
Linear beach, sandy to pebbly
sediment (medium- to very
coarse-grained, poorly sorted),
Aesthetic
Recreational
Cultural
Ecological
Attractive
landscape.
Beach
recreation.
-
Supports coastal
biodiversity
Attractive
landscape.
Beach
recreation.
-
Supports coastal
biodiversity
Scenic
embayment,
attractive
landscape.
Beach
recreation.
-
Supports coastal
biodiversity
Attractive
history and coastal
landscape.
processes.
Beach
recreation.
Probably visited
by Ferdinand
Support coastal
Magellan’s
biodiversity
Fleet in the 16th
Century.
Attractive
history and coastal
landscape.
processes.
Beach
recreation.
-
Supports coastal
biodiversity
Depositional history and
coastal processes.
Beach
recreation.
-
Supports coastal
biodiversity
Beach
recreation.
The name
Kulambu
derived a from
local story.
Supportss
coastal
biodiversity
Beach
recreation.
Ship wreck
site. Treasure
hunting site.
Supports coastal
biodiversity
Beach
recreation.
-
Supports
coastal
biodiversity
Attractive
landscape.
Beach
recreation.
-
Supports coastal
biodiversity
history, coastal processes Attractive
and source of black
landscape.
sediment.
Beach
recreation.
-
Supports
coastal
biodiversity
Beach
recreation.
-
Supports coastal
biodiversity
Beach
recreation.
Historic mineral Support coastal
exploration site. biodiversity
Attractive
landscape.
Rare tombolo,
depositional and erosional Picturesque
history and coastal
landscape.
processes.
Scenic
embayment,
history and coastal
attractive
processes.
landscape.
Scenic
embayment,
history and coastal
attractive
processes.
landscape.
Depositional history and
sea level changes.
Scenic
embayment,
history and coastal
attractive
processes.
landscape.
history, coastal processes Modest
and source of black
landscape.
sediment.
5
Joanes Muda
Table 3: Evaluation of the geotourism potential of the beaches in Northern Sabah, Malaysia.
Name of Beach
Evaluation of Geotourism Potential
Main Geological Heritage
Resources
Research
Education
Education on coastal
erosional and depositional
processes.
processes.
Kampung Kuala
Tajau
Linear beach, sandy
sediment.
-
Sampaping
Linear beach, sandy
sediment, remnant cliffs.
-
Tanjung Simpang
Mengayau
Pocket beach, sandy to
pebbly sediment, unique
pink sand (garnet).
Research on formation
of various coastal
features and processes,
processes.
source of pink sand.
Recreation
Suitable for various
beach recreational
activities.
beach recreational
activities.
Remarks
Potential for
geotourism.
Potential for
geotourism.
beach recreational
activities.
High potential for
geotourism.
processes.
beach recreational
activities.
processes.
processes.
beach recreational
activities.
Potential for
geotourism.
Probably visited
by Ferdinand
Magellan’s Fleet in
the 16th century.
Potential for
geotourism.
beach recreations.
Potential for
geotourism.
Kosuhui
Linear beach, extensive
sandy sediment.
-
Pongugadan
Pocket beach, sandy
sediment, cliffs, karrenlike feature.
-
Bawang Jamal
Linear beach, sandy
sediment.
-
Kulambu
Linear beach, sandy
sediment, remnant cliff,
remnant island (Pulau
Kulambu), tombolo,
pocket beach.
Research on formation Education on coastal
of various coastal
features and processes. processes.
beach recreational
activities.
High potential for
geotourism.
Loro Kecil
Embayed beach, sandy
sediment, cliff.
of embayed beach.
processes.
beach recreational
activities.
Kamihang
sediment, cliff.
-
processes.
processes.
beach recreational
acyivities.
beach recreational
activities.
High potential
for geotourism.
Remains of World
War II warship.
of various coastal
processes.
source of black sand.
beach recreational
activities.
Sikuati
Torongkongan
sandy sediment, terrace
beach.
sandy sediment, black
sandy patch (chromite,
zircon), remnant cliff,
rocky shore.
Research on terrace
beach.
processes.
Teluk Agal
sediment, cliff.
-
Marasimsim
Linear beach, sandy to
pebbly sediment, unique
of various coastal
processes.
source of black sand.
CONCLUSION
The study has unraveled the geological heritage values
of beaches based on scientific, aesthetic, recreational and
cultural values. The scientific values of beaches such as
the composition, morphology and sources of the beach
sediments have been identified. The occurrence of other
geomorphologic and geological features at or near beaches
such as remnant cliffs, faults, sea caves, tombolo and remnant
island enhances the aesthetic values and attractiveness
of beaches and therefore are appealing to visitors. These
features also enhance the scientific value of the beaches.
Any unregulated development, such as sand extraction along
coastal areas, will affect the beaches of Northern Sabah.
6
beach recreational
activities.
beach recreational
activities, former
mineral exploration
site.
Potential for
geotourism.
Potential for
geotourism.
High potential for
geotourism.
Potential for
geotourism.
High potential for
geotourism.
It is recommended that the beaches of Northern Sabah
to be conserved so as to protect the beautiful landscapes.
Geotourism could be promoted on some of the beaches
such as Tanjung Simpang Mengayau, Kulambu, Loro
Kecil, Torongkongan and Marasimsim. The development of
geotourism will ensure the sustainability and protection of
the beaches. The promotion of beach geotourism could be
carried out together with that at other potential geotourism
sites such as the Tanjung Simpang Mengayau (Tip of
Borneo) and the Kampung Minyak oil seeps. The study of
beaches for geotourism development is an innovative way
to add-value to their existing aesthetic attraction in order
to enhance and sustain the tourism industry in the State.
The
REFERENCES
Dockal, J. A., 2006. Sediment or sand observation and description.
Available from http://people.uncw.edu/dockal/gly312/
grainsize/grainsize.htm.
Folk, R. L. & Ward, W. C., 1957. Brazos River Bar: a study of the
significance of grain size parameters. Journal of Sedimentary
Petrology, 27, 3-27.
Joyce, E. B., 2006. Geomorphological sites and the new geotourism
in Australia. Available from http://web.earthsci.unimelb.edu.
au/Joyce/heritage/GeotourismReviewebj.htm.
King, A. M. C., 1972. Beaches and Coast. London, Edward Arnold,
570 p.
Manuscript received 7 December 2012
7
ASEAN Mineral Resources Information System using FOSS and
OGC-based standards
Joel Bandibas*, Koji Wakita & Tetsuji Ohno
Geological Survey of Japan, AIST
Site 7, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567, Japan
*E-mail address: joel.bandibas@aist.go.jp
Abstract: Highly accessible mineral resources information encourages investment and more sustainable utilization
of mineral resources. The Geological Survey of Japan, AIST developed the web based ASEAN Mineral Resources
Information System using Free and Open Source Software (FOSS) and the Open Geospatial Consortium (OGC) standards.
The use of FOSS and OGC compliant standards aims to make the mineral resources information system cost efficient,
interoperable and user friendly. The developed system is composed of 3 modules which are the Database, Web Services
and the Web Portal. The Database module is mainly PostGIS, a PostGreSQL open source object-relational database
management system software. It supports simple features defined by OGC and simple Sequential Query Language (SQL).
The Database module is a distributed database system comprising the individual mineral resources database of each
country in the ASEAN region. It also includes the database of the geological map of East Asia and some ASTER and
ALOS satellite images of the Geological Survey of Japan. The Web Service module is composed of the Web Processing
Service (WPS) and Web Map Service (WMS). WPS handles the database maintenance and queries, including the data
upload and download. WMS provides remote access to the mineral resources databases. It generates map images to be
displayed on the Web Portal module. The Web Portal Module provides the web based Graphic User Interface (GUI) of
the developed information system. It could also display map images provided by the Web Services module. The portal
is named the ASOMM WebGIS system. This project aims to make mineral resources information in the ASEAN region
easily available for use by policy makers, investors and the general public.
Keywords: Mineral Resources Information System, database, ASEAN
INTRODUCTION
The mineral sector has always been considered to be
an engine for greater economic growth and social progress
in the ASEAN region. Minerals in the region account
for a relatively large shares of world reserves (Short et
al., 2005). Easily accessible information about mineral
resources enhances trade and investment in the sector. It also
encourages environmentally sound and socially responsible
mineral development practices and optimum utilization of
mineral resources. A public that is well informed about this
important resource will also discourage corruption.
As the economic integration of the ASEAN region
progresses, unimpaired movement of capital and knowhow
across the region should be guaranteed. This requires the
creation of an information infrastructure that facilitates
unhindered and efficient sharing of information. This project
focuses on the creation of an information infrastructure that
promotes sharing of information about mineral resources
across the region, an initiative of the ASEAN Senior Officials
Meeting on Minerals (ASOMM). The project involves the
use of internationally accepted standards and cost efficient
software. Specifically, this project is aimed at creating the
web based ASEAN mineral resources information system
using Free and Open Source Software (FOSS) and Open
Geospatial Consortium Standards (OGC). OGC standards
are technical documents that detail interfaces or encodings
that software developers use to build open interfaces and
encodings into their products and services (OGC, 2012a).
The use of OGC standards and FOSS makes this information
system cost efficient and interoperable. The develop system
was also designed to be very accessible and easy to use. The
ultimate objective of this project is to create an information
technology platform for easy sharing and access of mineral
resources information among ASEAN countries. Successful
implementation of this project will make mineral resources
information easily available for use by policy makers,
investors and the general public.
ASEAN MINERAL RESOURCES INFORMATION
SYSTEM
The ASEAN Mineral Resources Information System
is a complete web-based system for storing, sharing and
viewing mineral resources information in the ASEAN
region. The system was developed following the application
development guidelines of GeoGrid, National Institute of
Advanced Industrial Science and Technology (AIST) which
are as follows:
1) user-friendly
2) cost efficient
3) interoperable.
The system is composed of 3 modules which are the
Database, Web Services and the Web Portal as shown in
Figure 1.
Figure 1: The 3 major components of the ASEAN Mineral Resources
Information System.
Figure 3: The Web Map Service (WMS).
Figure 2: The database module of the ASEAN Mineral Resources
Information System.
DATABASE MODULE
The database module is mainly a PostGIS database
system. PostGIS is PostGreSQL open source objectrelational database management system software that
supports simple features defined by OGC, and simple
feature Sequential Query Language (SQL). PostGIS supports
simple and complex spatial queries, functionalities that
are very important for handling mineral resources related
information. The database maintenance and queries are
initiated by Web Processing Service requests from the Web
Services Module. The database module of the ASEAN
Mineral Resources Information System is a distributed
database system consisting of the individual mineral
resource databases of the countries in the ASEAN region.
The composite database also includes the geological map
of East Asia and some ASTER and ALOS satellite images
databases of the Geological Survey of Japan (Figure 2).
Mineral resources information from individual databases
is served as Web Map Service s, which receives requests
from the Web Services module.
WEB SERVICES MODULE
Web Service Module follows the Open Geospatial
Consortium standards (OGC). The module is composed
mainly of the Web Processing Service and the Web Map
Service (WMS). It receives requests from the Web Portal
module, processes the requests and implements them on
the Database Module. The WPS handles the database
10
maintenance and queries, including the data upload and
download. The WPS component of this module is mostly
implemented using PHP scripts. WMS is a standard protocol
that provides a simple HTTP interface for requesting
geo-registered map images from one or more distributed
geospatial databases (OGC, 2012b). WMS provides map
images online generated by mapserver software, in response
to a GetMap request, using a GIS database (Figure 2). WMS
provides remote access to the databases in the Database
module, and generates map images for display on the Web
Portal module.
WEB PORTAL MODULE
The Web Portal Module provides the web based Graphic
User Interface (GUI) of the ASEAN Mineral Resources
Information System. The portal is named ASOMM WebGIS
system. It provides the interface and forms for the users to
upload and download data, query the database and display
the maps. Forms are provided for simple and complex
spatial queries. Figure 4 shows the main page and main
menu of the portal.
The portal uses the open source Openlayers Javascript
libraries (OSGeo, 2012) for displaying maps on the site.
The map images displayed are generated from the GetMap
requests pointed to the WMS servers on the Web Services
module. The site could display any kind of geographically
referenced data including satellite images. It provides the
standard GIS functions for manipulating maps. Figure 5
shows the map display page of the site showing metallic
mineral occurrence in ASEAN countries overlaid over the
geological map covering East Asia. Database queries could
also be performed easily using the site. Figure 6 shows a
single mineral query form of ASOMM WebGIS. Query
results could be downloaded in ArcGIS shape file or KML
formats. Figure 7 shows the downloaded query results in
KML format displayed using Google Earth.
SUMMARY
The ASEAN Mineral Resources Information System is
a web-based application that provides a cost efficient and
ASEAN Mineral Resources Information System
using
FOSS
and
OGC-based
standards
Figure 4: The main page of
ASOMM WebGIS.
Figure 5: The map display
page of the ASOMM
WebGIS.
Figure 6: The single
mineral query form of
ASOMM WebGIS.
11
Figure 7: Downloaded
query results in KML
format displayed
using Google Earth.
easy to use information technology platform for sharing
and accessing mineral resources information in the ASEAN
region. It is composed of independent modules which are
the Database, Web Services and the Web Portal. A series
of trial versions are presently being tested with promising
results. The database module of the system is currently
being updated, mainly the mineral information contents of
the database, with the cooperation of the countries in the
ASEAN region. The Geological survey of Japan has been
conducting a series of training sessions and workshops
about FOSS based database system development and Web
Services following OGC standards in the ASEAN region.
The main objective of these training sessions is to make
ASEAN countries acquire skills in creating and maintaining
their own databases, and formulate OGC based web services
to serve their mineral resource data to ASSOM WebGIS
portal. These human resource development activities are
also very important for the creation of cheap and user
friendly geoinformation platforms where people can access,
integrate and analyze a wide array of data sets to make them
understand the earth easily and accurately.
REFERENCES
OGC, 2012a. Making Location Count. OGC Standards and
Supporting Documents. Available online at http://www.
opengeospatial.org/standards (Accessed: 13 October 2012).
OGC, 2012b. Making Location Count. Web Map Service. Available
online at http://www.opengeospatial.org/standards/wms
(Accessed: 13 October 2012).
OSGeo, 2012. OpenLayers: Free Maps for the Web. Available at
http://www.openlayers.org/ (Accessed: 15 October 2012).
Short, C., Kim, Y., Ball, A., Schneider, K. & Love, G., 2005.
Developing the ASEAN Minerals Sector. A Preliminary Study.
REPSF Project No. 04/009a. Australian Bureau of Agricultural
and Resource Economics.
12
Geoheritage values of the Dong Van Karst Plateau Geopark:
A quantitative geomorphological and topographic analysis
Pham Viet Ha1*, Tran Tan Van1, Quach Duc Tin1,2, Ho Huu Hieu1,
Nguyen Dinh Tuan1 & Nguyen Quang Hưng2
2
1
Vietnam Institute of Geosciences and Mineral Resouces; Km9 Thanh Xuan, Hanoi
General Department of Geology and Minerals of Viet Nam, No. 6, Pham Ngu Lao, Hanoi
*Email address: Phamviethageo@gmail. com
Abstract: The main purpose of this study is to analyse the geomorphological charactertistics of the Dong Van Karst
Plateau Geopark (DVKPG) in the Ha Giang province of Vietnam. A digital elevation model (DEM) was generated using
SPOT5 imagery and elevation and slope maps were then extracted from the DEM. A geological map at the scale of
1:200,000 was constructed and used for analyzing and visualizing the carbonate rock in three dimensions. The results
show that there are two types of topographic development in the study area. The first, formed by tectonic movement and
affected by major faults, is distributed in a NW–SE direction. The second was formed by exogenous geomorphological
processes and influenced by both major and faults. It is distributed mainly in a NE–SW direction. Geological analysis
indicates that ten stratigraphic formations crop out in the study area but only six of these have correlations with karst
landscapes. Carbonate rocks are mainly distributed in the Dong Van district. They cover an area of 329.7 km2 (71.7%
of the entire district and 36.5% of study area). In constrast, there is few carbonate rocks in the Quan Ba district. In the
case of slope, the slope angels from 15–30° cover about 53.5% of the study area. There are 1261 karst sinkholes in the
study area with an average density of 1.4 sinkholes per km2.
Keywords: Dong Van, Ha Giang, karst plateau, geopark
INTRODUCTION
The Global Network of National Geoparks was
established under the aegis of UNESCO in 2004 aimed
at protecting some of the world’s most spectacular and
important geological sites. A geopark is defined as a a
nationally protected area containing a number of geological
heritage sites of particular significance, rarity or aesthetic
appeal and these heritage sites are developed as part of
an integrated concept of conservation, education and
sustainable development (UNESCO, 2006). According to
Azman et al., (2010), the main objectives of a geopark
are (1) protection and conservation, (2) tourism-related
infrastructural development and (3) socio-economic
development. Therefore scientific studies in these geoparks
may present opportunities to understand important events
in their geo-history and supply additional information on
permanent and protected sites where scientific ideas can be
tested for generations to come (Kusky et al., 2010). The
main objective of this study was to undertake quantitative
analyses of the geomorphology and topography of the
geoheritage of the Dong Van karst plateau in the Ha Giang
province of Vietnam.
STUDY AREA
The Dong Van karst plateau Geopark (Figure 1) is
located in Ha Giang province, in the northwesten part of
Vietnam. It covers an area of 2380 km2 in four administrative
districts: Dong Van (460 km2), Meo Vac (577.6 km2), Yen
Minh (785.2 km2), and Quan Ba (557.2 km2). The altitude
varies from 174 to 2,265 m.
DATA AND ANALYSIS
Digital elevation model and derivatives
A digital elevation model was generated from SPOT5
satellite imagery with a resolution of 15 m. Based on the
DEM, geomorphometric data was extracted using ArcGIS
10. 0 software. The elevation map was constructed with
elevation seven classes: 100–300 m; 300–600 m; 600–900
m; 900–1200 m; 1200–1600 m; 1600–2000 m and >2000m.
The characteristics of the elevation classes are shown in
Table 1 and Figures 2 and 3.
Table 1: Characteristics of elevation classes.
No
Elevation classes (m)
Area (km2)
Percentage
1
178 - 300
37. 2
1. 6
2
300 - 600
376. 3
15. 8
3
600 - 900
549. 1
23. 1
4
900 - 1200
623. 6
26. 2
5
1200 - 1500
592. 4
24. 9
6
1500 - 2000
197. 8
8. 3
7
2000 - 2260
3. 4
0. 1
The three elevation classes (600–900 m; 900–1200 m;
1200–1500 m) cover an area of 1,765 km2 (74.2% of the
study area) and contain impressive landscape characteristics.
In contrast, the elevation class >2000 m covers an area of
only 3.4 km2, distributed mainly in the rear of the plateau.
The elevation class of 600-900 m contains terrestrial (nonkarstic) landscapes with residual towers and cones on the
Figure 2: Frequency distribution of elevation classes in the studied
area.
Figure 3: Elevation map of the studied area and NW-SE Crosssections, A-B (upper), C-D (middle) and E-F(lower).
Figure 1: Location of study area.
14
slopes, and carren slopes. This elevation class is adjacent
to karst areas and terrestrial landscapes make a contrast to
surrounding karstic landscapes. For the elevation classes
900-1200 m and 1200-1500 m, karstic landscape features are
mainly steep cliffs, cones and towers that are distributed on
the top of mountain chains. In order to show the variation of
elevation in the DVPKG, three NW trending cross-sections
(Figure 3) were constructed.
The slope angle map (Figure 4) was constructed with
7 classes. Characteristics of the slope angle classes are
indicated in Table 2.
The areas of steep slope (15o-30o) account for 53. 9%
of the study area. They are characterised by limestone
mountains with non-karst landscapes, stone forests and
residual cones on the slopes. The inclined slope (5o-15o)
and comparatively steep slope (30o-45o) cover areas that
account for around 21.9% and 16. 5% of the study area,
respectively. The very gradual slopes (0° - 2°) and gradual
Geoheritage
values of the
Dong Van Karst Plateau Geopark: A quantitative
Figure 4: The slope angle map of the studied area. Refer to Figure
5 for legend of slope classes.
geomorphological and topographic analysis
Figure 6: Geological map of the studied area.
Figure 5: Frequency distribution of the slope classes.
Table 2. Characteristics of the slope classes.
No
Elevation classes (m)
Area (km2)
Percentage
1
Very gradual (0 - 2 )
31. 3
1. 32
2
Gradual (20 - 50)
92. 4
3. 88
3
Inclined (50-150)
522. 3
21. 94
4
Steep (15 - 30 )
1,283. 8
53. 94
5
Comparatively steep (300-450)
392. 5
16. 49
6
Very steep (450-600)
56. 8
2. 39
7
Abrupt (> 600)
0. 8
0. 03
0
0
0
0
slopes (2° - 5°) are mainly located in alluvial flats and
terraces along the Mien river. These areas contain karst
valleys. Generally, the slope angle map represents a high
contrast of landscape within the geoheritage area.
Geological map
The geological map (Figure 6) was constructed using
the Bao Lac and Ma Quan geological sheet maps at the scale
of 1:200.000 and was used for analyzing the distribution of
carbonate rocks. Lithological formations in the map were
updated using the SPOT5 satellite images. Fieldwork was
conducted to verify the results. A total of 10 lithological
formations were represented. They are Chang Pung (€3cp),
Lutxia (O1lx), Song Cau (D1sc), Mia Le (D1ml), Na Quan
(D1-2nq), Toc Tat (D3tt), Bac Son (C-P bs), Dong Dang
(P2dd), Hong Ngai (T1hn) and Song Hien (T1sh).
Figure 7: Distribution of carbonate rocks.
In this study, the lithological formations were divided
in to 2 groups: 1) carbonate rock with karst landscape
including Chang Pung (€2-3 cp), Lutxia (O1 lx), Toc Tat (D3
tt), Bac Son (C-P bs), Dong Dang (P2dd), and Hong Ngai
(T1hn) formations and 2) non-carbonate rock with non-karst
landscape. Using DEM, the distributions of different types of
rock in correlation with the elevation classes was analysed.
Distribution of the carbonate rocks are shown in Figure 7.
The carbonate rock covers of 71.7% area of the Dong Van
district, but only 19.5 % in the Quan Ba district (Table 3).
Table 3. Statistics of carbonate rocks in the study area.
Dong Van
Area
(km2)
460. 0
Meo Vac
577. 6
3
Yen Minh
4
Quan Ba
No
District
1
2
71. 7
Areas with carbonate
rocks (km2)
329. 7
36. 5
49. 7
287. 1
31. 8
785. 2
22. 7
178. 2
19. 7
557. 2
19. 5
108. 5
12. 0
%
%
The carbonate rocks with karst landscape cover an
area of 903.5 km2, distributed mainly in Dong Van and
Meo Vac districts. Carbonate rocks interbedded with non-
15
Table 4: Distribution of sinkholes and caves in correlation with
elevation classes.
1
Elevation
classes (m)
0-300
0
Number of
sinkholes
0
2
300-600
18
29. 0
9
0. 7
3
600-900
13
21. 0
43
3. 4
No
Number
of caves
0
%
%
0
4
900-1200
9
14. 5
281
22. 3
5
1200-1500
16
25. 8
742
58. 8
6
1500-2000
6
9. 7
186
14. 8
7
> 2000
0
0
0
0
Figure 8: Location of karst sinkholes and caves in the studied area.
Figure 9: Possitive lineaments map of the studied area.
Figure 10: Negative lineaments map of the studied area.
16
carbonate rocks are distributed in the districts of Quan Ba
and Yen Minh. These areas are characterized by diversity
in landscape, geological history and cave development and
therefore represent the geoheritage values of the DVKPG.
Distribution analysis of karst sinkholes and
caves
Karst funnels were interpreted by using SPOT5 imagery,
DEMs and topographic map. The location and shape of caves
were checked and mapped in field surveys by experts from
the Vietnam Institute of Geosciences and Mineral Resources
(VIGMR) and Belgian colleagues. A total of 1261 karst
sinkholes and 62 caves were identified in the study area
(Figure 7). An average density of karst sinkholes per 1 km2
is 1.4. The distribution of sinkholes and caves in correlates
with elevation classes as shown in Table 4.
The elevation class of 1200 – 1500 m has the highest
density of sinkholes (58.8%) and a high density of caves
(25.8%). The highest density of caves is in the elevation
class of 300-600 m. In constrast, there are no caves or
sinkholes in the elevation classes of 0-300 m and >2000 m.
Lineament analysis
In order to explore the trend of topographic features
in the study area, a lineament analysis was carried out.
Using the DEM, eight hillshade maps were created and
used to extract lineaments in the study area. This process
was carried out using PCI solftware.
Figure 9 shows positive lineament map of the study area.
The positive lineament map represents elevated topography,
topographic ridges and tectonic cliffs. In general, the positive
lineaments trend NW. This is the direction of trend of fault
scarps and lithological boundaries in the study area. This
is also the major trend of topographic development and
tectonic features in Vietnam.
A negative lineament map that represents topographic
featuress such as valleys, rivers and streams is shown in
Figure 10. In general, the density of negative lineaments
is higher than that of positive lineaments. The negative
lineaments are mainly short and discontinuous and trend
in a NE direction. This indicates that the topography was
formed by exogenous geomorphological processes (such
as slope erosion processes) or formed by a combination of
small faults (trending NE) with major faults (trending NW).
The DEM is also used as a basic data layer to show
the distribution of geoheritage sites in three dimensions in
the study area (Figure 10).
CONCLUSION
In this study, the geoheritage characteristics of the
Dong Van Karst Plateau Geopark were investigated through
geomorphological quantitative analysis. A digital elevation
model, elevation map, slope angle map and geological map
were used in the analysis. The results show that the study
area mainly lies within the three elevation classes (600-900
m; 900-1200 m; 1200-1600 m) which have special landscape
characteristics. There are 10 lithological formations that crop
Geoheritage
values of the
Dong Van Karst Plateau Geopark: A quantitative
geomorphological and topographic analysis
Figure 11: Distribution map of geoheritage sites in the study area.
out in the study area but only six of these were determined
as karst landscape-forming areas. Carbonate rocks are mainly
distributed in the Dong Van district.
Areas of steep slopes (15° - 30°) cover about 53.5% of
the study area and display impressive plateau characteristics.
There are 1261 karst sinkholes and 62 caves distributed in the
study area. Topography in the study area was influenced by
tectonic movement including major faulting and exogenous
geomorphological processes.
ACKNOWLEDGEMENT
The authors would like to thank the Vietnam Institute
of Geosciences and Mineral Resources (VIGMR) for
permission to use the results of the project KC. 08. 20:
“Investigating and researching the potential of geoheritage
and the prospects for building Geopark in North Vietnam”.
REFERENCES
Azman, N., Halim, S. A., Liu, O. P., Saidin, S. & Komoo, I.,
2010. Public education in heritage conservation for Geopark
community, In: Jelas, Z. M., Salleh, A., & Azman, N. (eds.)
International Conference on Learner Diversity 2010, Procedia
Social and Behavioral Sciences, 7, 504-511.
Kusky, T. M. , Ye, M. H., Wang, J. P. & Wang, L., 2010. Geological
evolution of longhushan world geopark in relation to global
tectonics: Journal of Earth Science, v. 21, 1-18.
UNESCO, 2006. Global Geoparks Network: Paris, Published by
Division of Ecological and Earth Sciences.
17
Geological interpretation based on satelite imagery: Updating
geological maps of Indonesia to 1:50,000 map scale
Geological Agency, Ministry of Energy and Mineral Resouces Republic of Indonesia
Jalan Diponegoro No 57, Bandung 40122, Indonesia
Abstract: Indonesia is an archipelago comprising over 13,700 islands and a total territory of more than seven million
km2.. Geologically, the earth’s crust in this region displays several special features as a result of the collision of three
mega plates, Eurasia, Indiaustralia and Pacific. Inter-related features such as island arcs, volcanic belts, seismic zones,
gravity anomaly zones, and deep sea trenches resulted from the collision process.
Knowledge of the regional geology of the entire Indonesian region was greatly advanced by the completion of
systematic geological mapping at the scale of 1: 100,000 of Jawa and Madura Islands and at the scale of 1:250,000 on
the other islands. A great quantity of data concerning various aspects of geology and geophysics, collected during more
than 50 years, has accumulated.
The need for geological information at a larger scale, however, is now increasing. This demand is related to national
development programs as well as to Indonesia’s industrial growth. Exploration for energy, mineral and ground water
resources, the generation of information for land-use planning and geological hazard mitigation will all benefit from the
availability of geological maps at the scale of 1:50,000. Therefore, since 2010 the Geological Agency, Ministry of Energy
and Mineral Resources of Republic of Indonesia, has initiated new geological mapping project starting with geological
interpretation based on data from satellite imagery combined with existing field data.
The methodology for geological interpretation is based on visual interpretation of remote sensing data of morphostructural aspects of the imagery combined with field data existing in a GIS environment. Interpretation keys were
determined in order to provide guidelines on how to recognize certain geological objects on satellite imagery. Preparation
of data including the creation of shaded relief of the digital surface model (DSM) and intensity layer of orthorectified
images (ORRI), contour generation, color composite of optical images, drainage pattern generation and fusion of passive
and active remotely-sensed images.
Keywords: geological map, remote sensing, Indonesia
BACKGROUND
Indonesia is the largest archipelagic country in the world,
which has five major islands and about 300 smaller island
groups. Altogether there are more than 13,700 islands. The
archipelago is situated at a junction between two oceans,
the Pacific and Indian oceans, and bridges two continents,
the Asian and Australian continents. Indonesia has a total
area of 9.8 million km2, of which more than 7.9 million
km2 is ocean.
From the point of view of earth science, Indonesia has
various unique geological phenomena due to its location at
the triple junction of three mega-plates: Eurasia, Indiaustralia
and Pacific (Figure 1). The involvement of these three
mega-plates interaction with each other, has resulted in the
formation of double island arcs, K-shaped islands, active
volcanic belts, active seismic zones, deep sea trenches
and the negative gravity anomalies. Morphologically this
condition has resulted in a distinct and varied relief with
high mountain belts, deep valleys, and high cliffs. Moreover,
due to this complex geological history, Indonesia also has a
huge amount of geological resources including oil and gas,
coal, gold, diamonds, iron, nickel and other mineral resources
such as clay and gem stones. However, the potency of geoPresented at 48th CCOP Annual Session
hazards such as earthquakes, landslides, volcanic activity,
floods and tsunami are also a major concern.
The knowledge of the regional geology of the entire
Indonesian region has been greatly advanced following
the completion of systematic geological mapping in 1995.
Much data concerning all aspects of geology and geophysics
has been acquired during more than 50 years of geological
mapping. From the compiled geological data, it is possible
to perceive the distribution of various kinds of rock units
ranging in age from Palaeozoic, through Mesozoic to
Cenozoic. The rock units consist of sedimentary, carbonate,
and volcanic rocks which are subdivided into broad groups
based on their ages, respectively; Quaternary, Tertiary, and
Pre-Tertiary ages. In addition, based on the rock lithology
and origin, some rocks are grouped into plutonic, ophiolite,
metamorphic and mélange rocks (Figure 2).
DEVELOPMENT OF GEOLOGICAL INFORMATION
The Center for Geological Survey, one of the units
of the Geological Agency of the Ministry of Energy and
Mineral Resources, continues its activities in mapping and
research on various aspects of geology and geophysics in
the entire Indonesian region, which originally was initiated
in 1850 by previous research institutions. The results of the
research, investigation and mapping have become national
assets represented by all the the geological and geophysical
data which are collected in the Geological Museum and
Library within the Center for Geological Survey of the
Geological Agency that was established in 1979.
The above activities in mapping and research of many
aspects of geology and geophysics were diversified and
reinvigorated with the commencement of the Indonesian
Five Year Development Plan in 1969. Systematic mapping
which initially was only applied to geology and geophysics,
were later been applied to construct other thematic maps,
such as seismotectonics, geomorphology, and Quaternary
geology. The research in aspects of geology and geophysics
also includes topics such as paleontology, sedimentology,
petrology, geochemistry, gravity, paleo-magnetics,
radiometric dating, rock physics, and structural geology.
Indonesia has now succeeded in the completion of
systematic geological mapping at the scale of 1:100,000 in
Jawa and Madura Island and 1:250,000 in the islands outside
Jawa and Madura together with the 1:1,000,000 map of the
entire Indonesian region. Based on these systematic maps,
geological and thematic maps at the scale of 1:5,000,000
have been compiled.
The need of geological information in Indonesia at
a larger scale is now increasing. This demand is related
to national development programs as well to Indonesia’s
industrial growth. Exploration for energy, mineral and
ground water resources, information required to aid land use
planning and geological hazard avoidance and mitigation
are all issues that argue for the development of geological
maps at the scale of at least 1:50,000. In order to answer
this demand, the Geological Agency as an Institution that
is responsible for geological survey, has been conducting
geological mapping program, which is planned to last from
year 2010 until 2025. This program was initiated employing
geological interpretation based on satellite imagery combined
with field data collected during from previous work. Later
on, validation will be conducted with ground truth in addition
to stratigraphic study and the collection of new field data.
Table 1: The extent of geologic units on land (1,925,814 km2),
calculated using grid by Handoko (Sukamto, 2000).
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
20
GEOLOGICAL UNIT
Quaternary sediments
Quaternary carbonates
Quaternary volcanics
Tertiary sediments
Tertiary carbonates
Tertiary volcanics
Tertiary-Cretaceous Sediments
Mesozoic sediments
Mesozoic carbonates
Mesozoic volcanics
Paleozoic rocks
Metamorphic rocks
Plutonic rocks
Melange rocks
Ophiolitic rocks
EXTENT (+ km2)
570,798
15,811
140,860
474,513
119,877
118,349
98,229
99,901
18,344
21,204
45,783
82,247
66,442
31,115
36,970
Figure 1: Indonesian archipelago location at the triple junction
of three mega plates, Eurasia, Indiaustralia and Pacific, modified
from Le Pichon (1968).
CURRENT KNOWLEDGE ON THE GEOLOGY OF
INDONESIA
The large quantity of geological and geophysical data
which are stored in the Geological Agency, Ministry of
Energy and Mineral Resources, is a national asset that
should be utilized by the broad geoscience communities,
domestic as well as international. Investigation, research and
mapping of the geology and geophysics during eight periods
of Indonesia’s Five-Year Development plans (1960-1999)
contributed very considerable and available data resources.
Systematic geological maps at a scale of 1:100,000 for Jawa
and Madura, 1:250,000 for islands outside Jawa and Madura,
and scale 1:1,000,000 for the entire Indonesian region are
now available. The Geological Map of Indonesia at a scale
of 1:5,000,000 has also been published (GRDC, 1992).
The simplified geological map of Figure 2 shows the
distribution of the geologic units on land which covers an
area of 1,952,814 km2. The extent of each geologic unit
is measured on the basis of the distribution of the unit
which appears on the Geological Map of Indonesia at scale
1:5,000,000 (GRDC, 1992). The extent of each geologic
unit of Quaternary, Tertiary, Mesozoic and Paleozoic age is
shown in Table 1; including geologic units based on their rock
association: metamorphic rocks, plutonic rocks, mélange
rocks and ophiolitic rocks. This summary information
about the geological units, based on the geological eras,
is introduced here to give an insight into the potential for
mineral and energy resources as well for geohazards that
possibly may occur within each geological unit.
The distribution of these various geological units may be
used in evaluating the veracity of the opinion that Indonesia
remains well endowed with mineral and energy resources.
Peat deposits, for example, have been estimated to be over
Geological
interpretation based on satelite imagery:
Updating
geological maps of Indonesia to
1:50,000
map scale
Figure 2: The geology of Indonesia simplified from the Geological Map of Indonesia, 1:5,000,000 compiled by Geological Agency
(GRDC, 1992).
2 m thick over a total area of 88,015 km2 in Sumatera,
Kalimantan and Papua (Soedradjat et al., 1991) in areas
(+570,798 km2) underlain by Quaternary sedimentary rocks.
Coal which originally was estimated to have a reserve
of + 32.1 billion tons (Soedradjat et al., 1991), later rising
to an estimated +36.34 billion tons (Suhala & Yoesoef,
1995), is found in Tertiary sedimentary rocks, which have
an areal extent of +474,513 km2. Tertiary sedimentary
rocks can also be used to re-evaluate sedimentary basins
that may contain hydrocarbon reserves. Quaternary, Tertiary
and Mesozoic carbonate rocks as potential raw material for
Portland cement and other industries are of very great extent
(+154,032 km2 ). Limestone layers may attain thickness of
hundreds of meters, so that when the average thickness is
estimated at only 100 m, the limestone would have a reserve
of at least 39.28 trillion tons (specific weight 2.55). This
figure is much higher than the previous estimated reserve
of limestone which was only + 20 billion tons (Soedradjat
et al., 1991).
Various kinds of geological units of which the extent
has been measured above may provide information for the
further exploration of various kinds of metallic minerals,
industrial minerals, coal and peat, petroleum and natural
gas. More intensive prospecting is still needed to explore
possible potential resources and this requires the detail
provided by geological maps at a larger scale of 1:50,000.
Such information on regional geology, which covers the
entire Indonesian region is an asset that can be used in
further investigation needed for mineral and energy resource
evaluation, geohazards and land use planning decisions
within a fully self supporting civil society.
RAPID MAPPING
In order to accelerate planning and to support national
development, the Geological Agency as the institution
responsible for national geological survey and mapping,
proposed a rapid mapping programme to cover Indonesia’s
entire land territory from 2010 until 2025. This programme
started with geological mapping based on interpretation
of remotely-sensed data combined with existing data in a
GIS environment. The programme is categorized as “rapid
mapping” because the final target is to complete more than
3700 updated map sheets at the scale of 1:50,000 by 2015.
Thereafter, the programme will be continued by a field
campaign as a method of verification until 2025. Geological
interpretation on the basis of remotely-sensed data combined
with the large quantity of geological and geophysical data,
which are stored in the Geological Agency can provide a
fast and effective way to produce geological maps at the
1:50,000 scale. Combination of an optical dataset (e.g.
Landsat ETM, ALOS DAICHI and ASTER) and synthetic
aperture radar (e.g. IFSAR, Radarsat-2 and TerraSAR-X)
should produce data of outstanding quality for analysing
and extracting surface geological phenomena for geological
interpretation maps.
The earths surface is composed of various lithological
units which are reflected in morphological complexity
because of the exogenous and endogenous geological
processes involved. Morphological features and resultant
landforms can be analyzed through field campaigns and
also from remotely-sensed data. Interpretation of geological
features from remotely-sensed data is aimed to collect
geological information for further applications. There are
21
some advantages of using such data as, for example, many
remote areas and small islands can be examined quickly
and without problems related to accessibility and difficult
terrain. Such a rapid mapping program can therefore reduce
both time and cost of obtaining detailed initial geological
information. However, the program will still need validation
in the form of a limited field campaign and the use of
specific computer aided tools.
GEOLOGICAL AND TECHNICAL CHALLENGES
Development of geological information at larger scales
(1:50,000) is a critical issue for the Geological Agency as
the institution responsible for systematic national geological
survey and mapping in Indonesia. However, resolving this
issue involves many practical challenges for the researchers
including the huge area of the Indonesian territory, its
archipelagic setting, the complexity of its geology and the
large number of remote areas involved. As mentioned above,
rapidly acquired, remote sensed data can partly resolve some
of these challenges.
The quality of the results of image interpretation depends
on a number of factors: the interpreter, the image data
used, and the guidelines provided. Professional experience,
including experience of image interpretation determines the
skills of an image-interpreter. A background in geological
interpretation is essential in order for the interpreter to
extract image features related to geological phenomena.
Furthermore, local knowledge, derived from field visits, is
required to help in the interpretation. Finally the quality of
interpretation guidelines are a large influence, for example
standards for the development of Indonesian geologic maps
have an important role in ensuring the replicability of work.
Geological interpretation in a tropical terrain is often
particularly challenging due to the dense vegetation cover in
heterogeneous rain forest and the thickness of weathered soil
that renders spectral information for the rock units beneath
difficult to recognize. The technical challenge in geological
interpretation was how to make the visual interpretation of
remotely-sensed data of morpho-structural aspects combine
with field data existing in a GIS environment. Interpretation
keys needed to be established such as tone/hue, texture,
shape, size, pattern, site and association which provide
guidelines on how to recognize certain geological objects
on satellite imagery. Other aspects used in geological
interpretation were landforms, relief, drainage pattern,
vegetation and land use.
The aim was to define and delineate the lithology of
geological units and recognise geological structures that
could be used to analyze and interpret sub-surface conditions
and geological relationships. Geological sections relatively
crossing or perpendicular to the main geometry of geological
structures were made and represented at the surface by
contours. Distributions of lithology in the subsurface were
interpreted from trends and steepness of slopes as seen on
the data images.
Updating geological maps to a larger scale in part
focuses on further subdividing the existing mapped
22
geological units by introducing new classes or categories
of units. Lineaments, scarps and land offsets are assigned
to geological structures which are categorized as faults,
joints, calderas, and bedding traces.
CRITERIA DATA NEEDED
The use of remote sensing data for geological application
has been applied by the Geological Bureau in Indonesia
since the beginning of 1960. In the beginning, the remotelysensed images were aerial photographs, which were analyzed
with stereoscopes to extract information about the surface
geology. Advanced technologies have led to the use of better
remotely sensed data leading to higher accuracy, precision
and detailed graphic and temporal resolution.
Some quality aspects regarding the remotely sensed data
that are used during identification of geological features in
the Indonesian archipelago are:
1. Technology must take account of the tropical climatic
condition in Indonesia.
2. Sensors for data acquisition must cover optical and
altitude information.
3. Up-to-date data acquisition and collection are of main
concern.
4. Datasets are expected to be processed with the latest
technologies in order to achieve a high quality standard
of radiometric correction, geometric correction,
enhancement, filtering, fusion, and classification.
