Climate variability in the SE Alps of Italy over the past 17000 years

s -.I
Climate variability in the SE Alps of Italy over the past 17000 years
reconstructed from a stalagmite record
SILVIA FRlSlA, ANDREA BORSATO, CHRlSTOPH SPÒTL,IGOR M. VILLA AND FRANCO CUCCHI
~
BO
DV
~
AC
,
r:;/
Frisia, s., Borsato, A., Spotl, C., Villa, l. M. & Cucchi, F. 2005 (November): Climate variability in the SE Alps
of Italy aver tbe past 17000 years reconstructed from a stalagmite record. Borea.\',Vol. 34, pp. 445-455. 0s10.
ISSN 0300-9483,
Stalagmite SVI from Grotta Savi, located at tbe SE margin of tbe European Alps (Italy), is tbe first Alpine
speleotbem tbat continuously spans tbe past c. 17kyr. Extension rate and o 180crecord far tbe Lateglacial
probably reflect a combination of temperature and rainfall, witb rainfall exerting tbe dominant effect. Low
speleotbem calcite 0180c values were recorded from c. 14.5 and 12.35kyr, during GI-1 (Belling-Alleroo)
interstadial, which, in our interpretation, was warm and wet. Tbe GS-l (Younger Dryas) was characterized by a
shifl to heavier 0180c,coinciding witb 013Ccenrichmentand extremely low extensionrate «811m/year). Tbese
characteristics indicate tbat GS-l climate was cool and dry in tbe SE Alps. Calibration using historical data
revealed tbat tbere is a positive 0180JdT relationship. A 1°C rise in mean annual temperatureshould correspond to c. 2.85%0increase of SV-l 0180c. We reconstructeda slow and steadytemperature rise of c. 0.5°C
since IO kyr BP, in broad agreement witb reconstructions from pollen data far SE Europe. Stalagmite SV1
indicates tbat climate variability in tbe SE Alps has been influenced by tbe Mediterranean Sea far tbe past
c. 17kyr.
Silvia Fri.l'ia (e-mai/: jri.via@mt.\'n,tn,it)and Andrea Borsato (e-mai/: borsato@mt.l'n.tn.iI),Mu.veoTridentino di
Scienze Natura/i, via Ca/epina 14, 1-38100 Trento, Ita/y; Christoph Spat/ (e-mai/: Chri.ltoph.Spoet/@uibk.
ac.at), ln.vtitut fiir Ge%gie und Pa/iiont%gie, Leopo/d-Franzen.v-Universitiit,lnnrain 52, A-6020 lnn.vbruck,
Austria; 19or M, Vi/la (e-mai/: igor@geo,unibe.ch), Diparlimento di Scienze Ge%giche e Geotecn%gie,
Università di Mi/ano-Bicocca, 1-20126 Mi/an, Ita/y, and ln.vtitutfiir Ge%gie, J.votopenge%gie, Unive1;l'itiit
Bem, Er/ach.vtra.vse9A, CH-3012 Berne, Switzer/and; Franco Cucchi (e-mai/: t"Ucchi@univ.trie.vte.ittl;4Dipartimento di Scienze Ge%giche, Ambienta/i e Marine, Universita' di Trie.vte,Via Wei.vs,
2, 1-34127 Trie.vte,Ita/y;
received 20th October 2004, accepted 21st Apri/ 2005.
J
The European Alps is a region very sensitive to
climatic change (Beniston & Jungo 2002), and it is
important to extend the existing climate records as far
back in rime as possible to detect any anthropogenic
climate signals. At present, there is a large set of
palaeoclimate and climate data from the CentraI and
Western Alps, but a fragmentary record from the
Eastern Alps (cf. Davis et al. 2003 and references
therein). A stalagmite record from northem ltaly
(McDermott et al. 1999) suggested that the CentraI.
Alps had a similar Rolocene climatic evolution as the
JUTaMountains and the French Alps. The easternsec..eograp
tor of the ltaltan
Alps ltes at the boundary betweenthe
CentraI and Southern European climate regions as
defined by pollen data (Davis et al. 2003) and, therefore, may show different climate evolution with
respect to the CentraI and Western Alps. The Eastern
ltalian Alps bave great pre-history importance, which
is documented by abundant archaeological evidence
for both indigenous and imported cultural 'packages'
(Mithen 2003). In the Dalmeri Shelter site, at 1240m
a.s.l. in NE ltaly, a unique finding of painted stones
dated at c. 13cal.kyr BP, which show lberian
naturalistic influence (Dalmeri et al. 2004), seems to
support Mithen's (2003) hypothesis that the Younger
@
~~~;~~~Cis
Dryas (YD) marked the end of the Palaeolithic paintersoA better insight into the climate evolution of the
SE European Alps from the Last Glacial Maximum
would greatly improve our understanding of Alpine
history. Rere we present an exceptional c. 17kyr
speleothemrecord from the southeasternmargin of the
ltalian Alps.
.