5. Digital technology will ensure that data is easy to
collect, process, duplicate, interpret, analyze, and store.
Several products that can meet acceptable quality
standards in geological mapping applications and have been
used by The Geological Agency are:
1. LANDSAT 7 ETM+; optical satellite observation with
orbital height of 705 km, temporal resolution 18 days,
swath 185 x 185 km, 7 bands with 30 x 30 m spatial
resolutions and 120 m thermal band resolution. Cloud
sensitive but having good spectral information for
surface geological survey.
2. ASTER – Advanced Spaceborne Thermal Emission
and Reflection Radiometer; 16 bands of optical earth
satellite observation with three sub system of 15 m
spatial resolution in visible near infra red (VNIR), 30 m
in short wave infra red (SWIR), 90 m spatial resolution
in thermal infra red (TIR). This sensor can run oblique
scanning to create three dimensional images or create
a digital elevation model (DEM).
3. SRTM – Shuttle Radar Topography Mission; radar
technology with 90 m and 30 m spatial resolutions.
Sensors used are C-band and X-band with capabilities
of three dimensional representation, cloud penetration,
and active sensor which could operate in day and night.
4. IFSAR – Interferometry Synthetic Aperture Radar;
an airborne radar technology with single-pass mode
of acquisition. This sensor produce digital elevation
model (DEM) and orthorectified radar image (ORRI).
Using X-band technology with 3 cm of wavelength
that can penetrate could, haze, dust, rain and night.
Geological
Updating
IFSAR type II, having spatial resolution of 5 m digital
surface model (DSM) with 1 m vertical accuracy and
2 m of horizontal accuracy. Spatial resolution of ORRI
product is 1.25 m with 2 m accuracy. IFSAR type I,
having spatial resolution of 5 m DSM with 15 – 50
cm vertical accuracy and 1 m of horizontal accuracy.
Spatial resolution of ORRI product is 0.625 m with 1
m accuracy.
5. Radarsat-2; Canadian satellite earth observation.
Launched in December 2007. Radar technology in
orbital height 798 km of sun-synchronous orbit and
using C-band and multi polarization of HH, VV, HV
and VH. Highest spatial resolution is 1 m in Spotlight
Mode, 3 m in Ultra Fine Mode with 100 m position
of accuracy.
6. TerraSar-X; German satellite earth observation.
Launched in June 2007 and operated since January
2008. Radar technology using X-band and multi
polarization of HH, VV, HV and VH. This sensor can
operate in day and night and in all weather conditions.
TerraSar-X is having 11 days of temporal resolution
and 1 m of spatial resolution. There are three modes
of data acquisition of TerraSar-X: Spot Light with 1
m of spatial resolution and swath 5 km x 10 km, Strip
Map with 3 m of spatial resolution and swath 30 km
x 50 km and finally Scan SAR with 18 m of spatial
resolution and swath 100 km x 150 km.
1:50,000
map scale
provides an essential aid in morpho-structural analysis
and characterization of landform-lithology in geological
interpretation and was derived from the digital surface
model data by using particular hydro-enforcement software.
Development of Existing Data
A great deal of data from various aspects of geology
and geophysics had been accumulated over the previous
fifty years. However, development of an inventory of such
a great amount of data can be a problem. Data collections
which are stored in the library are mostly only available
in non-digital format and must be converted into digital
data in the form of vector and raster layers together with
data attributes.
Building a geological database system referred firstly
to broad geological information in particular areas and
further pursued into local specific geological information.
A database inventory was collected and stored with the
information content including information on regional
geology, physiography, stratigraphy, geological structures,
tectonic setting, and energy and mineral resources. Specific
data wers stored in vector format in the following hierarchy:
project (Prj_ID), map sheet number (sheet_ID), region
(region_ID), location number (loc_ID), formation (Fm_ID),
symbols (symbol_ID), group (group_ID), class lithology
(litho_ID), environment (en_ID), era, period, epoch, fossil,
remarks, storage number (sto_ID) and references.
METHODOLOGY
Geological interpretation based on remotely sensed
data required datasets which contain specific information
on the earth’s surface. Spectral, altitude and terrain data
combined with secondary data regarding morphology,
lithology, location of observation, rock units, geochemistry,
measurements of strikes and dips and other local attributes
comprised the main information used to develop the
geological maps. In order to achieve a better performance
in interpretation work, it was necessary to develop all
information into a database format and process in a GIS
environment. Airborne and satellite images, field data,
and other secondary data were prepared before geological
interpretation started and finally compiled in a preliminary
geological map based on remote sensing data interpretation
(Figure 3).
Spatial Data Preparation
Preparation of data included the creation of shaded
relief of the digital surface model (DSM) and intensity layer
of orthorectified images (ORRI) taken from satellite radar
images which are posted by 50 m to generate contours at a
25 m interval. Data preparation on optical images (Landsat
ETM+7) included the creation of orthorectified images
and color composites of R/G/B: 4/5/7 in order to highlight
geological features in the areas of interest. Image fusion of
active and passive satellite imagery was also undertaken in
order to create datasets which have both spectral information
and highly detailed terrain information. The drainage pattern
Figure 3: Flow chart in updating geological maps of Indonesia to
1:50,000 map scale.
23
Development of the data base into a GIS environment
was necessary in order to support the geological interpretation
work and ensure that geological interpretation met a good
quality standard and used valid and precise information.
Geological Interpretation
Geological interpretation based on satellite images
was done by visual interpretation with computer aided
software. Specific computer software was used with
capabilities of digital image processing, modeling, three
dimensional visualization, hydro enforcement, and other
visual enhancement techniques. Overlays of various datasets
including field data in the form of vector data from previous
projects were combined to analyze and develop a preliminary
geological map. The interpretation was conducted by
overlaying information layers from vector and raster data
to extract new detailed geological information.
The method of interpretation was to describe
morphological features in a particular area, define the
landform genetics, and group into geo-morphological classes.
Key elements are shape, pattern, relief, drainage, vegetation
and dimension of a particular morphology. Furthermore,
other geological features were analyzed on the imagery to
differentiate and delineate lithologic units or rock units.
Optical satellite images can help to determine relatively
younger and older formations or rock units. Combination
with high resolution radar images may help to recognize
sediments, intrusions, alluvial deposits, metamorphic rocks,
and volcanic deposits.
Validation and Ground Truth
Ground truth and stratigraphic surveys were undertaken
for some area of interest which are believed to be key area
in order to validate the geological interpretation results.
For this purpose a limited number of objects or areas are
selected and visited in the field. The data collected in the
field is referred to as ground truth.
Geological interpretation results are inevitably
subjective results, therefore it is necessary to validate
and cross check the relationships of several ‘interpreted’
formations or rock units in the field. Field identification was
also undertaken to collect new authentic data as well as for
24
data validation in order to prove the interpretation results
and to check the correlation of rock units or formations in
a particular area.
Ground truth investigations were also conducted
by visiting areas in which there was ambiguity in the
interpretation of results. Furthermore, a more systematic
survey was also undertaken by carrying out stratigraphic
studies regarding rock formations that have already been
interpreted. Survey lines were prepared in order to make
new geologic cross sections of the interpretation maps at
1:50,000 scale. The data records that were collected during
field survey contain information of station number, date,
scale, formation, lithology, thickness, texture, sedimentary
structures, composition, fossils, color, strike/dip, sample
number, remarks and other descriptive information as thought
necessary. All data records were compiled and added as a
new information layer in geological interpretation map in
order to develop a preliminary geological map at 1:50,000
map scale.
Digital Layout
Geological interpretations based on remote sensing
data were prepared in a digital map format at 1:50,000
scale. The information includes boundaries of rock units,
geological structures, satellite/airborne imagery a as base
map (both optical and radar data), the geological map at
1:250,000 scale as reference data, topographic map, and
legend containing geological symbols (Figure 6).
UPDATING GEOLOGICAL MAP AT 1:50,000 MAP
SCALE
The project has so far been conducted for two years
starting from 2010. Until now it has produced geologic
interpretation maps for at least 1700 map sheets. The areas
covered areas are Sulawesi, Kalimantan, Bali, Nusa Tenggara
and Papua Island. Preparation of the maps in digital layouts
was done in 1:50,000 scale. The maps are represented as
geological maps based on interpretation of remote sensing
data (Figure 4).
In the year 2010 geological interpretation was done
for Sulawesi, Bali, and Nusa Tenggara Island with the
completion of more than 750 map sheets. The following
Figure 4: Planning for development of
geological mapping based on remote
sensing data interpretation (Sidarto,
2010).
Geological
Updating
1:50,000
map scale
Figure 5: Updating regional
geological map of 1:250,000
map scale into detailed
1:50,000 map scale.
Figure 6: Layout of geological
map based on remote sensing
data interpretation at 1:50,000
map scale.
year (2011) geological interpretation was done for the
island of Kalimantan with the completion of more than
800 map sheets. By mid 2012 the completed geological
interpretations have produced more than 200 map sheets
which cover Papua Island.
Creation of the larger map scale (1:50,000) divides
a sheet of the regional geological map at 1:250,000 scale
into 24 sheets of the new geological maps (Figure 5). There
are several improvements in the updated geological map of
Indonesia regarding detailed information on boundaries of
rock units. As compared to the previous geological maps
(1:250,000 map scale) rock formations can be divided into
several lithological units or rock types. For example, in the
new geological interpretation map a sedimentary formation
may be subdivided into sandstone, clay and conglomerate/
coarse sandstone. Formations of volcanic rocks may be
divided into several classes as lava flows, volcanic breccias,
tuffs and lahars. In addition, it may be possible to gain more
information on the source of eruption.
Other improvements in geological interpretation at
1:50,000 map scale are the recognition of geological
lineaments which appear as minor structures in the imagery
25
but could not be found in the field. These were successfully
mapped as faults, anticlines and synclines and categorized
as new geological information in the interpreted maps. This
can be used to describe and to explain the detailed tectonic
setting in local areas.
CONCLUSION
The methodology for updating existing geological maps
to 1;50000 scale has depended on geological interpretation
that is based on visual interpretation on remote sensing data,
which means that all the interpretation results still need to
be validated in the real world. It is therefore necessary to
mount a field campaign to cross check the relationships
between classes of interpreted rock units and define them
based on new and authentic data.
The quality of the result of an image interpretation
depends on a number of factors: the interpreter, the image
data used, and the guidelines provided. The professional
experience and the experience of image interpretation
determine the skills of an image-interpreter. Therefore, it
is important to define interpretation keys, which provide
guidelines on how to recognize certain geological features
on satellite imagery and to establish standardization for
development of Indonesian geologic maps, thus ensuring
the reproducability of the work.
These new geological interpretation maps are not
standard geological maps; they are preliminary maps
providing guidelines for conducting detailed geological
mapping and selecting the priority areas throughout
Indonesia in order to accelerate the needs of geological
information for national development purposes.
REFERENCES
Le Pichon, X., 1968. Sea-floor spreading and continental drift.
Journal of Geophysical Research, 73(12), 3661–3697
GRDC (Pusat Penelitian dan Pengembangan Geologi), 1992. Peta
Geologi Indonesia skala 1:5.000.000
Sidarto, 2010. Perkembangan Teknologi Inderaan jauh dan
Pemanfaatannya untuk Geologi di Indonesia. Publikasi Khusus
Badan Geologi, Kementerian Energi dan Sumber Daya Mineral.
Soedrajat, S., A. Noer, L. Sumiarso, S. Suhala, M. Arifin, T.S.
Kurnat, A. Muis, A.E. Hermantoro, S. Herwanto, M. Wijono
& S. Prawira, 1991: Potensi dan prospek investasi di sector
pertambangan dan Energi; Yayasan Krida Caraka Bhumi,
Jakarta, 548 p.
Suhala, S. &Yoesoef, A.F., 1995. Teknologi Pertambangan di
Indonesia; Direktorat Jendral Pekerjaan Umum, PPTM
Bandung.
Sukamto, R., 2000. Pengetahuan Geologi Indonesia: Tantangan
dan Pemanfaatan; Publikasi Khusus Pusat Penelitian dan
Pengembangan Geologi; Direktorat Jendral Geologi dan
Sumber Daya Mineral.
26
Global Heritage Stone Resource
Hirokazu Kato
Geological Survey of Japan, AIST
(National Institute of Advanced Industrial Science and Technology)
Abstract: A designation as a Global Heritage Stone Resource (GHSR) provides international recognition of a natural
stone resource that has achieved important utilisation in human culture. Stones used for heritage construction and
sculptural masterpieces, as well as in utilitarian (yet culturally important) applications, are obvious candidates for the
GHSR designation. The GHSR designation is essentially a “world heritage” naming of a stone type. The benefits of
the designation include legal definition of an historic stone type, prevention of stone resource depletion, and improved
restoration of stone heritage. The GHSR designation may encourage developers of new stone materials to aspire to major
projects, international exports, and hence new market opportunities.
The Heritage Stone Task Group (HSTG) was established by the International Union of Geological Sciences (IUGS).
The HSTG is also a working party under the Building Stone and Ornamental Rocks Commission of the International
Association of Engineering Geology and the Environment (IAEG C-10). The HSTG Board of Management was established
in August 2012 at the 34th International Geological Congress. The board is supposed to approve GHSR nominations and
promote the designation. Trial nominations are being prepared for Portland Stone and Welsh Slate in the United Kingdom
and Podpeč Limestone in Slovenia.
In this paper the Hiroshima-type Granite (Cretaceous), the Koto Rhyolite (Paleogene) and Hakone Andesite (Quaternary),
which are some of the most famous building stones for Japanese castles, are introduced as examples for potential GHSR
designation. In East and Southeast Asia there will be many stone types with potential to be designated as GHSRs.
Keywords: Global Heritage Stone Resource, heritage building
INTRODUCTION
The Global Heritage Stone Resource (GHSR)
designation provides international recognition of a natural
stone resource that has achieved important historic utilisation
in human culture. Stones used for sculptural masterpieces
and in construction of buildings forming an important part
of an area’s cultural heritage are obvious candidates for the
GHSR designation.
The GHSR designation is essentially a “world heritage”
naming of a stone type and the benefits of the designation
include legal definition of an historic stone type, prevention
of stone resource depletion, and improved restoration of
stone heritage. The GHSR designation may also encourage
developers of new stone materials to aspire to major projects,
international exports, and hence new market opportunities.
THE HERITAGE STONE TASK GROUP
The Heritage Stone Task Group (HSTG) was established
by the International Union of Geological Sciences (IUGS).
The HSTG is also a working party under the Building Stone
and Ornamental Rocks Commission of the International
Association of Engineering Geology and the Environment
(IAEG C-10). The HSTG Board of Management was
established in August 2012 at the 34 th International
Geological Congress. The board is supposed to approve
GHSR nominations and promote the GHSR designation.
Currently the Board of Management consists of:
President (ex officio Chair IAEG C-10): Dr Björn
Schouenborg (Swedish National Testing and Research
Institute, SWEDEN)
Secretary General: Dr Barry J. Cooper (University of
South Australia, AUSTRALIA)
Vice President Southern Europe: Professor Dolores
Pereira (Institute for Science and Technology Studies,
SPAIN)
Vice President Central Europe: Dr Sabina Kramar
(Institute for the Protection of Cultural Heritage of
Slovenia, SLOVENIA)
Vice President Western Europe: Prof. Dr. Jan Elsen
(Department of Earth and Environmental Sciences,
BELGIUM)
Vice President North America: Dr Joseph T. Hannibal
(Cleveland Museum of Natural History, USA)
Vice President North America: Professor Brian R. Pratt
(Geological Sciences University of Saskatchewan,
CANADA)
Vice President North America: Dr Nelson R. Shaffer
(Indiana Geological Survey, USA)
Vice President South America: Professor Fabiano Cabañas
Navarro (Institute of Science and Technology, BRAZIL)
Vice President East Asia: Dr Hirokazu Kato (Geological
Survey of Japan, AIST, JAPAN)
Vice President South Asia: Dr. Harel Thomas (Applied
Geology, School of Engineering & Technology, INDIA)
Vice President Africa: Dr Phil Paige-Greene (Infrastructure
Engineering CSIR Built Environment, SOUTH
AFRICA)
Member: Dr Brian R. Marker (Independent Consultant,
UNITED KINGDOM)
Hirokazu Kato
Table 1: Checklist for the “Global Heritage Stone Province” citation.
Formal Name for this proposed “Global Heritage Stone Province”:
Origin of Name (optional):
Other Names: (This may include other names given to the designated province)
Area of Occurrence: (This specifies the geographic area where the designated province occurs)
List of constituent “Global Heritage Stone Resource” designations that are included within this designated Province: (This
lists those stone types within the province for which a separate formal description as a designated ‘Global Heritage Stone
Resource’ has been prepared)
List of other known constituent heritage stone types, not otherwise designated, with assessment of international/national/
regional status that are also included within this designated Province: (This lists other heritage stone types having
international, national or regional significance)
Geological Setting:(Information on geology that places the designated province in a wider geological perspective)
Unifying geological characteristics within this province: (Information on the geology that specifies the unifying geological features
of heritage stone within the province)
Natural variation of geology within this province: (Information on any natural changes within the designated province)
Vulnerability: (This should assess the overall availability of stone types in the province for future use and the constraints on supply)
Historic Use and Geographic Area of Utilisation: (This should provide a brief summary statement on the historic and geographic
use of the stone from the designated province)
Construction: (This should provide an exemplary list of the most significant use of specified stone from this province)
Principal Literature related to the Designated Stone Province: (list major scientific papers, books and popular literature dealing
with the designated province)
Any other items:
Person(s)/ Organisation(s) making submission:
Date of Submission:
Trial nominations are being prepared for Portland
Stone and Welsh Slate in the United Kingdom and Podpeč
Limestone in Slovenia. Table 1 summarises the information
called for in seeking citation as a Global Heritage Stone
Province.
POSSIBLE GSRH EXAMPLES IN JAPAN:
HISTORY AND GEOLOGY OF STONE WALLS OF
SOME TYPICAL JAPANESE CASTLES
Osaka Castle
In 1583, Hideyoshi Toyotomi (1536-1598) began to
construct Osaka Castle and the surrounding castle town
which is the origin of modern Osaka City, southwest Japan.
During his reign, he set up a central administrative network in
Osaka, ended the century-long civil wars and established the
Toyotomi Government. However, his administration lasted
only 15 years and ended with his death. Furthermore, Osaka
Castle and town were destroyed by fire in 1615 because of
so-called “Osaka Summer War” in which Toyotomi’s allied
forces were defeated by Tokugawa’s allied forces. Then the
castle was reconstructed between 1620 and 1629 under the
rule of the Tokugawa Shogunate.
Origin of the Osaka Castle stones
These mainly consist of Cretaceous granite which
is widely distributed in southwest Japan, comprising the
so-called Hiroshima-type granite, a mainly coarse-grained
biotite granite.
The granite building stones, exceeding 500,000 in
number, were gathered from various areas including
mountainous regions such as the Rokko Mountains
28
Figure 1: Origin of the granite used to construct the stone walls
of Osaka Castle.
(“Mikage”, the local place name of the quarry in these
mountains is a synonym of granite building stone in Japan.)
and from islands of the Inland Sea (Setonaikai) (Figure 1).
One can find seals or markings on the stone surfaces showing
the origin and work areas assigned to the Daimyo, feudal
lords, and also building information such as construction
methods.
Giant stones of the walls of Osaka Castle
In the walls surrounding the courtyards of the gates of
the castle are five stone blocks weighing over 100 tons and
16 blocks weighing more than 50 tons. The largest block is
called “Tako-ishi” (“Tako” means octopus and “ishi” means
stone in Japanese, Figure 2). Although the front surface of
this stone is about 59.43 square meters and it weight is 108
Figure 2: “Tako-ishi”
Figure 3: Transportation
using “Shura”.
Figure 4: Castle tower and base stone wall of
Hikone Castle.
tons, its thickness is only 70 to 90 cm. This is because of
the technical difficulty in cutting and transport (Figure 3)
and because the builders wanted to have as wide a surface
as possible. Almost all the stone blocks except these huge
ones have a depth of between two or three times their
width or height.
Hikone Castle
Hikone Castle with its twin moats and chalk-white
walls is a hilltop-type castle and has for long been a
landmark on the shores of Lake Biwa, the biggest lake in
Japan (Figures 4 and 5). It is located in Hikone City, Shiga
Prefecture, southwest Japan and is one of the four National
Treasure Castles.
History of Hikone Castle
The victory of so-called “the Battle of Sekigahara”
in 1600 between Tokugawa and Toyotomi allied forces is
one of the most important events in the medieval history of
Japan, because it founded the Edo (Tokugawa) Shogunate.
On account of his contribution to the victory, Naomasa Ii,
one of the Four Guardians of the Tokugawa, was given
Sawayama Castle which was built at the beginning of the
Kamakura Period (1192-1333) and became the first Lord of
the Hikone Domain. His son and successor was permitted by
the Tokugawa Shogunate to move the castle to Mt. Hikone
because of its convenience and geopolitical importance.
In 1604, he commenced the construction and transported
much of the mountaintop Sawayama Castle’s stonework
and buildings and also the stonework of other nearby old
castles so that it is often called “A Recycled Castle” (Figure
6). The castle was completed in 1622.
Figure 5: Locality map in and around Hikone Castle.
Geological setting of building stones
The main building stone is from the Koto Rhyolites
formed during the igneous activity of the Koto Cauldron
(Figures 10 and 11).
Edo Castle
Old Edo castle was built in 15th century. About 130 years
later, Ieyasu Tokugawa who unified the nation completely,
rebuilt the castle and developed Edo town, one of the
Figure 6: Origin of stones used in Hikone Castle. Many structures
such as main keep, towers etc. were taken from other nearby
castle because it was necessary to complete the castle as soon as
possible in order to monitor the Toyotomi faction after the Battle
of Sekigahara. The Hikone Castle stone was taken from the Late
Cretaceous-Palaeogene Koto Rhyolite.
29
Hirokazu Kato
Figure 7: Stonework of Hikone Castle. Two-storied turret at the
gates, which has been repaired many times, especially in 1854. The
stone wall of right hand side was made in the original Gobozumi
style of stone work. The left side was made by the later Otoshizumi
style, because it was destroyed by the earthquake and re-built.
Figure 8: Vertical stoneworks, “Tate-ishigaki” in Japanese. “Tate”
stands for vertical, and “ishigaki” is stonewall. Vertical stoneworks
run from the top to the bottom of a hill to prevent an enemy attack.
The top of the stonework is surrounded by a wall with tiles on top.
Figure 9: Inner Moat Stonework. Around the lower part of the
earthen embankment known as Hachimaki Ishigaki (“Hachimaki”
means headband) and Koshimaki Ishigaki (“Koshimaki” means
waistband type underwear of women). This type of stonework is
rarely seen in the Kansai region, southwest Japan.
biggest town in the world in those days. He enlarged the
castle from 1604 to 1635. The castle is now used as the
Imperial Palace.
Edo Castle stones
Mainly consisting of Quaternary andesite lava, the main
quarrying places were several tens to more than 100 km away
from Edo such as in Kanagawa and Shizuoka Prefectures.
Manazuru-misaki (“misaki” means peninsula in
Japanese) is located 70 km southwestward from Tokyo (in
Kanagawa Prefecture) and situated at the northeast end of
Izu Peninsula, which is the northern end of Izu-Ogasawara
Arc. In this area, Quaternary volcanic products are widely
distributed and divided roughly into two groups, that is the
Hakone Volcanoes comprising the Hakone Volcano (0.4
Ma to present) and Yugawara Volcano (0.4-0.2 Ma), and
the slightly older Usami-Taga Volcanoes. These rock types
30
Figure 10: The Koto Rhyolites consist of welded tuff, pumiceous
tuff, silicic pyroclastics including quartz porphyry of the latest
Cretaceous to Plaeogene.
Figure 11: Outcrop and quarry of the Koto Rhyolite.
Figure 12: The keep (left) and stone wall (right) around the moat of Edo Castle.
Figure 13: Structure of the stonewall.
Figure 14: Regular-cut blocks of the stonewall.
Figure 17: Summary of geology in the Atami area including Manazuru peninsula
(Oikawa and Ishizuka, 2011).
Figure 15: Manazuru-misaki Quarry.
Figure 18: Index map of three castles.
Figure 16: Stamped stone block.
31
Hirokazu Kato
are mainly olivine-clinopyroxene or olivine- clinopyroxeneorthopyroxene basalt to andesite, and clinopyroxeneorthopyroxene andesite to dacite. Some of them were used
as building stones. The typical and famous usage of this
stone was to build the stone walls of Edo Castle. Edo is the
old name of Tokyo, the capital city of Japan. Edo Castle
was built at the beginning of 17th century.
Hon-komatsu Lavas consisting of dacite lava whose
K-Ar age is 0.18~0.17 Ma, 0.25 ±0.01 Ma, and Manazurumisaki Lava consisting of andesite lava and pyroclastics
whose K-Ar age is 0.15 ±0.01 Ma, are Hakone Volcanic
products, dating from the Middle Pleistocene. Hon-komatsu
Lavas are called Hon-komatsu-ishi as the name of building
stone, and Manazuru-misaki Lava is called Shin-komatsuishi.
FURTHER COMMENT
In the near future, the author proposes to compile and
edit a book, “Stone Heritage in East and Southeast Asia”,
in cooperation with relevant CCOP Member Countries.
REFERENCES
Cooper, B.J., Marker, B.R. & Thomas, I.A., 2012. Towards
International Designation of a Heritage Dimension Stone.
Global Stone Congress, Portugal.
Oikawa, T. & Ishizuka, O., 2011. Geology of the Atami district.
Quadrangle Series, 1:50,000, Geological Survey of Japan,
AIST, 61 p (in Japanese with English abstract).
Manuscript received 25 January 2013
32
Middle Permian Radiolarians from the siliceous mudstone block
near Pos Blau, Ulu Kelantan and their significance
Basir Jasin*, Atilia Bashardin & Zaiton Harun
Pusat Pengajian Sains Sekitaran dan Sumber Alam
Universiti Kebangsaan Malaysia, 43500 Bangi, Selangor
*Email address: basir@ukm.my
Abstract: A large siliceous sedimentary block was exposed in the vicinity Pos Blau, Ulu Kelantan. The block is a part
of mélange in the Bentong-Raub Suture Zone. The lower part of the block is composed of ribbon chert and the upper
part consists of interbedded siliceous mudstone and tuffaceous mudstone. Five samples from the siliceous mudstone
yielded very low number of individuals but fairly high number of species. Fourteen radiolarians taxa were identified.
The radiolarians are divided into two assemblage zones namely Pseudoalbaillella fusiformis Zone and Follicucullus
monacanthus Zone indicating Middle Permian age. The occurrence of tuffaceous material in Middle Permian siliceous
rock in Peninsular Malaysia was related to volcanic activities as a result of collision between Palaeo-Tethys oceanic crust
and the East Malaya terrane. The source of the tuffaceous material was from the East Malaya terrane. The tuffaceous
sediments became widespread in Late Permian and Triassic. This indicates the early stage of closing the Palaeo-Tethys.
Abstrak: Satu blok batuan sedimen bersilika yang besar terdedah pada kawasan berhampiran dengan Pos Blau, Ulu
Kelantan. Blok ini sebahagian daripada mélange dalam Zon Sutura Bentong-Raub. Bahagian bawah blok terdiri daripada
rijang ribbon dan bahagian atas terdiri daripada selang-lapis batu lumpur bersilika dan batu lumpur bertuf. Lima sampel
daripada batu lumpur bersilika menghasilkan bilangan individu yang sedikit tetapi bilangan spesies agak tinggi. Empat
belas taksa radiolarian telah dikenal pasti. Radiolaria dibahagikan kepada dua zon himpunan iaitu Zon Pseudoalbaillella
fusiformis dan Zon Follicucullus monacanthus yang menunjukkan usia Perm Tengah. Kewujudan bahan bertuf dalam
batuan bersilika Perm Tengah di Semenanjung Malaysia berkait dengan kegiatan volkano hasil daripada pelanggaran
antara kerak lautan Palaeo-Tethys dan teran Malaya Timur. Punca bahan bertuf itu daripada teran Malaya Timur. Sedimen
bertuf tersebar luas pada Perm Akhir dan Trias. Ini menunjukkan tahap awal penutupan Palaeo-Tethys.
Keywords: Radiolaria, siliceous mudstone, tuffaceous mudstone, Middle Permian, Palaeo-Tethys
INTRODUCTION
Chert and siliceous mudstone occur as blocks in the
mélange of Bentong-Raub Suture Zone. The siliceous rocks
yielded Late Devonian, Early Carboniferous and Permian
radiolarians. The late Devonian radiolarians were reported
from Bentong area (Spiller & Metcalfe, 1995; Spiller, 2002;
Basir et al., 2004). Early Carboniferous radiolarians were
recorded from Langkap (Spiller & Metcalfe, 1995; Spiller,
2002; Basir & Che Aziz, 1997a). In Pos Blau area, the
siliceous sedimentary sequence comprises ribbon chert at the
lower part and interbedded siliceous mudstone and tuffaceous
mudstone in the upper part. The ribbon chert block yielded
well-preserved and high diversity Early Permian radiolarian
assemblages belonging to Pseudoalbaillella lomentaria and
Pseudoalbaillella scalprata m. rhombothoracata Zones
(Spiller & Metcalfe, 1995, Basir & Che Aziz, 1997b; Spiller,
2002). The siliceous and tuffaceous mudstone yielded an
early Middle Permian radiolarian assemblage indicating the
uppermost part Pseudoalbaillella longtanensis – lowermost
part of Pseudoalbaillella globosa Zones (Spiller & Metcalfe,
1995; Spiller, 2002). Chert and siliceous mudstone represent
oceanic sediments. These rocks were folded, faulted and
highly deformed. The chert blocks represent the remnant
of Palaeo-Tethys.
Recently, twenty two samples of siliceous mudstone
were collected from an outcrop of abandoned timber track
(Figure 1). The rocks comprise thinly bedded siliceous
mudstone interbeds with tuffaceous mudstone and steeply
dipping towards southeast. Five samples yielded very low
number of individuals but fairly well preserved specimens.
GEOLOGICAL SETTING
The Bentong-Raub suture zone is a belt of mélange
consisting of olistromal blocks of oceanic sediments
such as chert, siliceous mudstone, tuffaceous mudstone,
sandstone, limestone, with minor serpentinite bodies. Some
of these rocks are sheared, faulted and embedded in the
sheared matrix of mudstone. Tjia & Almashoor (1996) had
conducted a detailed mapping of the Bentong-Raub Suture
Zone in Southwest Kelantan. The rocks generally strike in
a north-south direction and they recorded at least seven
tectonic units representing imbricate thrust slices which
formed a compressed accretionary prism. They estimated
the width of this accretionary prism is at least 18 km. This
rock assemblage could be classified as a lithodemic called
complex and the most appropriate term is Bentong Complex.
The biggest siliceous sediment block is located at
the eastern part of the Bentong-Raub Suture Zone in the
Figure 3: Stratigraphic distribution of radiolarians in the study
section.
Figure 1: Map showing study area and fossil locality.
is approximately 10 m wide consisting of thinly bedded
siliceous mudstone interbeds with tuffaceous mudstone.
The rocks are highly weathered and steeply dipping towards
southeast (Figure 2).
Figure 2: Outcrop of the interbedded siliceous mudstone and
tuffaceous mudstone showing sampling sites.
vicinity of Pos Blau. The block extend further south into
the oil palm plantation. The size of the block cannot be
properly estimated because lacking of outcrop. The chert
block exhibits thinly bedded chert interbeds with siliceous
mudstone and tuffaceous mudstone. Well bedded ribbon chert
is exposed at km 38 Gua Musang-Cameron Highland road.
DESCRIPTION OF OUTCROP
The outcrop is located at an abandoned timber track near
Pos Blau (4°45’13”N, 101°45’3”E) (Figure 1). The outcrop
34
RESULTS AND DISCUSSION
Radiolarians and Age
Twenty two samples of siliceous mudstone were
collected and only 5 samples yielded quite well-preserved
radiolarians. The radiolarians exhibit relatively high
specific diversity but low number of individuals. A total
of fourteen species radiolarians were identified (Plate 1).
Stratigraphic distribution of the species is listed in Figure 3.
The radiolarians can be grouped into two assemblage zones
i.e. Pseudoalbaillella fusiformis Zone and Follicucullus
monacanthus Zone.
Pseudoalbaillella fusiformis Zone
The zone is characterized by the occurrence of
Pseudoalbaillella fusiformis (Holdsworth and Jones) (Pl. 1,
figs. 1,2,3), Pseudoalbaillella globosa Ishiga and Imoto (Pl.
1, figs. 4,5,6), Albaillella cf. asymmetrica Ishiga and Imoto
(Pl.1, fig 7), Pseudoalbaillella cf. longtanensis (Sheng and
Wang) (Pl.1, fig. 8), Pseudoalbaillella convexa Rudenko and
Panasenko (Pl. 1, fig. 9), Pseudoalbaillella cf. longicornis
Ishiga and Imoto (Pl. 1, fig. 10), and Pseudoalbaillella
aidensis Nishimura and Ishiga (Pl. 1, fig. 11). This zone
was proposed by Zhang Ning et al. (2010). The lower
Middle Permian Radiolarians
from the siliceous mudstone block near
Pos Blau, Ulu Kelantan
and their significance
Plate 1: Middle Permian radiolarians from Pos Blau, Kelantan. Scale bar is indicated in the parenthesis.
1, 2. 3. Pseudoalbaillella fusiformis (Holdsworth and Jones) (100µm). 4, 5, 6. Pseudoalbaillella globosa Ishiga
and Imoto (100µm). 7. Albaillella cf. asymmetrica Ishiga and Imoto (100µm). 8. Pseudoalbaillella cf. longtanensis
(Sheng and Wang)( 100µm). 9. Pseudoalbaillella convexa Rudenko and Panasenko (135 µm). 10. Pseudoalbaillella
cf. longicornis Ishiga and Imoto (100 µm). 11. Pseudoalbaillella aidensis Nishimura and Ishiga (100 µm).
12, 13. Follicucullus monacanthus Ishiga and Imoto(100 µm). 14. Latentibifistula asperspongiosa Sashida and
Tonishi (176 µm). 15. Latentibifistula sp. (120 µm). 16. Hegleria mammilla Sheng and Wang (138 µm). 17. Gustefana
obliqueannulata Kozur (120 µm). 18. Ruzhencevispongus girtyi Nazarov and Ormiston(100 µm). 19. Latentifistula
sp. (137 µm).
35
boundary of the zone is based on the first occurrence of
Pseudoalbaillella fusiformis. This zone is equivalent to the
top part of the Pseudoalbaillella globosa Zone (Ishiga,
1991) indicative an age of late Raordian, early Middle
Permian. The assemblage is recorded from samples BC
18 to BC 20.
Follicucullus monacanthus Zone
The zone is marked by the occurrence of zonal marker
Follicucullus monacanthus (Pl. 1, figs. 12, 13) which
restricted to the zone. Other species found are Latentibifistula
asperspongiosa Sashida and Tonishi (Pl. 1 fig. 14),
Latentibifistula sp. (Pl. 1. Fig.15), Hegleria mammilla
Sheng and Wang (Pl. 1, fig. 16), Gustefana obliqueannulata
Kozur (Pl. 1, fig. 17), Ruzhencevispongus girtyi Nazarov
and Ormiston (Pl. 1, fig. 18) and Latentifistula sp. (Pl. 1,
fig 19). The assemblage is obtained from samples BC21
and BC22. This assemblage suggests Wordian age, middle
Middle Permian.
Pseudoalbaillella fusiformis, Pseudoalbaillella convexa,
Pseudoalbaillella cf. longicornis, Hegleria mammilla, and
Latentifistula sp. occur in both zones.
Spiller & Metcalfe (1995) and Spiller (2002)
were also discovered Pseudoalbaillella cf. longicornis,
Pseudoalbaillella fusiformis, pseudoalbaillella longtanensis
and Albaillella asymmetrica from the tuffaceous argillite and
chert near Pos Blau, Kelantan. They assigned the assemblage
to the uppermost part Pseudoalbaillella longtanensis –
lowermost part of Pseudoalbaillella globosa Zones. The
zone is older than the present material.
Occurrence of Middle Permian Radiolarians in
Peninsular Malaysia
Middle Permian radiolarians were also reported from
the siliceous sediment from Jengka area, Central Pahang
(Basir et al., 1995), Kuala Ketil and Pokok Sena, Kedah
(Sashida et al., 1995; Basir et al., 2005; Basir, 2008)(Figure
4). Nine species radiolarians were identified i.e. Entactinia
itsukaichiensis, Entactinia sp., Hegleria mammilla,
Hegleria sp., Copycyntra sp., Copiellintra sp., Follicucullus
monacanthus, Follicucullus japonicus and Pseudoalbaillella
globosa. This assemblge was previously assigned to the
Follicucullus japonicus Zone of Ishiga (1991). Follicucullus
japonicus Ishiga (1991) is a junior synonomy of Follicucullus
porrectus Rudenko (1984). The assemblage is now included
in the Follicucullus monacanthus Zone.
In the Western Belt of Peninsular Malaysia, Middle
Permian Radiolarians were reported mainly from the
Semanggol Formation at Bukit Yoi, Pokok Sena, Kedah
(Basir, 2008) and from Bukit Kukus, Kuala Ketil area, south
Kedah (Basir et al., 2005). Middle Permian Radiolarians
from Bukit Yoi comprise Pseudoalbaillella globosa together
with Pseudoalbaillella yanaharensis, Pseudoalbaillella
fusiformis, Pseudoalbaillella cf. longicornis, Latentifistula
texana, Raciditor inflata, Pseudoalbaillella sp. and Ishigaum
sp. This assemblage is indicating Roardian in age. Middle
Permian Follicucullus monacanthus Zone was also reported
36
from Bukit Barak, near Pokok Sena, Kedah (Sashida et al.,
1995). In Kuala Ketil area, south Kedah two Middle Permian
radiolarian zones were recognized namely Follicucullus
monacanthus and Follicucullus porrectus Zones (Basir et
al., 2005). The zones contain very low number of species.
The most common feature shared by the Middle Permian
siliceous sediments from the three areas namely Jengka,
Pahang; Pos Blau, Kelantan; Bukit Yoi, and Bukit Kukus,
Kedah is the occurrence of tuffaceous sediments interbedded
with siliceous mudstone. The tuffaceous mudstone was
reported from Jengka (Basir et al., 1995), Bukit Kukus
(Basir et al., 2005), Bukit Yoi (Basir, 2008) and Pos Blau
(Spiller & Metcalfe, 1995; Spiller, 2002). Middle Permian
tuffaceous material was also recorded from Northern Johor
(Sone et al., 2003) and Bera, south Pahang (Sone & Leman,
2005). This suggests that tuffaceous material was quite
widespread in the Middle Permian of Peninsular Malaysia.
At Bukit Kukus, Kedah the tuffaceous material was found
below the Pseudoalbaillella scalprata rhombothoracata
Zone in Early Permian (Basir et al., 2005). The tuffaceous
material had diluted the siliceous sediments and prevented
the formation of radiolarians chert during Middle Permian.
Tectonics implications
Paleozoic-Lower Mesozoic sedimentary sequences in
Langkawi and Perlis consist of shallow marine environment
namely the Machinchang, Setul, Singa, Kubang Pasu and
Chuping Formations. The whole sequences were deposited
in continental shelf environment. In Kedah, the sedimentary
sequences of the Mahang, Kubang Pasu and Semanggol
Formations were deposited in deeper water ranging from
deep-sea fan (continental rise) to basin environment (Basir,
1999). These formations represent the passive continental
margin of the Sibumasu terrane.
Since the Sibumasu terrane was a passive margin,
the source of the tuffaceous material was originated from
the volcanism in the East Malaya/Indochina terrane. This
volcanism was related to an early phase of closing the
Palaeo-Tethys where the oceanic plate of the Palaeo-Tethys
subducted under the East Malaya/Indochina terrane during
Middle Permian. Azman (2009) reported the oldest acid
volcanic rock from Pulau Sibu, Johor which indicate an
age of 297 Ma, Early Permian. This was probably the
source of tuffaceous material in the Permian sediments. The
collision took place at Bentong-Raub Suture Zone where the
accretionary complex developed (Tjia & Almashoor, 1996).
The occurrence of Middle Permian oceanic sediments
(radiolarian bearing siliceous sediments) indicate the PalaeoTethys was divided into two depositional basins namely
the Semanggol basin in the Western Belt and Semantan/
Gua Musang/Aring basin in Central Belt (Sashida et al.,
1995). These basins were separated by Bentong-Raub Suture
Zone (Figure 5). The Palaeo-Tethys became narrow and
shallow during Triassic where patchy of limestone beds
were deposited (Fontaine et al., 1995) and the volcanic
activities became more intense in the Central Belt. At the
end of Triassic there was an uplifting episode caused by
Middle Permian Radiolarians
from the siliceous mudstone block near
Pos Blau, Ulu Kelantan
and their significance
the emplacement of granite and finally the Palaeo-Tethys
diminished.
CONCLUSION
Middle Permian radiolarians from Pos Blau were
recovered from the siliceous mudstone interbeds with
tuffaceous mudstone. Two radiolarian assemblages were
identified namely, Pseudoalbaillella fusiformis and
Follicucullus monacanthus Zones, which represent late
Roardian and Wordian age respectively. Similar radiolarian
assemblages were also reported in siliceous mudstone
associated with tuffaceous sediments from the Semanggol
Formation in the Western Belt and in Jengka area Central
Belt. Widespread occurrence of tuffaceous material in
Western and Central Belts was related to volcanism as a
result of collision between Palaeo-Tethys oceanic crust and
the East Malaya terrane. The Palaeo-Tethys subducted under
the East Malaya terrane, the convergence processes continued
and the Palaeo-Tethys became narrower and shallower in
Triassic. Finally, Palaeo-Tethys disappeared in Late Triassic
by an uplifting episode caused by granite intrusion.
ACKNOWLEDGEMENT
We would like to thank Universiti Kebangsaan Malaysia
for providing research grant UKM-GUP-PLW-08-11-141.
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38
Beberapa fitur dan tapak bernilai warisan geologi di Pulau Sibu,
Mersing, Johor
Pusat Pengajian Sains Sekitaran dan Sumber Alam, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia
43600 Bangi, Selangor, Malaysia
Abstrak: Terdapat empat tapak di Pulau Sibu yang bernilai warisan dan berpotensi dijadikan geotapak iaitu Pantai Tanjung
Musoh, Pantai Tanjung Semanggar, Pantai Berkembar (Twin Beach) dan Tanjung Keramat. Pantai Tanjung Musoh dan
Pantai Tanjung Semanggar mempunyai singkapan pelbagai batuan piroklas dan lava serta boleh dijadikan sebahagian
daripada lokaliti tip bagi Formasi Sedili. Pantai Berkembar dan Tanjung Keramat mempunyai morfologi yang terhasil dari
proses hakisan dan pengendapan seperti tombolo, gerbang laut dan turus laut. Kesemua tapak tersebut menjadi tumpuan
pelancong samada untuk aktiviti skuba, snorkel atau berkelah. Konsep geologi pemuliharaan dan geopelancongan perlu
diterapkan bagi memastikan kedua-dua pemuliharan dan pembangunan selari.
Geological heritage values of several features and sites of
Pulau Sibu, Mersing, Johor
Abstract: There are four sites in Pulau Sibu that have geological heritage value and potential to be geosite namely Pantai
Tanjung Musoh, Pantai Tanjung Semanggar, Pantai Berkembar (Twin Beach) and Tanjung Keramat. Pantai Tanjung Musoh
and Pantai Tanjung Semanggar have various pyroclastic rocks and lava outcrop and can be part of type location for
Sedili Formation. Pantai Berkembar (Twin Beach) and Tanjung Keramat have morphology from erosion and deposition
processes such as tombolo, sea arch and sea stack. All these sites are tourist attraction for activities such as scuba diving,
snorkeling or picnic. Geological conservation and geotourism concepts need to be applied to ensure both conservation
and development could work hand in hand.
Keywords: geological heritage, geological conservation, geotourism, Pulau Sibu
PENGENALAN
Geologi warisan adalah sumber geologi dan landskap
yang menyimpan rekod sejarah bumi penting, unik,
jarang dijumpai, mempunyai bentuk sangat menarik,
mempunyai perkaitan rapat dengan ketamadunan manusia
atau mempunyai keindahan tabii dikategorikan sebagai
sesuatu yang bernilai warisan. Ibrahim Komoo (2000)
membahagikan nilai warisan sesuatu sumber geologi atau
landskap kepada empat iaitu nilai saintifik, nilai estetik,
nilai rekreasi dan nilai budaya.
Sumber geologi yang terdiri daripada batuan, mineral,
fosil dan rupabumi merupakan aset kekayaan negara.
Pembentukannya yang mengambil masa jutaan tahun
akan musnah dalam masa yang singkat sekiranya tiada
langkah-langkah pemuliharaan diambil. Pembangunan
pada beberapa dekad yang lalu lebih memfokus ke arah
pembangunan prasarana dan eksplorasi sumber secara
meluas hingga melampaui tampungan alam sekitar.
Kepentingan pemuliharaan di dalam sesuatu perancangan
pembangunan perlu diberi perhatian serius di dalam usaha
untuk mengekalkan aset penting yang berusia jutaan tahun
ini.
Pulau-pulau di Daerah Mersing, Johor mempunyai
pelbagai khazanah warisan geologi yang jarang ditemui
di tempat lain, termasuklah kepelbagaian jenis batuan,
morfologi, landskap dan pantai (Mohd Fauzi Rajimin,
2009). Salah satu pulau yang mempunyai khazanah ini
adalah Pulau Sibu (Rajah 1). Keseluruhan Pulau Sibu telah
wartakan sebagai salah satu Pulau Taman Laut Malaysia
pada tahun 1994 di bawah Akta Perikanan 1985. Kertas ini
ditulis dengan matlamat untuk menonjolkan khazanah pulau
ini dari aspek geologi serta mendedahkannya kepada umum
terutamanya fitur dan tapak yang bernilai warisan geologi.
Pendedahan ini sekurang-kurangnya akan menambah lagi
inventori tapak warisan geologi yang berpotensi sedia ada.
TOPOGRAFI DAN GEOMORFOLOGI
Keseluruhan Pulau Sibu merupakan tanah rendah yang
landai dan tiada bukit yang tinggi (Rajah 2). Puncak yang
tertinggi hanyalah 155 m iaitu Bukit Sibu berhampiran
Kampung Duku. Batuan sekitarnya yang terdiri daripada
batuan piroklas yang tidak padat menyebabkan terdedah
kepada proses hakisan. Morfologi hakisan pantai seperti
tunggul laut, gerbang laut, gua dan dataran hakisan pantai
banyak terdapat di bahagian timur pulau ini yang mana
terdedah kepada angin monsun timur laut. Pantai di bahagian
timur kebanyakannya memperlihatkan ciri pantai berbatu
yang mempunyai tebing yang tinggi dan hampir menegak
seperti di Tanjung Semanggar, Tanjung Pasir Belakang,
Tanjung Batu Birod dan Tanjung Keramat. Morfologi tebing
tinggi juga terdapat di bahagian utara pulau iaitu di sekitar
Tanjung Buntot Meriam.
Rajah 1: Kedudukan Pulau Sibu
di kepulauan luar pantai Mersing.
Rajah 2: Peta topografi dan saliran Pulau Sibu.
Rajah 3: Peta geologi ringkas Pulau Sibu.
Di bahagian pantai barat pulau ini lebih terlindung dari
angin monsun dan ombak yang kuat. Morfologi pengendapan
banyak mendominasi kawasan ini. Pemendapan pasir
yang banyak membentuk gumuk pasir di bahagian selatan
pulau. Kawasan Kampung Duku, Teluk Tagal dan Tanjung
Busung adalah terdiri daripada gumuk pasir tersebut.
Sebahagian kawasan ini akan tenggelam semasa air pasang
dan membentuk kawasan air laut yang cetek. Keadaan ini
merbahaya kepada bot-bot yang tidak biasa melalui kawasan
ini kerana boleh tersangkut dan terperangkap.
piroklastik sebagai formasi volkanik Sedili. Nama formasi
volkanik Sedili diambil sempena Sungai Ulu Sedili yang
mengalir ke barat Gunung Sumalayang. Chong et al. (1968)
dan Suntharalingam (1973) telah menamakan batuan sama
yang terdapat di Pahang dan di utara Johor sebagai volkanik
Jasin sempena nama Sungai Jasin. Sugeng (2007) pula telah
mengumpulkan kesemua batuan volkanoklastik dan lava
di timur Johor, termasuk volkanik Jasin, Pulau Sibu dan
Pulau Tinggi, sebagai Formasi Sedili. Berdasarkan kolerasi
dengan Formasi Dohol dan Formasi Linggiu, Formasi Sedili
dianggarkan berusia sekitar Perm Tengah hingga Perm Akhir.
Keunikan pulau ini terletak pada kepelbagaian jenis
lapisan volkanik bermula dari sedimen piroklas yang bersaiz
halus (tuff) hinggalah lapisan piroklas yang mempunyai
klasta-klasta yang bersaiz bungkah (bom) serta beberapa
singkapan lapisan lava. Menurut Rajah (1968), kebanyakan
singkapan lava yang ditemui bercampur dengan batuan
piroklastik. Singkapan lava kebanyakannya ditemui di
kawasan antara Gunung Chemendong ke Bukit Simbang,
di bahagian barat laut Johor Timur. Sugeng (2007) walau
bagaiman pun tidak pula menjumpai sebarang singkapan
lava di situ. Namun begitu, singkapan lava dan batuan
GEOLOGI PULAU SIBU
Keseluruhan pulau ini didominasi oleh Formasi Sedili
dan endapan kuaterner. Formasi Sedili terdiri daripada batuan
igneus volkanik iaitu jenis lava dan piroklas manakala
endapan kuaterner terdiri dari endapan pasir dan pasir
pantai (Rajah 3). Pada awalnya, Scrivenor (1931) telah
menamakan kesemua batuan volcanik dan piroklastik di
Semenanjung Malaysia sebagai Siri Volkanik Pahang
(Pahang Volcanic Series). Rajah (1968) yang telah membuat
pemetaan geologi dari Gunung Belumut hingga Gunung
Sumalayang menamakan singkapan batuan volkanik dan
40
Beberapa
fitur dan tapak bernilai warisan geologi di
piroklastik di Pulau Sibu adalah jelas dan boleh di cerap
dengan mudah. Singkapan ini boleh dijadikan lokaliti tip
(type location) mewakili singkapan lava Formasi Sedili.
TAPAK BERNILAI WARISAN GEOLOGI DI PULAU
SIBU
Terdapat empat tapak di kawasan sekitar Pulau Sibu
yang dikenalpasti berpotensi dijadikan geotapak iaitu
Pantai Tanjung Musoh, Pantai Tanjung Semanggar, Pantai
Berkembar (Twin Beach) dan Tanjung Keramat (Rajah 4).
Pemilihan tapak-tapak ini adalah berdasarkan nilai-nilai
saintifik, pendidikan dan rekreasi yang ada pada setiap tapak.
Rajah 4: Lokasi tapak berpotensi Pulau Sibu.
Tapak Pantai Tanjung Musoh
Di Pantai Tanjung Musoh terdapat singkapan sedimen
piroklas berlapis yang paling jelas di pulau ini. Tidak seperti
di kebanyakan singkapan lain yang terletak di bawah aras air
pasang, singkapan di tapak ini masih boleh dicerap dengan
baik pada waktu air pasang. Singkapan boleh dicerap di
sepanjang pantai hingga 150m ke utara (Rajah 5). Sekiranya
air surut singkapan boleh dicerap sehingga Tanjung Yaina
dan bersambung hingga Tanjung Buntot Meriam. Lapisan
adalah berjurus sekitar 0° hingga 20° dengan kemiringan
sekitar 40° hingga 45°. Cerapan log AB, CD, dan EF
menunjukkan lapisan di Tanjung Musoh adalah paling muda
manakala ke utara (Tanjung Yaina) semakin tua (Rajah 6).
Di sepanjang AB iaitu di kawasan berhampiran Tanjung
Yaina, lapisannya tebal tetapi kurang jelas. Keseluruhannya
singkapan adalah merupakan endapan aliran piroklastik
(pyroclastic flow deposits). Bahagian paling bawah lapisan
terdiri daripada breksia gunung berapi diikuti dengan tuf
lapili di bahagian tengah dan tuf (Rajah 7a) di bahagian atas.
Singkapan di CD pula merangkumi kawasan pantai
antara kawasan Tanjung Yaina dan Tanjung Musoh. Batuan di
bahagian bawah terdiri daripada tuf dengan kandungan bahan
piroklas bersaiz abu sangat dominan (Rajah 7b). Terdapat
juga bom volkano (volcanic bomb) yang berupa bahan-bahan
piroklas bersaiz pebel yang jatuh di atas beberapa lapisan
(Rajah 7c). Lapisan batuan mulai berubah pada ketebalan 16
m. Setiap lapisannya mempunyai butiran yang mengkasar
ke atas. Pada bahagian dasar lapisan batuannya padat,
berbutiran halus dan mengaca. Bahagian atasnya pula mulai
kasar dan terdapat buih-buih kaca (vesikel) yang tertanam
pada batuan (Rajah 7d). Batuan ini merupakan riolit dan
lapisan-lapisan ini merupakan aliran lava.
Singkapan EF merangkumi kawasan Tanjung Musoh.
Pada umumnya batuannya hampir sama dengan batuan
Rajah 5: Peta lokasi dan peta laluan cerapan
log tapak Tanjung Musoh.
41
Rajah 7: (a) Batuan tuf yang terdapat di Tanjung Yaina iaitu
sekitar B. (b) Batuan tuf yang berlapis di sekitar kawasan CD. (c)
Bom volkano bersaiz pebel yang jatuh memasuki lapisan tuf (anak
panah). (d) Lapisan riolit yang mempunyai vesikel kaca di atasnya.
Rajah 6: Log tapak Tanjung Musoh: Log (a) merupakan jujukan
paling tua (berhampiran Tanjung Yaina) manakala (c) jujukan paling
muda (Tanjung Musoh).
(c)
Rajah 8: (a) Singkapan berhadapan chalet De’ Coconut, jurus/
kemiringan: 0°/45° yang terdiri daripada lapisan riolit bersaiz
lumpur atau berkaca. (b) Fotomikro nikol silang menunjukkan
vesikel-vesikel (buih) yang halus pada bahagian atas lapisan riolit.
(c) Fosil Stigmaria yang dijumpai di Tanjung Musoh.
berhampiran D tetapi kebanyakkan lapisan adalah nipis
sekitar 0.5 m hingga 1 cm. Buih-buih kaca seperti di CD
juga terdapat pada beberapa lapisan di sini tetapi sangat
kurang. Lapisan yang mempunyai butiran bersaiz lumpur
atau berkaca adalah dominan (Rajah 8a). Fotomikro pada
Rajah 8.b menunjukkan buih-buih kaca (vesikel) yang
lebih halus pada bahagian atas lapisan. Batuan di kawasan
ini adalah riolit dan boleh ditafsirkan sebagai sambungan
aliran lava dari kawasan CD. Di kawasan ini juga dijumpai
fosil Stigmaria (Seaward, 1910) di lokasi ‘fosil 1’ pada
Rajah 5. Fosil ini berkemungkinan merupakan akar pokok
dari genus Lepidodendron atau genus Sigillaria yang hidup
sekitar Karbon hingga Awal Perm (Rajah 8c).
42
Tapak Tanjung Semanggar
Tanjung Semanggar terletak di kawasaan paling utara
Pulau Sibu. Tapak ini meliputi kawasan Tanjung Semanggar
dan teluk tiada bernama yang terletak di antara Tanjung
Semanggar dan Tanjung Buntot Meriam. Teluk ini terlindung
dari kedua-dua monsun dan mempunyai arus yang tenang.
Banyak terumbu karang yang tumbuh di teluk ini dan
merupakan tumpuan rekreasi snorkel. Laluan cerapan log,
kedudukan fosil dan log untuk Tapak Tanjung Semanggar
di tunjukkan pada Rajah 9 dan Rajah 10.
Singkapan GH berada di hadapan chalet D’Rimba
yang paling ke barat sekali. Singkapan ini berada di bawah
garisan air pasang dan tenggelam semasa air pasang. G
merupakan singkapan yang paling hujung terdedah semasa
air surut. Kebanyakan lapisan adalah bersaiz butiran lumpur
atau mengaca seperti aliran lava di Tanjung Musoh. Namun
demikian, sebahagiannya mempunyai jalur-jalur nipis
yang beralun berketebalan sekitar 10 mm hingga 5 mm di
dalamnya (Rajah 11a). Foto mikro jalur ini menunjukkan
pengendapan normal (menghalus ke atas) butiran-butiran
kuarza (kaca?) yang berulang-ulang (Rajah 11b). Jalur-jalur
halus ini seperti terendap di dalam air dengan butiran yang
besar dan berat terendap dahulu kemudian diikuti dengan
butiran yang lebih halus yang mudah terampai. Selang lapis
tuf dan riolit ini kadang kala sukar ditentukan di lapangan
kerana hampir sama pada pandangan mata kasar.
Fosil batang kayu dijumpai di lokasi yang bertanda ‘fosil
2’ pada Rajah 9. Urat-urat kayunya masih jelas kelihatan
namun kulit luarnya sukar untuk dikenal pasti (Rajah 12).
Seperti fosil Stigmaria di Tanjung Musoh, fosil batang kayu
ini juga berkemungkinan dari pokok genus Lepidodendron
atau genus Sigillaria yang hidup sekitar Karbon hingga
Awal Perm.
Singkapan IJ pula didapati hampir sama dengan
singkapan AB di Geotapak Tanjung Musoh. Namun demikian
agak sukar menentukan lapisan yang atas atau bawah kerana
lapisannya tidak jelas dan berkecamuk. Endapan piroklas
Beberapa
Rajah 9: Peta lokasi laluan cerapan log tapak Tanjung Semanggar.
dengan pelbagai saiz menjulat dari abu hingga bom atau
bongkah. Bermula dari I, batuan adalah jenis tuf lapili dengan
bahan piroklas bersaiz lapili adalah dominan (Rajah 13a).
Semakin menuju ke J, bahan piroklas bersaiz bom mulai
dominan (Rajah 13b). Di J, batuan semakin bercampur
aduk sehinggakan terdapatnya lapisan-lapisan nipis riolit
yang beralun di antara lapisan breksia yang kurang jelas
(Rajah 13c). Di hujung Tanjung Semanggar pula terdapat
konkresi-konkresi besi yang kelihatan seperti cendawan
gergasi (Rajah 13d).
Tapak Pantai Berkembar (Twin Beach)
Hampir keseluruhan tapak ini merupakan endapan
kuaterner yang terdiri daripada endapan pasir dan pasir
pantai. Terdapat sedikit perbezaan antara endapan pasir
yang berada di tengah kawasan tapak dengan yang berada
di pantai. Pasir pantai didapati lebih halus dan padat
berbanding pasir di kawasan tengah yang mempunyai saiz
butiran kasar hingga sangat kasar. Kebanyakan butiran pasir
yang kasar mempunyai kebulatan bersegi hingga subsegi,
menunjukkan pasir diendap tidak jauh dari sumbernya.
Terdapat sedikit singkapan tuf dan tuf lapili di bahagian
hujung tapak. Perlapisannya tidak jelas dan mempunyai
beberapa blok piroklas yang bersaiz kobel.
Tapak ini berada di bahagian genting di tengah-tengah
Pulau Sibu yang ramping hingga Pantai Pasir Belakang di
bahagian timur dan Pantai Teluk Perepat di bahagian barat
hampir bercantum (Rajah 14). Landskap ini sebenarnya
merupakan morfologi tombolo iaitu gumuk pasir yang
terhasil daripada pengendapan pasir persisir pantai yang
menghubungkan antara dua pulau. Ini bermakna Pulau Sibu
ini pada asalnya terbahagi kepada dua iaitu utara dan selatan.
Proses pengendapan pasir yang berterusan menghasilkan
morfologi tombolo di antara kedua-dua pulau. Penurunan
aras laut menyebabkan tombolo ini menjadi lebih tinggi dan
Rajah 10: Log tapak Tanjung Semanggar.
Rajah 11: (a) Lapisan tuf yang mempunyai jalur-jalur halus
(singkapan di hadapan chalet D’ Rimba). (b) Jalur-jalur halus
tersebut terdiri daripada butiran-butiran kuarza (kaca?) terendap
secara normal (menghalus ke atas).
Rajah 12: (a) Fosil batang kayu yang dijumpai di Teluk Semanggar.
(b) Fotomikro tanpa nikol keratan fosil mengikut urat kayu
menunjukkan bekas sel-sel pokok yang jelas. b) Keratan fosil
memotong urat kayu.
43
Rajah 13: Singkapan batuan di Tanjung Semanggar: (a) Batuan
tuf lapili. (b) Batuan breksia gunung berapi di Tanjung Semanggar.
Kelihatan bahan piroklas yang bersaiz bom. (c) Lapisan nipis riolit
(anak panah) di dalam breksia gunung berapi. (d) Konkresi besi
yang berceracak seperti cendawan gergasi.
Rajah 14: Imej satelit dari Google Earth jelas menunjukkan pantai
Pasir Belakang dan pantai Pasir Teluk Penepat yang bersebelahan
(berkembar).
Rajah 15: Pentas abrasi di Kampung Kambau, berhampiran Pantai
Berkembar.
lebar seperti sekarang. Penemuan morfologi pentas abrasi
di Kampung Kambau (berhampiran Pantai Berkembar)
yang berada di atas aras air pasang penuh menyokong teori
penurunan aras laut ini (Rajah 15). Ciri pantai berkembar
ini juga secara tidak langsung menyediakan tempat rekreasi
yang unik dan jarang sekali terdapat di tempat lain.
Tapak Tanjung Keramat
Keseluruhan tapak ini terdiri daripada batuan piroklas
jenis tuf, tuf lapili dan lapili bertuf. Perlapisan batuan jelas
tetapi sukar ditentukan jurus kemiringannya kerana agak
rencam. Batuan ini membentuk tebing-tebing yang curam
dan hampir tiada pantai berpasir.
Tapak ini istimewa kerana mempunyai morfologi
hakisan pantai yang jelas seperti gua, gerbang laut dan
turus laut. Ketiga-tiga morfologi ini saling berkait dalam
proses pembentukannya. Hakisan pantai yang aktif pada
tebing akan menghakis satah yang lemah lalu membentuk
gua. Hakisan yang berterusan akan menyebabkan dua atau
lebih gua bercantum membentuk gerbang lautan. Apabila
bumbung atau bahagian atasnya runtuh dan terpisah dari
daratan, turus laut pula terhasil.
Selain faktor hakisan, pembentukan morfologi ini juga
dipengaruhi oleh faktor batuan dan struktur. Batuan piroklas
di kawasan ini secara keseluruhannya kurang terkonsolidat
terutama batuan tuf lapili dan lapili bertuf. Klasta-klastanya
mudah tercabut dari batuan dan memudahkan lagi proses
44
Rajah 16: (a) Aras jurus sesar dan kekar serta kedudukan gerbang
laut dan turus laut (imej satelit diambil dari Google Earth). (b)
Morfologi gerbang laut. (c) Morfologi turus laut.
hakisan. Faktor struktur pula berperanan untuk menentukan
arah dan tempat morfologi ini terbentuk. Arah jurus kekar
dan sesar yang memotong batuan adalah sekitar 70°, 170°
dan 320°. Kebanyakan muka gua berarah sekitar 70° dan
320° iaitu mengikut arah kekar dan sesar (Rajah 16).
PERNYATAAN PENUTUP
Hasil kajian ini mencadangkan keempat-empat tapak
di Pulau Sibu ini dipulihara sebagai geotapak bertaraf
kebangsaan dengan Pulau Sibu sendiri diangkat sebagai
salah satu geotop di Malaysia. Tapak Tanjung Musoh dan
tapak Tanjung Semanggar mempunyai nilai saintifik yang
tinggi dan jarang di temui di Malaysia. Singkapan lava dan
batuan piroklasnya jelas dan segar berbanding di tempat lain
di Semenanjung Malaysia. Sebagai contoh, singkapan di
Sungai Jasin dan di pantai Mersing (juga dikenali sebagai
volkanik Jasin) tidak mengandungi urutan atau siri yang
Beberapa
lengkap (breksia gunung berapi - lapili - tuf - lava) seperti
di Pulau Sibu. Kebanyakannya telah mengalami metamorf
sentuh akibat rejahan granit. Begitu juga di Pahang, di mana
hanya batuan tuf sahaja yang biasa di temui. Kehadiran
batuan breksia gunung berapi menunjukkan punca letusan
dekat dengan singkapan. Di samping itu keseluruhan Pulau
Sibu terdiri daripada batuan gunung berapi dan tiada batuan
jenis lain yang dijumpai. Ini membuktikan bahawa Pulau
Sibu itu sendiri merupakan sebuah gunung berapi kuno
yang meletus sekitar Akhir Perm. Batuan Formasi Sedili
di sekitar Sedili dan Johor Timur berkemungkinan besar
datangnya dari letusan ini terutama batuan tuf yang berasal
dari debu gunung berapi.
Selain dari itu tapak Pantai Berkembar dan tapak
Tanjung Keramat juga memperlihatkan fitur-fitur geologi
yang memberikan nilai pelajaran dan rekreasi. Satu-satunya
morfologi gerbang laut dan turus laut yang terbina dari
batuan gunung berapi (piroklas) di Malaysia hanya terdapat
di Pulau Sibu. Di Langkawi dan sekitar pantai barat
Semenanjung Malaysia morfologi ini biasanya terbina dari
batu kapur dan batu pasir. Di bahagian pantai timur pula
seperti di Mersing dan Trengganu kebanyakannya terbina
dari batuan metasediman. Ini mengukuhkan lagi bahawa
tapak-tapak yang dicadangkan ini bernilai tinggi dan layak
bertaraf kebangsaan.
Diharap dengan adanya kajian warisan geologi ini
akan dapat menambahkan lagi sumber tarikan pelancong
selain dari aktiviti skuba dan rekreasi yang lain. Pewartaan
sebagai geotapak bertaraf kebangsaan dapat meningkatkan
kesedaran untuk memelihara sumber warisan ini. Konsep
geologi pemuliharaan dan geopelancongan perlu diterapkan
bagi memastikan kedua-dua pemuliharan dan pembangunan
selari.
REFERENCES / RUJUKAN
Chong, F.S., Cook, R.H., Evans, G.M. & Suntharalingam, T., 1968.
Geology and Mineral resources of the Melaka-Mersing area.
Geological Survey of Malaysia Annual Report 1968. pp. 89-94.
Ibrahim Komoo, 2000. Conservation geology: A multidisciplinary
approach in utilization of earth resources without destruction.
In: Ibrahim Komoo and Tjia, H.D. (ed.) Resource Development
for Conservation and Nature Tourism. Geological Heritage of
Malaysia. Bangi: LESTARI UKM.
Mohd Fauzi Rajimin, 2009. Kompleks igneus Kepulauan Mersing
– Warisan Geologi Negeri Johor. Warisan Geologi Malaysia:
Ke arah memartabatkan Sumber Geowarisan, 8, 79-72.
Rajah, S.S., 1968. Geology of the Gunong Blumut Area. Geological
Survey of Malaysia Annual Report 1968. pp 79-83.
Scrivenor, J.B., 1931. The geology of Malaya. London: Macmillan.
Suntharalingam, T., 1973. The Geology and mineral resources of
the Ulu Sedili area, Johore. Geological Survey of Malaysia
Annual Report 1973. pp 94-101.
Sugeng, S.S., 2007. Stratigrafi dan Sedimentologi Lembangan
Paleozoik Johor Timur, Semenanjung Malaysia. Unpubl. PhD
thesis, Universiti Kebangsaan Malaysia.
Manuscript received 5 June 2012
Revised manuscript received 20 January 2013
45
Sedimentologi Lapisan Perantaraan Formasi Kubang Pasu dan
Formasi Chuping, Beseri, Perlis
Pusat Pengajian Sains Sekitaran dan Sumber Alam, Fakulti Sains dan Teknologi,
Abstrak: Lapisan perantaraan Formasi Kubang Pasu dan Formasi Chuping tersingkap di kawasan Beseri, Perlis. Hasil
daripada cerapan di lapangan dan kajian terperinci di Kuari B, empat fasies sedimen telah dikenalpasti iaitu selang lapis
batu pasir dan lumpur nipis, batu lumpur tebal, batu pasir berpelapisan tebal dengan sedikit lumpur dan batu pasir yang
terbioturbasi. Secara keseluruhan, jenis litologi yang secara umumnya berbutir halus dan semakin berkalka ke atas jujukan
ini menunjukkan sekitaran pengendapan di dalam laut cetek. Analisis jujukan pula mendapati terdapat dua jenis jujukan
batuan iaitu jujukan mengkasar ke atas yang menandakan proses pengendapan di dalam sekitaran maraan garis pantai
dan jujukan yang menghalus ke atas yang menandakan endapan di dalam sekitaran alur. Perulangan jujukan mengkasar
dan menghalus ke atas ini menunjukkan terdapatnya kemungkinan bahawa lapisan perantaraan formasi ini terendap di
dalam fasa regresi di dalam sekitaran pasang surut dan pelantar benua.
Sedimentology of the Passage beds between the Kubang Pasu Formation and
Chuping Formation, Berseri, Perlis
Abstract: The Passage beds between the Kubang Pasu Formation and Chuping Formation crops out in Beseri, Perlis. A
detailed sedimentological study was carried out at Quarry B from which four facies have been identified. These facies are
sandstone interbedded with thin mudstone beds facies, thickly-bedded mudstone, thickly-bedded sandstone with thin mud
and bioturbated sandstone. In general the sequence is fine-grained with increasing calcareous content towards the upper
part of the Passage beds showing evidence that these facies were deposited in a shallow marine environment. Meanwhile,
the relationships among these facies show that there are two trends which can be differentiated by its lithological pattern.
There are coarsening upwards trends which indicate depositional that took place on regressing shoreline environment and
also fining upwards trend showing that deposition happened otherwise. The recurrence of these sequences overlapping each
other indicates a third order regressive and transgressive phase which may take place in the shallow marine environment.
Keywords: sedimentology, Passage beds, regression, continental shelf
PENGENALAN
Lapisan perantaraan Formasi Kubang Pasu (Formasi
Singa di Kepulauan Langkawi) dan Formasi Chuping
terdiri daripada jujukan batuan klastik yang berubah
secara beransur-ansur kepada jujukan batu kapur Formasi
Chuping (Fontaine, 2002). Perubahan litologi ini mungkin
berkait rapat dengan perubahan sekitaran pengendapan dan
keadaan fizikal lembangan pada masa pengendapan berlaku
serta perubahan aras air laut. Di Perlis, lapisan perantaraan
ini wujud di antara Formasi Kubang Pasu dan Formasi
Chuping dan banyak tersingkap di sekitar Chuping dan
Beseri. Sementara, di Langkawi pula jujukan perantaraan
di antara Formasi Singa dan Formasi Chuping tersingkap
di Pulau Singa Kecil dan Pulau Singa Besar.
Formasi Kubang Pasu adalah setara dengan Formasi
Singa namun dibezakan dari segi litologi. Meor & Lee
(2005) menyatakan kedua-dua formasi ini menindih Formasi
Timah Tasoh. Namun di Perlis, terdapat ketakselarasan di
antara formasi ini dengan Formasi Kubang Pasu. Kedua-dua
formasi ini ditindih secara selaras oleh Formasi Chuping di
bahagian atas. Formasi Singa terdiri daripada lapisan tebal
batu pasir kuarza dan batu pasir kaya felspar berwarna
kelabu, merah dan ungu dan berselang lapis dengan batu
lumpur yang terdiri daripada pelbagai warna (Gobbett, 1973).
Bahagian bawah Formasi singa dikenali sebagai Lapisan
Merah Langgun dan ditemui tersingkap di Kepulauan
Langkawi (Cocks et al., 2005). Manakala Formasi Kubang
Pasu pula terdiri daripada selang lapis batu pasir, lodak dan
syal dengan sedikit rijang di bahagian bawahnya. Di Kedah,
formasi ini dinamakan sebagai Formasi Kampong Sena oleh
Burton (1966). Yap (1991) telah membahagikan jujukan
Formasi Kubang Pasu ini kepada tiga fasies iaitu fasies
batuan argilit di bahagian bawah, diikuti oleh fasies batu
pasir dominan dan fasies perantaraan di bahagian atas. Usia
formasi ini dianggarkan sebagai Devon ke Permian (Foo,
1983) dan Yap (1991) merekodkan usia fasies perantaraan
Formasi Kubang Pasu dan Formasi Chuping sebagai Akhir
Permian. Antara spesis fosil yang pernah direkodkan di
dalam fasies perantaraan ini adalah Cancrinella cf. cancrini
(Toriyama et al., 1975), alga, fenestellid bryozoa, brakiopod,
dan mollusc (Jones et al., 1966). Sekitaran pengendapan
Formasi Kubang Pasu direkodkan berubah-ubah iaitu dari
sekitaran pengendapan laut cetek di Perlis ke sekitaran laut
yang lebih dalam di Kedah (Basir Jasin, 1995).
yang berbeza mewakili proses pengendapan yang berbeza.
Warna batuan juga kadang kala memainkan peranan dalam
penentuan sekitaran. Sebagai contoh, batuan sedimen yang
berwarna merah selalunya mencirikan endapan dalam
keadaan teroksida manakala yang berwarna kelabu selalunya
mencirikan sifat kanduangan batuan yang berkarbon.
Struktur sedimen pula adalah merupakan parameter
yang sangat penting berbanding parameter-parameter
penentuan sekitaran yang lain kerana ia terbentuk semasa
pengendapan berlaku di dalam sekitaran tersebut sendiri.
Struktur sedimen juga digunakan untuk memberi maklumat
seperti kedalaman air, tenaga dan halaju serta arah arus
semasa pengendapan berlaku.
Fosil juga penting dalam penentuan sekitaran kerana
cara mereka hidup dan berinteraksi antara satu sama lain
dikawal oleh jenis sekitaran dan habitat di mana mereka
tinggal. Dua jenis fosil yang selalu digunakan dalam
penafsiran sekitaran ialah mikrofosil dan fosil surih. (Felix,
2000)
Bagi tujuan kajian ini, terdapat sebanyak 6 lokaliti
telah dgunakan dan dibuat cerapan iaitu dua singkapan di
kuari A, tiga singkapan di kuari B dan satu singkapan di
Bukit Merah (Rajah 1).
Rajah 1: Peta lokaliti kawasan Beseri, Perlis.
Kajian sedimentologi ini dilakukan untuk mengenalpasti
unit-unit batuan dan fasies pengendapan yang terdapat
pada kawasan fasies perantaraan Formasi Kubang Pasu di
Beseri, Perlis. Menurut Jones (1981), kawasan ini terdiri
daripada dua formasi yang menindih secara selaras antara
satu sama lain, iaitu Formasi Kubang Pasu dan Formasi
Chuping. Analisis dilakukan terhadap data batuan yang
dicerap semasa di lapangan melalui saiz dan jenis butiran,
struktur sedimen dan fosil.
KAEDAH PENYELIDIKAN
Bagi tujuan penakrifan sesuatu fasies, analisis dan
cerapan secara terperinci di lapangan telah dilakukan
dengan mengambil kira setiap aspek-aspek yang boleh
mencirikan sekitaran pengendapan yang berbeza. Perincian
ini bergantung kepada ketebalan jujukan yang diukur.
Semakin banyak data dan cirian yang dicerap, semakin
banyak maklumat yang kita boleh perolehi daripada
singkapan tersebut. Selain daripada cerapan di lapangan,
data dari makmal seperti kajian petrografi juga digunakan
dalam perincian tersebut.
Di lapangan, pengelasan unit batuan yang berbeza
dilihat daripada aspek-aspek seperti jenis dan saiz butiran,
warna, bentuk dan struktur sedimen, dan fosil. Jenis dan
saiz butiran adalah digunakan untuk membezakan jenis
litologi yang berbeza seperti breksia, konglomerat, batu
pasir, batu lumpur, syal, batu kapur dan lain-lain. Litologi
48
Lapisan Perantaraan
Rajah 2 menunjukkan log sedimen yang telah dicerap
melalui kajian terperinci singkapan lapisan perantaraan
Formasi Kubang Pasu dan Formasi Chuping di Kuari B. Log
ini dibahagikan kepada dua bahagian iaitu hasil pencerapan
dan hasil tefsiran. Hasil pencerapan menunjukkan maklumat
yang diperoleh di lapangan seperti ketebalan lapisan, jenis
litologi, struktur sedimen dan kandungan fosil. Manakala
hasil tafsiran pula menunjukkan maklumat pengelasan
fasies, jenis jujukan, tafsiran sub-sekitaran pengendapan
dan sekitaran pengendapan bagi keseluruhan lapisan
perantaraan ini.
Pemerhatian di lapangan mendapati bahawa bahagian
bawah lapisan perantaraan yang telah tersingkap di kuari B
ini dicirikan oleh jujukan batu pasir berbutir halus dengan
pebel batu lumpur di bahagian permukaan dan berlaminasi
silang. Unit ini diikuti oleh selang lapis nipis batu lumpur
dan batu pasir berbutir halus dan berlaminasi bergelombang
yang kemudiannya ditindih oleh batu syal tebal berwarna
hitam dengan fosil surih di bahagian permukaannya (Rajah
3B dan 3F).
Unit ini diikuti oleh selang lapis nipis batu pasir dan
batu lumpur sebelum ditindih oleh jujukan batu pasir berbutir
sederhana tebal yang diselangi di antaranya oleh selang
lapis dominan batu pasir berbutir halus dan batu lumpur
nipis (Rajah 3A). Batu syal hitam tebal ditemui menindih
lapisan ini dan diikuti oleh jujukan tebal selang lapis batu
pasir dan syal dengan kewujudan klasta lumpur di dalam
lapisan batu pasirnya. Ini menandakan keadaan arus aliran
air yang berubah-ubah semasa pengendapan berlaku.
Jujukan ini kemudian diikuti oleh batu pasir berbutir
sederhana dengan struktur palung di bahagian bawah dan
“mud-partings” di bahagian atasnya. Struktur palung ini
Sedimentologi Lapisan Perantaraan Formasi Kubang Pasu
dan
Rajah 3: Fotograf menunjukkan (A) Selang lapis batu pasir dan syal
fasies perantaraan Formasi Kubang Pasu, (B) Laminasi bergelombang
dalam batu pasir, (C) Struktur palung yang menunjukkan endapan
alur, (D) Kesan riak simetri, (E) Fosil brakiopod yang dijumpai
pada permukaan batu pasir halus dan (F) Limpahan fosil surih.
Rajah 2: Penafsiran fasies lapisan perantaraan Formasi Kubang
pasu di Kuari B. JKA adalah merupakan jujukan mengkasar ke atas
manakala JHA mewakili jujukan menghalus ke atas.
ditemui secara turut menurut di dalam lapisan batu pasir
yang seterusnya menunjukkan pengendapan di sekitaran
alur (Rajah 3C). Kesan riak simetri juga ditemui di dalam
jujukan ini dan diikuti oleh perulangan batu pasir dan syal
yang sama tebal (Rajah 3D).
Di bahagian atas selang lapis ini dijumpai pula lapisan
batu pasir berkalka sebanyak 13 cm tebal yang menandakan
bahawa jujukan batuan perantaraan ini semakin bersifat
berkalka iaitu menghampiri sempadan antara batuan klastik
Formasi Kubang pasu dan batuan karbonat Formasi Chuping.
Tren mengkasar ke atas ini juga menunjukkan sekitaran
yang semakin mencetek.
Batu pasir berkalka ini kemudian telah ditindih oleh
batu pasir berbutir halus dan sederhana dan dikuti oleh batu
lumpur hitam berfosil. Kajian petrografi menunjukkan batu
lumpur ini mempunyai spesis fosil yang pelbagai iaitu terdiri
daripada foraminifera, gastropod, krinoid, bivalvia, alga
dan bryozoa (Rajah 4). Fosil-fosil ini mempunyai simen
yang berbentuk berbilah dan isopak (sama panjang) yang
menandakan proses diagenesis yang berlaku di sekitaran
phreatic marin (Flugel, 2004).
Jujukan ini diikuti dengan jujukan tebal selang lapis
batu pasir dan syal nipis dengan laminasi selari dan kesan
riak di beberapa tempat. Di bahagian tengah jujukan selang
lapis ini, fosil brakiopod dijumpai di dalam lapisan batu
pasir berbutir halus (Rajah 3E). Di bahagian atasnya pula
terdapat perulangan struktur palung dan kesan riak yang
menunjukkan endapan sekitaran alur.
Jujukan ini kemudian ditindih oleh batu pasir yang telah
terbioturbasi iaitu hasil daripada kesan kacau aktiviti fosil
semasa sedimen terendap (Brenchley, 1981). Iknofosil juga
dijumpai di dalam jujukan ini. Bahagian atas dan terakhir
singkapan ini dicirikan oleh lapisan batu pasir berbutir
halus dan tebal.
SEKUTUAN FASIES
Secara keseluruhannya kawasan kajian ini terdiri
daripada perulangan batu pasir berbutir sederhana, batu
pasir berbutir halus, batu lumpur dan syal. Bagi tujuan
pembahagian fasies, parameter seperti litologi, ketebalan
lapisan, fosil dan sruktur sedimen yang menggambarkan
sekitaran pengendapan yang berbeza akan digunakan.
Dengan menggunakan parameter-parameter ini, singkapan
ini bolehlah dibahagikan kepada empat fasies iaitu selang
lapis batu pasir dan batu lumpur nipis, batu lumpur tebal,
batu pasir berpelapisan tebal dengan sedikit lumpur dan
batu pasir yang terbioturbasi.
Fasies selang lapis batu pasir dan lumpur nipis
Fasies ini terdiri daripada batu pasir yang berselang
lapis dengan batu lumpur nipis. Lapisan batu pasir di
dalam jujukan ini adalah dominan berbutir halus dan
mempunyai ketebalan 1 ke 10 cm manakala batu lumpur
49
cetek. Struktur palung pula menandakan pengendapan arus
bertenaga tinggi.
Rajah 4: Fotomikrograf menunjukkan limpahan fosil di dalam
sampel daripada Kuari B (A) Fosil Foraminifera di dalam batu
lumpur hitam. (B) Alga. (C) dan (D) limpahan fosil bryozoa dan
alga dalam matrik lumpur kalsit. (E) Fosil yang mempunyai simen
jenis berbilah dan isopak yang menunjukkan sekitaran diagenesis
phreatic air tawar. (F) Fosil krinoid dalam batu pasir kaya kuarza.
pula adalah 0.5 ke 5 cm tebal. Antara struktur sedimen yang
dijumpai dalam fasies ini adalah laminasi silang, laminasi
bergelombang, palung dan klasta lumpur tercabut. Fasies
ini juga mempunyai fosil yang terdiri daripada fosil surih
dan brakiopod. Jujukan selang-lapis seperti ini menunjukkan
keadaan kawasan yang mempunyai tenaga arus yang
berubah-ubah dan terendap secara gabungan mendapan dan
seretan (Felix, 2000).
Fasies batu lumpur tebal
Fasies ini adalah merupakan jujukan batu lumpur
tebal, lebih daripada 0.5 meter tebal dan berwarna kelabu
gelap. Fosil surih dan struktur palung boleh dijumpai di
dalam beberapa lapisan. Fasies ini ditafsirkan sebagai
endapan secara ampaian di kawasan yang tenang dan
mempunyai tenaga arus yang perlahan. Kehadiran fosil
surih mecadangkan kawasan ini dihuni oleh organisma
kawasan air cetek.
Fasies batu pasir berpelapisan tebal dengan
sedikit lumpur
Fasies ini terdiri daripada jujukan lapisan batu pasir
tebal, 0.2 ke 3 meter tebal dengan sedikit lumpur dalam
bentuk lapisan nipis (<2 cm) dan klasta kecil. Batu pasir
ini terdiri daripada batu pasir berbutir halus ke sederhana
dan mempunyai struktur sedimen kesan riak dan palung.
Bentuk kesan riak adalah merupakan riak simetri dan ditafsir
sebagai riak ombak yang terbentuk di kawasan lautan sangat
50
Fasies batu pasir yang terbioturbasi
Fasies ini adalah merupakan jujukan batu pasir yang
telah mengalami perubahan dari segi struktur disebabkan
oleh proses biologi, juga dikenali sebagai gangguan biologi.
Ini ditunjukkan dengan adanya fosil surih dan litologi yang
bercampur aduk, iaitu batu pasir dan batu lumpur (Hart et
al., 2011). Keadaan litologi yang terdiri daripada batu pasir
dan batu lumpur ini menunjukkan bahawa batuan ini telah
termendap di kawasan yang tenaga arusnya berubah-ubah.
Kewujudan bukti aktiviti biologi pula menandakan kawasan
yang mempunyai tenaga arus sederhana (Alonso et al., 2011).
Oleh yang demikian ditafsirkan bahawa butiran pasir ini
telah dienapkan oleh arus yang tinggi dan kemudian berlaku
perubahan pasir yang dikacau oleh bioturbasi setelah air
kembali tenang.
Setelah fasies-fasies yang berbeza telah dikenalpasti,
hubungan antara fasies-fasies ini dilihat dari segi pola jujukan
iaitu samada mengkasar ataupun menghalus ke atas. Ini akan
memberikan gambaran yang lebih jelas mengenai sekitaran
pengendapan yang terlibat kerana kedua-dua jenis jujukan
ini menunjukkan jenis sekitaran yang berbeza.
Analisis fasies bagi singkapan ini menunjukkan terdapat
dua jenis jujukan batuan iaitu jujukan mengkasar ke atas
(JKA) dan jujukan menghalus ke atas (JHA). Jujukan
mengkasar ke atas adalah dimulai dengan fasies I dan dikuti
oleh fasies III. Jujukan ini kebanyakkannya mempunyai
kesan riak simetri ataupun gelombang laut cetek dan
ditafsirkan sebagai maraan garis pantai. Jujukan menghalus
ke atas pula dimulai oleh fasies III dan dikuti oleh fasies I
dan II. Terdapat banyak struktur palung di dalam jujukan
ini. Fasies ini ditafsirkan sebagai endapan alur.
Perulangan jujukan batuan yang mengkasar dan
menghalus ke atas ini menunjukkan adanya perubahan aras
laut yang berlaku berulang kali yang mempengaruhi tenaga
aliran arus dan punca sedimen semasa proses pengendapan
berlaku.
TAFSIRAN SEKITARAN PENGENDAPAN
Penafsiran sekitaran pengendapan dilakukan dengan
melihat hubungan antara satu sekutuan fasies dengan
fasies di sekitarnya. Sekutuan ini melambangkan sekitaran
pengendapan yang berlaku pada masa yang berbeza. Merujuk
pada Rajah 2, bahagian bawah lapisan perantaraan ini adalah
terendap dalam sekitaran alur iaitu melihat pada struktur
lapisan silang, palung dan riak yang ada. Alur ini mungkin
terbentuk di kawasan maraan garis pantai di mana sumber
sedimen yang lebih kasar hadir dan terendap membentuk
jujukan yang mengkasar ke atas.
Jujukan seterusnya menunjukkan pola menghalus ke
atas menandakan berlakunya proses transgressi ataupun
kenaikkan aras air laut. Struktur-struktur palung yang banyak
ditemui di sepanjang fasies ini menggambarkan adanya
pengaruh alur di dalam kawasan pengendapan jujukan ini
iaitu kawasan air cetek.
Sedimentologi Lapisan Perantaraan Formasi Kubang Pasu
Jujukan baru yang mengkasar ke atas dan disempadani
oleh batuan terbioturbasi di bahagian atas pula menunjukkan
berlakunya proses regressi. Proses ini menyumbang kepada
perubahan sumber sedimen daripada yang lebih halus di
bahagian bawah kepada yang lebih kasar di bahagian ataas.
Selang lapis nipis di dalam jujukan ini menunjukkan adanya
perubahan tenaga arus (Felix, 2000) di kawasan pasang
surut. Keadaan perubahan arus ini juga boleh berlaku dengan
adanya perubahan cuaca yang menyebabkan keadaan banjir
dan tenang. Tenaga arus ini menjadi lebih tenang kemudian
di mana lapisan batu pasir yang agak tebal terbentuk di
bahagian atas jujukan dengan beberapa pengaruh organisma.
Sempadan terbioturbasi ini boleh mewakili permulaan
transgressi (flooding surface). Jujukan yang mengkasar ke
atas seterusnya menunjukkan bahawa proses regressi berlaku
sekali lagi dan menyumbang kepada pengendapan di dalam
sekitaran yang lebih cetek.
KESIMPULAN
Secara keseluruhannya perubahan jujukan-jujukan
fasies di dalam lapisan perantaraan Kubang Pasu ini
menunjukkan bahawa berkemungkinan proses pengendapan
lapisan ini berlaku secara berulang kali, disebabkan oleh fasa
regresi dan transgressi di kawasan laut cetek (Sukhantar,
2004; Felix, 2000). Pengendapan sedimen karbonat Formasi
Chuping berkemungkinan berlaku apabila keadaan aras
laut telah menjadi stabil melalui proses biokimia. Keadaan
air yang tenang membenarkan pembiakan organisma dan
hidupan laut yang menyumbang kepada pembentukkan
rangka karbonat. Pemendapan secara organik ini juga
dipengaruhi oleh beberapa faktor penting yang lain seperti
suhu, kemasinan dan kedalaman air serta pengaruh sedimen
klastik (Felix, 2000).
Alonso-Zarza A.M., Geniseb, J.F. & Verdec, M., 2011.
Sedimentology, diagenesis and ichnology of Cretaceous and
Palaeogene calcretes and palustrine carbonates from Uruguay.
Sedimentary Geology. 236, 46-51.
Basir Jasin, 1995. Occurence of bedded radiolarian chert in the
Kubang Pasu Formation, North Kedah, Peninsular Malaysia.
Warta Geologi, 17 (2), 73-79.
dan
Brenchley, G., 1981. Disturbance and community structure: An
experimental study of bioturbation in marine soft-bottom
sediments. Journal of Marine Research, 39 , 767-790.
Burton, C.K. 1966. Palaeozoic orogeny in north-west malaya. Geol.
Magazine 103, 167-187
Cocks, L. R. M., Fortey R. A. & Lee C. P. 2005. A review of Lower
and Middle Paleozoic Biostratigraphy in West Peninsular
Malaysia and Southern Thailand in its Context Within the
Sibumasu Terrane. Journal of Asian Earth Sciences 24, 703-717.
Felix Tonkul, 2000. Sedimentologi. Penerbit Universiti Kebangsaan
Malaysia.
Flugel, E., 2004. Microfacies of Carbonate Rocks. Springer,
Germany. 996 p.
Fontaine H., 2002. Permian of Southeast Asia: an overview. Journal
of Asian Earth Sciences, 20, 567-588
Foo K.Y., 1983. The Palaeozoic Sedimentary Rocks of Peninsular
Malaysia – Stratigraphy and Correlation. Proceedings of
the Workshop on Stratigraphic Correlation of Thailand and
Malaysia, p. 1-19.
Gobbett, D. J. & Hutchison C. S. (eds), 1973. Geology of The Malay
Peninsula. John Wiley & Sons, New York.
Hart, M.B., Bromley, R.B. & Packer, S.R., 2012. Anatomy of the
stratigraphical boundary between the Arnager
Greensand and Arnager Limestone (Upper Cretaceous) on
Bornholm, Denmark. Proceedings of the Geologists’Association,
123, 471-478.
Jones, C.R. 1981. The Geology and Mineral Resources of Perlis,
North Kedah and the Langkawi Islands. Geological Survey
of Malaysia Memoir 17, 1-257.
Jones, C. R., Gobbett, D.J. & Kobayashi, T. 1966. Summary of
fossil record in Malaya and Singapore 1900-1965. Geol.
Palaeontology Southeast Asia, 2, 309-359.
Meor Hakif Hassan & Lee C. P. 2005. The Devonian-Lower
Carboniferous Succession in Peninsular Malaysia. Journal of
Asian Earth Sciences 24, 719-738.
Sukhtankar, R.K., 2004. Applied Sedimentology. CBS Publishers
& Distrubutors.
Toriyama, R., Hamada, T., Igo, H., Ingavat, R., Kanmera, K.,
Kobayashi, T., Koike, T., Ozawa, T., Pitakpaivan, K., Piyasin,
S., Sakagami, S., Yanagida ,J. & Yin, E.H., 1975. The
Carboniferous and Permian Systems in Thailand and Malaysia.
Geol. Palaentology of Southeast Asia. 95, 39-76.
Yap, K. F., 1992. Geologi Am Kawasan Timur-laut Perlis, Perlis
Indera Kayangan. Unpubl. B.Sc. thesis, Universiti Kebangsaan
Malaysia.
Manuscript received 1 August 2012
Revised manuscript received 23 January 2013
51
Sumber permineralan emas dan bijih timah di Jalur Barat
Semenanjung Malaysia: Bukti dari kajian geokimia dan mineral
berat
Mahat Hj Sibon1,2*, Habibah Jamil1, Mohd Rozi Umor1 & Wan Fuad Wan Hassan3
1
Program Geologi, Pusat Pengajian Sains Sekitaran dan Sumber Alam, Fakulti Sains dan Teknologi,
2
Jabatan Mineral dan Geosains Malaysia, Selangor
3
Jabatan Geologi, Fakulti Sains, Universiti Malaya, 50603 Kuala Lumpur
*Email address: mahat@jmg.gov.my
Abstrak: Semenanjung Malaysia secara tradisinya telah dibahagikan kepada tiga jalur mineral, iaitu Jalur Barat untuk
bijih timah, Jalur Tengah bagi emas dan Jalur Timur untuk kedua-dua bijih timah dan emas. Walaupun Jalur Barat diterima
sebagai jalur bijih timah, penyiasatan terperinci peta dan laporan-laporan geologi mendedahkan bahawa emas juga berlaku
di pelbagai tempat di dalam lingkaran timah ini. Di Tapah-Bidor, Perak dan Batu Cave, Selangor, emas telah dikumpul
sebagai hasil sampingan dari perlombongan bijih timah plaser. Longgokan bijih timah dijumpai meluas di Jalur Barat,
sedikit di Jalur Timur manakala tiada di Jalur Tengah. Satu kajian geokimia sedimen sungai di kawasan Tapah telah
dijalankan untuk melihat corak taburan kedua-dua unsur tersebut. Konsentrat mineral berat yang didulang dari sedimen
sungai dikaji melalui mikroskop binokular. Batuan dasar di kawasan tersebut terdiri daripada granit dan metasedimen.
Di kawasan Tapah, kepingan halus emas dan butiran kasiterit adalah biasa dan pelbagai diperhatikan
dalam hampir semua konsentrat mineral berat yang dikutip. Apabila nilai geokimia unsur-unsur diplotkan
di atas peta, emas dan bijih timah mempunyai corak taburan berbeza. Konsentrat dengan kepingan emas
terbatas kepada kawasan metasedimen manakala kasiterit didapati di kawasan metasedimen dan juga granit.
Ini mudah dijelaskan kerana telerang kasiterit, yang berasal dari jasad batuan granit, boleh merentasi kedua-dua batuan
granit dan batuan metasedimen setempat. Kasiterit berasal dari cecair magma lewat dan dibawa oleh cecair hidroterma dari
magma dan dimendap dalam telerang-telerang tanpa mengira jenis batuan dasar. Emas berasal daripada batuan sedimen.
Ia dirembes keluar dari batuan metasedimen dan diuraikan oleh air hidroterma yang beredar didorong oleh haba semasa
penerobosan batuan igneus dan dimendap di dalam telerang. Oleh kerana ia tidak berasal dari bendalir granit, ia didapati
jauh dari batuan granit.
Sources of gold and tin mineralization in the Western Belt of Peninsular Malaysia:
Evidence from geochemical and heavy mineral studies
Abstract: Peninsular Malaysia has traditionally been divided into three mineral belts, viz the Western Belt for tin, the
Central Belt for gold and the Eastern Belt for both tin and gold. Although the Western Belt is accepted as the tin belt,
close examination of geological maps and reports revealed that gold do occur in various places in this tin belt. In Johor
and Negeri Sembilan gold has been mined and in Tapah-Bidor, Perak and Batu Cave, Selangor gold has been recovered
as a byproduct in placer tin mining. Tin deposits are widespread in the Western belt, some in the Eastern Belt and absent
in the Central Belt. A study of heavy mineral concentrates in the stream sediments in Tapah area in Perak was carried
out to determine their distribution patterns. The heavy mineral concentrates were panned from the streams and studied
under a binocular microscope. Bedrock geology is underlain by granite and metasediments.
In Tapah area, fine gold flakes and cassiterite grains are common and variably observed in almost all heavy mineral
concentrates collected. When their respective geochemical values were plotted on a map, gold and tin have dissimilar
distribution patterns. Concentrates with gold flakes are confined to the metasedimentary areas, whereas cassiterite bearing
concentrates are found both in the metasedimentary areas as well in the granite areas. This is because cassiterite veins
originated from the granite bodies can cut across both the granite and the metasediment country rock. Cassiterite originates
from late magmatic fluids and being carried by hydrothermal solution from the magma and deposited in veins regardless
of the bedrock type. Gold on the other hand originates from the sedimentary rocks. It is being squeezed out from the
metasedimentary rocks, dissolved by circulating hydrothermal fluids and deposited in the veins. Since it originates not
from granitic fluid, it is found away from the granite.
Keywords: gold and tin mineralization, Western Belt, heavy minerals, geochemistry
PENDAHULUAN
Emas dan bijih timah adalah antara komoditi mineral
yang tidak asing dengan Semenanjung Malaysia. Negara
kita telah dikenali lama dahulu dengan panggilan Aurea
Chersonesus (Semenanjung Emas) kerana aktiviti
pengeluaran emas dan pernah juga menjadi pengeluar
bijih timah utama di dunia yang kebanyakkannya dari
sumber alluvium pada separuh pertama abad yang lalu.
Scrivenor (Scrivenor, 1928) ialah pengkaji yang pertama
memperkenalkan konsep tiga jalur permineralan di
Semenanjung Malaysia. Beliau membahagikan Jalur Barat
untuk bijih timah, Jalur Tengah untuk emas manakala
Jalur Timur untuk bijih timah dan emas. Yeap, 1993 telah
memperincikan jalur permineralan tersebut dengan empat
pemineralan emas tambahan berdasarkan taburan dan gaya
pemineralan yang berlaku (Yeap, 1993).
Bijih emas ditemui dalam Jalur Tengah bermula dari
Jeli di sempadan Kelantan-Thailand, menganjur ke selatan
melalui Sokor dan Pulai di Kelantan, melalui Merapoh,
Penjom, Selinsing, Raub di Pahang, Bahau, Kuala Pilah
di Negeri Sembilan dan berakhir di kaki Gunung Ledang,
Johor. Di Jalur Timur, emas di temui bermula di Sungai
Pelentong, Setiu, menganjur ke Rusila Terenganu, ke
Bukit Ibam di Pahang dan berakhir di Mersing, Johor. Di
Jalur Barat pula walaupun peta geologi menunjukkan ada
penemuan emas dalam saliran sungainya, namun belum
ada pengusahaan perlombongan emas komersial. Hampir di
semua tempat di Semenanjung Malaysia jumpaan emas jauh
dari jasad granit (Hassan et al., 1997). Longgokan emas di
sini dikelaskan sebagai mesoterma orogeni (Flindell, 2005)
iaitu berasal daripada larutan hidroterma jauh dalam bumi,
yang naik melalui struktur. Dalam hal demikian, peranan
magma granit hanya sebagai pembekal haba dan bukannya
asalan punca emas.
Bijih timah pula terdapat di sepanjang Jalur Barat dan
Jalur Timur, dan hampir tiada di Jalur Tengah. Di kebanyakan
tempat, telerang timah terdapat sama ada dalam jasad pluton
granit, dalam batuan metasedimen sekeliling atau dalam
kedua-duanya sekali. Bagi longgokan bijih timah, kajian
literatur menunjukkan asalan timahnya ialah granit dan
sebab itulah telerang timah tidak berjauhan dari jasad granit.
Objektif kertas ini ialah untuk menunjukkan bahawa
unsur timah dan emas yang terdapat di Semenanjung
Malaysia mempunyai punca asalan berlainan iaitu bukan
semuanya berasal daripada granit manakala longgokan bijih
timah berpunca daripada pluton granit.
KAEDAH KAJIAN
Kajian geokimia dan mineral berat telah dijalankan
pada sedimen saliran sungai di kawasan Tapah, Negeri
Perak, meliputi kawasan seluas 250km². Sebanyak 462
sampel kelodak sungai, 397 konsentrat minerat berat dan
28 sampel batuan dikutip dari kawasan kajian dan dianalisis.
Persampelan geokimia telah dijalankan berdasarkan panduan
oleh (Hamzah et al., 2003).
Persampelan sedimen sungai dibuat pada lokaliti sungai
aktif yang bertenaga tinggi dan rendah dan mewakili setiap
54
lembangan sungai yang terdapat di kawasan kajian. Sampel
kelodak dipungut secara berasingan di aliran air yang aktif
dan bertenaga rendah pada setiap lokasi persampelan.
Anggaran berat sampel yang dikutip adalah 60 g dan
dianalisis kandungan Pb, Cu, Zn, Au dan Sn. Kekerapan
persampelan kelodak ialah 0.5 km2 hingga 0.7 km2 bagi
setiap sampel. Sampel konsentrat mineral berat dipungut di
lokasi yang sama dengan lokasi kelodak. Sampel konsentrat
diperolehi dengan cara mendulang menggunakan dulang
piawai yang berisipadu 5 liter. Sampel konsentrat yang
dikutip dibahagikan kepada dua bahagian iaitu sebanyak lima
kali pendulangan piawai untuk analisis Au. Ia mengandungi
konsentrat mineral berat seberat 30 g - 40 g setelah
dikeringkan. Sampel ini tidak didulang sehingga bersih bagi
mengelakkan kehilangan butiran halus emas (Au) dan perlu
mengandungi nisbah pasir dengan konsentrat dengan kadar
1:3. Sampel konsentrat kedua dikhususkan untuk analisis
unsur Sn. Sampel ini terdiri daripada 3 dulang piawai
konsentrat mineral berat yang berat keringnya kira-kira 5 g
- 10 g dan didulang sehingga bersih tanpa kandungan pasir.
Kekerapan persampelan konsentrat ialah satu sampel setiap
0.5 km hingga 1.0 km persegi atau satu sampel konsentrat
bagi tiga sampel kelodak.
Sampel-sampel sedimen sungai akan dikeringkan dan
dianalisis berasingan bagi mendapatkan komposisi kimia
bagi Au (fire-assay-AAS) dan Sn (kolorometri). Sebilangan
sampel konsentrat tertentu dianalisis secara kualitatif (QME)
bagi mengasing dan mendapatkan peratusan kandungan
mineral emas dan kasiterit pada setiap lokasi tersebut.
Sampel konsentrat dipisahkan daripada mineral lebih ringan
menggunakan cecair bromoform dan dipisah mengikut daya
kemagnetan mengguna alat isodinamik Frantz. Sampel
bagi setiap tahap asingan diperiksa mengguna mikroskop
binokular. Sampel batuan yang dipungut adalah sampel yang
mewakili unit litologi dalam sesuatu kawasan. Keutamaan
persampelan batuan ini adalah di kawasan pemineralan
dan zon ubahan. Secara am persampelan batuan dilakukan
setiap 1.5 km persegi.
ANALISIS DATA
Semua keputusan analisis geokimia dianalisis dan diolah
bagi mendapatkan paras statistik untuk digunapakai dalam
interpretasi semasa persembahan data. Pemprosesan dan
pengolahan data geokimia dibuat menggunakan perisian
Excel dan xlstat yang mana paras statistik yang diperolehi
daripada analisis data-data tersebut digunakan dalam
menentukan kawasan anomali unsur-unsur yang berkaitan.
Dalam interpretasi taburan unsur, paras nilai persentil
digunapakai. Parameter ini digunakan bagi menggariskan
sempadan anomali pelbagai unsur dalam kelodak dan
konsentrat. Taburan anomali unsur-unsur kemudiannya
disintisiskan bagi mendapatkan peta taburan kawasan
anomali pelbagai unsur.
KEPUTUSAN
Parameter statistik
Hasil pengolahan data-data geokimia, pengkelasan
Sumber
permineralan emas dan bijih timah di
Jalur Barat Semenanjung Malaysia: Bukti
Jadual 1: Ringkasan kaedah analisis geokimia dan QME.
Media
Unsur
i) Kelodak Sungai
Au
Sn
ii) Konsentrat Sungai
Au (Sampel 5 dulang piawai) Sn (Sampel 3 dulang piawai) iii) Batuan
Au
Sn
iv) Qualitative Mineral
Mineral berat dan lebih ringan
Examination (QME)
Pelbagai tahap magnet
Penentuan mineral
dari kajian geokimia dan mineral berat
Kaedah Analisis
Fire Assay - AAS
Kolorometri
Fire Assay - AAS
Kolorometri
Fire Assay - AAS
Kolorometri
Cecair bromoform,
Pemisah Isodinamik Frantz
Mikroskop binokular
Jadual 2: Pengelasan parameter statistik.
Persentil Keterangan
50 persentil
< 85 persentil
> 85 persentil
> 97 persentil
> 99 persentil
Nilai penengah
nilai latar belakang
nilai latar belakang tinggi
nilai anomali
nilai anomali tinggi
Nota: Paras statistik yang
dipaparkan adalah untuk
semua unsur yang dianalisis
melainkan nilai anomali
unsur Au pada 95 persentil.
parameter statistic bagi nilai latar belakang dan anomali
ditunjukkan di Jadual 2.
Taburan nilai unsur-unsur diplotkan pada peta dasar pada
skala 1:50,000. Anomali unsur-unsur ditentukan mengikut
kaedah persentil seperti dinyatakan di atas, manakala
kawasan anomali unsur-unsur digariskan mengikut kawasan
tadahan. Parameter statistik pelbagai unsur dalam kelodak
dan konsentrat ditunjukkan dalam Rajah 1 hingga 4.
Kepingan emas
Sebanyak enam puluh tiga (63) lokasi telah ditemui
kepingan emas. Bilangan kepingan emas yang ditemui
dalam lima dulang piawai berjulat antara 1 – 62 kepingan.
Antara kawasan ditemui kepingan emas adalah Sungai
Cherok (Sg. Gading dan anak-anak sungai tidak bernama)
dengan julat antara 2 – 62 kepingan, Sungai Chenderiang
(Sg. Jong dan Sg. Cheras) antara 1 – 50 kepingan, Sungai
Batang Padang (Sg. Mas, Sg. Pana dan anak sungai tidak
bernama) antara 1 – 33 kepingan, Sungai Gempe (Sg.
Kelindo, Sg. Kemoi) antara 1 – 30 kepingan, Sungai Jangka
antara 2 – 16 kepingan. Secara umumnya kepingan emas
yang ditemui di dalam kawasan kajian adalah bersaiz antara
0.1 mm hingga 3 mm panjang dan bersifat bersudut hingga
subbundar. Rajah 5 menunjukkan taburan kepingan emas
di dalam kawasan kajian.
Taburan Unsur Au
Rajah 6 menunjukkan taburan Au dalam kelodak dan
konsentrat di kawasan kajian serta menunjukkan terdapat
sepuluh lokaliti anomali dan lima lokaliti beranomali tinggi
di dalam kelodak manakala terdapat lapan lokaliti anomali
dan empat lokaliti beranomali tinggi di dalam konsentrat.
Sejumlah satu hingga enam puluh dua kepingan emas ditemui
di 63 lokaliti di mana sampel konsentrat dikutip. Anomali
Au dalam kawasan kajian secara amnya bertumpu di Sungai
Jong, anak Sungai Cheras dan anak Sungai Cerok (ke timur
Sungai Cheras) di bahagian utara Bandar Tapah serta Sungai
Rajah 1: Parameter statistik unsur Au dalam kelodak.
Rajah 2: Parameter statistik unsur Au dalam konsentrat.
Rajah 3: Parameter statistik unsur Sn dalam konsentrat.
Rajah 4: Parameter statistik unsur Sn dalam kelodak.
55
Jangka, Sungai Kemoi, Sungai Kelindo dan Sungai Mas di
bahagian tenggara Bandar Tapah. Nilai anomali Au dalam
kelodak berjulat dari 0.17 - 0.46 ppm. Nilai anomali Au
dalam konsentrat pula berjulat antara 206 -448 ppm.
Nilai tertinggi Au dalam konsentrat diperolehi dari
Sungai Jangka iaitu 2,904 ppm dengan 16 kepingan emas
ditemui. Jumlah kepingan emas terbanyak ditemui ialah di
anak Sungai Cherok iaitu berjumlah 62 kepingan. Selain
daripada sungai-sungai di atas, kepingan emas halus juga
ditemui di Sungai Jong, Sungai Cheras, Sungai Jangka,
Sungai Mas, timur Sungai Mas, Sungai Pana, Sungai Kemoi
dan Sungai Kelindo. Secara keseluruhan dua kawasan
didapati berpotensi dengan anomali Au iaitu disekitar utara
Bandar Tapah dan tenggara Bandar Tapah.
Taburan kepingan emas dalam konsentrat mineral
berat dan emas dalam kelodak mempunyai pola tersendiri
iaitu secara keseluruhan taburannya tertumpu di kawasan
batuan metasedimen, manakala dalam kawasan batuan granit
nilainya rendah. Terdapat satu sampel konsentrat yang
mengandungi sedikit emas dalam kawasan granit di bahagian
selatan kawasan kajian, tetapi inipun apabila diteliti, adalah
hasil pembawaan oleh sungai dari kawasan metasedimen.
Taburan Unsur Sn
Taburan Sn dalam kelodak dan konsentrat mineral
berat sungai kawasan Tapah ditunjukkan dalam Rajah 7.
Terdapat sepuluh lokaliti anomali dan lima lokaliti anomali
tinggi dalam kelodak berjulat 170 ppm hingga 381 ppm
manakala dalam konsentrat terdapat tujuh lokasi anomali
dan lima lokasi anomali tinggi berjulat 269,273 ppm
hingga 350,000 ppm.
Anomali Sn dalam kelodak dikesan di Sungai Gempe
dan anak-anak Sungai Batang Padang manakala dalam
konsentrat, anomali unsur ini dikesan di Sungai Kenoh,
Sungai Kelindo dan anak Sungai Batang Padang (barat
Sungai Pana). Nilai tertinggi Sn dalam kelodak dengan
nilai 8,120 ppm telah dikesan di sekitar lembangan Sungai
Gempe dan anak Sungai Batang Padang manakala nilai
tertinggi Sn dalam konsentrat pula dikesan di Sungai
Kelindo dengan nilai 450,00 ppm. Selain dari itu Sn juga
dikesan dalam konsentrat di Sungai Kenoh dan anak sungai
di timur Sungai Pana.
Pola taburan Sn dalam kelodak dan konsentrat didapati
berbeza daripada taburan emas. Taburannya terdapat dalam
kedua-dua kawasan batuan metasedimen dan juga kawasan
batuan granit.
PERBINCANGAN
Sumber emas dalam longgokan emas hidroterma telah
menjadi suatu persoalan sejak sekian lama. Ada yang
mengatakan emas berasal daripada air hidroterma granit
fasa lewat (Emmons, 1933). Kebelakangan ini ramai mulai
berpendapat emas bukan berpunca daripada magma granit
tetapi daripada pengikisan batuan oleh air hidroterma
terhadap batuan sekeliling (Boyle, 1987; Groves et al.,
1998). Dalam pandangan ini, jasad granit berperanan sebagai
pembekal haba yang menyebabkan air hidroterma berkitar
keliling jasad granit.
Rajah 5: Lokasi dan bilangan kepingan emas dalam sedimen sungai kawasan Tapah, Perak.
56
Rajah 6: Anomali Au di dalam kelodak dan konsentrat. Perhatikan bahawa hampir semua
sampel mengandungi emas terdapat di kawasan metasedimen, bukan granit. Satu dua sampel
yang terdapat di kawasan granit, apabila dilihat dengan teliti, juga berasal dari kawasan
metasedimen, dibawa oleh sungai ke kawasan granit.
Rajah 7: Anomali Sn di dalam kelodak dan konsentrat. Taburan anomali merangkumi
kedua-dua kawasan batuan, granit dan metasedimen.
57
dari kajian geokimia dan mineral berat
Jalur Barat Semenanjung Malaysia: Bukti
permineralan emas dan bijih timah di
Sumber
Sekiranya emas berpunca daripada granit, maka telerang
emas akan memotong batuan granit dan batuan sekeliling.
Sekiranya sumber emas ialah daripada batuan bukan granit,
maka sudah tentulah kebanyakan emas akan dijumpai di
kawasan bukan granit atau jauh daripadanya. Sebaliknya
kalau inilah keadaannya, kita akan mendapati emas sama
ada dalam konsentrat mineral berat atau kelodak sungai
paling banyak di kawasan batuan granit. Dapatan kajian ini
bahawa taburan emas tertumpu di kawasan metasedimen
sahaja menunjukkan sumber emas bukan dari granit tetapi
dari batuan metasedimen. Air hidroterma yang berkitar
disebabkan rejahan granit mengikis emas daripada batuan
sekeliling dan memendakknya dalam telerang yang jauh dari
granit. Mengikut Boyle (1987), emas dirembes daripada
batuan sekeliling ketika berlakunya metamorfisme akibat
rejahan jasad igneus.
Timah sebaliknya menunjukkan pola berlainan iaitu
ditemui dalam konsentrat mineral berat dan kelodak
sungai dalam kawasan granit dan juga kawasan batuan
metasedimen. Ini lebih menjurus kepada sumber Sn daripada
hidroterma granit fasa lewat, iaitu Sn berpunca dari granit.
Taburan emas dan timah berbeza ini pernah dilaporkan
dari kawasan Bahau, Negeri Sembilan (Hassan, 1995). Di
tempat tersebut terdapat emas dalam mineral berat sungai
di kawasan metasedimen manakala timah terdapat di
kedua-dua kawasan granit dan metasedimen. Di situ juga
terdapat dua perlombongan emas dan kedua-duanya terletak
di kawasan metasedimen. Di Jalur Tengah Semenanjung
kebanyakan permineralan emas yang dikerjakan berada
berjauhan daripada jasad igneus (Lee et al., 1980). Hassan
et al. (1997) menunjukan kebanyakan jasad permineralan
emas di Semenanjung Malaysia berada pada jarak melebihi
1 km daripada pluton igneus terdekat.
KESIMPULAN
Taburan emas dan timah di kawasan Tapah menunjukkan
pola berbeza antara satu sama lain. Taburan emas dalam
sedimen sungai tertumpu di kawasan batuan dasar
metasedimen sahaja manakala taburan timah dalam sedimen
sungai pula tertumpu di kawasan metasedimen dan juga
kawasan granit. Taburan timah dalam kawasan granit dan
metasedimen menunjukkan sumber permineralan timah
ialah daripada larutan hidroterma magma. Taburan emas
pula berjauhan daripada kawasan granit iaitu tertumpu di
kawasan metasedimen menunjukkan sumber emas ialah
daripada larutan hidroterma bukan magma iaitu daripada
air dalam batuan keliling.
Kajian geokimia di kawasan Tapah, Perak ini juga
mendapati dua kawasan anomali pelbagai unsur. Kedua-dua
kawasan dikategorikan berkeutamaan 1 dengan unsur Au
dan Sn sebagai tumpuan. Kawasan-kawasan anomali ini
perlu kepada kajian susulan dan terperinci dengan tumpuan
kepada unsur Au dan Sn. Adalah disyorkan supaya kawasan
berkenaan diberi keutamaan untuk dibuat kajian lanjut oleh
pihak yang berminat.
Sebagai usaha untuk menambahkan pangkalan data
mineral berlogam, maklumat-maklumat geokimia dan
kawasan-kawasan beranomali boleh dijadikan panduan untuk
meneruskan kajian susulan terhadap unsur-unsur berlogam
pada masa hadapan selain data-data yang diperolehi boleh
digunakan bagi perancangan gunatanah serta pemantauan
alam sekitar di negeri ini.
Boyle, R. W., 1987. Origin of Epigenetic Gold Deposit-secreation
theory. Gold: History and Genesis of Deposits. New York:
Van Nostrand Reinhold.
Emmons, J., 1933. On the mechanism of the deposition of certain
metalliferous lode systems associated with granitic batoliths,
Ore deposits of the Western United States. Amer. Inst. Min.
Metll. Petrol. Engineers, Lindgren Volume, 327-439.
Flindell, P., 2005. Avocet Mining - Exploration and Developement
Across Central and Southeast Asia [Online]. www.smedg.org.
au/Tiger/Penjom.htm. Accessed 12 August 2012.
Groves, D. I., Goldfarb, R. J., Gebre-Mariam, M., Hagemann, S.
G. & Robert, F., 1998. Orogenic gold deposits: a proposed
classification in the context of their crustal distribution and
relationships to other gold deposits types. Ore Geology
Reviews, 13, 7-27.
Hamzah, A. H. B., Mohd, H. M. B., Zakaria, M. R. B., Hamzah,
M. B., Wan, R. B. C. & Husin, Z. B., 2003. Panduan Ringkas
Eksplorasi Geokimia. Jabatan Mineral & Geosains Malaysia.
Hassan, W. F., Almashoor, S. S., Tan, T. H., Mohamad, H., Wood,
K. H. & Hamzah, M. S., 1997. Kajian Status Potensi Emas
Dalam Batuan Sedimen di Semenaanjung Malaysia. Laporan
Akhir Program Penyelidikan IRPA 4-07-03-0025 Universiti
Kebangsaan Malaysia.
Hassan, W. F. W., 1995. Mineral Berat dalam Sedimen Sungai di
Kawasan Johol-Dangi, Kuala Pilah, Negeri Sembilan Darul
Khusus dan Implikasinya kepada Permineralan Emas. Sains
Malaysiana, 24, 59-76.
Lee, A. K., Foo, K. Y. & Ong, W. S., 1980. Gold Mineralizations
and prospect in North Pahang Darul Makmur, Peninsular
Malaysia. Ipoh, Jabatan Penyiasatan Kajibumi.
Scrivenor, J. B., 1928. The Geology of Malayan Ore Deposits,
London, Macmillan.
Yeap, E. B., 1993. Tin and Gold Mineralizations in Peninsular
Malaysia and Their Relationships to the Tectonic Developement.
Journal of Southeast Asian Earth Sciences, 8, 329-338.
Manuscript received 19 June 2012
Revised manuscript received 28 June 2013
58
Microfacies and diagenesis in the Setul Limestone in
Langkawi and Perlis
Che Aziz Ali1 & Kamal Roslan Mohamed2
2
1
Pusat Penyelidikan Langkawi, LESTARI
Pusat Pengajian Sains Sekitaran dan Sumber Alam
43600 UKM Bangi, Selangor
Abstract: The Setul limestone outcrops in Langkawi and Perlis show a variety of facies consisting of thickly bedded
mudstone, wackestone, packstone, grainstone and dolomitic limestone. Seven microfacies have been recognized comprising
of dolomicritic mudstone, bioclastic wackestone, peloidal wackestone, intraclastic wackestone, pelloidal packstone, pelloidal
grainstone and dolomitic limestone. The presence of bioclasts such as brachiopods, trilobites, ostracods, bivalves, crinoids
and the microfacies spectrum reflect that the sediments were deposited in broad environments ranging from tidal flats to
lagoon and shallow subtidal of a carbonate ramp. The diagenetic processes that have taken place include cementation,
dolomitization, stylolitization, neomorphism, dissolution, compaction and micritization. Petrographic studies show that
diagenesis took place in wide digenetic environments including freshwater phreatic zone, marine phreatic zone, mixing
zone and deep burial zone.
Keywords: carbonate sedimentology, carbonate diagenesis, Setul Formation, depositional environment
INTRODUCTION
The Setul Formation is widely distributed in the
Northwestern part of the Peninsular Malaysia and southern
Thailand (Figure 1). The limestone forms a broad range of
hills extending up to 30 km from Kuala Perlis to Thailand.
The Setul Formation was first described by Jones (1981) as
a prominent limestone of considerable thickness forming
the rugged karst topography the Setul Boundary Range in
west Perlis and also occurs extensively in the eastern part
of Langkawi Island. The same limestone is known as the
Thung Song Limestone in Thailand. In the Kilim area of
Langkawi, this limestone which forms picturesque tower
karsts standing out from the dense green mangrove forests
is a great tourist attraction. The landscape was carved by
prolonged geomorphological processes especially dissolution
that took place in a humid tropical climate when it was
exposed to the atmosphere.
This paper will focus on describing the microfacies in
this rock and also the diagenetic aspects which have not
been described in detail before.
METHODOLOGY
Samples of the Setul Limestone were collected from
Kilim area in Langkawi and close-spaced sampling was
done at the Kang Giap Quarry in Perlis. About 200 samples
from the quarry in Perlis and sea-cliffs in the Kilim area in
Langkawi were thin-sectioned and studied under the polarizer
microscope for detailed petrographic investigation to classify
the limestone and diagenetic studies. Thin sections were
stained prior to study under the petrographic microscope
according to the procedure described by Friedman and
Johnson (1992) in order to discriminate ferroan calcite,
non-ferroan calcite and dolomite. The rock microfacies
were classified according to Dunham (1962).
GEOLOGICAL SETTING
The study area covers a limestone quarry in Northern
Perlis and limestone exposures in the western part of the
Langkawi Island. Basically the geology of the northwestern
part of the Malaysia Peninsula is dominated by a complete
sequence of Paleozoic sedimentary rocks. The deposition
started with an Upper Cambrian clastic Machinchang
Formation deposited under fluviodeltaic conditions which
was then followed by the deposition of the subsequence
younger sedimentary sequence that was almost uninterrupted
until the Upper Permian and Triassic time.
The Setul Limestone was deposited conformably on
top of the clastic rock of the Machinchang Formation. This
gradual change was suggested to be due to the reduction of
clastic input as the source area was peneplained ( Lee, 2005).
Gobbett in his chapter in Gobbet & Hutchison (1973)
has interpreted the Setul Limestone to be Ordovician in
age based on its fossil content. Jones (1981) however, has
assigned the age of this rock formation to Ordovician –
Lower Devonian. This is further confirmed by Lee (2001;
2005) who found Scyphocrinites loboliths in the upper part
of the formation which he interpreted to represent the late
Silurian – early Devonian time.
Jones (1981) has divided the Setul Formation into four
units namely Lower Limestone Member, Lower Detrital
Member, Upper Limestone Member and Upper Detrital
Member. The base of the formation is not exposed but
the passage beds are exposed at Kuala Kubang Badak
inLangkawi while the top is exposed on Pulau Langgun
where the Singa formation rests unconformably. The total
thickness was estimated to be around 2000 meters.
The rock of the Setul Formation comprises crystalline,
hard brittle, dark colored, thick bedded, variably impure,
crystalline limestone with subordinate detrital facies
composed of quartzite, flagstone, carbonaceous shale, slate
and black cherty mudstone (Jones, 1981). In the field (Figure
2) the Setul Formation appears dark grey in colour with
massive and thick layers. Wavy stromatolites are common
features in this rock formation and columnar stromatolites
are also found at two localities in the Kang Giap Quarry in
Perlis. Generally, the rock is devoid of sedimentary structures
but in certain areas, weak evidence of rare current bedding
occurs as shown by weak cross bedding.
Figure 1. Distribution of the Setul Formation in Northwest Peninsular
Malaysia and Thailand.
Figure 2: A. Karst morphology on the Setul Limestone. B. Color
variation at outcrop related to mud content in the limestone. Muddier
facies appears darker. C. Wavy stromatolites are common features
in the limestone. D. The Detrital Member in the Setul limestone.
E. Columnar stromatolite found at the quarry.
60
CARBONATE MICROFACIES
The limestone is normally made up of allochems, matrix
and cement. All these three components are found in most
of the samples collected from the study areas. Allochems
in the Setul Limestone comprise skeletal materials, peloids,
ooid and some intraclasts. Skeletal and peloidal grains are
widely distributed in the rock but ooids and intraclasts
are rather limited. The main skeletal components found in
this limestone are bivalves, tentaculites, pelecypods and
some trilobite skeletal fragments. Micrite is also a major
component in this rock consisting of microcrystalline
carbonate material of less than 5µm in size. It normal
forms the background material in most of the samples.
Cement is another important component that binds the rock
together. Different cement types occur in this rock and will
be discussed in greater detail later.
Studies of thin sections of the rock samples from
Langkawi and Perlis show that the the carbonate rocks of
the Setul Formation can be divided into several microfacies
based on Dunham’s (1962) classification. The major
microfacies are mudstone, wackestone, packstone, and
grainstone (Figure 3). The microfacies have been either
partly or fully dolomitized. The fully dolomitized rock has
become a new microfacies called dolomite.
Mudstone
Description: The mudstone microfacies consists almost
entirely of carbonate mud and the allochems do not exceed
5% (Figure 3A). The facies appears thickly bedded and
dark grey at outcrops. The allochem comprises mainly of
crinoids, shell fragments (of gastropods and brachiopods)
and peloidal materials. This microfacies has been partly or
fully dolomitized and turned into dolomicritic mudstone
characterized by the presence of lime mud with dolomite
crystals disseminated in the matrix. The well formed crystals
are fine in size and show euhedral hipidiotopic texture.
Interpretation: At present, most of lime muds
accumulate in a wide range of environments ranging from
intertidal to lagoonal and basinal areas (Gischler et al, 2013;
Adjas et al, 1990, Wright, 1990; Scoffin, 1987). In the Setul
Limestone however, the microfacies is interpreted to have
been deposited in a shallow but quite water setting as shown
by the association of this microfacies with other shallow
water facies. This condition might occur in protected areas
of an open shelf.
Microfacies
and diagenesis in the
Setul Limestone
Wackestone
Description: The wackestone facies in the Setul
Limestone is made up of allochems embedded in a matrix
of lime mud (Figure 3B) and the rock appears fine to
medium grained at outcrops. The allochems are represented
by fragments of crinoids, bryozoans, trilobites, brachiopods,
thin shelled bivalves and some peloidal materials. The grains
made up about 10% of the rock volume. There are two
types of wackestone microfacies found, namely bioclastic
wackestone and peloidal wackestone depending on the
major allochem present. Bioclastic wackestone in the Setul
formation is characterized by the presence of fragments
of various skeletal materials including trilobites, bivalves,
crinoids and some brachiopods shells. Some peloidal
materials are also present some of which could have been
produced from the micritized skeletal fragments.
Peloidal wackestone on the other hand contains about
10 % of peloidal material embedded in micrite. There are
also some minor amounts of skeletal material present in
this microfacies. The peloids range from 0.05 to 3 mm in
size and most of them are either rounded or elongated in
shape. Some of these peloids could have originated from
the micritization of skeletal grains while some others could
represent fecal pellets.
Interpretation: This microfacies was deposited in a
low energy environment but the allochem might have been
derived from high energy areas as shown by the battered
and fragmented nature of the grains. The grains could have
been transported into deeper quiter water during storms or
accumulated at the foot of gentle slopes.
Figure 3: Microfacies in the Setul Limestone. A. Mudstone;
B. Wackestone; C. Peloidal Packstone; D. Bioclastic Packstone;
E. Peloidal Grainstone; F. Dolomite.
in
Langkawi
and
Perlis
Packstone
Description: Packstone is a grain-supported microfacies
consisting of a mixture of allochems and lime mud matrix
(Figure 3C & D). Peloids and bioclastic tests are the main
components that make up this microfacies producing two
types of packstone i.e. peloidal packstone and bioclastic
packstone. The bioclasts are represented by crinoids, bivalve
shells and styliolinid tests. The presence of bioclasts is
less than 25% while the percentage of peloids ranges from
10 to 45% in the samples. Some of the peloids had been
compressed and aligned parallel to the bedding plane due
to compaction while some other peloids have undergone
dolomitization. The euhedral dolomite grains however were
not compressed indicating that dolomitization took place
after the sediment has been buried deeper in the subsurface.
The packstone microfacies is the most dominant facies
representing about 43 percent of the total rock in the Kilim
area.
Interpretation: The texture of this microfacies reflects
deposition that took place under slightly higher energy
conditions compared to the wackestone and mudstone
microfacies. This is shown by the nature of the allochems
that appear battered, broken and abraded reflecting the
high energy condition closer to that of a skeletal shoal on
a carbonate platform (Wilson, 1975).
Grainstone
Description: Grainstone is grain supported microfacies,
with minimum amount of micrite present (less than 5%)
and the rock is cemented by calcite cements. The amount
of allochem is about 35% to 55% of the total rock volume,
comprising peloids, bioclasts and some intraclasts (Figure
3E). In some samples, the pelloidal materials are so dominant
that the rock can be classified as peloidal grainstone. The
peloids were arranged parallel to the bedding plane during
compaction. Calcite cements make up about 30% to 50%
and dolomite is also present ranging from 1% to 10%. Figure
3E is a photomicrograph of the microfacies.
Interpretation: Its coarse grain texture and the lack of
micritic material indicate that this microfacies was deposited
in a high energy environment while peloids are derived
from shallow water areas such as in the back barrier. The
widespread cementation in the microfacies however indicates
that the peloids and other allochems were deposited in rather
open and agitated areas forming peloidal-skeletal shoals.
Dolomite
Description: This facies consists entirely of coarse
grained replacive dolomite. It is quite impossible to
recognize the original facies and grain type in this facies
due to extensive dolomitization that had taken place and
obliterated the original texture and fabrics of the rocks.
Judging from the evenness of the dolomite grains however,
we can deduce that the original microfacies could be lime
mudstone with no significant amounts of allochem presents.
Interpretation: The evenness of the crystal sizes,
together with some large and well formed crystals produced
61
by extensive dolomitization indicate that dolomitization
occurred late during diagenesis. Dolomitization in this
microfacies had almost completely replaced both the
grains and matrix. This process normally occurs deep in
the subsurface where all crystals have enough time to grow
and form euhedral texture.
Microfacies distribution
This facies is not evenly distributed laterally and
vertically in the Kilim area. Since no sedimentary logging
was carried out in Kilim area, the distribution can only be
mapped laterally as shown in Figure 4. The mudstone and
wackestone make up the bulk of the facies found in Kilim
and they represent about 43 percent of the total sample
collected in Langkawi. Meanwhile, the sequence at the Kang
Giap Quarry is dominated by packstone and grainstone.
Packstone is the second largest facies representing about
33 percent of the total samples collected whilst grain stone
is the least with an amount of about 5 percent. About 18
percent of the total samples collected are represented by
dolomite. The dolomite microfacies is seen to be associated
with or to occur close to the mudstone microfacies. This
phenomenon might indicate that a close genetic relationship
for these two microfacies.
Detailed logging and mapping was at the Kang Giap
Quarry have resulted in the lateral and vertical facies
distributions presented in Figures 5 & 6. The microfacies
changes from mudstone and wackestone into packstone
and grainstone and continue further up with bioclastic
wackestone and dolomitic limestone from bottom to top.
Figure 4: Microfacies distribution in Kilim Langkawi.
62
The original texture of the microfacies cannot be ascertained
due to pervasive dolomitization in the samples examined.
Wavy stromatolites can be seen dominating this facies in
the outcrop.
DIAGENESIS
Diagenesis involves processes that caused the physical,
chemical and mineralogical changes in limestone. These
processes had occurred since the sediment was deposited
and normally it would lead to a more stable condition.
Factors that control the digenetic processes include the
original composition of the sediment, pore water chemistry
and its movements in the subsurface and also the time
involved (Scoffin, 1987). Diagenesis can occur in various
environment such as vadose, freshwater phreatic, sea water
Table 1: Microfacies percentage in the Setul Limestone from the
Kilim area, Langkawi.
.
Mudstone-wackestone
Packstone
Grainstone
Dolomite
43 %
33 %
5%
18 %
Figure 5: Limestone sequence logged at the Kang Giap Quarry.
Microfacies
Setul Limestone
phreatic and in the deep burial environment in the subsurface.
Each of the environments will produce different diagenetic
textures and fabrics.
Diagenesis in the Setul Limestone occurred very early
even during deposition as shown by the presence of early
marine cements. The various effects of diagenesis can be
observed in the samples collected from Kilim and Kang
Giap Quarry such as micritization, cementation, compaction,
dissolution, neomorphism, dolomitization and silicification
(Figure 7).
Cementation
Cementation was not a dominant diagenetic process
in the Setul Limestone. Only minor amounts of calcite
cementation are observed in the samples collected. Two
generations of cement are observed in the Setul Limestone.
The first generation is represented by fibrous isopachous
calcite rim. This cement was superseded by the second
generation cement consisting of blocky calcite cement.
The fibrous cement can be recognized from the presence
of radiaxial fibrous calcite which had evolved from the
originally microfibrous calcite cement. The cement was
precipitated early during diagenesis when the sediment was
still in a marine phreatic condition at or near the surface
(Kendall, 1985). Another type of early generation cement
occurs in the form of syntaxial overgrowth that affects mostly
crinoid grains where the grain is now enveloped by a large
calcite crystal. This type of cementation normally occurs
in freshwater phreatic condition or deep in the subsurface
Figure 6: Microfacies distribution at Kang Giap Kuari in Perlis.
in
Langkawi
and
Perlis
when there is fresh water recharge to the environment.
The final stage of cementation took place in deep burial in
reducing conditions. This has brought about the precipitation
of ferroan calcite as shown in Figure 7D
Dolomitization
Dolomitization is another dominant process that took
place in the limestone. About half of the rock volume in
the Setul Formation has been dolomitized. It involves direct
precipitation of dolomite minerals and also replacement
of calcite by dolomite. Early dolomitization occurs in
discontinuity in the rock mass such as stylolites. Most
dolomite in stylolites show fine and well formed crystals.
Meanwhile the replacive dolomite tends to occur everywhere
in the rock replacing matrix, grains and calcite cements.
Almost all samples contain some amount of dolomites.
The dolomite crystals show subhedral to euhedral
rhombohedron crystals with idiotopic texture. There is also
some hipidiotopic dolomite texture found in the samples.
Large dolomite crystals that were produced during
late stage deep burial diagenesis can also be found in the
samples. They are represented by baroque dolomites or
saddle dolomites. This type of dolomite is characterized by
big crystals with curved boundaries and showing undulose
extinction. Petrographic evidence clearly shows that there
Figure 7: Diagenesis in the Setul Limestone. A. Compaction
often produces fracture fabric in the rock. B. Loosely packed
fabric produced by dissolution in the limestone. C. Cementation
has plugged up all interparticle porosities. D. Late stage calcite
cementation precipitated ferroan calcite in the remaining pore
spaces. E. Replacive dolomitization produced dolomite crystals
seen floating in calcite cements. F. Late stage compaction postdates
cementation as seen in this image.
63
Micritization
Micritization is a process that took place soon after
the sediment was deposited. Observations in samples from
the Setul Formation show that most shelly materials and
algae have undergone micritization. Some peloids may
have resulted from prolonged micritization processes.
Micritization normally take place in quiet environment such
as lagoon or back reef areas.
Figure 8: Paleokarst as seen in a sequence on Pulau Langgun
Langkawi.
Figure 9: A late stage silica replacement found in a sample from
Kang Giap Quarry.
is a mutual exclusion between saddle dolomite and other
dolomite types
Compaction
It is a widely accepted fact that, increasing overburden
stresses on carbonate sediment will lead to compaction. In
the Setul Limestone, mechanical compaction which involves
rearrangement of particles and closer grain packing began
as soon as there is any overlying sediment. The effects of
compaction are more noticeable in more muddy sediments
where labile grains such as peloids have been compressed.
Chemical compaction and pressure solution are also very
common in the muddy sediment of the Setul Limestone. The
effect of chemical compaction is shown by the presence of
dissolution seams and stylolites. Dissolution seams which
lack the distinctive sutures of stylolites mostly go around and
between grains. It is assumed that dissolution seams were
formed at a very early stage during shallow burial as they
have low amplitude and no accumulated clay seams. This
phenomenon is common and has been widely described by
earlier workers (e.g. Bathurst, 1971; Rickens, 1985; Koch
& Schorr, 1986).
Unlike dissolution seams, stylolites are normally seen
in tightly cemented grainy limestone (packstone). Some
of them are seen cross-cutting the cements, indicating that
their formation postdate calcite cementations (Figure 13).
64
Dissolution and neomorphism
Dissolution is not a common feature found in this rock.
Where it is present dissolution is normally shown by the
poorly packed fabric with a lot of pore space. Dissolution
involves matrix and bioclasts especially bivalve and other
shell fragments. The pore spaces produced during dissolution
were later plugged up by calcite cement during deeper burial
diagenesis. Dissolution is normally related to the invasion of
fresh water into the rock formation especially when the rock
was exposed to the atmosphere during low sea-level. This
kind of dissolution normally produces micro karsts as shown
by a section on Pulau Langgun in Langkawi (Figure 8).
In contrasts to dissolution which involves destruction of
depositional fabrics, neomorphism often led to preservation
of the original structure of skeletal material. A considerable
portion of skeletal materials were altered into low Mg-Fecalcite. This type of neomorphism normally produced a
non-ferroan microspar mosaic. Neomorphism also occurs
in matrix and produced microspars.
Silicification
Silicification was also observed in the samples from
the Setul Limestone. Like dolomitization, silicification can
take place during early or late diagenesis (Tucker, 1991).
In the Setul Limestone silicification takes the form of
pervasive replacement. The silica occurs as microquartz and
calcedonic quartz replacing grains cement and matrix. The
nature of replacement indicates that silicification processes
took place very late in the diagenetic sequence of the Setul
Limestone (Figure 9).
Diagenetic sequence
The Setul Limestone has a long and complicated
diagenetic history. A wide spectrum of diagenetic processes
and products has been recognized including cementation,
near surface dissolution, dolomite precipitation and burial
calcite precipitation. Some of the processes were controlled
by relative sea-level changes.
The Setul Limestone diagenetic spectrum can be
subdivided into three stages: 1) early marine, 2) near surface
and 3) deep burial. The diagenetic sequence is depicted in
Table 2.
Early marine diagenesis is recorded by the presence of
fibrous cements. The fibrous cements grew in interskeletal
and intraskeletal pores. The cements were later stabilized,
recrystalized and evolved into bladed cements. The presence
of these cements seems to be very important in consolidating
the sediments.
Microfacies
Setul Limestone
Meteoric diagenetic processes occurred during the
relative sea-level lowstands and were only detected from
one locality on Pulau Langgun in Langkawi just below the
transgressive sequence. The second diagenetic stage took
place in the deeper burial environments and involved late
stage cement precipitation including blocky calcite and
saddle dolomite. Some of these diagenetic features were
later obliterated by the silicification processes that took
place at the latest stage.
DEPOSITIONAL ENVIRONMENT
Various environments of deposition in the Setul
Limestone have been identified. These include tidal flat,
lagoon or protected environment, skeletal shoal and deeper
outer ramp. Muddy microfacies with wavy stromatolites
laminae or laterally linked hemispheroids can be interpreted
to represent tidal flat deposits or on protected shorelines
(Hoffman, 1976). Most of the other fine grained facies
including mudstone and wackestone were deposited either
in protected environments or deepwater outer ramp areas.
Coarse-grained microfacies such as packstone and grainstone
could represent higher energy setting in shallower water
areas such as skeletal banks. The abundance of peloidal
materials in the limestone again reflects the quietness of the
depositional environment in general during the deposition
of the Setul Limestone
According to Wright (1990) stromatolites morphology
can be used as an indicator of energy condition. The presence
of columnar stromatolites in the Kang Giap Quarry in Perlis
(Figure 2E) reflects deeper water condition with high energy
setting. In Shark Bay, this type of stromatolites occurs on
headlands fully exposed to waves.
The overall facies indicates the changes in environment
of deposition that might have been controlled by the sealevel changes. The relationship between the facies and the
sea-level changes is shown in Figure 10.
CONCLUSION
Generally, the rock of the Setul Formation is muddy
in nature as shown by the presence of abundant muddy
microfacies. The rock also contains both shallow and deep
marine elements. The presence of tentatculites, graptolites
and loboliths indicates that there were times when the
limestone was deposited in deeper marine condition as shown
in Figure 10. In contrast, there are also evidences that point
to very shallow water conditions as shown by the presence
of shallow marine benthic fossils such as brachiopods and
trilobites. At a locality on the Langgun island there is even an
indication of sub-aerial dissolution preserved in the sequence.
In conclusion, it can be said that the Setul Limestone was
deposited in a ramp setting with depositional environments
ranging from intertidal to deep open marine. The limestone
is also rich in peloidal and algal materials. In places peloids
become the main component in this limestone and it could
be related in origin to coccoidal microbes. Normally peloids
collect in lagoons and shallow intertidal zones where they
are protected from rough ocean currents. Sun and Wright
in
Langkawi
and
Perlis
(1989) who studied the limestone in the Weald Basin have
interpreted that peloids were produced microbially either
by direct precipitation or by induction in areas which had
relatively low framework growth rate, low sedimentation
rate and moderate energy level.
The limestone has undergone complete diagenetic
processes right from the time of deposition at the surface
up to the time when it was buried deep in the subsurface.
Petrographic evidences show that during deposition and
near surface burial the sediment was affected by very little
early marine cementation as shown by the rare occurrence
Table 2: Paradiagenesis of the Setul Formation.
Figure 10.:A composite log measured at the Kang giap Quarry
showing the facies changes, major limestone components and the
interpretation of the relative sea-level during deposition.
65
of early marine cementation in the rock sequence. This
evidence together with the fossil occurrence support the
earlier interpretation that most of the sediment was deposited
in deeper water setting except for the algal rich part of
the limestone facies. Soon after deposition, the sediment
was subjected to compaction that resulted in development
dissolution seams and distortion of labile grains such as
peloids. During the depositional processes there were times
when the area was subject to the sub aerial exposure due the
lowering of sea-level. This has resulted in the formation of the
karstic surface. Further burial processes have produced late
stage calcite cementation represented by large crystal calcite
mosaic crystals followed by dolomitization. Dolomitization
took place in two phases. The first phase of dolomitization
occurred mainly through stylolites and spread outwards
replacing whatever material that contain high amount of
magnesium (high magnesium calcite) whilst the second phase
occurred very late and produced large crystals of saddle
dolomite. All in all, the Setul Limestone was deposited in
a broad depositional setting ranging from shallow to deep
marine condition and experienced all stage of diagenetic
sequence in it history. The Lower Setul Limestone was
basically deposited in shallow marine conditions. At one
stage there are areas where the sediments were exposed to the
atmosphere. This phenomenon marked the end the deposition
of the Lower Setul Limestone. It was then transgressed
by the sea water leaving behind an evidence of shallow
water inundation as shown by the presence of the trilobite
layer in the lower part of the Lower Clastic Member. The
environmental deposition of the Lower Detrital Member
was then drastically change to deep marine as shown by
the occurrence of thinly bedded cherty mudstone in the
top of this sequence. Then suddenly the area once again
witnessed the change of sediment type to generally muddy
carbonates in the area during the deposition of the Upper
Setul Limestone. This limestone member was deposited
in deeper marine conditions as shown by the presence of
Scypocrinites lobolith and tentaculites in this part of the
Setul Limestone. It was then followed by the deposition of
another clastic interval of the Upper Detrital Member which
also occurred in deep marine conditions. Evidence of deep
marine again was shown by the presence of tentaculites in
this member.
ACKNOWLEDGEMENT
We wish to thank Lee, C.P for his critical revision of
the manuscript. This paper was produced from the fieldwork
funded by grants from GUP (DPP-2013-065) and PIP-2013001 of Universiti Kebangsaan Malaysia.
REFERENCE
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carbonates in nearly closed reef environments: Mataiva and
Takapoto atolls, central Pacific Ocean. Sedimentary Geology
67, 115–132.
Bathurst, R. G. C. 1971. Carbonate Sediments and their Diagenesis.
Elsevier, Amsterdam, 620 pp
Dunham, R.J. 1962. Classification of carbonate rocks according
to depositional texture. In: Classification of Carbonate Rocks
(Ed. By W.E. Ham) Mem. Am. Ass. Petro. Geol. 1, 108 – 121.
Friedman, G.M. & Johnson K.G. 1992. Exercise in Sedimentology.
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Gischler, E., Dietrich, S., Harris, D.,. Webster, J. M. & Ginsburg
R. N., 2013. A comparative study of modern carbonate mud
in reefs and carbonate platforms: Mostly biogenic, some
precipitated. Sedimentary Geology 292, 35-55.
Gobbett, D.J. & Hutchison, C.S., 1973. Geology of the Malay
Peninsular. Wiley Interscience, New York, p 61-96.
Hoffman, P. ,1976. Environmental diversity of Middle Precambrian
stromatolites. In: Stromatlites (Ed. By M.R. Walter) Elsevier,
Amsterdam, 599 – 611.
Jones, C.R., 1981. The Geology and Mineral Resources of Perlis,
North Kedah and the Langkawi Islands., District Memoir 17.
Geological Survey Malaysia, 257 pp
Kendall, A.C., 1985. Radiaxial fibrous calcite: a reappraisal. In:
N. Schneidermann & P.M. Harris (eds) Carbonate Cements.
Spec. Publ. Soc Econ. Paleont. Miner. 36, 59-77.
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(eds.) Reef Diagenesis, 211-224.
Lee C.P., 2001. Occurrences of Scyphocrinites loboliths in the Upper
Silurian Upper Setul limestone of Pulau Langgun, Langkawi,
Proceedings Annual Geological Conference, Pangkor Island,
Perak, 2nd–3rd June (2001) . 99–104
Lee, C.P., 2005. Discovery of plate-type scyphocrinoid loboliths
in the uppermost Pridolian – lowermost Lokhovian Upper
Setul Limestone of Peninsular Malaysia. Geological Journal,
vol. 40, 331-342.
Rickens, W., 1985. Epicontinental marl-limestone alternations: Event
deposition and diagenetic bedding ( Upper Jurassic, Southwest
Germany). Lecture Notes in Earth Sciences Volume 1, 127-162
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Rocks. Blackie Glasgow, 274 pp
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reefal limestone, Weald basin, Southern England. Sedimentary
Geology, V. 65, Issues 1-2, 165-181.
Tucker, M. E., 1991. Sedimentary Petrology. Blackwell Scientific
Publication, 260 pp.
Wilson, J. L., 1975. Carbonate Facies in Geologic History. SpringerVerlag New York Heidelberg Berlin, 471pp
Wright, V.P., 1990. Reefs. In: M.E. Tucker & V.P. Wright (eds.)
Carbonate Sedimentology. Blackwell Scientific Publications,
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Manuscript received 21 January 2010
Revised manuscript received 23 October 2013
66
Evidence of Holocene and historical changes of sea level in the
Langkawi Islands
H.D. Tjia
Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor
Email address: tjiahd@gmail.com
Abstract: About eighty radiometrically dated biogenic and morphological indicators of sea level of the Langkawi Islands
prove that since the maximum Mid-Holocene inundation, the paleo-sea surface descended stepwise thrice to reach its
current position several hundred years ago. In presumably historical time some parts of the island group were raised
between 0.5 and one meter. One of such events was related to the Aceh/Simeulue mega-earthquake of December 2004
which caused live bands of rock-clinging oysters and barnacles to shift 30 to 40 centimeters upward at Teluk Burau. GPS
study also yields evidence of 9 to 11 millimeters co-seismic uplift of the northwestern sector of Peninsular Malaysia.
The anomalously high sea stands in the early part of the Holocene and latest Pleistocene in northwestern Peninsular
Malaysia remain the most outstanding issue in this investigation. Comparison with recently published sea-level curves
of the Sunda Shelf strongly suggests that the geoid of the Strait of Malacca was 50 to 40 meters higher in the period of
the LGM (Last Glacial Maximum: 21 ka to 19 ka) to the early half of the Holocene at 10 ka to 5 ka. In the early period
of the Holocene, sea level was still up to 24 meters higher than over the Sunda Shelf.
Keywords: geoid high, stepwise descent since Mid-Holocene, effect of Aceh mega-earthquake.
INTRODUCTION
Peninsular Malaysia is located on the Sunda subplate,
which has the geological characteristics of a Cenozoic semicratonic platform devoid of explosive andesitic volcanism,
of strong vertical movement, of tectonically folded Tertiary
sediments, and of devastating seismicity. The geological
outcrops are also predominantly of pre-Tertiary age, implying
absence of major subsidence in the Cenozoic. Magnitude
of long-term vertical displacement of the crust is in the
hundredths to thousandths millimeters per year range and
is thus distinctly different from centimeter-rates of crustal
uplift and subsidence associated with reef terraces in the
tectonically mobile island arcs framing the Sunda subplate.
Figure 1 indexes the localities treated in this article.
Recent observations, however, have yielded evidence
of moderate but localised co-seismic ground disturbance,
morphological anomalies and GPS- determined ground
movements in historical time that imply minor differential
crustal deformation in the Langkawi Islands. The dated
evidence is discussed according to three periods, that is, with
reference to latest Pleistocene - Early Holocene sea stands,
with respect to the systematically descending sea levels
during the Mid-Holocene to the present interval, and those
that occurred in historical time. The radiometrically dated
evidence for paleo-sea levels of the Peninsular Malaysia
region are tabulated in Tjia & Sharifah Mastura (2013). The
paleo-sea level data include geographic coordinates, type of
dated material, position with respect to current sea level (most
commonly the in situ determined high-tide), the radiocarbon
ages and the associated laboratory or original publication.
The age of shoreline indicators consisting of marine material
has also been corrected for the ‘marine reservoir effect’.
At this stage of knowledge, the correction applied was by
subtracting 400 years from all previously published age
data. No MRE correction is needed for radiometric ages
of plant material (mainly mangrove and peat).
Figure 1: Index of localities mentioned in the article. Width of the
main island measures 70 kilometers.
H.D. Tjia
LATEST PLEISTOCENE TO EARLY HOLOCENE
SEA LEVELS
A score of fossil mangrove and peat material from the
bottom of the Strait of Malacca define the Late Pleistocene
to Early Holocene sea stands (Geyh et al., 1979; Streif,
1979). Figure 2 compiles this information showing a
steadily rising sea from a depth of around 68 meters about
Figure 2: The Late Pleistocene to Early Holocene sea levels indicated
by radiocarbon ages of paleo-shoreline indicators in Strait Malacca
and Langkawi Islands. The questionable data points concern plant
material (including ‘wood’) without specific reference to sea level.
34 000 years ago to reach current sea level position by the
Mid-Holocene. The average rate of inundation amounts to
2.4 millimeters annually. The available data points suggest
that, during the Last Glacial Minimum (LGM) at 21 to 19 k
years ago, sea level in the Strait was at least 75-80 meters
higher than the -130 m lowstand generally accepted for that
period. Shorelines of the Early Holocene are represented by
a scatter of data points time-wise and also in elevation sense
An extreme elevation of 23 m above high tide was reported
for fossil rock-clinging oysters occurring in a notch in the
Setul Limestone of Pulau Tanjung Dendang (Zaiton Harun
et al., 2000). The notch profile is of the fish-hook type and
should have been related to stable crustal condition of the
sample location. Figure 3 illustrates the two contrasting
basic notch profiles that develop on a tectonically stable
coast (fish-hook) and tectonically rising coast (lazy-V). The
deepest cut of a notch corresponds with mean sea level;
the opening height is dependent on tidal range and arriving
wave strength. The lower, gently sloping segment of the
fish-hook notch merges very gradually into the almost-level
wave-base position. In contrast the lower sloping arm of
the lazy-V notch joins the wave-base level with a distinct
break-in-slope (Figure 3).
During this period between 34k and 5k years, sea stands
in the Strait of Malacca (including the Langkawi Islands)
were thus significantly higher compared to those interpreted
for western Southeast Asia as a whole (e.g. Sathiamurthy
& Vorhis, 2006). Hanebuth et al. (2000) showed sea-level
over the Sunda Shelf during the period 14.6 - 14.3 ka to
have risen from -96 m to - 80 m. During the same period
the Strait of Malacca was covered by about 40-meter deep
sea, again indicating a 40 to 50 m difference from that of
the South China Sea (Figure 4). One plausible cause could
Figure 3: Notches in limestone cliffs. (a) and (b) are of the lazy-V
type characteristic for rising coasts in tectonically mobile regions:
respectively Selu Island (Tanimbar group, Outer Banda Arc, eastern
Indonesia) and Semporna (eastern Sabah). Its MRE corrected
radiocarbon age is 18 630 + 450 y BP. At that time of the LGM,
Figure 4: Radiometrically dated paleo-sea level indicators
global seas were at their minimum position at least 100 m below
representing Peninsular Malaysia. Five pre-6000 y BP data points
current datum. The Semporna reef sample represents tectonic uplift
from Langkawi presumably relate to a high geoid position. Most
of > 102 m or an average of 5.5 mm each year. Figures 3 (c) and (d)
of data points fall within the two wavy solid lines as well as within
illustrate fish-hook type notches in the limestone cliff of Kodiang
the stepwise descending grey zone. Elevation and occurrence of
(Kedah) and Pulau Tanjung Dendang, Langkawi, respectively. The
stacked notches in Langkawi and elsewhere in the Peninsula are
fish-hook notch profile of (d) implies the current high position of
in agreement with the stepwise descent of the sea during the Later
the Mid-Holocene rock-clinging oysters was reached by secular
Holocene (discussion in the text). Each of the paleosea stillstands
drop of sea level.
lasted 1000 to 1200 years.
68
Evidence
of
Holocene
and historical changes of sea level in the
be that the geoid had a different configuration. At present,
the Strait of Malacca roughly coincides with a neutral geoid.
zone that demarcates a positively high geoid culminating
some 60 meters in the New Guinea region from a negative
geoid region that reaches a deep 100 meters depression in
the Srilangka region. During a reduction of the angular
velocity of the Earth’s rotation, geoidal relief will probably
“flatten” and its neutral zone shifts westward. This westward
shift brings Peninsular Malaysia into the positive geoidal
region concomitant with high sea stands.
Radiometrically dated paleo-sea level indicators of
Peninsular Malaysia is shown on Figure 4. Seven of the data
points represent sea stands in the pre-6000 y BP interval. Five
of these data points originate from the Langkawi Islands and
possess distinctly anomalous positions with respect to the
projected sea level rise in the Malacca Strait (single black
line on Figure 2). Sea levels during the Early Holocene (10
k to 6 k years) in Langkawi were 20 to 24 m higher than
projected. The most extremely high position is that of 6600
years BP rock-clinging oysters at Pulau Tanjung Dendang
situated 24 m above current mean sea level (Zaiton Harun
et al., 2000). The fossil oysters are hosted in a typical fishhook notch profile (Figure 2d) which should correspond
with a tectonically stable substrate. These five anomalously
high paleo-sea level indicators of Langkawi most probably
represent a geoid high.
The other two post-6000 y BP data points are from
the west coast and from the east coast of the Peninsula,
respectively.
MID - HOLOCENE TO RECENT SEA STANDS
Approximately 80 data points of paleo-sea level
indicators on the coasts of Peninsular Malaysia define
secular changes during the later part of the Holocene
(Figure 4). More than a third of the data points originates
from the Langkawi Islands and nearby shores of Perlis and
northern Kedah. The paleo-sea level indicators include fossil
rock-clinging oysters, mollusc beach ridges, coral, some
calcareous algal crusts, calcareous beachrock, and coastal
plant remains, notably mangrove parts. The radiometric
ages of the paleo-sea level indicators of marine origin were
adjusted for marine reservoir effect, which at this stage was
determined to be 400 years younger. The MRE adjustment
possibly needs refinement when new reliable standards
become available.
The scatter of data points is generally contained within
either the progressively descending zone demarcated by the
wavy black solid lines, or reside within the step-like grey
zone. A third and simpler explanation favoured by other
paleo-sea level researchers is for a Mid-Holocene high sea
level in Peninsular Malaysia between 5000 and 4000 y BP
followed by a general decrease to the present datum level.
This opinion is, however, not borne out by field observations
or clustering of radiocarbon ages of paleo-sea level indicators
as will be shown below. The scatter of data points in terms
of elevation may be attributed to various uncertainties in
determining the corresponding position of the paleo-sea.
Langkawi Islands
Among these are range of paleotides, the original position
of the fossil oyster within the paleotidal range, and paleowave height influenced by coastal configuration at different
elevation of the former seas. The material collected for the
laboratory analysis was measured at the site with respect
of the reigning high tide level, which is the most practical
benchmark recognisable as slope breaks of the beach surface,
up-beach limit of loose shells and other flotsam. The hightide mark may vary in excess of a meter depending on the
season. In view of these variables, it has been impractical to
apply corrections to the vertical positions of the paleo-sea
indicators. Nevertheless, the distinct clustering of data points
in Figure 4 has been considered sufficiently representative
of the paleo-sea level changes of the younger part of the
Holocene.
Initially my close collaborators on paleo-sea levels
and I (Tjia et al., 1977) preferred the wave-like descent of
sea level since the Mid-Holocene for Peninsular Malaysia.
Resulting from many follow-up studies, including coastal
observations on other islands of the tectonically stable
Sunda Shelf, e,g, the Indonesian tin islands of Bangka,
Belitung and Kundur, it became clear that stacked LaterHolocene sea level indicators are common occurrences.
The compelling evidence consists of sea-level notches and
clusters of fossil rock-clinging oysters arranged at three or
more levels at various locations in the region. A still stand
-however temporary- of sea level is required to develop the
notches. Still stands of the descending post-Mid Holocene
sea are best explained by the stepwise descent in Figure
4. Figure 5 illustrates the situation at Pulau Ular, a small
islet just off the southwest coast of Langkawi main island.
Pulau Ular consists of the Permo-Carboniferous Singa
Formation that crops out as three low hills protruding
several meters from a base of a well-developed abrasion
platform approximately 1 to 1.5 m above current high tide.
Three notches at 5.5 m, 2.7 m and corresponding with the
1.5 meter above high tide abrasion platform are stacked on
the face of the northern hill side. The lowest notch is of a
typical fish-hook type. The elevations of the three notches
correspond with paleo-sea levels at around 2300 y BP (1.5
m above high tide), 4400 - 3800 y BP (2.7 m aht), and the
Mid-Holocene inundation peak between 5000 and 4400 y
BP (5.5 m high notch).
An other example suggesting stepwise change of paleosea level during post-Mid Holocene are several abrasion
terraces cut across granite at Teluk Burau which is located
on the west central coast of Langkawi main island (Figure
6, upper). Four levels of abrasion benches, each several
meters wide correspond with former low-tides at 0.5 m aht
(above high tide, or a corresponding sea level at 1.5 m),
1.75 - 2 m aht (representing 2.75 to 3 paleo-sea level), 3.5
m aht (its associated paleo-sea level was 4.5 m) and 5.5 m
aht (of paleo-sea level at 6.5 m). Each of the virtually level
bench surfaces indicates approximately the corresponding
wave base or paleo-low-tide .
The lower Figure 6 is a synoptic sketch of fossil oyster
positions within Gua Kelawar, a short through cave in the
69
H.D. Tjia
Kilim Geoforest Park, northwest Langkawi. The higher
oyster cluster is located 1.2 m to 2.2 m above current high
tide; the lower oyster cluster is 0.35 to 0.4 m above high
tide. Samples GK-1 and Gk-2 were collected for pending
radiocarbon age analysis. The Gua Kelawar fossil oysters
suggest that no sun or day light was required for their
existence. Note also the so called ‘wind-vane’ stalactites
at one of the exits of Gua Kelawar.
General tectonic stability of the main Langkawi Island
is also demonstrated by the well-developed fish-hook notch
on the cliff of a small peninsula of Setul Limestone located
on the southeast of the big island (Figure 7). The crystalline
Setul Limestone is laced with crinkly siliceous laminations
mistakenly indicated as ‘stylolites’ in the ‘Geology of
the Malay Peninsula’ (Jones, 1973, p. 35). The smooth,
uniformly abraded surface of the lower leg of the notch
distinctly contradicts the notion that notches in coastal
limestone cliffs are products of bio-erosion (Hodgkin,
1970). Instead mechanical down wear or abrasion has been
the cause. Figure 7 further shows the top limit of live rockclinging oysters equates with the high tide level.
CRUSTAL DEFORMATION IN HISTORICAL TIME
In historical time, crustal deformation of parts of the
Langkawi Islands are implied by the following evidence.
Analysis of GPS records of ground movements
attributed to the 26 December 2004 mega-earthquake of
Simeulue in the Indian Ocean west of Aceh in northern
Sumatera, shows vertical displacements in Peninsular
Malaysia. Ami Hassan Md Din et al. (2012) computed 9 to
11 mm uplift in GPS stations in Perlis and northern Kedah,
while recording subsidence of similar values for southwest
Johor. The co-seismic ground displacements were lowest
in Negeri Sembilan-Selangor region.
Just two years and a few months after the December
2004 disaster, the coastal exposure at Teluk Burau, westcentral part of Langkawi, was captured in Figure 8. Live
barnacles occupy positions up to 30 centimeters above the
top of rock-clinging oyster clusters, a position commonly
seen on Malaysian shores. The top limit of growing oysters
also marks the maximum reach of high tide. The exposure
at Teluk Burau consists of two barnacle- oyster bands. The
upper band of 54 centimeters is populated by live specimens.
The small size of the live oysters indicate young age. This
upper barnacle-oyster association is followed downward
by a 35 cm lower barnacle-oyster band that ultimately
disappears below loose beach sand (Figure 8), whose surface
is approximately a meter above current low tide. The lower
barnacle-oyster band has no living individuals and the dead
oyster shells have a greenish sheen. The exposure at Teluk
Burau appears to indicate: (a) very recent -in historical
sense- ground subsidence of at least 35 cm that caused
beach sand to smother the lower barnacle-oyster association;
(b) followed by uninterrupted development of a younger
barnacle-oyster band higher up on the same granite surface;
and finally (c) scouring by tidal currents that re-exposed
part of the lower dead barnacle-oyster band. The youthful
small size of the live oysters could well equate with growth
following the tsunami inundation of the western coast of
Langkawi which accompanied the Simeulue mega-quake
of December 2004.
Figure 6: More stacked paleosea-level indicators in Langkawi.
Upper: Four abrasion benches at 0.5 m, 1.75 - 2 m, 3.5 m and 5.5
m aht were cut across hard granite . Lower: In the dark throughcave named Gua Kelawar, Setul Limestone of the Kilim Geoforest
Figure 5: Three sea-level notches stacked in the cliff of Pulau Ular
Park, are two clusters of fossil rock-clinging oysters. The higher
that consists of clastics of the Late Paleozoic Singa Formation.
cluster extends from 2.2 m to 1.2 m aht; the lower cluster is 0.35 to
Development of each notch would require the paleosea to have
0.4 m aht. The higher oyster cluster may be of near Mid-Holocene
maintained position for some duration. Figure 4 suggests that the
age; the lower could be in the 2 ka - 3 ka age bracket according to
paleoseas associated with the notches existed between 5 ka and 4 ka
Figure 4. Radiometric dating of samples GK-1 and GK-2 should
(forming the 5.5 m aht notch), 4.4 ka and 3.8 ka (2.7 m aht notch),
provide reliabler ages. Note the so called ‘wind-vane’ stalactites at
and ~2.3 ka (1.5 m aht notch with corresponding abrasion platform).
the cave entrance. Similar forms are common in limestone caves.
70
Evidence
of
Holocene
and historical changes of sea level in the
Stacked, relatively shallow notches in the Setul
Limestone of the Kilim Geoforest Park are exposed along the
Kilim river and its branches. Figure 9 illustrates three stacked
notches. The photograph was taken at the approximate time
of mean sea level that corresponds with the lowest exposed
notch position. The top limit of live rock-clinging oyster
cluster is ~1.5 m above this lowest notch. Approximately
0.5 m above the live oyster limit is a relatively shallow
notch with irregular lateral extent. This notch is oblique to
stratification of the limestone which is moderately steep.
Figure 7: A typical fish-hook notch profile in Setul Limestone of
Penarak, small promontory in SE Langkawi. The Setul Limestone
is laced with subparallel ~ 1 cm wide siliceous laminae that are
harder than the host limestone. The lower leg of the notch profile is
smooth, thus proving that mechanical abrasion was the cause. Bioerosion could not be expected to evenly smoothed out the surface as
grazing and other forms of feeding by organisms would have been
discrminatory. Further discussion was published earlier (Tjia 1985).
Langkawi Islands
Although irregular, the notch closely parallels the sea surface.
A well-developed notch is ~ 1.2 m above the top limit of
live oysters. This notch has a lazy-V profile (marked X)
that should represent formation associated with falling sea
level caused by land uplift.
In the limestone cliffs along Pantai Beringin, a stretch
of only a few hundred meters long between Pantai Syed
Omar and Tanjung Cawat, southeast Langkawi, both lazy-V
together with fish-hook notch profiles occur side by side
close above present sea level. The occurrence is interpreted
as result of recent differential ‘tectonic’ behaviour, that is
presumably attributable to compartmentalisation of the
coastal stretch. The Kisap Thrust zone runs nearby (see
Jones 1978, pages 158-170; and also Figure 1). Apparently
ground disturbance -in historical time as the closeness to
current sea level suggests- only affected the coast with
lazy-V notch profile.
CONCLUSIONS
During the period of ~ 36 ka to ~5 ka (latest Pleistocene
to Mid-Holocene) sea level in the Langkawi-Malacca Strait
zone was between 40 m to 24 m higher compared to sea
level on the Sunda Shelf of the South China Sea. This
condition can be attributed to a geoid configuration that
differed from the current situation. Currently the roughly
North-South trending zero geoid zone occupies Strait
Malacca. A prominent geoid high (+80 m) is located in
the West Papua region 42 degrees longitude to the East of
the Strait, while a current geoid depression (-100 m) lies
off Srilangka some 20 degrees to the West. If the Earth’s
rotation decreases, one could expect the geoid relief to
flatten and to shift westward. The opposite will probably
happen if the angular velocity accelerates.
Figure 8: Teluk Burau, two years and five months following the
mega-disaster caused by the Simeulue and Indian Ocean-wide
tsunami, hosts the exposure in the figure. A dead barnacle-oyster band
Figure 9: Three notches in the Setul Limetone lining Sungai Kilim.
and a higher positioned growing barnacle-oyster band are attached
The lowermost notch corresponds with current mean sea level
to the same granite surface of a coastal outcrop. The occurrence
position. A shallow notch that extends laterally in irregular fashion
suggests that the lower barnacle-oyster band was recently buried
is 0.5 m above current high tide, which corresponds with the top
and killed by land subsidence of at least 35 cm. A new band of the
limit of the cluster of rock-clinging oysters. A higher, shallow but
organisms grew at the higher level. Tidal currents exhumed the
well-developed notch is located 1.2 m above current high tide. Its
lower band just before the photograph was taken.
lazy-V profile is at X.
71
H.D. Tjia
From the Mid-Holocene maximum inundation of the
region at 4400 yr BP onward, regional sea level progressively
dropped stepwise three times. Periods of sea level stillstands,
each of about 1100 to 1200 years duration, allow abrasion
to develop level benches on hard rock (granite at Teluk
Burau) and notches on limestone cliffs. Figure 4 shows the
elevation of the stepwise descent.
Effects of mega-earthquakes, estimated to occur in
periods of 400 to 1000 years apart, appear to have extended
into the Langkawi areas. Local crustal deformation of the
Simeulue event of December 2004 probably caused the 35cm ground subsidence at Teluk Burau burying and killing
a band of barnacle-oyster while permitting a new barnacleoyster band to evolve at a higher elevation (Figure 8).
The majority of notches in Langkawi are of the fishhook type indicating development during ground stability.
At Pantai Beringin and nearby Tanjung Cawat notches of
the fish-hook as well as of the lazy-V types are located side
by side and occur close to current mean sea level.Their
position with respect to the current sea surface implies
recent ages. Compartmentalisation by the Kisap Thrust
zone may account for differential ground instability along
this short coastal reach.
REFERENCES
Ami Hassan Md Din, Kamaludin Mohd Omar, M. Naejie & Sharum
Ses, 2012. Long-term sea level change in the Malaysian seas
from multi-mission altimetery data. International Journal of
Physical Sciences, 7 (10), 1694-1712.
Geyh, M.A., Kudrass, H.R. & Streif, H. 1979, Sea level changes
during the Late Pleistocene and Holocene in the Strait of
Malacca. Nature 278 (5703), 441-443.
Hanebuth, T., Stattegger K. & Grootes, P.M., 2000. Rapid flooding
of the Sunda Shelf: A Late-Glacial sea-level record. Science
288, 1033-1035.
Hodgkin, E.P., 1970. Geomorphology and biological erosion of
limestone coasts in Malaysia. Geological Society of Malaysia,
Bulletin 3, 27-51.
Jones, C.R., 1978. Geology and Mineral Resources of Perlis, North
Kedah and the Langkawi Islands. Geological Survey Malaysia,
District Memoir 17, 257 pp.
Jones, C.R., 1973. Lower Paleozoic. In: Gobbett, D.J. & Hutchison,
C.S. (eds.) Geology of the Malay Peninsula. New York, Wiley,
25-60.
Sathimurthy, E. & Vorhis, H.K., 2006. Maps of the Holocene
transgression and submerged lakes on the Sunda Shelf. The
Natural History Journal of the Chulalongkorn University,
Supplement 2, 1-44.
Streif, H., 1979. Holocene sea level changes in the Straits of Malacca.
In Proceedings 1978 International Symposium on Coastal
Evolution in the Quaternary, Sao Paolo, Bresil: 552-572.
Tjia, H.D., 1985. Notching by abrasion on a limestone coast.
Zeitschrift fuer Geomorphologie 29 (3), 367-372.
Tjia, H.D., 1996. Sea-level changes in the tectonically stable MalayThai Peninsula. Quaternary International 31, 95-101.
Tjia, H.D. Fujii, S. & Kigoshi, K., 1977. Changes of sea level in
the southern South China Sea area during Quaternary times.
United Nations, ESCAP-CCOP Technical Publication 5, 11-36.
Tjia, H.D. & Sharifah Mastura Syed Abdullah, 2013. Sea Level
Changes in Peninsular Malaysia: A Geological Record. Penerbit
Universiti Kebangsaan Malaysia, Bangi, 1-146.
Zaiton Harun, Basir Jasin & Kamal Roslan Mohamed, 2000.
Takik laut kuno: Suatu warisan tabii yang perlu dipulihara.
Warisan Geologi Malaysia: Pengembangan sumber untuk
pemuliharaan dan pelancongan tabii, 3, Universiti Kebangsaan
Malaysia,163-172.
Manuscript received 19 April 2013
72
Input geologi untuk Sistem Sokongan Membuat Keputusan dalam
pengurusan risiko bencana: Kajian kes
Universiti Kebangsaan Malaysia
Nurfashareena Muhamad, Choun-Sian Lim, Mohammad Imam Hasan Reza &
Joy Jacqueline Pereira*
Southeast Asia Disaster Prevention Research Institute (SEADPRI)
*Email address: joy@ukm.my
Abstrak: Kajian ini menerangkan tentang penggunaan maklumat geologi dan penilaian terain dalam Sistem Sokongan
Membuat Keputusan (Decision Support System, DSS) untuk menangani masalah kejadian tanah runtuh di kampus Universiti
Kebangsaan Malaysia (UKM) Bangi, Malaysia. Zon-zon prioriti telah diperolehi daripada analisis sistematik data lapangan
dan tindan-lapis peta terain geologi, lokasi tanah runtuh dan pelbagai elemen berisiko dengan menggunakan teknologi Sistem
Maklumat Geografi. Antara kriteria-kriteria yang digunakan untuk mengenal pasti zon-zon prioriti tersebut ialah keseriusan
impak tanah runtuh, keboleh-tangani melalui langkah pencegahan, keterdesakan dalam keperluan untuk menyelesaikan
masalah dan potensi kemerosotan. Berdasarkan hasil yang diperolehi, DSS berasaskan geologi memudahkan Jabatan
Pembangunan dan Penyelenggaraan (JPP) UKM dalam perancangan dan membuat keputusan terhadap zon-zon tersebut.
Kata kunci: Sistem Sokongan Membuat Keputusan, tanah runtuh, peta terain geologi, zon prioriti
Geological input for Decision Support System to manage the risk of disasters:
A case study of Universiti Kebangsaan Malaysia
Abstract: This paper describes the use of geological information and terrain assessment in a Decision Support System
(DSS) to address landslide problems in the campus of Universiti Kebangsaan Malaysia (UKM) in Bangi, Malaysia.
Zones of priority were derived from systematic analysis of field data and overlays of the geological terrain map, landslide
location, and various elements at-risk, using Geographic Information System (GIS). Among the criteria used to identify
the zones of priority are seriousness of landslide impacts, manageability of mitigating measures, urgency in the need to
resolve the problem and the potential for further deterioration. Results indicate that this geological-based DSS facilitates
the Development and Maintenance Department (Jabatan Pembangunan dan Penyelenggaraan, JPP) of UKM in planning
and decision-making with respect to such zones.
Keywords: Decision Support System, landslide, geological terrain mapping, priority zones
PENGENALAN
Kekerapan berlakunya kejadian bencana seringkali
berkait rapat dengan kepesatan dan kemajuan serta
pertambahan kepadatan populasi sesebuah negara (Coppola,
2007). Bencana biasanya peristiwa katastropik yang
berpunca daripada bahaya yang bersifat semulajadi serta
bahaya cetusan manusia yang umumnya bersifat teknologi
dan sengaja ataupun antropogenik (Lim, 2004; Coppola,
2007). Kemusnahan akibat daripada bencana sukar untuk
diukur malah ia seringkali berbeza-beza mengikut lokasi
geografi dan tahap kerentanannya (Ghosh, 2012). Bagi
kebanyakan negara Asia, bahaya yang bersifat semulajadi
seperti tanah runtuh, banjir, gempa bumi, letusan gunung
berapi, ribut dan tsunami menjadi kebimbangan paling
utama (Kishore, 2003; Billa et al., 2006; UNISDR, 2006;
Djalante & Thomalla, 2012). Jenis-jenis bahaya semulajadi
yang dihadapi oleh sesuatu negara juga bergantung kepada
keadaan iklim, geografi, geologi dan amalan penggunaan
tanah negara tersebut. Bahaya semulajadi seperti ini
seterusnya berganjak menjadi malapetaka ataupun bencana
apabila berlakunya kemusnahan harta benda, infrastruktur,
kehilangan nyawa, gangguan ekonomi, kemusnahan alam
sekitar serta mengganggu fungsi kehidupan (McEntire, 2001;
Coppola, 2007; Palliyaguru et al., 2010).
Di samping itu, banyak kajian literatur telah menjelaskan
bahawa bencana lebih cenderung berlaku di kawasan bandar
malah kesannya adalah lebih signifikan (Bendimerad, 2003;
Bull-Kamaga et al., 2003; Wisner et al., 2003; Khailani &
Perera, 2013). Dalam Satterthwaite et al. (2007), kawasan
bandar ditafsirkan sebagai rumah kepada sebahagian
besar populasi di dunia, aktiviti-aktiviti ekonomi dan
infrastruktur fizikal yang sudah sedia ada berisiko bahaya
dan kemudiannya dijangka akan bertambah serta bertukar
menjadi bencana. Proses pembangunan kawasan bandar
dikenali sebagai perbandaran. Sungguhpun aktiviti-aktiviti
perbandaran sebenarnya membawa kemajuan kepada
Nurfashareena Muhamad, Choun-Sian Lim, Mohammad Imam Hasan Reza, & Joy Jacqueline Pereira
sesebuah negara, namun, secara tidak langsung, proses ini
mengalu-alukan juga kesan negatif terhadap alam sekitar
sekiranya tidak ditadbir-urus secara lestari. Kesan-kesan
daripada aktiviti perbandaran adalah seperti kepadatan
populasi penduduk, aktiviti pembangunan yang tidak
terancang, aktiviti-aktiviti antropogenik yang lain dicetuskan
oleh manusia dan sebagainya sebenarnya merupakan faktor
penyumbang kepada bencana. Lantaran, aktiviti-aktiviti ini
telah meletakkan bandar sebagai kawasan yang terdedah
kepada bencana (disaster prone area); dan juga rentan
(vulnerable) apabila terdapat banyak unsur yang mengalami
risiko (elements at risk) seperti nyawa manusia (warga kota
dan pelawat), harta benda (bangunan dan infrastruktur), dan
perkhidmatan (services). Justeru itu, kawasan bandar yang
telah ditenggelami oleh aktiviti perbandaran yang pesat
telah mendedahkan masyarakat tempatan untuk hidup di
kawasan yang terdedah pada risiko bencana. Seperti yang
sedia tahu, bencana tidak dapat dielakkan, malahan adalah
mustahil untuk kerosakan dan kemusnahan akibat daripada
bencana untuk pulih sepenuhnya (Billa et al., 2006). Namun,
usaha untuk mencegah bencana dapat dilakukan dengan
meminimumkan impak dan mengurangkan keretanannya
(vulnerability) melalui usaha pengurangan risiko bencana
(disaster risk reduction). Oleh itu, strategi pengurangan
risiko yang berkesan dengan dilaksanakan dengan cara yang
betul merupakan unsur penting dalam usaha meminimumkan
impak bencana daripada berlaku.
Secara umumnya, Malaysia yang beriklim tropika,
mempunyai taburan hujan yang tinggi dan kepadatan
populasi yang besar tidak terkecuali daripada berhadapan
dengan isu-isu bencana. Kejadian banjir, banjir kilat, tanah
runtuh dan episod jerebu yang sangat teruk merupakan
antara bahaya semulajadi yang biasa berlaku di negara ini
(Mohamed Shalluf & Ahmadun, 2006). Banjir di Malaysia
seringkali dikaitkan dengan kesan daripada musim tengkujuh
yang menyebabkan penurunan hujan dalam jumlah yang
banyak yang seterusnya menjadi pencetus kepada berlakunya
bahaya semulajadi tersebut. Sebaliknya, tanah runtuh pula
biasanya ditemui dalam bentuk kegagalan cerun di cerun
buatan manusia, terutama sekali cerun yang terlibat dengan
aktiviti tarahan dan penambakan yang sering berlaku
sepanjang kawasan lebuhraya, perumahan dan kawasan
bandar (Ibrahim Komoo et al., 2011). Dapat disimpulkan
di sini bahawa, kedua-dua peristiwa ini yakni banjir dan
tanah runtuh telah mengancam nyawa manusia, harta-benda,
alam sekitar, dan sebagainya. Berikutan dengan peningkatan
kekerapan berlakunya bencana sejak akhir-akhir ini, usaha
mengurangkan risiko bencana merupakan satu pendekatan
yang relevan agar kesan-kesannya dapat dibendung. Lebih
penting lagi, mengetahui bagaimana untuk melaksanakan
strategi pengurangan risiko dan kerentanan bencana dengan
lebih berkesan merupakan salah satu tugas yang agak
rumit. Jelas sekali di negara ini, segala koordinasi yang
berkaitan dengan hal-hal bencana lazimnya diuruskan oleh
aktor-aktor utama dalam setiap peringkat iaitu persekutuan,
negeri dan daerah (Ibrahim Komoo et al., 2011). Selain
itu, pihak-pihak berkepentingan (stakeholders) utama
74
(terutama sekali para pembuat keputusan atau decisionmakers) yang biasanya datang dari agensi-agensi kerajaan
memainkan peranan penting dalam menangani isu ini.
Pihak-pihak ini memerlukan satu medium yang berupaya
menyokong serta menyediakan mereka input-input yang
boleh dipercayai, berguna dan berkesan dalam proses
membuat keputusan (decision-making process) untuk
mengurangkan risiko bencana. Oleh yang demikian, usaha
mewujudkan satu rangka kerja konsep yang dikenali sebagai
Sistem Sokongan Membuat Keputusan (Decision Support
System, DSS) merupakan satu pendekatan bijak yang
sejajar dengan keperluannya berdasarkan realiti masa kini.
DSS merupakan satu sistem sokongan yang mempunyai
keupayaan untuk membantu para pembuat keputusan ke arah
membuat keputusan dengan lebih baik (Pick, 2008) dalam
mengurangkan risiko bencana dan seterusnya mempengaruhi
susun-atur strategi pengurangan risiko yang lebih sistematik
dan berkesan.
Kertas ini mengemukakan satu kajian kes bagaimana
aplikasi maklumat berorientasi geologi dimanfaat sebagai
alat sokongan untuk perancangan pengurangan risiko
bencana untuk satu bandar-mini, iaitu sebuah kampus
universiti. Kajian ini akan menerangkan penggunaan data
geologi dan analisis terain dalam sistem sokongan membuat
keputusan atau DSS bagi konteks pengurusan pembangunan
kawasan bercerun dan masalah tanah runtuh di dalam
kawasan lingkungan kampus Bangi, Universiti Kebangsaan
Malaysia (UKM). Justeru, bahagian berikut kertas ini
secara umum akan membincangkan tentang peta terrain
dan juga DSS. Diikuti dengan penjelasan tentang kaedah
serta latarbelakang kawasan kajian, hasil dan perbincangan
serta akhir sekali kesimpulan.
Peta Terain Geologi
Untuk pengurusan dan pengurangan risiko bencana
terutamanya dalam bencana tanah runtuh, pihak pengurusan
atau khasnya perancang bandar memerlukan input maklumat
penting seperti geologi, topografi, bentuk muka bumi,
keadaan cerun dan zon berpotensi bahaya dan kesesuaian
pembangunan. Maklumat ini juga perlu dipakejkan
dalam bentuk yang mudah difahami (Lim et al., 2000)
seperti peta dan kod atau pengelasan yang ringkas tetapi
bermaklumat untuk perancang atau pembuat keputusan
membuat pertimbangan dan keputusan secara tepat. Peta
pengelasan terain dan peta-peta tematik yang lain seperti
bentuk muka bumi, hakisan, kekangan fizikal, kesesuaian
pembangunan dan sebagainya dapat berfungsi sebagai alat
ataupun perkakas untuk mencapai tujuan berkenaan. Peta
terain geologi (geological terrain map) menggunakan
pendekatan penilaian terrain merupakan salah satu maklumat
penting yang dapat membantu dalam proses membuat
keputusan untuk pengurangan risiko bencana. Secara umum,
peta ini merupakan sejenis peta yang mengkategorikan,
menerangkan dan menggambarkan ciri-ciri dan attribut
bahan-bahan surficial, rupabumi (landforms), dan proses
geologi dalam landskap semulajadi (Forest Practice Code,
1999). Aplikasi sistem penilaian terrain ini telah digunapakai
Input
geologi untuk
Sistem Sokongan Membuat Keputusan
oleh beberapa negara untuk tujuan tertentu seperti Skema
Amerika (American Scheme) digunakan untuk pengurusan
dan hakisan tanah (Waynell, 1978), Sistem British (British
System) untuk geologi dan rupabumi (Lawrance, 1972),
kaedah Kanada (Canadian method) berkaitan dengan litupan
tumbuhan (Vold, 1981), dan Hong Kong pula menghasilkan
peta terrain digunakan untuk perancangan pembangunan
yang betul dan selamat serta banyak lagi. Di Malaysia,
peta terain dihasilkan oleh Jabatan Mineral dan Geosains
Malaysia merupakan versi yang telah diubahsuai daripada
model Hong Kong (Zakaria Mohamad & Chow, 2003).
Peta terain geologi Malaysia dihasilkan oleh Jabatan
Mineral dan Geosains mengikut kaedah dalam Zakaria
Mohamad & Chow (2003) dan Chow & Zakaria Mohamad
(2002) digunakan untuk tujuan menilai morfologi bumi,
keadaan hakisan permukaan, kesesuaian pembinaan dan
kekangan fizikal. Kelebihan peta ini ialah peta-peta ini
dihasilkan dalam Sistem Maklumat Geografi (Geographic
Information System, GIS) mengikut tema-tema peta yang
lazim diperlukan oleh perancang bandar. Format peta dalam
GIS juga membolehkan tindan-lapis maklumat ini dengan
maklumat perancangan lain seperti kawasan cadangan
tapak dengan mudah. Dalam Zakaria Mohamad & Chow
(2003), Peta Terain Geologi mempertimbangkan empat
atribut utama dalam pengelasan terain iaitu sudut cerun;
terain dan morfologi; fitur hakisan dan ketidakstabilan pada
cerun; dan aktiviti atau sejarah cerun (Chow & Zakaria
Mohamad, 2002). Peta Terain Geologi ini memberikan lima
peta tematik utama iaitu:
Peta Rupabumi - Peta ini meringkaskan keadaan
bentuk muka bumi am iaitu terain dan morfologi cerun dan
keadaan sudut cerun, untuk tujuan maklumat rupabumi am
dan boleh digunakan oleh ahli teknikal dan bukan teknikal.
Peta Hakisan – Peta ini menunjukkan keadaan
permukaan fitur hakisan dan ketidakstabilan pada cerun
yang wujud. Peta ini boleh digunakan oleh ahli teknikal dan
bukan teknikal untuk melihat tahap hakisan dan sebarang
ketidakstabilan pernah wujud untuk kegunaan perancangan
dan kejuruteraan.
Peta Kekangan Fizikal – Peta ini merupakan
intepretasi kekangan atau kesesuaian fizikal sumber bumi
untuk jenis pembangunan berdasarkan keadaan terain untuk
perancangan dan pembangunan kejuruteraan. Peta ini juga
sesuai digunakan oleh ahli teknikal dan bukan teknikal.
Peta Geologi Kejuruteraan – Peta ini menggunakan
atribut pengelasan terain dengan gabungan data geologi
lain seperti peta geologi, peta bencana geologi dan lainlain. Peta ini menggambarkan taburan bahan-bahan geologi
berdasarkan pencirian sifat kejuruteraan mereka. Peta ini
sesuai digunakan untuk ahli teknikal yang memerlukan
maklumat geoteknikal untuk perancangan strategik dan
kejuruteraan.
Peta Kesesuaian Pembinaan – Peta ini menggunakan
atribut pengelasan terain untuk menggambarkan pembatasan
atau rintangan geoteknikal dan kesesuaian kegunaan
pembinaan dalam bentuk empat klasifikasi: Kelas 1 dan
Kelas 2, ialah masing-masing limitasi geoteknikal rendah
dalam pengurusan risiko bencana
kepada sederhana; Kelas 3 ialah pembatasan geoteknikal
tinggi; dan Kelas 4 ialah pembatasan geoteknikal yang
ekstrim. Pembatasan geoteknikal rendah menggambarkan
kesesuaian untuk pembangunan tanah dan kemungkinan
masalah geoteknikal yang rendah, manakala limitasi
geoteknikal yang tinggi hingga ekstrim menggambarkan
kesesuaian untuk pembangunan tanah, kemungkinan
untuk menghadapi masalah geoteknikal amat tinggi dan
kos pembangunan juga akan bertambah. Sebarang kerja
pembangunan pada Kelas 3 dan Kelas 4 adalah amnya kurang
sesuai dan tidak sesuai, dan juga diwajibkan penyiasatan
tapak yang intensif
Dalam konteks kajian ini, kompilasi input geologi
penting dalam peta terain akan diintegrasikan dalam DSS
supaya dapat membantu pembuat keputusan, perancang
bandar dan pihak-pihak berkepentingan menggunapakai
output yang berfungsi sebagai alat sokongan untuk mencegah
dan mengurangkan risiko bencana serta kerentanannya
dengan lebih teratur dan sistematik.
Sistem Sokongan Membuat Keputusan (Decision
Support System, DSS) ditakrifkan secara meluas sebagai
sistem interaktif yang berasaskan komputer, menggunakan
komunikasi teknologi, data, pengetahuan dan model, bagi
menyediakan maklumat untuk membantu para pembuat
keputusan menyelesaikan masalah separa berstruktur dan
tidak berstruktur (Sprague & Watson, 1989; Gheorge &
Vamanu, 2004; Power & Sharda, 2009; Alter, 2002). Dalam
usaha untuk mencapai mencapai prestasi DSS yang tinggi
dan berkesan, terdapat beberapa syarat yang harus diambil
kira semasa membangunkan sistem ini (Sprague & Watson,
1989). Ini termasuklah:
DSS seharusnya menyediakan sokongan kepada para
pembuat keputusan di samping memberi penekanan
terhadap keputusan-keputusan separa struktur dan
tidak berstruktur.
DSS harus memberikan sokongan dalam membuat keputusan
kepada semua peringkat pengurus, dan membantu dalam
integrasi antara mana-mana peringkat pada masa yang
bersesuaian.
DSS harus menyokong keputusan yang saling bergantung
dan tidak bergantung
DSS harus menyokong semua fasa proses membuat
keputusan tetapi tidak bergantung kepada mana-mana
satu.
DSS haruslah mudah dan mudah difahami.
Secara amnya, DSS adalah sistem sampingan yang
digunakan untuk menyokong keputusan pengurusan
dengan bantuan pelbagai teknologi geospatial moden
seperti teknologi penderiaan jauh (Remote Sensing),
Sistem Maklumat Geografi (GIS), kartografi, pengukuran
dan pemetaan dan fotogrametri (Billa et al., 2004; Chang,
2012). Namun, dalam kajian ini, teknologi GIS akan
diberikan keutamaan. GIS akan berfungsi sebagai landasan
kepada proses DSS (Billa et al., 2006). Selain daripada itu,
DSS bukanlah bertujuan untuk menggantikan kemahiran
75
para pembuat keputusan malah ia bukan juga ‘automated
decision-making’ (Power & Sharda, 2009). Namun, dalam
kes-kes tertentu, membuat sesuatu keputusan adalah sukar
dan kompleks tanpa bantuan yang berasaskan komputer
(Pick, 2008) seperti DSS terutamanya dalam isu-isu
berkenaan bencana.
Umumnya, DSS telah diguna-pakai di luar negara
seperti Thailand (Moe & Pathnanarakul, 2006), Caramanico
Itali (Muthu & Petrou, 2007), Bandar Quetta (Nazir et al.,
2006) dan Taiwan (Liu et al., 2008) dalam menangani
masalah-masalah pengurangan risiko ataupun pengurusan
bencana. Namun, di Malaysia, penerbitan literatur mengenai
penyelidikan sebegini masih lagi terhad. Dalam konteks
kajian ini, DSS berupaya menguruskan pengurangan risiko
bencana dengan lebih terurus dan sistematik. Sementara
itu, perlaksanaan DSS tanpa memahami faedah yang bakal
diperolehi tidak akan mencapai matlamat yang utama dalam
menyumbang kepada prestasi sesebuah organisasi (Power
& Sharda, 2009). Manfaat yang akan didapati melalui DSS
dapat membantu dan menyokong para pembuat keputusan
untuk mendapatkan keputusan yang lebih baik dan tepat
bagi merangka strategi tindakan seterusnya supaya lebih
berkesan dan jika ia tidak dapat memberikan keputusan
yang muktamad, kualiti proses dalam membuat keputusan
dapat diperbaiki menjadi lebih baik ataupun kedua-duanya
sekali. Produk yang terhasil melalui DSS akan berfungsi
sebagai sebagai alat atau perkakas penting dalam membuat
keputusan. Justeru, keberkesanan DSS dapat dinilai melalui
output yang bakal hasil.
Matlamat utama DSS dibangunkan dalam kajian ini
adalah untuk menyokong dan menyediakan keputusan
yang lebih baik dalam usaha pengurangan risiko bencana
kepada para pembuat keputusan. Keputusan yang lebih
baik dalam erti kata, sebaik sahaja ia dilaksanakan, ia
memberi kesan yang signifikan seperti risiko bencana dapat
dikurangkan, kerentanan diminimumkan, pengurangan
kos mengendalikan bencana, peningkatan tahap kesedaran
dan pemahaman semua pihak berkepentingan, peranan
a
b
c
d
institusi dan agensi-agensi yang mengendalikan bencana
lebih cekap dan sebagainya. Sebaliknya, jika DSS tidak
membawa kepada keputusan yang lebih baik, ia mungkin
dapat mempertingkatkan kualiti dalam proses membuat
keputusan (Pick, 2008). Terdapat pelbagai cara yang jelas
dilihat dengan apabila kualiti proses membuat keputusan
diperbaiki. Antaranya; i) output yang terhasil mungkin sama,
namun, proses yang dipandu DSS mungkin lebih cepat
dan menjimatkan kos, ii) proses yang diperbaiki mungkin
lebih memberi gambaran pemahaman terperinci terhadap
apakah punca risiko dan kerentanan bencana meningkat
dan sebagainya. Sehubungan dengan itu, dalam kajian ini,
DSS dapat dilihat sebagai satu rangka kerja konsep yang
bertindak sebagai penyelesai masalah dalam mengurangkan
risiko bencana dengan cara membantu, menyokong dan
memandu para pembuat keputusan dan pihak berkepentingan
dalam membuat keputusan. Lantaran, strategi tindakan yang
dirancang seperti langkah-langkah mitigasi berstruktur yang
diambil selepas ini akan lebih efektif.
LATARBELAKANG KAWASAN KAJIAN
Sejak November 2012, berikutan rentetan hujan lebat
yang luar biasa (data stesen cuaca JMM 2013) di kawasan
Bangi, sebanyak 16 lokasi cerun di dalam kampus Universiti
Kebangsaan Malaysia (UKM) telah mengalami kegagalan.
Rajah 1 menunjukkan beberapa gambar lokasi kejadian tanah
runtuh di UKM. Tanah runtuh yang berlaku pada masa ini
menyebabkan kerosakan harta benda dan infrastruktur serta
menimbulkan gangguan dan ketidakselasaan kepada warga
universiti. Walaupun tiada nyawa yang terkorban tetapi pihak
pengurusan telah menggerakkan langkah proaktif dalam
pengurusan risiko bencana secara bersepadu. Kebanyakan
cerun telah dipotong sejak tahun akhir 1970-an dan 1980-an,
dan UKM mempraktikkan pemeliharaan estetik landskap
tabii dengan tidak menggalakkan pembinaan benteng atau
struktur mitigasi buatan yang extensif.
Geologi dan geomorfologi
UKM Bangi terletak di pertemuan antara Sungai
Langat dan Sungai Semenyih. Ia bertemu pada lingkungan
koordinat 101.75-101.79oT dan 2.90-2.94oU, kita-kira 2
km dari pekan Bandar Baru Bangi dan 35 km dari Kuala
Lumpur (Rajah 2). Geomorfologi kampus terdiri daripada
perbukitan beralun rendah, ketinggian kawasan berjulat
18 m hingga 110 m, saliran utama di sektor barat hingga
utara mengalir ke Sungai Langat manakala saliran utama
di sektor selatan mengalir ke Sungai Semenyih. Geologi
kawasan Bangi termasuk UKM terdiri daripada batuan
sedimen atau metasedimen klastik yang digolongkan dalam
Formasi Kenny Hill. Istilah metasedimen juga digunakan
untuk menjelaskan batuan sedimen yang mengalami
metamorfisme rendah. Formasi Kenny Hill terbentuk terdiri
daripada batuan utama iaitu filit, syis, kuarzit, metagrewaik
dan telerang dan kekanta kuarza adalah lazim. Batuan utama
yang lazim tersingkap di kawasan UKM ialah batuan filit
dan batu pasir hingga kuarzit. Batuan di permukaan dan
cerun terdedah kebanyakannya telah mengalami perluluhawa
Rajah 1: Lokasi kejadian tanah runtuh, a) Berhadapan Fakulti Sains
Sosial dan Kemanusiaan, b) Berdekatan dengan rumah haiwan, c)
Berhadapan Puri Pujangga, d) Di antara bangunan Fakulti Teknologi
Maklumat.
76
Input
geologi untuk
tinggi kepada lempung berpasir, lodak berpasir atau pasir
berlodak. Lapisan tanah aluvium sungai biasanya dijumpai
di sepanjang koridor saliran terutamanya kawasan rendah
yang elevasi kurang daripada 20 m.
Dalam Stauffer (1973) dan Abdulah Sani (1976; 1985),
batuan Formasi Kenny Hill berupa perlapisan batu pasir, syal,
filit, batu lumpur, lodak, sabak, batu pasir masif sedikit rijang.
Batuan ini menunjukkan kesan kekar dan isian telerang
kuarza dan beberapa sesar juga memotong. Telerang kuarza
memotong perlapisan dan kekanta kuarza yang selari dengan
perlapisan. Litologi utama terdiri daripada selang lapis syal,
batu lodak dan batu pasir. Lapisan batu lodak dan batu pasir
biasanya lebih dominan dari segi ketebalan berbanding
dengan syal. Syal dan batu lodak ini menunjukkan sifat
sebagai filit Formasi Kenny Hill dikatakan termendap pada
sekitaran marin yang berdekatan dengan jasad terhakis
yang merupakan sedimen pada beza-tinggi (relief) rendah
atau sederhana. Batuan formasi ini menganjur hingga ke
kawasan Sepang. Formasi ini telah sedikit termetamorf
kepada metasedimen jenis meta-argilit dan meta-arenit.
Singkapan perbukitan rendah di Bukit Unggul (Tunggul),
UKM (kampus Bangi), Bangi Lama, Bukit Tunku (Kenny
Hill), Bukit Gasing, Bukit Pantai, Bukit Damansara dan
Bukit Canggang. Sedikit pebel dijumpai dalam lapisan batu
pasir. Perlapisan batu pasir dan syal membentuk kekanta.
Batu pasir masif dalam selang lapis dijumpai terutamanya
di kawasan Sepang.
Penilaian cerun dalam kajian kes ini melibatkan empat
peringkat, iaitu; (a) Analisis terain geologi, (b) Kerja
lapangan, (c) Penilaian bencana, dan (d) Penentuan zon
prioriti bencana.
Analisis terain geologi
Pemetaan terain geologi kawasan UKM telah dijalankan
dan petanya dihasilkan oleh Jabatan Mineral dan Geosains
(JMG) Selangor dalam bentuk GIS menggunakan perisian
ESRI ArcGIS. Peta tersebut telah diperolehi secara ehsan
daripada JMG Selangor atas dasar memorandum kerjasama
dengan Institut Kajian Bencana Asia Tenggara (SEADPRIUKM). Peta Terain Geologi ini (JMG 2012) diperolehi dari
pihak JMG Selangor pada 12 Disember 2012. Kelas-kelas
terain dalam kawasan UKM dikenalpasti secara umum
melalui peta ini (Attribut serta jenis-jenis kelas telah
diterangkan di bahagian pengenalan).
Kerja Lapangan
Kerja lapangan awalan melibatkan pengesahan umum
jenis geologi, geomorfologi dan attribut dalam peta terain
geologi (JMG 2012) yang diperolehi dan ditentusahkan
Penilaian cerun UKM
Pemetaan terawal mengenai kegagalan cerun di sekitar
kawasan kajian oleh Ibrahim Komoo (1984; 1987) iaitu
cerapan dilakukan sejak kampus ini mula beroperasi pada
tahun 1977 sehingga 1984 menunjukkan terdapat 19 lokasi
cerun di UKM telah mengalami kegagalan, di mana terdapat
3 kegagalan bersaiz agak besar (isipadu jasad gagal melebihi
1000 meter padu, kebanyakan antara antara 1000-1600),
1 kegagalan bersaiz sederhana besar (isipadu jasad gagal
antara 500-1000 meter padu), dan 15 kegagalan kecil (isipadu
jasad yang gagal antara 0-500, kebanyakan tidak melebihi
100 meter padu). Hampir kesemua cerun yang gagal ini
bersudut antara 30o- 45o dan telah terluluhawa tinggi sehingga
gred V dan VI, malahan sesetengah potongan cerun juga
mendedahkan batuan gred III dan IV.
Tambahan kepada 16 lokasi tanah runtuh yang berlaku
pada tahun 2012, mengikut rekod yang dapat dikumpul ke
belakang hingga tahun 2009 terdapat 6 kejadian tanah runtuh
pernah berlaku diantara tahun 2009 hingga 2011. Akan
tetapi, mungkin disebabkan perbezaan faktor pendorong
dan pencetus, pada penghujung tahun 2012 menyebabkan
lebih banyak cerun yang gagal. Kejadian kali ini juga telah
mencetuskan kebimbangan banyak pihak kerana berlaku
berhampiran dengan kawasan kediaman pelajar, bangunanbangunan akademik dan infrastruktur penting UKM.
KAEDAH KAJIAN
Kaedah dalam kajian ini dilaksanakan melalui penilaian
cerun untuk pengurangan risiko bencana dalam UKM.
Rajah 2: Peta lokasi Universiti Kebangsaan Malaysia, kampus
Bangi.
77
dengan keadaan di lapangan. Survei cerun sepintas lalu juga
dijalankan untuk mengenalpasti kewujudan cerun-cerun yang
pernah gagal dan pemetaan terdahulu oleh Ibrahim Komoo
(1984; 1987). Kejadian serta lokasi tanah runtuh dalam
UKM juga telah dikenalpasti dan dikumpulkan. Pemetaan di
tapak tanah runtuh dijalankan untuk 16 lokasi tanah runtuh
yang berlaku pada tahun 2012 melibatkan mengenalpasti
kedudukan tanah runtuh, morfologi cerun, bahan geologi dan
mengenalpasti faktor penyebab kegagalan cerun. Kedudukan
setiap lokasi tanah runtuh diplotkan ke dalam GIS. Maklumat
di lapangan seperti dalam Chow & Zakaria Mohamad (2002)
iaitu sudut cerun; terain dan morfologi; fitur hakisan dan
ketidakstabilan pada cerun; dan aktiviti atau sejarah cerun
juga dicerap. Selain itu, beberapa kawasan hotspot juga
telah dikenalpasti oleh pihak pengurusan universiti dan
Jabatan Pembangunan dan Penyelenggaraan (JPP) UKM
sebagai kawasan kritikal dan memerlukan perhatian segera
kerana kepentingan dan bilangan pengguna (nyawa) yang
menggunakan kawasan tersebut amat banyak.
Kerja lapangan di setiap tapak tanah runtuh juga
diluaskan ke kawasan sekitar yang berdekatan. Pemetaan
unsur binaan seperti bangunan dan infrastruktur dan utiliti
sekitar tempat kejadian tanah runtuh juga dilakukan. Ini
juga mengambilkira binaan yang telah mengalami kerosakan
impak tanah runtuh dan potensi terdedah kepada ancaman
bahaya jika aktiviti tanah runtuh merebak secara progresif
atau retrogresif.
Penilaian bencana
Penilaian bencana tanah runtuh merupakan penilaian
tahap bahaya (hazard) tanah runtuh, bergantung kepada
faktor fizikal/alam sekitar yang mengawal kestabilan cerun
seperti jenis geologi, terain, cerun, gangguan kepada cerun
dan kewujudan sejarah kejadian ketidakstabilan tanah
runtuh. Kajian ini menggunakan peta geologi terain (JMG
2012) yang mempertimbangkan kesesuaian pembinaan
berdasarkan atribut-atribut geologi dan terain penilaian
keadaan cerun di UKM. Maklumat lokasi kejadian tanah
runtuh yang dikumpul melalui data lapangan ditindanlapis
bersama-sama dengan peta tersebut.
Penentuan zon prioriti bencana
Pengurusan risiko bencana dalam konteks perancangan
gunatanah dan sokongan pembuat keputusan mempunyai
perkaitan yang rapat. Persoalan utama dalam pengurusan
risiko oleh para pembuat dasar dan pembuat keputusan
ialah status semasa dan kawasan prioriti yang perlu
didahulukan untuk tindakan mitigasi jangka masa segera
dan langkah kedua untuk tindakan jangka masa sederhana
dan pengurangan risiko jangka panjang. Penilaian risiko
kajian ini menerokai percubaan untuk membantu para
pembuat keputusan untuk menterjemah peta terain geologi
JMG. Analisis tambahan dibuat dengan mengezonkan
kawasan yang berisiko dan berkepentingan utama untuk
membolehkan pembuat dasar mengambil tindakan. Dua
pertimbangan utama iaitu prioriti dan risiko perlu diambilkira
dalam kajian ini.
78
Magnitud prioriti atau keutamaan bergantung
kepada kriteria Model SMUG (Natural Disasters
Organisation, 1991; FEMA, 2011) dalam mengenalpasti
dan mengutamakan risiko yang berkaitan dengan bencana
berpunca dari bahaya semulajadi dan cetusan manusia seperi
teknologi. Model SMUG merupakan singkatan kepada
keseriusan (seriousness), keboleh-tangani (manageability),
keterdesakan (urgency) dan rebakan (growth) yang telah
dicipta oleh ‘Australia Natural Disaster Organisation´
pada awal tahun 1990 dan digunapakai di negara seperti
New Zealand (Cunningham, 2006), Cape Town (Disaster
Management Framework, 2007) dan beberapa sektor lain
seperti kesihatan umum (World Health Organisation, 1998),
pengurusan kecemasan (Natural Disasters Organisation,
1992) dan sebagainya. Zon prioriti untuk kajian ini
ditentukan melalui pertimbangan empat kriteria SMUG
iaitu keseriusan, keboleh-tangani, keterdesakan, dan rebakan
dan termasuk juga risiko. Risiko merupakan satu fungsi
gabungan kemungkinan sesuatu bencana dan konsekuen
suatu kejadian (UNISDR, 2007). Geoscience Australia
(2012) mentakrifkan risiko sebagai (Risk = Hazard x
Elements at Risk x Vulnerability). Dalam kata lain, risiko
juga ialah satu fungsi gabungan kemungkinan suatu bencana,
unsur yang menghadapi risiko dan kerentanan, iaitu Risiko
= Bencana x Unsur Mengalami Risiko x Kerentanan.
Keseriusan merupakan impak relatif sesuatu bencana yang
diukur berdasarkan nilai matawang dan nyawa manusia
manakala keboleh-tangani adalah kebolehan untuk komuniti
berbuat sesuatu untuk mengurangkan kesan bencana.
Keterdesakan membawa maksud betapa segera sesuatu
perlu dilaksanakan serta rebakan ialah kemungkinan untuk
menjadi lebih buruk jika tiada tindakan diambil.
Peta zon prioriti dihasilkan melalui analisis peta
tindanlapis peta-peta berikut:
Peta terain geologi JMG – Kelas kesesuaian pembinaan.
Peta lokasi tanah runtuh untuk semua tanah runtuh sejak
tahun 2009. Tanah runtuh yang bukan cetusan geologi
tidak diambilkira dalam pengiraan. Tanah runtuh yang
bersaiz lebih besar, adanya rekod perulangan kejadian
pada tapak sama atau menunjukkan potensi merebak
untuk merosak bangunan atau utiliti lain juga diberi
penarafan lebih tinggi.
Peta unit perbukitan yang didelineasi daripada peta shadedrelief. Peta shaded-relief yang dijana dengan bantuan
peta kontur, sempadan bawah setiap bukit dikenalpasti
(Rajah 3). Proses ini membahagikan kawasan kepada
unit pemetaan lebih kecil yang digelar unit terain atau
wilayah terain (van Zuidam, 1985; Way, 1978) di mana
geomorfologi permukaan bumi dibahagikan kepada
unit-unit geomorfologi permukaan bumi lebih kecil
mengikut jasad timbul, dalam kes ini sempadan setiap
bukit kecil di dalam UKM.
Peta tapak bangunan dan Jalan Utama, peta ini digunakan
sebagai data Unsur Mengalami Risiko (Elements at
Risk) yang bermakna bangunan-bangunan dan jalan
raya ini mungkin rosak akibat bencana.
Atribut tambahan kepada data tapak bangunan dan diberi
Input
geologi untuk
Jadual 1: Lokasi tanah runtuh di Universiti Kebangsaan Malaysia 2009-2012.
Tahun
2009
Lokasi
Tinggi
Cerun
(m)
Sudut
Cerun
(°)
Saiz runtuhan Sejarah / tanda(tinggi, m)
tanda pernah
berlaku
Runtuhan cerun di Fak. Sains
Teknologi menuju ke Kolej Pendeta
Za’aba
*45
7.0
n.a
Runtuhan cerun berhampiran tempat
letak kenderaan di PUSANIKA
*45
7.5
n.a
Runtuhan cerun berhampiran tangki
air lingkungan 2, Fakulti Pendidikan
*45
6.0
n.a
Runtuhan cerun berhampiran tangki
air lingkungan 2, Fakulti Pendidikan
*45
6.0
n.a
2010
Runtuhan cerun di Jalan Satria
(berhampiran dengan Lereng bukit
Permata Pintar)
*45
7.5
n.a
2011
Runtuhan cerun di tepi Jalan Wira
berhampiran dengan Kolej Keris Mas
*35
5.0
n.a
2012
Tempat letak kereta bersebelahan
dengan DECTAR
17.0
20
5.0
tiada
Runtuhan cerun berhadapan dengan
Fak. Sains Sosial & Kemanusiaan
28.2
42
28.2
ya
Runtuhan cerun berhampiran dengan
Pakar runding UKM
10.5
30
10.5
ya
Runtuhan cerun di Jalan Gelanggang
37.5
48
30.0
ya
Runtuhan cerun di belakang laluan
Fak. Pendidikan
35.2
58
35.2
ya
Runtuhan cerun di selekoh Kolej
Pendeta Za’aba
24.5
52
24.5
ya
Runtuhan cerun di belakang Bangunan
Penyelidikan
21.6
43
21.6
ya
Runtuhan cerun di Fak. Teknologi
Sains & Maklumat
3.0
90
3.0
tiada
Elektron Mikroskopi
14.1
48
14.1
ya
Nuklear
30.0
30
20.0
tiada
Runtuhan cerun di Kolej Ungku Omar
10.0
35
10.0
ya
Runtuhan cerun di belakang loji pandu
menuju ke Fak. Sains & Tek.
24.2
32
5.0
tiada
Runtuhan cerun di Kolej Aminuddin
Baki
51.2
50
15.0
tiada
Runtuhan cerun antara Bangunan
Wawasan dan Dewan Gemilang
15.2
34
3.0
tiada
Runtuhan cerun di EiMAS
35.7
60
35.7
ya
Runtuhan cerun di Kolej Pendeta
Za’aba
30.0
40
10.0
ya
Catatan
**Cetusan pokok
tumbang ditiup
angin
**Hakisan air
**Kerosakkan
benteng
**Kerosakkan
benteng
*- anggaran daripada peta, ** - ditafsirkan cetusan bukan faktor geologi /geomorfologi tabii, n.a – tiada maklumat
79
Rajah 3: Sebahagian daripada unit
perbukitan (bertanda merah) yang
didelineasi di bahagian timur-laut
menggunakan peta shaded-relief dan
kontur.
Jadual 2: Kelas terain bagi setiap lokasi runtuhan cerun di Universiti
Kebangsaan Malaysia.
Kelas Terain
I
Lokasi
Runtuhan cerun di Jalan Gelanggang
Runtuhan cerun antara Bangunan Wawasan dan
Dewan Gemilang
Runtuhan cerun berhadapan dengan Fak. Sains
Sosial & Kemanusiaan
II
Runtuhan cerun di belakang bangunan Elektron
Mikroskopi
Runtuhan cerun di belakang Bangunan Nuklear
Runtuhan cerun di Kolej Ungku Omar
Runtuhan cerun di tepi Jalan Wira berhampiran
dengan Kolej Keris Mas
Runtuhan cerun berhampiran tempat letak
kenderaan di PUSANIKA
Runtuhan cerun di belakang laluan Fak.
Pendidikan
III
Penyelidikan
Runtuhan cerun di belakang loji pandu menuju
ke Fak. Sains & Tek.
Runtuhan cerun di Kolej Aminuddin Baki
Runtuhan cerun di Kolej Pendeta Za’aba
Runtuhan cerun di Fak. Sains Teknologi menuju
ke Kolej Pendeta Za’aba
Runtuhan cerun di selekoh Kolej Pendeta Za’aba
IV
Runtuhan cerun di EiMAS
Runtuhan cerun di Jalan Satria (berhampiran
dengan Lereng bukit Permata Pintar)
Runtuhan cerun berhampiran tangki air
lingkungan 2, Fakulti Pendidikan
80
penarafan atau ranking lebih tinggi bergantung kepada
bilangan orang yang menduduki bangunan, status atau
nilai utiliti/aset/peralatan yang mahal dan kewujudan
bahan berbahaya (kimia/radioaktif).
Penilaian dan cerapan lapangan mengenai keadaan cerun,
fitur hakisan dan sejarah tanah runtuh lama.
HASIL DAN PERBINCANGAN
Kejadian bencana yang berlaku dalam UKM telah
mencetuskan kebimbangan ramai pihak di mana bencana
yang amat jarang kedengaran berlaku di UKM ini berlaku
sekaligus sehingga 16 kejadian dalam masa sebulan. Rajah
4 menunjukan illustrasi peta lokasi kejadian tanah runtuh
manakala Jadual 1 menyenaraikan lokasi kejadian dari tahun
2009 hingga 2012. Seterusnya maklumat lokasi kejadian
tanah runtuh bersama kedudukan binaan dalam UKM seperti
tapak bangunan dan jalanraya yang dikumpul melalui data
lapangan telah ditindan-lapis bersama-sama dengan Peta
terain geologi (JMG 2012). Huraian klasifikasi terain telah
diterangkan di bahagian pengenalan. Jadual 2 menunjukkan
kelas terain bagi setiap kawasan tanah runtuh di UKM.
Didapati bagi kelas terain I, terdapat dua lokasi tanah
runtuh manakala kelas terain II mempunyai enam lokasi
tanah runtuh. Untuk kelas terain III dan IV, masing-masing
mempunyai enam dan empat lokasi tanah runtuh. Jadual
ini tidak termasuk sekali kejadian yang bukan disebabkan
cetusan faktor geologi.
Korelasi kedua-dua maklumat (taburan lokasi tanah
runtuh berbanding kelas terain daripada Peta Terain Geologi
JMG ) memberikan maklumat yang amat baik, kebanyakan
cerun tinggi (>10m) yang gagal terdiri daripada Kelas
III dan IV (seperti yang ditunjukan di Rajah 5). Ini juga
menunjukkan peta terain geologi JMG amat praktikal, ia
bukan sahaja sesuai digunakan untuk menilai kesesuaian
Input
geologi untuk
dan kestabilan cerun pra-pembinaan tetapi juga untuk
kes pos-pembinaan. Berdasarkan Jadual 2, terdapat juga
lokasi kejadian tanah runtuh yang jatuh pada kelas I dan
II. Namun, secara keseluruhan, pengkaji lepas menjelaskan
bahawa terdapat banyak kegagalan cerun dan tanah runtuh
telah berlaku di UKM, antaranya disebabkan oleh luluhawa
pantas pada muka cerun terdedah, hujan dan resapan ke
dalam tanah, satah gelinciran pada sempadan gred luluhawa
terdedah, dan saliran permukaan cerun (Ibrahim Komoo,
1987); dan kelemahan dalam aspek kejuruteraan dan bahan
cerun mudah terhakis, pengumpulan air yang berlebihan
di bawah tanah, kekurangan langkah-langkah mitigasi ke
atas cerun, dan tidak semua cerun dibetulkan dan ada yang
terbengkalai tanpa apa-apa tindakan (Jaafar et al., 2011).
Prognosis awal kajian ini terhadap siri kejadian yang
tiba-tiba mendapati beberapa faktor pencetus dan pendorong
yang menyumbang kepada fenomena ini, iaitu:
Jumlah hujan yang luar biasa untuk jangka masa
sebulan merupakan antara pencetus utama. Berdasarkan
data stesen cuaca terdekat di Empangan Semenyih (JMM
2013) merekodkan jumlah hujan bulanan pada Oktober 2012
(336.6mm), November 2012 (826.0mm), dan Disember
Rajah 4: Peta lokasi kejadian tanah runtuh bersama hotspots di
Universiti Kebangsaan Malaysia.
2012 (271.6mm); jumlah hujan yang turun dalam 14 hari
sebelum kejadian pertama (11 Nov 2012) telah mencapai
422.8mm manakala jumlah hujan pada bulan November itu
sendiri merupakan 2-3 kali ganda hujan bulanan.
Masalah saliran cerun menjadi salah satu punca
pencetus. Saliran atas cerun yang tidak berfungsi seperti
tersumbat dan terputus atau tidak efisyen untuk mengalirkan
air dan mengurangkan air menyerap ke dalam cerun.
Cerun uzur, dalam kebanyakan kes, cerun di sekitar
UKM telah dipotong sejak 20-30 tahun dahulu pada akhir
tahun 1970-an dan awal 1980-an. Keluluhawaan dan
hakisan telah melemahkan ketahanan bahan dalam cerun
dan kestabilan cerun juga turut menyosot.
Selain itu, kebanyakan cerun yang gagal merupakan kes
perulangan di mana pada cerun tersebut atau bersebelahan
mempunyai petanda sejarah gerakan cerun pada masa
lepas. Tanda-tanda ini dapat diperhatikan semasa kajian
lapangan yang menunjukkan kesan ceburam cerun tersebut
telah pernah bergerak atau gagal. Rekod penyelenggaraan
juga menyokong ada beberapa cerun yang diperbaiki pada
kali kedua.
Perubahan bentuk rupabumi disebabkan oleh
pembangunan pesat dihadapi di UKM serta aktiviti-aktiviti
antropogenik yang dijalankan di atas cerun-cerun tersebut.
Peta jasad timbul atau shaded-relief telah dijana untuk
membahagikan kawasan UKM kepada unit pemetaan lebih
kecil yang digelar unit terain atau wilayah terain (van
Zuidam, 1985; Way, 1978). Rajah 6 menunjukkan tindanlapis peta shaded-relief, bersama kelas terain III dan IV
dan lokasi tanah runtuh serta hasil akhir yang diperolehi
iaitu Peta Zon Prioriti. Hasil analisis mengenalpasti 4 zon
prioriti utama yang perlu perhatian segera, di mana 3 zon
yang dikenalpasti mempunyai kepadatan bangunan dan
kependudukan bilangan manusia yang tinggi, 1 zon lagi
(Bangunan Elektron Mikroskopi) menempatkan peralatan
mahal, jalan raya ke kawasan tersebut merupakan jalan
tunggal yang tidak ada jalan alternatif dan wujudnya sejarah
perulangan kejadian tanah runtuh pada lokasi yang sama
dan berdekatan.
Rajah 5: Peta lokasi kejadian tanah runtuh bersama klasifikasi
Rajah 6: Peta pengezonan kawasan prioriti di Universiti Kebangsaan
terrain kelas III dan kelas IV di Universiti Kebangsaan Malaysia.
Malaysia.
81
Pengurusan risiko bencana secara bersepadu memerlukan
rekod dan satu sistem maklumat atau pangkalan yang baik
untuk menyokong membuat keputusan secara bermaklumat.
Namun, antara kekangannya ialah maklumat kejadian
tanah runtuh dalam institusi ini belum direkodkan secara
terurus dan sistematik, lokasi kejadian tanah runtuh dan
kegagalan cerun yang telah dan belum dibaik pulih juga
tidak direkodkan dalam satu sistem yang berpusat. Contoh
lain, jurang rekod pemetaan awal Ibrahim Komoo (1984)
yang mencatatkan kawasan tanah runtuh pada 1984 dan
diikuti oleh Jaafar et al. (2011), sehinggalah pemetaan
selepas kejadian tanah runtuh pada tahun 2012. Maklumat
kejadian bencana pada masa lepas dan penyelenggaran
berkala adalah penting dalam usaha pencegahan bencana.
Maka, senario ini telah menggesa usaha pengurangan
risiko bencana dalam kawasan kampus. Oleh itu, kajian
ini telah mencadangkan pembangunan DSS untuk UKM
bagi membantu dan menyokong para pembuat keputusan
dan pihak berkepentingan dalam membuat keputusan yang
berkesan untuk mengurangkan risiko bencana dalam UKM.
Rajah 7 telah mempamerkan rangka kerja konsep DSS
dicadangkan untuk UKM yang mana, hasil akhir DSS ini
merupakan satu peta risiko bencana. Melalui sistem ini,
dapat dilihat pelbagai attribut penting mengenai bencana,
seperti faktor yang mempengaruhi (causative factors/
environmental factors) dan meningkatkan keretanan
bencana telah disatukan menggunakan keupayaan GIS.
Seperti yang diterangkan dalam Pick (2008), DSS yang
bersifat menyeluruh bukan sahaja menyediakan maklumat,
tetapi membantu, memanipulasikan, meringkaskan, dan
menganalisis data dan maklumat tersebut dalam usaha
memberi bantuan. Hasil yang diperolehi dipercayai dapat
membantu dalam membuat keputusan serta mengesyorkan
cadangan-cadangan yang relevan untuk digunapakai dalam
mengurangkan risiko bencana di UKM.
Justeru, dengan bantuan DSS, peta kejadian tanah runtuh
dari tahun 2009 hingga 2012 telah dibangunkan. Kesemua
rekod kejadian tanah runtuh di UKM dapat dikumpulkan
dengan bantuan maklumat dari pihak JPP UKM dan hanya
kejadian yang berlaku dari tahun 2009 sehingga 2012 sahaja
dapat diakses buat masa ini. Melalui kajian ini, kawasan
hotspot di kawasan kajian dikenalpasti berdasarkan kawasan
yang mempunyai kepadatan populasi terutama sekali
pelajar yang tinggi (vulnerable community) yang mana
meletakkan komuniti ini di tahap keretananan yang tinggi
serta lokasi kejadian yang berlaku berhampiran dengan
kolej kediaman, bangunan akademik serta infrastruktur
penting UKM. Peta Zon Prioriti telah dihasilkan berdasarkan
Decision Support System Disaster Risk Management Inventory Environmental Factor Slope gradient
Geog. terrain class
Land use & Land cover
Soil erosion
Disaster Management Element at Risks Primary data
Buildings
Secondary data
Road
Preventive Measures
Curative Measures
Before Disaster
Disaster Mitigation Disaster Preparation After Disaster
Disaster Response Disaster Recover & Rehabilitation Essential facilities Hotspot Map
Literature (Saaty, 2000)
Expert Judgments (Questionnaires/Interview)
Disaster Risk Reduction Hazard Modelling 


Hazard Map
Construction Suitability Map Engineering Geological Map Physical Constraints Map
Disaster Risk Map & Priority Zoning Map B: Model development/Mapping Users
Other stakeholders Decision‐makers Policy makers Planners
C: End‐user A: Important attributes – attribut penting, B: Model development/Mapping – pembangunan model/pemetaan, C: End-user - pengguna
82
Rajah 7: Rangka kerja konsep Sistem Sokongan Membuat Keputusan untuk Pengurangan Risiko Bencana.
RAJAH 7
•
•
A: Important Attributes
Input
geologi untuk
tindan-lapis beberapa lapisan peta dan penilaian kriteria.
Justeru, berdasarkan output yang diperolehi, kajian ini telah
memberikan input yang berguna kepada pihak JPP UKM
supaya fokus yang lebih dapat diberi kepada kawasan yang
berada dalam zon dan perhatian yang secukupnya diberikan
terhadap komuniti yang tinggal di zon tersebut.
Sebagai satu unit perancangan dan pengurusan
universiti, JPP UKM perlu mengurus-tadbir keseluruhan
kawasan universiti yang seluas 1,100 hektar. Tugas jabatan
ini melibatkan perancangan, pembinaan dan penyelenggaraan
semua infrastruktur di dalam kampus termasuk bangunan,
infrastruktur, kemudahan dalam bangunan dan aset-aset
universiti. Kapasiti dan tugas JPP UKM hampir setara
dengan sebuah pejabat Pihak Berkuasa Tempatan dalam
mengurus-tadbir sebuah pekan kecil. Sebagai end-user
untuk DSS yang dicadangkan, setakat ini, pihak JPP UKM
telah mengambil tindakan berdasarkan peta yng dihasilkan
ini. Malah melalui peta ini, bukan sahaja membantu dan
memudahkan pihak JPP membuat keputusan, malah ia
merupakan satu cara untuk mengkoordinasikan strategi
mitigasi berstruktur agar yang lebih berkesan dan membantu
merancang perbelanjaan supaya ia selaras dibelanjakan
untuk aktiviti-aktiviti pencegahan dan pemulihan dalam
kampus ini. Malah maklumat zon-zon prioriti yang
ditonjolkan di UKM ini disifatkan sebagai inisiatif awal
untuk memulakan perancangan jangka panjang untuk
pencegahan bencana dalam kawasan kampus ini. Malah,
melalui DSS juga sifat tanggungjawab pihak berkepentingan
dalam UKM meningkat apabila kesemua mereka sedar akan
tanggungjawab mereka dan masing-masing bekerjasama
dalam menangani isu pengurangan risiko bencana.
KESIMPULAN
Sebanyak 22 kejadian tanah runtuh telah dikenalpasti di
UKM dalam tempoh empat tahun iaitu dari 2009 hingga 2012.
Berdasarkan penilaian beberapa kriteria seperti keseriusan
(seriousness), keboleh-tangani (manageability), keterdesakan
(urgency) dan rebakan (growth) bersama dengan tindan-lapis
beberapa peta tema dengan menggunakan teknologi GIS,
empat zon prioriti telah dikenalpasti di kawasan UKM.
Maklumat zon-zon prioriti ini didapati sangat berguna
oleh pihak Jabatan Pembangunan dan Penyelenggaraan
(JPP) UKM. Pihak tersebut telah menggunakan maklumatmaklumat ini dalam menyokong untuk membuat keputusan
dalam mengkoordinasikan strategi mitigasi berstruktur agar
lebih berkesan dan membantu merancang perbelanjaan
supaya ia selaras dibelanjakan untuk aktiviti-aktiviti
pencegahan dan pemulihan dalam kampus ini. Maklumat
ini juga dapat membantu dalam menonjolkan komuniti serta
infrastruktur yang berada dalam kerentanan untuk diberi
perhatian di samping merancang pelan tindakan semasa
bencana berlaku (emergency action plan during disaster).
Malah maklumat ini disifatkan sebagai inisiatif awal untuk
memulakan perancangan jangka panjang untuk pencegahan
bencana dalam kawasan UKM. Secara keseluruhan, Sistem
Sokongan Membuat Keputusan (DSS) diperkukuhkan lagi
dengan data-data geologi untuk bencana tanah runtuh. Sistem
ini juga berguna untuk menyokong penggubalan dasar dan
perancangan pembangunan.
PENGHARGAAN
Penyelidikkan ini telah dibiayai oleh peruntukkan Dana
Pembangunan Penyelidikkan kod projek DPP-2013-078
dan Dana COE kod projek XX-07-2012. Yuran pengajian
penulis pertama dibiayai oleh Kementerian Pengajian Tinggi
Malaysia melalui MyBrain. Setinggi-tinggi penghargaan
dan jutaan terima kasih kepada pihak Jabatan Mineral dan
Geosains (JMG) Selangor terutama sekali kepada Dato’
Zakaria Mohamad selaku Pengarah JMG Selangor, Encik
Mahisham Ibrahim dan Encik Qalam A’zad Rosle serta
Jabatan Pembangunan dan Penyelenggaraan (JPP) UKM
terutama sekali pada Encik Zulkepli di atas penyediaan
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84
Chert blocks in Bentong-Raub Suture Zone:
A heritage of Palaeo-Tethys
Basir Jasin
Pusat Pengajian Sains Sekitaran dan Sumber Alam, Fakulti Sains dan Teknologi
Email address: basir@ukm.my
Abstract: Bentong-Raub Suture Zone is considered as a collision zone between the Sibumasu and East Malaya (Indochina)
terranes. Sibumasu was a part of the Cimmerian plate, which was attached to Gondwana during the Carboniferous. East
Malaya was attached to the Indochina plate. From the Devonian to the Permian the Sibumasu and East Malaya blocks
were separated by an ocean called Palaeo-Tethys. The closure of Palaeo-Tethys was completed during the Triassic. The
major part of the history of the Palaeo-Tethys was destroyed and only a small portion is still preserved in blocks of oceanic
sedimentary rocks such as cherts. The chert blocks are exposed in several localities along the Bentong-Raub road (3°35’N,
101°54’E), Gua Musang-Cameron Highland road (4°45’N, 101°45’E) and at a road-cut in Langkap (2°38’N, 102°21’E).
The chert blocks consist of thinly bedded chert interbeded with mudstone. Some chert layers contain radiolarians. The
oldest chert block found at Bentong-Raub road-cut yielded an assemblage of radiolarians belonging to the Trilonche minax
Zone of early Frasnian, (early Late Devonian) age. A chert block from Langkap, Negeri Sembilan yielded radiolarians
belonging to the Albaillella deflandrei Assemblage Zone, Tournaisian, (Early Carboniferous) age. Permian radiolarians were
retrieved from several chert blocks in the vicinity of Pos Blau, Ulu Kelantan. The youngest radiolarian assemblage in the
area is from the Follicucullus monacanthus Assemblage Zone indicating Wordian, (Middle Permian) age. The occurrence
of radiolarian chert suggests high plankton productivity during the Late Devonian, Early Carboniferous and Permian.
These chert blocks are the natural heritage of the Paleo-Tethys which needed to be conserved as National Heritage sites.
Keywords: chert block; Benton-Raub Suture Zone; radiolarians, Palaeo-Tethys, heritage
Abstrak: Zon Sutura Bentong-Raub dianggap sebagai satu zon pelanggaran antara teran Sibumasu dan teran Malaya Timur
(Indochina). Sibumasu merupakan sebahagian daripada kepingan Cimmeria yang masih bercantum dengan Gondwana
semasa Karbon. Teran Malaya Timur pula bercantum dengan Kepingan Indochina. Dari Devon hingga Perm Sibumasu
dan Malaya Timur dipisahkan oleh lautan yang dikenali sebagai Palaeo-Tethys. Penutupan Palaeo-Tethys tamat pada masa
Trias. Sebahagian besar sejarah Palaeo-Tethys telah termusnah, hanya sebahagian kecil yang masih terawet dalam batuan
enapan kelautan seperti rijang. Bongkah rijang tersingkap di beberapa lokaliti di sepanjang jalan Bentong-Raub (3°35’U,
101°54’T), Gua Musang - Cameron Highland (4°45’U, 101°45’T) dan singkapan jalan dekat Langkap (2°38’U, 102°21’T).
Bongkah terdiri daripada lapisan nipis rijang berselang lapis dengan batu lumpur. Beberapa lapisan rijang mengandungi
radiolarian. Bongkah rijang yang paling tua ditemui dekat singkapan jalan Bentong-Raub yang menghasilkan himpunan
radiolarian daripada Zon Himpunan Trilonche minax berusia Frasnian awal, awal Devon Akhir. Bongkah rijang dari
Langkap, Negeri Sembilan menghasilkan radiolaria daripada Zon Himpunan Albaillella deflandrei, Tournaisian, Karbon
Awal. Radiolaria Perm ditemui dalam beberapa bungkah rijang dekat Pos Blau, Ulu Kelantan. Himpunan radiolaria yang
termuda di kawasan ini ialah daripada Zon Himpunan Follicucullus monacanthus menunjukkan usia Wordian, Perm
Tengah. Kewujudan rijang berradiolaria mencadangkan berlaku produktiviti plankton yang tinggi semasa Devon Akhir,
Karbon Awal dan Perm. Bongkah-bongkah rijang ini merupakaan warisan tabii Palaeo-Tethys yang perlu di pulihara
sebagai tapak Warisan Kebangsaan.
INTRODUCTION
The Bentong–Raub Suture Zone (Metcalfe, 2000)
extends from Tomo, southern Thailand southwards through
Bentong and Raub to Melaka (Tjia, 1989) (Figure 1). It is
an extension of the Nan-Uttaradit suture of Thailand. The
Bentong-Raub line was proposed by Hutchison (1973) as the
major tectonic boundary between the Western and Central
belts of Peninsular Malaysia. Hutchison (1975) named it
the Bentong-Raub ophiolite line. Tjia (1989) extended to
the suture further south to Bengkalis, Sumatra and named
it the Bentong-Bengkalis suture. The suture zone extends
northwards to Lancangjian, Changning–Menglian, Yunnan
Province Southwest China and Chiangmai, north Thailand
(Metcalfe, 2000). The Lancangjian, Changning–Menglian,
Chiangmai and Bentong-Raub suture Zones represent the
main Palaeo-Tethys ocean.
The Bentong-Raub suture Zone in Peninsular Malaysia
is located between the Sibumasu Terrane and the East Malaya
(Indochina) Terrane. The Sibumasu terrane was attached to
the Cimmerian plate and the East Malaya terrane attached
to the Indochina and the South China plate. The Sibumasu
and East Malaya blocks were separated by an ocean called
Paleo-Tethys. The opening of the Palaeo-Tethys was initiated
when the sliver of North and South China, Indochina and
Tarim plate rifted from Gondwanaland during Devonian. The
Palaeo-Tethys was diminished when the Sibumasu terrane
Basir Jasin
collided with East Malaya (Indochina) terrane during the
Triassic. The remnant of Palaeo-Tethys was only preserved
in the chert blocks in the Bentong-Raub Suture Zone.
GEOLOGY OF BENTONG-RAUB SUTURE ZONE.
The Bentong-Raub Suture Zone is well-exposed at
road-cuts along the Gua Musang-Cameron Highland road,
Karak Highway and Bentong- Raub road. The suture is an
approximately13 km wide zone of deformed rocks consists
of schist, phyllite, meta-sedimentary rocks, sandstone,
cherts, olistostrome and mélange (Tjia & Almashoor, 1996).
Metcalfe (2000) estimated the suture to be approximately
20 km wide. Small serpentinite bodies are also found in
the suture zone at Pos Mering, Sungai Cheroh, Durian
Tipus and Bukit Rokan (Metcalfe, 2000). But there is little
evidence to support the presence of true ophiolites along
the Bentong–Raub Suture Zone.
The Bentong-Raub Suture Zone is marked by a belt of
mélange and olistotrome which comprise blocks or clasts
of cherts, sandstone, limestone, conglomerate, interbedded
sandstone and mudstone and tuffaceous mudstone embedded
in a sheared matrix of mudstone. The sizes of clasts vary
from a few cm to hundreds of meters. The most important
clasts/ blocks are cherts which are considered to represent
the oceanic sedimentary rocks.
WHAT IS RADIOLARIAN CHERT
Radiolarian chert (radiolarite) is a microcrystalline or
cryptocrystalline biogenic sedimentary rock composed of
siliceous skeletons of radiolarians (Figure 2). The chert
comprises chalcedony or opaline silica, usually as thinly
bedded ribbon chert. Radiolarians occur almost exclusively
in the open ocean as part of the plankton community.
Their skeletons occur abundantly in oceanic sediments.
Development of radiolarian chert is related to the planktic
productivity of the ocean at a distance from the continental
margin. The plankton productivity is controlled by the
amount of nutrients. High productivity is related to the
upwelling of nutrient-rich bottom water which brings the
material to the surface. The deposition of chert is usually
episodic. The radiolarian cherts are well-developed in
an oceanic realm where the supply of clastic material is
lacking. The chert can be used as an indicator of oceanic
sediment. The occurrence of radiolarian chert blocks in the
Bentong-Raub Suture Zone represents the remnant of the
Palaeo-Tethys sediments.
THE OCCURRENCE OF CHERT BLOCKS
The chert blocks in the Bentong-Raub Suture Zone are
mainly associated with clastic sediments such as mudstone
and sandstone, which were metamorphosed in places to form
schist or/and phyllite. This rock association is considered as
a continental margin chert association (Jones & Murchey,
1986). Although blocks of serpentinite were reported in
Sungai Rokan, Negeri Sembilan, Sungai Cheroh, Pahang,
and Sungai Cherderoh, Kelantan (Metcalfe, 2000) there
was no apparent ophiolitic-chert association observed in
the zone. Spiller & Metcalfe (1995) reported that Cerium
anomaly values indicate the chert was deposited in an
ocean basin. The absence of carbonate rock in the chert
sequence suggests that the chert was deposited in a deep
marine environment below the calcite compensation depth.
Chert blocks have been recorded in many localities in the
suture zone at Langkap, Negeri Sembilan; Genting Sempah,
Selangor; Karak and Bentong, Pahang; and Pos Blau,
Kelantan (Spiller, 2002; Basir & Che Aziz, 1997a,1997b,
Basir et al., 2004). Three of these chert blocks yielded
significant radiolarian faunas and are hereby proposed to
be considered for conservation as heritage of the Malaysian
Palaeo-Tethys (Figure 1).
• Chert block from Bentong, Pahang.
• Chert block from Langkap, Negeri Sembilan
• Chert block from Pos Blau, Kelantan.
The chert blocks yielded three different radiolarian
assemblages belong to three different ages.
Chert Block from Bentong, Pahang
The chert block is exposed at a road-cut of BentongRaub road (3°35’N, 101°54’E). The outcrop consists
of mélange containing blocks of ribbon chert, siliceous
mudstone and massive dark gray sandstone. The width of
the chert block is approximately 30m. The chert layers are
strongly faulted (Figure 3).
Basir et al. (2004) identified ten taxa of radiolarians
and wrongly assigned it to Femennian age. The occurrence
of Trilonche minax (Hinde), Trilonche davidi (Hinde),
Figure 1: Bentong-Raub Suture Zone and the radiolarian chert
blocks localities.
86
Chert
blocks in
Bentong-Raub Suture Zone: A heritage
of
Palaeo-Tethys
Figure 2: Photographs of radiolarian chert in thin section (Scale
bar = 0.3mm).
Figure 3: Chert block exposed at Bentong-Raub road (3°35’N,
101°54’E).
Figure 4: A small part of the chert block exposed at Langkap,
Negeri Sembilan. The outcrop is covered by thick vegetations
(2°38’N, 102°21’E).
Figure 5: Ribbon chert exposed at Pos Blau Ulu Kelantan. (4°45’N,
101°45’E) (Scale bar = 1m).
Trilonche vestusa Hinde, Trilonche tretactinia (Foreman),
and Stigmosphaerostylus herculean (Foreman) (Plate 1,
figs. 1-5) represent the Trilonche minax assemblage zone
of Aitchison et al., (1999) indicating early Frasnian (early
Late Devonian) age. This is the oldest radiolarian chert
in Bentong-Raub Suture Zone. Spiller (2002) reported
Holoeciscus Assemblage Zone, middle and upper Famennian
(late Devonian) from radiolarian chert blocks in Karak,
Pahang.
Albaillella undulata Deflandre, Albaillella indensis
ambigua Braun, Ceratoikiscum avimexpectans Deflandre,
Ceratoikiscum berggreni Gourmelon, and Ceratoikiscum
umbriculum Won (Plate 1, figs. 6-12) indicates a Tournaisian
(Early Carboniferous) age. Spiller & Metcalfe (1995), and
Spiller, (2002) reported the occurrence of Late Devonian
and Early Carboniferous radiolarians from the same locality.
Chert Block from Langkap, Negeri Sembilan
The Langkap chert is exposed at a road-cut near
Langkap, Negeri Sembilan (2°38’N, 102°21’E), The chert
block is located within the Bentong-Raub Suture Zone.
It is faulted and folded. The chert layers strikes 060° and
dips 50° (Figure 4). The chert block is approximately 105
m long. The lower part comprises chert layers interbedded
with thinly bedded mudstone. The top part consists of
black laminated mudstones which contain well-preserved
radiolarians.
The chert sequence in Langkap yielded 34 radiolarians
(Basir & Che Aziz, 1997a). The occurrence of Albaillella
deflandrei Gourmelon, Albaillella paradoxa Deflandre,
Chert Blocks from Pos Blau, Kelantan
Several chert blocks are exposed at the Gua MusangCameron Highland road. The sizes of the chert blocks range
from 30 m to several hundred metres. The largest block is
located at Pos Blau (4°45’N, 101°45’E). The block has red
coloured ribbon-chert (Figure 5).
Twenty two species of radiolarians were identified
from the chert block (Basir & Che Aziz, 1997b). The
zone is characterized by the occurrence of the zonal
marker Pseudoalbaillella lomentaria Ishiga and Imoto,
Pseudoalbaillella ornata Ishiga and Imoto, Pseudoalbaillella
sakmarensis Kozur, Pseudoalbaillella scalprata scalprata
Ishiga and Pseudoalbaillella scalprata postscalprata Ishiga
(Plate 2, figs.1-5). The assemblage is indicative of a late
Asselian-early Sakmarian (Early Permian) age.
87
Basir Jasin
Plate 1: Late Devonian and Early Carboniferous radiolarians from Bentong-Raub
Suture Zone. (Scale bar is indicated in the parentheses). 1. Trilonche minax (Hinde)
(100µm), 2. Trilonche davidi (Hinde)( 75µm), 3. Trilonche vitusta (Hinde) (100µm),
4. Trilonche tretactinia (Foreman) (100µm), 5. Stigmosphaerostylus herculean
(Foreman) (75µm), 6. Albaillella deflandrei Gourmelon (100µm), 7. Albaillella
paradoxa Deflandre (200µm), 8. Albaillella undulata Deflandre (133µm), 9.
Albaillella indensis ambigua Braun (100µm), 10. Ceratoikiscum avimexpectans
Figure 6: Stratigraphic distribution of radiolarian Deflandre (133µm), 11. Ceratoikiscum berggreni Gourmelon (100µm), 12.
Ceratoikiscum umbraculum Won (133µm).
cherts in the Bentong-Raub Suture Zone.
Recently, more radiolarian species have been recovered represent the Follicucullus monacanthus Assemblage
from a chert block near Sungai Berok (4°44’49’’N Zone of Wordian (Middle Permian) age (Ishiga, 1990).
101°45’05’’E). The chert yielded at least two assemblages of This Follicucullus monacanthus zone is the youngest zone
radiolarians. The first assemblage contains Pseudoalbaillella obtained from the chert blocks in the Bentong-Raub Suture
longtanensis Sheng & Wang, Pseudoalbaillella nanjingensis Zone to date.
Sheng & Wang, Pseudoalbaillella globosa Ishiga &
Imoto, Pseudoalbaillella cf. longicornis Ishiga & Imoto,
HISTORICAL SIGNIFICANCE OF CHERTS
Albaillella asymmetrica Ishiga and Imoto, Pseudoalbaillella
The radiolarian cherts in the Bentong-Raub Suture Zone
fusiformis Holdsworth & Jones (Plate 2, figs. 6-11). indicate that radiolarian productivities were very high at
This assemblage belongs to Pseudoalbaillella globosa times during the Late Devonian, Early Carboniferous, and
Assemblage Zone (Ishiga, 1990). Another assemblage late Early Permian to Middle Permian (Figure 6). The Early
contains Follicucullus scholasticus Ormiston & Babcock, Carboniferous and Middle Permian radiolarian cherts were
Follicucullus monacanthus Ishiga & Imoto, and Hagleria deposited during the global hypersiliceous period (Racki
mammilla (Sheng and Wang) (Plate 2, figs. 12-15) that & Cordey, 2000).
88
Chert
blocks in
of
Palaeo-Tethys
Plate 2: Permian Radiolarians from Chert
Block Pos Blau, Ulu Kelantan. (Scale bar=
100µm).
1. Pseudoalbaillella lomentaria Ishiga &
Imoto,
2. Pseudoalbaillella sakmarensis (Kozur),
3. Pseudoalbaillella scalprata m.
rhombothoracata Ishiga and Imoto,
4. Pseudoalbaillella scalprata m. scalprata
Holdsworth & Jones,
5. Pseudoalbaillella scalprata m.
postscalprata Ishiga,
6. Pseudoalbaillella longtanensis Sheng
& Wang,
7. Pseudoalbaillella nanjingensis Sheng
& Wang,
8. Pseudoalbaillella globosa Ishiga & Imoto,
9. Pseudoalbaillella cf. longicornis Ishiga
& Imoto,
10. Albaillella asymmetrica Ishiga & Imoto,
11. Pseudoalbaillella fusiformis Holdsworth
& Jones,
12. Follicucullus scholasticus Ormiston &
Babcock,
13, 14. Follicucullus monacanthus Ishiga
& Imoto,
15. Hagleria mammilla (Sheng & Wang).
Radiolarian chert blocks in the Bentong-Raub Suture
Zone are the remnants of oceanic sediments deposited in
Palaeo-Tethys Ocean. The Palaeo-Tethys was developed
during the Early or Middle Devonian. During the early
Frasnian (Late Devonian), the Palaeo-Tethys was an ocean
where the oldest radiolarian chert was deposited. The
Palaeo-Tethys became wider during the Carboniferous.
The Palaeo-Tethys oceanic crust collided and subducted
eastwards under the East Malaya terrane during Late Permian
(Mitchell, 1977). The Palaeo-Tethys became a shallow
sea during Early Triassic and was dominated by scattered
fossiliferous limestone (Fontaine et al., 1995). The closure
of Palaeo-Tethys was completed during Triassic and to form
the Bentong-Raub Suture Zone (Figure 7). More than 120
million years history of sedimentation of the Palaeo-Tethys
has been destroyed by the collision and only small fractions
of the palaeo-ocean are preserved in the chert blocks within
the mélange of the Bentong-Raub Suture.
CHERTS AS NATURAL HERITAGE
The operational guideline for implementation of the
World Heritage Convention (UNESCO, 1995) has set up a
list of criteria for natural heritage sites. The sites nominated
should be outstanding examples representing major stages
89
Basir Jasin
of earth’s history, including the record of life, significant
on-going geological processes in the development of land
forms, or significant geomorphic or physiographic features.
The chert blocks of the Bentong-Raub Suture Zone
represent a very important history of the Palaeo-Tethys
and should be conserved as a National heritage. It is
recommended that these three sites of the chert blocks from
Langkap. Negeri Sembilan; Bentong, Pahang; and Pos Blau,
Kelantan to be proposed at least as National Heritage sites
and perhaps even as a regional heritage sites.
CONCLUSION
Radiolarian cherts are oceanic sedimentary rocks usually
deposited in deep-ocean basins. The cherts are thinly bedded
and known as ribbon cherts. The absence of calcareous
fossils in the cherts indicates that the cherts were deposited
below the Calcite Compensation Depth. Radiolarian chert
blocks in the Bentong-Raub Suture Zone are remnant
of the Palaeo-Tethys ocean. They are very important for
age determination and paleobiogeographic studies. The
occurrence of Frasnian radiolarian chert suggests that the
Palaeo-Tethys already existed during the early Late Devonian
and continued through to the Carboniferous and Permian. The
youngest chert in the Bentong-Raub Suture Zone is Wordian
(Middle Permian). The deposition of chert was diminished
in the Late Permian and the Palaeo-Tethys became a narrow
shallow sea during Triassic. The 120 million years history
of Palaeo-Tethys was partially recorded in the radiolarian
cherts blocks. The oceanic sedimentary rocks were deformed
and destroyed during the collision of Sibumasu terrane and
East Malaya Terrane. Only chert blocks are left as remnants
of the Palaeo-Tethys. The chert blocks could be conserved
as National Heritage sites.
ACKNOWLEDGEMENTS
I would like to express our gratitude to Cik Atilia
Bashardin for her help in sample preparation. I would like
to thank Prof. Dr. Lee Chai Peng for critical comments on
the manuscript. I would like to thank Universiti Kebangsaan
Malaysia for the research grant UKM-GUP-PLW-08-11-141.
REFERENCES
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Basir Jasin & Che Aziz Ali, 1997a. Significance of Early
Carboniferous Radiolaria from Langkap, Negeri Sembilan,
Malaysia. Geol. Soc. Malaysia Bull., 41, 109-125.
Basir Jasin & Che Aziz Ali, 1997b. Lower Permian radiolarian from
the Pos Blau area, Ulu Kelantan, Malaysia. Journal of Asian
Earth Sciences, 15(4/5), 327-339.
Basir Jasin, Zaiton Harun & Uyop Said, 2004. Some Devonian
radiolarians from chert blocks in the Bentong-Raub Suture
Zone, Pahang. Geol. Soc Malaysia Bull., 48, 81-84.
Fontaine, H., Ibrahim, B. A. & Vu Khuc, D., 1995. Triassic
Limestones of Southwest Kelantan (East and south of Pos
Blau) and north Pahang (Merapoh area), Peninsular Malaysia.
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Ishiga, H., 1990. Paleozoic radiolarians. In: Ichikawa, K., Mizutani,
S., Hara, I., Hada, S., Yao, A. (Eds.), Pre-Cretaceous Terranes
of Japan. Publication of IGCP Project 224, Nihon-Insatsu,
Osaka, pp. 285–295.
Jones, D. L., & Murchey, B., 1986 Geological significance of
Paleozoic and Mesozoic radiolarian chert. Ann. Rev. Earth
Planet. Sci., 14, 455-492.
Metcalfe, I., 2000. The Bentong-Raub Suture Zone. Journal of
Asian Earth Sciences 18, 691–
712.
Mitchell, A. H. G., 1977 Tectonic setting for emplacement of
Southeast Asia. Geol. Soc. Malaysia Bull., 9, 141-158.
Racki, G. & Cordey, F., 2000. Radiolarian palaeoecology and
radiolarites: is the present the key to the past? Earth-Science
Reviews 52, 83–120.
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Malaysia and Implications for Regional Palaeotectonics and
Palaeogeography. Palaeontographica Abt. A. 266, 1-91.
Figure 7: Evolution of the Palaeo-Tethys based on radiolarian
cherts (modified after Metcalfe, 2000). A. Opening of Palaeo-Tethys
during Devonian, B. Palaeo-Tethys became wider ocean during
Carboniferous, C. The Palaeo-Tethys subducted under the East
Malaya / Indochina Terrane, D. Collision between Sibumasu and
East Malaya / Indochina terranes during Late Permian- Triassic.
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from the Bentong-Raub suture and the Semanggol Formation
of Peninsular Malaysia- initial results. J. Southeast Asian Earth
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Manuscript received 1 September 2012
Revised manuscript received 4 November 2013
91
Discovery of Late Devonian (Frasnian) conodonts from the “Sanai
limestone”, Guar Jentik, Perlis, Malaysia
Aye Ko Aung*, Meor Hakif Amir Hassan & Ng Tham Fatt
Department of Geology, University of Malaya, 50603 Kuala Lumpur, Malaysia
*Email address: akageol@um.edu.my
Abstract: Late Devonian (Frasnian) conodonts (Ancyrodella, Ancyrognathus, Palmatolepis, Polygnathus, Icriodus,
Ozarkodina and Belodella) of linguiformis Zone, which includes the Upper Kellwasser Event recorded in Europe, North
America, China and elsewhere, are for the first time recorded from Perlis, Malaysia. The conodonts are fairly rich in
the uppermost part of the “Sanai limestone” which was previously reported as of the upper part of Upper Devonian
(Famennian) age. Stratigraphically it is located near the top of the Jentik Formation, unconformably overlain by the
Lower Carboniferous Kubang Pasu Formation. The limestone is pelagic in nature and consists of planar bedded, grey
micritic limestone, with thin shale partings and styliolites. In addition to the conodonts, the limestone contains abundant
fossils of tentaculitids, straight-coned nautiloids, trilobites and bivalves. The “Sanai limestone” has a limited distribution
in Malaysia and the assemblage of Malaysian Frasnian conodonts are closely compared with some conodont fauna
(linguiformis Zone) of northwestern Thailand.
Keywords: Malaysia, Late Devonian, Frasnian, conodonts
INTRODUCTION
Late Devonian (Frasnian) conodonts have not been
previously reported from Perlis, Malaysia, in fact even the
presence of Late Devonian conodonts (asymmetricus Zone)
were described from the Public Works Department Quarry,
Gunong Kantang, District of Kinta, Perak, Malaysia (Lane et
al., 1979). Meor & Lee (2002) had mapped the area in this
study and first proposed the Jentik Formation with a brief
description of the “Sanai limestone” and consequently, the
limestone has been described in detail (Meor & Lee, 2003).
Field trips were carried out in 2011 to 2012 at Hill B locality,
in the Kampung Guar Jentik by two of us (AKA & MHH)
and some postgraduate and undergraduate students from
the Geology Department, University of Malaya (Mahfuzah,
Atirah, Zahid and Kadeah). The comprehensive reports
on the stratigraphy of the Hill B sections at Guar Jentik,
produced by Meor (2004), Meor & Lee (2003, 2005) and
Noor Atirah (2010) are essentially being used as the frame
of the present report.
“THE SANAI LIMESTONE”
The “Sanai limestone” (Meor & Lee, 2003) was
named after Guar Sanai ridge, in Kampung Guar Jentik,
Beseri District, Perlis, just south of the Timah Tasoh Dam,
approximately 10 km north of Kangar (Figure 1). The
section exposed in the northwestern part of the ridge is about
50m thick and the beds dip about 60° towards northeast.
It consists of fine-grained limestone. Fresh samples are
light grey in colour, weathering to reddish white. Large,
black coloured mottles in the rock may be impurities of
either carbonaceous or intraclastic material. Large bivalve
shells and cephalopod fossils are commonly found in it.
Petrographically, the limestone is a sparse biomicrite, or
wacke, with skeletal grains representing crinoid, trilobite,
tentaculitid and ostracod fossils (Meor & Lee, 2003).
The limestone contains abundant pelagic fossils
including tentaculitids, conodonts, straight-coned nautiloids
together with some ostracods and trilobites. The depositional
environment is interpreted as relatively deep water marine.
The limestone shows many sedimentary features of deeper
water, pelagic limestone facies, including the fine-grained,
thin-bedded nature of the limestone with shale partings and
the predominance of pelagic fossils (Scholle et al., 1983).
The conodonts give further support to this interpretation.
Following the conodont biofacies classification of Sandberg
& Dreesen (1984), the palmatolepid-polygnathid association
(most abundant conodonts in the section) is restricted to their
biofacies II, which indicates a slope to basin environment.
The unit is strictly confined to Hill B and stratigraphically
restricted laterally. The lithologic boundaries of the “Sanai
limestone” is marked by two unconformities with the Lower
Devonian Timah Tasoh Formation below and the Lower
Carboniferous Kubang Pasu Formation) above in this area
(Figure 2).
MATERIAL AND METHODS
A number of spot samples were first collected from the
prominent limestone outcrops occurring within the “Sanai
Limestone” in 2011. Preliminary work on the conodonts
from the “Sanai limestone” in Guar Jentik showed that they
are richest in the top section (Table 1) with 50 conodonts
per kilogram of the samples, especially in palmatolepids
and polygnathids. More selective re-collecting of previously
collected limestone outcrops was made during the second
trip in 2012. The detrital limestones from the sequence
were sampled between 3 to 10 meter intervals or at closer
when necessary. Twenty two samples with an average
weight of 10kg from three biostratigraphic sections at
Hill B (B1-3) were collected (Table 1). Conodonts were
richest in the light grey, fine-grained limestone containing
2043 specimens from 80 kg of samples. Laboratory work
and conodont taxonomy were undertaken at Geology
Department, University of Malaya. The limestone samples
were leached in 60 % industrial acetic acid for a period of
two days. The dissolved material was then sieved. Mesh of
16 microns was set up over 180 microns mesh. The residues
were thoroughly washed. The mixed solution was then slowly
poured through the sieves. Any residue in upper part sieve
is returned to a plastic container for further acid treatment.
The residue was dried overnight on a hot plate at a very low
setting or under a heat lamp or in low-temperature oven.
The conodonts were picked from the dried residues under
a binocular microscope and stored in wall slides.
The photographs of the conodonts were taken using a
digital camera (Nikon D300) attached to a Nikon Opthiphot
microscope illuminated using a Nikon fiber optic light source.
The camera was connected to a computer and the exposure
was set manually using the software Nikon Camera Control
Pro. The microscope stage was adjusted until the top-most
part of the conodont is in focus and a photograph was taken.
The stage was then raised so that a slightly lower part of
the conodont is in focus and another photograph was taken.
This was repeated until the lowest-most part of the conodont
was photographed. Generally, for a single conodont, between
10 to 20 photographs, each focused at different parts of the
conodont were taken. These photographs were merged using
the focus stacking software Combine ZM, which produce
a sharp image of the whole conodont.
SANAI CONODONT FAUNAS
The conodonts examined in this study and figured
specimens are housed in the Department of Geology,
University of Malaya (prefix UM). The zonal classification
of Frasnian conodont zones used in this paper follows
(Klapper & Becker, 1999, Text-fig. 1).
One conodont zone, linguiformis Zone has been
recognized in the three measured stratigraphic sections
sampled for conodonts (B1, B2, and B3) (Figs 1&3). The
section B1 is in the southern part of the outcrop at Hill B
where there is a clear lithologic contact between the “Sanai
limestone” and the underlying Lower Devonian Timah Tasoh
Formation. The section B2 is through the larger “Sanai
limestone” lens where the base of the limestone is faulted,
and B3 at northern part of Hill B (Figure 3). Conodonts
recovered from the measured sections indicate that the “Sanai
limestone” represents only one conodont zone, linguiformis
Zone of Upper Frasnian age. The yields are low in the lower
beds (B1-42, B2-1, 2) become more common in beds B2-2,
5 and are highest in bed B3 at the top of the section. The
systematic study of the Sanai conodonts is in progress.
The stratigraphically lowest sample (B1-42) at 2 m
above the base of section B1, produced a useful single
conodont, Palmatolepis linguiformis Müller (1956), the
zonal form for the uppermost zone (linguiformis Zone)
of Frasnian, and (B2-1) at 3 m above the base of section
B2, contains five specimens of Ozarkodina sp. and one
Belodella sp. with no other conodonts occuring in this level.
The conodonts are barren in other two beds of the “Sanai
limestone” (B1-45, 48) in section B1. The sample from
bed B2-2, at 4m above the base of the section produced
three specimens of Palmatolepis linguiformis co-occur
with large number of Palmatolepis hassi, Müller & Müller,
Figure 1: Location map of Hill B, Guar Jentik, Perlis, Malaysia
Figure 2: Stratigraphic units of the Guar Jentik area, Perlis, northwest
and outcrop of the Sanai Limestone.
Peninsular Malaysia.
94
Discovery
of
Late Devonian (Frasnian)
conodonts from the
“Sanai
limestone”,
Guar Jentik, Perlis, Malaysia
Table 1: Distribution of the conodonts in the section (B2) at lower to middle part, and B3, the topmost part of the Sanai Limestone, Hill
B, Guar Jentik, Perlis, northwest Peninsular Malaysia.
Conodont zone
Sample no.
Meters above base of section
Sample weight (kg)
Ancyrodella gigas
Ancyrodella nodosa
Ancyrognathus asymmetricus
Palmatolepis hassi
Palmatolepis jamieae
Palmatolepis rhenana
Palmatolepis linguiformis
Polygnathus decorosus
Polygnathus webbi
Icriodus alternatus
Ozarcodina sp.
Belodella sp.
B2-1
3
1
0
0
0
0
0
0
1
0
0
0
5
1
B2-2
4
3
0
0
0
58
0
0
3
8
3
4
2
0
B2-3
5
1
0
0
0
0
0
0
0
0
0
0
0
0
B2-4
5.5
1
0
0
0
0
0
0
0
0
0
0
0
0
1957, Polygnathus decorosus Stauffer, 1938, Polygnathus
webbi Stauffer, 1938, Icriodus alternatus Branson & Mehl,
1934 and Ozarkodina sp. (Table 1), suggests this particular
horizon to be already within the linguiformis Zone and
possibly not many metres below the Frasnian-Famennian
boundary. The next sample, 6m above the base (B2-5),
yielded more conodonts faunas including Ancyrodella gigas
Younquist, 1947, Ancyrodella nodosa Ulrich & Bassler,
1926, Ancyrognathus asymmetricus Ulrich & Bassler,
1926, Palmatolepis linguiformis Müller, 1956, Palmatolepis
hassi, Polygnathus decorosus, Polygnathus webbi, Icriodus
alternatus, Ozarkodina sp., and Belodella. sp.
The conodont fauna from the higher bed of section B3
at 48 m above the base of the section, is heavily dominated
by palmatolepids, polygnathids, and icriodids, and it
includes the recently described Palmatolepis linguiformis,
Palmatolepis hassi, Palmatolepis jamieae, Ziegler &
Sandberg, 1990, Polygnathus decorosus, Ancyrognathus
gigas, Ancyrognathus nodosa, Icriodus alternatus and
Palmatolepis rhenana Bischoff, 1956. The two palmatolepid
species, Pa. hassi and Pa. rhenana are likely to be among
the few survivors from the lower level (rhenana Zone).
All the above conodonts are illustrated in (Figures 6 & 7).
It therefore appears that the “Sanai limestone” is of latest
linguiformis Zone age.
DISTRIBUTION OF FRASNIAN CONODONTS IN
SOUTHEAST ASIA
Apart from the “Sanai Limestone” at Hill, B, Guar
Jentik, Perlis, the Frasnian conodonts are only known
from only one locality in Perak, Peninsular Malaysia. Lane
et al. (1979) first reported and described Devonian and
Carboniferous conodonts from a slightly metamorphosed
sequence of carbonates at the Public Works Department
Quarry at Gunong Kantang in Perak. The fauna includes
standard Euro-North American conodont zones from the
late Lower Devonian gronbergi Zone to the early Upper
Devonian asymmetricus Zone and Carboniferous faunal
assemblages of late Visean or early Numurian age. They
also described a new conodont genus (Klapperina, Lane et
linguiformis
B2-5
B2-6
6
9
1
1
6
0
3
0
1
0
34
0
12
0
2
0
2
0
17
0
4
0
3
0
1
0
3
0
B2-7
15
1
0
0
0
0
0
0
0
0
0
0
0
0
B2-8
18
1
0
0
0
0
0
0
0
0
0
0
0
0
B2-9
19
1
0
0
0
0
0
0
0
0
0
0
0
0
B3
48
70
23
13
3
951
15
0
16
759
8
77
3
2
a
Fault
42
b
Figure 3: a. Stratigraphic measured section across Hill B showing
locations of the conodont sampling, b. Sketch of outcrops at Hill B.
al., 1979) of Frasnian age. The Late Devonian (FrasnianFamennian) conodonts (late rhenana to middle triangularis
Zones) are known from the Thong Pha Phum area, western
Thailand (Savage et al., 2006). The Frasnian-Famennian
conodonts, mostly of cosmopolitan species are abundant
with 80 conodont faunas from 10 zones (late rhenana,
linguiformis, triangularis, crepida, rhomboidea, marginifera,
trachytera, postera, expansa, and praesulcata Zones) from
the Mae Sariang section of Northwestern Thailand (Savage,
2013).
95
Figure 4: Outcrops of the “Sanai limestone” at Hill B. Photographs taken facing east.
A. Base of the “Sanai limestone”, section B1, bed B1-42; B. Section B2, bed B2-1;
C. bed B2-2; D. bed B2-5; E. B2-9 (black shale) and outcrops of the topmost part.
Figure 5: The Frasnian conodont succession at Hill B: 1a-d. Palmatolepis linguiformis
Müller, 1965; 2a-c. Icriodus alternatus Branson & Mehl, 1934; 3. Ozarkodina sp.; 4a,b.
Polygnathus decorosus Stauffer, 1938; 5. Ancyrodella nodosa Ulrich & Bassler, 1926; 6.
Ancyrodella gigas Younquist, 1947; 7. Palmatolepis rhenana Bischoff, 1956; 8. Palmatolepis
jamieae Ziegler & Sandberg, 1990; 9. Ancyrognathus asymmetricus Ulrich & Bassler, 1926;
10. Polygnathus webbi Stauffer, 1938; 11. Polygnathus sp. (conodont figures not to scale).
MP – Mempelam Limestone (Silurian), TT – Timah Tasoh Formation, black shale (Lower
Devonian), SN – “Sanai Limestone” with black shale intercalations (Upper Devonian), KP
– Kubang Pasu Formation, sandstone – shale interbeds (Lower Carboniferous).
96
Discovery
of
conodonts from the
“Sanai
limestone”,
Figure 6: Frasnian (linguiformis Zone) conodonts of the Sanai Limestone, Guar Jentik, Perlis, Malaysia. 1A, B; 6A, B) Ancyrodella gigas
Younquist, 1947, 1A, B) oral views of P element UM10565; 6A, B) oral and aboral views of P element UM10567; 2A, B. Ancyrodella
nodosa Ulrich & Bassler, 1926, oral and aboral views of P element UM10566; 3A, B) Ozarkodina sp.A, lateral views of P element
UM110576; 13 A, B) Ozarkodina sp. B, lateral views of P element UM10577; 4A, B) Polygnathus webbi Stauffer, 1938, aboral and oral
views of P element UM10575; 5A-C; 8A, B) Icriodus alternatus Branson & Mehl, 1934, 5A-C) aboral and lateral views of P element
UM10568; 8A, B) oral and lateral views of P element UM10569; 7A-C) Ancyrognathus asymmetricus Ulrich & Bassler, 1926, aboral,
lateral and oral views of P element UM10570; 9A, B; 14A, B) Pelmatolepis hassi Müller & Müller, 1957, 9A, B) oral and aboral views
of P element UM10573; 14A, B) oral and aboral views of P element UM10574; 10A, B) Polygnathus decorosus Stauffer, 1938, lateral
and oral views of P element UM10572; 11A, B) Belodella sp., lateral views of coniform element UM10588 ; 12A, B) Pelmatolepis
jamieae Ziegler & Sandberg, 1990, oral and aboral views of P element UM10571; 15A, B) ?Polygnathus sp., aboral and oral views of
P element UM10589.
97
Figure 7: Frasnian (linguiformis Zone) conodonts of the Sanai Limestone, Guar Jentik, Perlis, Malaysia. 1A, B; 2; 3A, B; 4A, B; 5)
Palmatolepis linguiformis Müller, 1965, 1A, B) oral and aboral views of P element UM10590; 2) oral view of P element UM10591; 3A,
B) oral and aboral views of P element UM10592; 4A, B) oral and aboral views of P element UM10593; 5) Palmatolepis sp., aboral view
of P element UM10594; 6A, B) Ancyrognathus asymmetricus Ulrich & Bassler, 1926, oral and aboral views of P element UM10595;
7A, B) Palmatolepis rhenana Bischoff, 1956, oral and aboral views of P element UM10596; 8) Polygnathus decorosus Stauffer, 1938,
oral view of P element UM10597; 9A, B) Ancyrodella sp., oral and lateral views of P element UM10598; 10A, B) Icriodus alternatus
Branson & Mehl, 1934, oral and lateral views of P element UM10599; 11) Ozarkodina sp. B, lateral view of P element UM10600; 12)
Bellodella sp., lateral view of coniform element UM10601.
CONCLUSION
Available conodont data indicate that at Hill B, Kg.
Guar Jentik, Perlis, the “Sanai limestone” is of latest Frasnian
(latest linguiformis Zone age). The conodonts confirm that
the recognized species are mostly cosmopolitan. The Hill
B-Sanai section includes the global Upper Kellwasser event
that marks at the top of Frasnian (Figure 5) recorded in other
part of the world. There is no conodont evidence which may
represent the presence of Famennian age in this section.
This suggests that there may be two regional unconformities
present. The first is between this limestone and Timah Tasoh
Formation of Lower Devonian age below, and the second is
with the Kubang Pasu Formation of Lower Carboniferous
age above. The Perak conodonts of early Upper Devonian
(asymmetricus Zone) are much earlier than that of the Perlis
late Upper Devonian (late linguiformis Zone) which are in
part contemporary to those of north-western Thailand.
98
ACKNOWLEDGEMENT
Professor Dr Thomas Becker and Dr Sarah Aboussalam
of Westfälische Wihelms-Universität Münster, Institut für
Geologie und Paläontologie, Germany, provided helpful
comments on some of the Sanai conodonts. Mahfuza Musali,
Noor Athirah, Muhammad Zahid, Kadiah and Kherman
Bin Mahali of the Department of Geology, University of
Malaya assisted us in the field. Professor Dr Lee Chai
Peng of Department of Geology, University of Malaya
thoroughly reviewed this paper. Facilities provided by the
Department of Geology, University of Malaya are gratefully
acknowledged. This work is supported by the University of
Malaya Research grant RG147/11AFR to AKA.
REFERENCES
Bischoff, G., 1956. Oberdevonische Conodonten (to I delta) aus
dem Rhenischen Schiefergebirge. Notizblatt des Hessischen
Landesamtes für Bodenforschung zu Wiesbaden, 84, 115-137.
Discovery
of
conodonts from the
Branson, E. B. & Mehl, M. G., 1938. The conodont genus Icriodus
and its stratigraphic distribution. Journal of Paleontology, 12,
156-166.
Klapper, G. & Becker, R. T., 1999. Comparison of Frasnian (Upper
Devonian) conodont zonations. Bollettino della Società
Paleontologica Italiana, 37, 2-3, 339-348.
Lane, H. R., Müller, K. J. & Ziegler, W., 1979. Devonian and
Carboniferous conodonts from Perak, Malaysia. Geologica
et Paleontologica, 13, 213-226.
Meor Hakif Hassan & Lee, C. P., 2002. Stratigraphy of the Jentik
Formation, the transitional sequence from the Setul Limestone
to the Kubang Pasu Formation at Guar Sanai. Guar Jentik,
Beseri, Perlis – a preliminary study. Geological Society of
Malaysia Bulletin, 45, 171-178.
Meor Hakif Hassan & Lee, C. P., 2003. The Sanai Limestone
Member – a Devonian limestone unit in Perlis. Geological
Society of Malaysia Bulletin, 46, 137-141.
Meor Hakif Hassan & Lee, C. P., 2005. The Devonian-Lower
Carboniferous succession in Northwest Peninsular Malaysia.
Journal of Asian Earth Sciences, 24, 719-738.
Müller, K. J., 1956. Zur Kenntnis der Conodonten-Fauna des
europäischen Devons, 1. Die Gattung Palmatolepis: Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft,
494, 70p.
Müller, K. J. & Müller, E. M., 1957. Early Upper Devonian
(Independence) conodonts from Iowa, Part 1. Journal of
Paleontology, 31, 1069-1108
Noor Atirah, 2010. Sedimentology of Hill B, Guar Jentik, Beseri,
“Sanai
limestone”,
Perlis, Northwest Peninsular Malaysia. Unpublished BSc thesis,
Department of Geology, University of Malaya.
Sandberg, C. A. & Dreesen, R., 1984. Late Devonian icriodontid
biofacies models and alternate shallow-water conodont
zonation. In: D.L. Clerk (Ed.), Conodont biofacies and
Provincialism. Geological Society of America Special Paper
196.
Scholle, P. A., Arthur, M. A., & Ekdale, A. A., 1983. Pelegic
environments. In: Scholle, P. A., Bebout, D. G. & More, C.
H. (Eds.), Carbonate Depositional Environments. Memoir of
American Association of Petroleum Geologists, 33.
Savage, N., 2013. Late Devonian conodonts from Northwestern
Thailand. A Trinity Press Co. Oregon, USA, 48p.
Savage, N., Sardsud, A. & Buggisch, W., 2006. Late Devonian
conodonts and the global Frasnian-Famennian extinction event,
Thong Pha Phum, western Thailand. Palaeoworld, 15, 171-184.
Stauffer, C. R., 1938. Conodonts of the Olentangy Shale. Journal
of Paleontology, 12, 411-443.
Ulrich, E. O. & Bassler, R. S., 1926. A classification of the toothlike
fossils, conodonts, with descriptions of American Devonian
and Mississippian species. Proceedings of the U.S. National
Museum, 68-12, 63.
Younquist, W. L., 1947. A new Upper Devonian conodont fauna
from Iowa. Journal of Paleontology, 21, 95-112.
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121, 1-115.
Manuscript received 30 August 2013
Revised manuscript received 11 September 2013
99
Geological landscape and public perception: A case for Dataran
Lang viewpoint, Langkawi
Tanot Unjah*, Mohd Shafeea Leman & Ibrahim Komoo
Institute for Environment and Development (LESTARI)
Universiti Kebangsaan Malaysia, Bangi Selangor, Malaysia
*Email address: tanot-u@ukm.my
Abstract: In order to understand the aesthetic value of geological landscape, a study was conducted at Dataran Lang
viewing point, Kuah, Langkawi based on horizontal viewpoint landscape mapping and public perception survey method.
From the mapping exercise several types of landforms and landscapes have been identified and were associated to their
various geological formations. In addition to these natural landforms, several man-made landscapes were also identified.
Data obtained were transformed into a simple schematic sketch to relate the landscapes with the rock types. Using this
sketch as a guide, a public perception survey was carried out to find out the visitors’ understanding and perception on
landscape of scenic beauty and their relationship with geology. The survey has shown that most visitors agreed that
landscapes seen from Dataran Lang have scenic appeal or aesthetic value. The sketch was useful to help them relating
the different landscapes with different geological or scientific information. The schematic geological sketch interpretation
is an important tool for enhancing public understanding on geological landscape, geoheritage, and geotourism as well as
a tool in future development planning related to the aesthetic geological landscapes.
Keywords: geological landscape, public perception, geoheritage, geotourism
INTRODUCTION
Geological landscape is a term used to describe the
natural physical landscape or natural environment that is
viewed from a geological perspective. From this perspective
a natural landscape is perceived as an assemblage of
landforms that contains enormous intrinsic value associated
with its formation. In understanding the origin and the
formation of natural landscape it is crucial to understand the
properties of the earth material which form the landscape, the
natural processes responsible in crafting various landforms,
and the evolutionary stages which make it unique at present
time and scenario. Therefore, the beauty of the landscape
is the mixture of intrinsic value of the above assemblages
and the extrinsic value manifested informs of mountain,
gorge and hill
Geological landscape has been closely connected to man
since the existence of human kind. The terms such as hill,
river, gully, barrow and mountain in name of places are a
manifestation of landscape in most geographic destination or
addresses clearly indicated human appreciation to geological
landscape. Among world famous geological landscapes are,
Arthur’s Seat of Edinburg, Scotland which is an extinct
volcano system, Table Mountain of Cape Town, South Africa,
a mesa made of sandstone bed, and Sugarloaf Mountain
of Rio De Janeiro, Brazil, a granite bornhardt landform.
As long as man and landscape live side by side, they will
always tried to explain this connection in various manners
through various perspectives.
In Malaysia, geological landscape has been fundamental
to most of the ecotourism industries, even before the word
ecotourism was created (Ibrahim Komoo, 1997a; Mohd
Shafeea Leman, 1997). Tourists from local and abroad
for examples have flocked to Langkawi, Tioman, Taman
Negara, Gunung Kinabalu and Gunung Mulu merely to
enjoy the natural beauty behind these geological landscapes.
As a matter of fact it was due to these phenomena that
the Malaysian Geological Heritage Group was established
to look at matters pertaining to research on geoheritage
conservation in this country (Ibrahim Komoo, 1997b).
Public without adequate geological background
often looks at geological landscape solely on its beauty,
hence only value it based on the geometrical shape and
vegetation cover. Various studies in the past decades have
recognised that substantial components of the world’s
landscapes were shaped not on the Earth’s surface, but at
the base of the regolith (Twidale, 2002; Garcia-Quintana
et al., 2004). Surface geomorphic processes are strongly
influenced by the physical properties of the rocks, in terms
of restively toward weathering and erosion, the chemical
properties as well as the structural properties of the rocks.
Therefore, understanding on basic geology is as important
as understanding on geomorphic processes in the study
of geological landscape. This paper wills elaborate on the
relationship between geological landscape and the geology
that formed the landscape. A horizontal view from Dataran
Lang Langkawi from where geological landscapes of various
origins are seen will be ideal to demonstrate this relationship.
Landscape as perceive by human is an area, as perceived
by people, whose character is the result of the action and
interaction of natural and/or human factor (Council of
Europe, 2007). Human perception is therefore very important
in determining the significance, the potential for sustainable
utilisation and the need for conservation of geological
landscape. The establishment of first national park in America
i.e. Yellowstone National Park in 1872, a conservation
statue for large area was due to the aesthetic beauty of its
landscape (Yard, 1920). Based on this understanding this
current study aims to introduce the geological component
embedded within a landscape and how it has influenced the
beauty or aesthetic of an area
In conservation geology the increasing awareness
in geology among the public will benefit the long term
protection and management of geological heritage resources
(UNESCO, 2006). Thus, there is a need to provide and
implant as much as possible of geological information
on geological heritage of a sites on this case a geological
landscape. This has been done through publications of
geological material, exhibitions on geology, series of talk,
seminars and dialogues with various stakeholders as well
as on site information on panels (Dias & Brilha, 2004;
McKeever, 2009). However, more often than not information
given was either very highly scientific or very dilute, hence
losing some essential the facts and meanings. In general it can
be said that the geology are yet to reach the public at large.
In tackling these issues a study has been conducted on
evaluating efficiencies of geological communication to the
public using simplified geological landscape.
GEOLOGICAL LANDSCAPE FOR THE PUBLIC
Numerous studies have been carried out in interpreting
and assessing the values of landscape to the public, such
as Zube et al. (1974, 1982) through public perception
assessment on landscape of scenic beauty. This work
identified differences on the results based on the types of
evaluator known as expert technique, quantitative survey,
focus group and individual experiential. The application
of this landscape assessment approach was carried out
in various subjects and perspectives. Among the sound
approach was from psychology perspective by Bernaldez &
Parra (1979), Kane (1981), Daniel (1990), Purcell & Lamb
(1998) and Canas et al. (2009), management approach as
promoted by Brown et al. (1990) and Ulrich et al. (1991)
and cultural perspective by Zube et al. (1974), Tips &
Savasdisara (1986), Hull & Grant (1989) and Terkenli
(2001). The common principle of assessment in these
studies indicates differences between the onsite and indoor
approach by using photographs, slides and at the landscape
while filling in the questionnaires (Shafer & Brush, 1977;
Kaplan & Kaplan, 1989; Canas et al., 2009).
Most of these studies were dealing with landscape
as a land cover or cultural landscape parallel with the
definition of European convention on landscape. For such,
the landscape means an area, as perceived by the people,
whose character is a result of the action and interaction of
natural environment and/or human factors. The assessment
of landscape beauty by integrating geology and landscape or
geological landscape has been introduced by Tanot Unjah &
Ibrahim Komoo (2004; 2005; 2007). They have made their
assessment based on the physical component of geological
landscape. The physical component includes types of rock
that form the landscape, geological structures that control
the landscape (e.g. bedding properties, joints and faults) and
geological processes that continue to shape it (e.g. erosion,
102
dissolution and mass wasting). Basically, the appreciation
and understanding of these physical components of the
landscape is the key to sharing geological knowledge to
the public. Application of landscape beauty assessment
using geological landscape components had been applied
at Lata Chenai, Kelantan and while horizontal landscape
mapping had been experimented at Kilim and Selat Kuah,
both in Langkawi, Kedah.
Previous experiment on horizontal landscape mapping
at Kilim only developed basic technique and procedures
on viewpoint landform mapping and characterization of
carbonate rock landform. The need for more comprehensive
study on the characterization of other types of rock is critical.
Beside the ability of the landform data to be used as part of
the knowledge tourism, is crucial in creating appreciation
toward the landscape. In order to incubate appreciation we
have to understanding how scientific knowledge contributes
to the beauty of the landscape.
DATARAN LANG
A study was conducted at Dataran Lang, Kuah in
Langkawi Geopark (Figure 1), the first national geopark in
Southeast Asia and the 52nd member of Global Geopark
Network supported by UNESCO. Being part of the geopark,
it is crucial to have protected geological, cultural and
biological sites. For this purposes numerous tourism sites
have been promoted either by adding simple geological
information for existing cultural sites or establishing new
geologically based sites such as Pantai Pasir Hitam (Black
Sand Beach), Pantai Pasir Tengkorak, Gua Kelawar (Bat
Cave,) Tasik Dayang Bunting and Pulau Anak Tikus (Mohd
Shafeea Leman et al., 2006; 2007).
Dataran Lang is one the well-known site for viewing
Langkawi’s beautiful landscape. It is where the grand eagle
statue that signified Langkawi’s identity was erected. It
is a small esplanade at one corner of the Straits of Kuah,
connected by bridges to the Lagenda Park and the Kuah
Jetty Port. The area was developed by the local authority
with recreational facilities such as benches, gardens, craft
arcades, tiled pathways and open spaces (Local Management
Plan District of Langkawi, 2003).
APPROACH AND METHODOLOGY
Horizontal Viewpoint Landscape Mapping
The viewpoint mapping is the mapping of landforms
from a selected viewing point. The best viewpoint is a site
where one can observe a landscape at horizontal level with
furthest distance of clarity (Tanot Unjah & Ibrahim Komoo,
2005). Landforms observed from the selected viewing point
are sketched and described based on their rock types with
related geological structures and processes.
The mapping can be divided into four levels known
as identification of view point, scope of observation, field
landscape sketch and landscape analysis. A viewpoint is
identified from the topographic map, having the best view
of the surrounding areas with minimum crossing angle of
observation. This is followed by identification and selection
Geological
landscape and public perception:
A case
for
Dataran Lang
Table 1: Landform classification based on types of rock (modified after Tanot Unjah &
Ibrahim Komoo, 2007 and Tanot Unjah, 2011).
on scope of observation. The scope of observation is read
based on 360o degrees in the horizontal view. It can be
captured during field observation and later confirmed using
a topographic map. Next is the field landscape sketching
and this can be divided into two levels of sketching, i.e.
general landscape on the area and the specific sketch of the
landform. Basically, the general sketch directly captures the
whole area with a degree of observation while the specific
sketch of the landform component must consider the
distance between the view point and the landform. Groups
of landforms are later sketched based on 0.5 km intervals
up to the last visible object. Each landform component
is identified as one of several shapes simplified into an
alphabetical code to minimize the space in the sketch.
Analysis of data was then carried out to understand the
dominant landform, and to interpret the major geological
processes and history of the area.
Landscape analysis was carried out using the landform
classification by Tanot Unjah & Ibrahim Komoo (2005;
2007). The classification is an identification of landform
according to rock type. Three types of rock in the area are
carbonate sedimentary rocks, clastic sedimentary rocks
and igneous rocks (Table 1). Examples of the landform
representing different types of rock are shown in Figures
1, 2 and 3.
Carbonate sedimentary rock landforms
Tanot Unjah & Ibrahim Komoo (2005) classified
carbonate rock into 10 major landforms. The landforms
are mogote with rounded top (L1), mogote with flat top
(L2), cone tower hill (L3), cone hill (L4), coconut shell-like
hill (L5), pinnacle (L6), karst stack (L7), structure-control
hill (L8), dome (L9) and structure-control pinnacle (L10).
Some images on the observed carbonate sedimentary rock
landforms are shown in Figure 1.
viewpoint,
Langkawi
Figure 1: Among the carbonate sedimentary
rock landforms at Kilim Geoforest Park are
cone tower hill (trapezoid) or L2 (A) and cone
hill or L3 (B).
Clastic sedimentary rock landforms
Clastic sedimentary rock was classified into six main
landforms (S1 to S6). Each of these landforms shows the
influence of bedding and erosion. The landforms are: rounded
to almost rounded to flat top with medium slope hill (S1),
one sided cone hill (S2), irregular top and gentle slope hill
(S3), low cone with gentle slope hill (S4), flat top or ridgeslike with gentle slope hill (S5), and sea stack or isolated hill
due to erosion (S6). Some images of the observed clastic
sedimentary rock landforms are shown in Figure 2.
Igneous rock landform
There are three types of igneous rock landforms in
Langkawi (G1 to G3, Figure 3). They are symmetrical hill
with gentle slope (G1), flat and almost rounded top hill with
medium slope (G2) and ridge-like hill (G3).
Public Perception Survey
Surveys were carried out using a set of questionnaire
on respondent’s personal particulars, basic ideas of scenic
landscape, perception on scenic landscape in Langkawi,
scientific input on geology and perceived plan for future
development of the area surrounding the landscape.
Questionnaire was prepared specially for groups that
directly interact with the landscape. In this study, tourists
were the main aim as it was purposely used to identify the
beauty of this area. The questionnaire was based on the focus
group method, usually used for social research techniques
to understand and describe the feelings and perceptions of
groups of people who interact with the landscape (Zube
et al., 1982). A simplified questionnaire was prepared to
test the participant understanding on the scenic value of a
landscape in relation to its scientific geological input. A total
of 35 respondents mainly tourists that visited Dataran Lang
were interviewed at different times over several weeks of
103
Figure 2: Among the clastic sedimentary rock landforms at Pulau Ular are identified as S2 (A) a low con with gentle slope at Tanjung
Baru Besar, and Pulau Tuba (B) identified as S4.
Figure 3: Among the igneous landforms observed in Langkawi are A) symmetrical cone hill with height equal to half of the width at
Gunung Raya known as G1, and B) rounded top with medium slope at Burau bay or known as G2.
2008. The data from the questionnaire was later analyses
using a Statistical software (SPSS).
Figure 4: Dataran Lang viewpoint and the angle of observation
from the area.
Table 2: Landform distribution according to rock type observed at
the Dataran Lang viewpoint.
104
RESULT AND DISCUSSION
Topographic sketches of landforms for each 180° have
been made from Dataran Lang with Bt Panchor being
referred as starting viewing angle (i.e. 0°). Dataran Lang
is a perfect viewing point where various landforms can be
observed for a complete 360° circle up to 6 km without
much object of interference (Figure 4). From these sketches,
three groups of landforms reflecting clastic sedimentary,
carbonate sedimentary and igneous rocks can be observed
and classified in detail. The clastic sedimentary rocks are
represented by the Machinchang and Singa formations,
while the carbonate sedimentary rocks are represented by
the Setul and Chuping formations. The igneous rock is made
up of Gunung Raya Granite. Quaternary sediments are less
obvious as much have been cover by vegetation or part of
the man-made landscape.
The observation from Dataran Lang view point
identified four types of landform each for clastic and
carbonate sedimentary rocks and three types of igneous
landform (Figure 5 and Table 2). The carbonate landforms
are represented by two mogotes (L1), three cone towers
(trapezoid) (L2); five conical hills (L3), and one structurally
controlled hill (L5). Meanwhile clastic sedimentary
landforms consist of five one sided cone with bedding
influence (S2), two hills with irregular top and gentle
slope (S3), three low conical hills with gentle slope (S4)
and one flat top hill with gentle slope (S5). On the other
hand igneous landforms are identified as one symmetrical
hill with gentle slope (G1), three rounded hills with gentle
slope (G2) and three ridges (G3).
Although the landscape is dominated by sedimentary
rocks, rare igneous landscapes are still outstanding in size
Geological
A case
for
Dataran Lang
viewpoint,
Langkawi
Figure 5: Landform sketches from the Dataran Lang viewpoint.
and height as seen in Figure 5. The landforms observe
from this viewpoint are mainly due to weathering and
mass wasting. Heavy annual rainfalls contributed to the
well-formed carbonate rock and symmetrical peak of the
igneous rock landforms. Mass wasting which include rock
falls and landslides create steep slopes and rugged peaks.
Perceptions obtained from questionnaire survey
revealed that 82.9% of the respondents are domestic tourist
and 17.1% of the visitors are foreign tourists mostly from
Australia, Brunei, Singapore, Indonesia and Taiwan. The
high number of the local tourist in comparison to the
international strongly indicates their appreciation on local
tourist destination. Perhaps this is due to the extensive
promotion by the Tourism Ministry and the local authority
on the natural beauty of the island as well as its reputation
as duty free island. Most tourists are English literate. In
terms of age, 40% of the respondents come from 25 to 34,
22.9% from 35 to 40, 20% from 15-24, 14.3% from 45 to
54 and 2.9% from 55 to 64 years age groups (Figure 6).
The highest age group are also known to be generation X
and Y which they are known to have the powerhouse in
generating next economic and they are known as educated
buyer (William & Page, 2011).
In term of educational background most of the
respondents are degree holder (42.9%), the rests are senior
high school students and school leavers (40%) and diploma
holder (11.4%). Others are students from junior secondary
schools (2.9%) and Master or PhD holder (2.9%). For the
detail of the distribution please refer to Figure 7.
Most of the respondents (88.6%) came to Dataran Lang
as part of their holiday trip to Langkawi, while 8.6% of
them are on official trip and only 9% are local people. In
terms of occupation, 40% of the respondents are working
with private company, 20% are student and retiree, 17.1
% are government employee, 8.6% each are involved in
academic and business and 5.7% as professional (Figure 8).
The survey also shows that only 31.4% of the respondents
come to Dataran Lang for the first time while others have
been to this place several times.
On their basic idea of scenic landscape, all of them
agree that the landscapes viewed from Dataran Lang have
great scenic beauty. However, their criteria or element of
scenic beauty vary from mixture of natural and man-made
landscape (54.3%), totally natural landscape (40%) and
solely man-made landscape (5.7%).
For comparative beauty 34.0% of the respondents
considered this area as the most scenic spot in Langkawi,
while 25.0% of them choose Machinchang Cable Car,
17.0% choose Pantai Chenang and 3.0% each refer to
Gallery Perdana, Padang Matsirat, Pasir Tengkorak, Porto
Malai, Tanjung Rhu, Telaga Habour and Telaga Tujuh as
the most scenic spot in Langkawi (Figure 9).
On perceived scientific inputs toward the sketched on
display, 88.6% of the respondents indicated that they have
never came across such a sketch. However, 82.9% of them
say that they can relate the actual landscape with the sketch,
while the other 17.1% cannot. For those who respond, their
understanding of the sketch and landscape were varied from
natural topography at 31.4%, man-made topography with
17.1%, panoramic perspective in the sketch with 17.1%,
diversity of geological and geomorphological 45.7% and
sketch that portray the landscape with 34.3%.
After being briefed on the science of the sketch , more
than 57% respondents agree that the information give
additional value to the landscape while 34% consider it
does not add any value, while 9% thought the information
somehow degrade the value of the landscape beauty.
105
Figure 6: The distribution of the age of the respondents.
Figure 7: The education background of the respondents.
Figure 8: The occupation of the respondents.
Figure 9: The distribution of comparative beauty of scenic spots
in Langkawi.
CONCLUDING REMARKS
The finding of this study concludes that geological
landscape approach have the ability to link observed
landforms recognised through their physical appearance
with knowledge on geological structure, as well as physical
properties and erosion attribute to different types of rocks.
Observation through horizontal viewpoint has the advantage
of having a common view with general tourists. It provides
a platform to enhance the observed landscape by providing
various scientific values. This approach has the ability
to expose the various hidden value of natural resources
for ecotourism or specifically geotourism in landscape
perspective.
The survey on public perception on landscape of
scenic beauty shows that the common public recognised the
106
importance of geological sketches in promoting the scenic
value of the area. The survey offered more option for tourists
in terms of their preference on viewing and understanding
of scenic landscapes on the island. As mentioned by Fyhri
et al. (2009) research on the qualitative survey of public
perception is vital in areas where tourism is a key economic
factor. It is also very important in understanding the
awareness level among the local residents and in assessing
development and other environmental challenges that have
visual consequences. As a global geopark, Langkawi has
the responsibility to enhance current tourist attractions
by introducing knowledge based tourism, particularly
knowledge on geology
The study also agree with Jensen & Koch (1998) that
this kind of research seeks for better comprehension of
various recreationists’ landscape preference by looking
forward for nature management staff and several other
landscape–related decision-makers on their perspectives
of scenic beauty. Therefore, their expertise and knowledge
contribute to better recommendations on recreation and
tourism with respect to nature and various environmental
problems (Vining, 1992). As for Langkawi, since public
knowledge enhancement, geotourism and environmental
sustainability are among key objectives of the transformation
of Langkawi into a geopark (Mohd Shafeea leman et al.,
2007), data and other types of information gathered through
this landscape study approach will certainly be very useful
in future development planning of the geopark.
ACKNOWLEDGMENT
This research is made possible by research grant XX001-2005, Assessment of Natural and Cultural Resource
for Tourism at Selat Kuah, Langkawi led by Prof. Dr.
Mohd Shafeea Leman, Langkawi Research Centre, and
UKM-GUP-PLW-08-11-317, Development of Geological
landscape for education, conservation and tourism led
by Prof. Dr. Ibrahim Komoo to which we are grateful.
Thanks are also due to Dr. Sharina Abdul Halim and Ms
Zanisah Man on comment during the reconstructing of the
questionnaire and SPSS analysis assistance. Thanks are
also to the reviewer of this article for the helpful advice
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107

Bulletin of the Geological Society of Malaysia

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