Samplmg and analytlcal
G
h . l tI
procedures
'
lca se mg
The 27-cm-high, candle-shaped,stalagmite SVI was
sampled in Grotta Savi, a cave located at 441 m a.s.l.
north of Trieste (4S03ios"N, 13°S3'10"E) (Fig. l).
The outer surface of the stalagmite was whitish,
translucent and wet, a typical feature of active
stalagmites from the southem watershed of the Alps.
At the time of removal, SVI was fed by a constant
drip (c. 10drops/min) from a stalactite growing about
30m above the stalagmite. The Savi cave is cut in
fissuredlimestoneoverlainbythin«SOcm)grassland
soil cover, a situation which optimizes the potential for
a rapid responseto climate changes.The present-day
DOI: 10.1080/03009480500231336 @ 2005 Taylor & Francis
I
,
446
Silvia Frisia et al.
BOREAS
34(2005)
dissolved
spike.
an
Th
ion
and
equilibrated
and
U were
exchange
using
the
(2000)
to
were
low
were
(7 to
a
103),
of
1.3%
-24,
the
SVl-22)
linear
-27,
(Table
1).
expressed
before
in
the
up
age
years
(yr)
2000
or
(Fig.
al.
(from
ratios
contamination.
detrital
of
Th
the
error)
to
(see
Fig.
ranging
17%
for
model
(SVI-BI
based
on
corrected
thousands
3
from
subsamples
is
the
by
detrital
fraction
between
year
content
initial
Th
et
activity
(2a
The
interpolation
U
ratio
detrital
by
Cheng
corrections
-28)
highest
calculated
detrital
far
yields
-229Th
containing
in
low
activity
which
(SVI
with
suggesting
corrected
1.34+0.31/-0.25
Appendix),
were
230Th/232Th
230Th/232Th
component
ages
had
the
23~
columns
reported
samples
and
therefore
utilizing
e
AlI
ppb)
a mixed
in
The
constants
I).
220
Ages
and
re sin.
decay
(Table
146
with
separated
of
a
ages
years
(kyr)
3).
Stableisotopes
Samples
for
were
37mm
In the
r
~
1. Location
position
of Savi Cave
of stalagmite
map shows
SVI
tbe location
and Soreq
Cave
(S),
witbin
ofthe
geological
Caverna
setting
and
Morpurgo
Late Palaeolithic
addition,
the
axis
stable
using
250 m
Fig.
In
originaI
passage.
Dalmeri
an
The
Shelter
(D)
(Sq).
I
..
c 1mate
ized
1S su
by
cool
and
temperatures
Below
zero
dry
auturnns.
afe
+1.5°C
mean
ear
(
1terranean,
winters,
Mean
winter
+17.5°C,
are
re~o~de.d
1841
to
1996)
II).
using
19
NBS
to
1a
(1IOmm),
a~ut
SVI
started
highest
(126mm)
almost
h
standard,
Vienna
Pedee
precision
of
and
d
recor
O
age
mo
th
~
lor
SVI
was
cut
paraI
to
(265
its
vertical
mm
slabs
and
thin
sections
base.
The
rime
scale
18 U/Th
inductively
ICPMS)
University
calcite
specimen
ages
coupled
at
the
of
(Fig.
plasma
Berne,
lying
Subsamples
SVI
with
mass
of
in
axis,
on
is
an
of
in
growth
on
t
e pas
results
are
Belemnite
~180
16.6
to
+ 0.5
the
by
reported
(YYDB)
and
~13C
kyr
BP
stan-
values
is
and
I
w
10.6
extension
1S
to
~e
first
continuous
e t a. l
19gemann
composrte
slow
(~1
C.
t
a
.
(N
from
very
From
highest
presento
preserves
17kyr
C.
BP.
(MC-
150
to
axial
part
U/Th
dating
the
were
5.7
to c.
relatively
is
jlm
(2003)
samples).
O jlm/yr)
c.
7.5kyr
rate
(32
there
was
thick
tively
possibility
Il
of
2000)
(Fig.
(24
at
composed
et al.
BP
growth
stabilized
translucent
resolved
4.4 kyr
fast
rate
(Frisia
brown,
250mg
of
c.
SVI
a
50
Geochemistry,
on
for
its
impure
based
spectrometry
the
and
examined
multiple-collector
Isotope
Switzerland,
drilled
2).
was
of
measured
Laboratory
subsamples
growth
high)
(clastic)
of
system
accompl1shed
The
to
up
BP,SVI
to
43
jlm/yr).
.
polished
total
The
e
leI
portion
the
that
a record
rate
was
its
From
centraI
(Fig."2).
preparatio~
the
at
up
10.6:t0.22kyr
l
fonn
speleothem
records
an
from
were
measured
equipped
with
was
and
continuously
D
.
d
~arb?nate
bit.
laY~!l
.-.gre
..
prov1ded
d
levels
Standard1zatton
to
1S
November
(105mm).
The
lnner
part
ofthe
cave
as a
t
t
d
t
t
tur
f 12 3+0
2 C
cons
an
alT an
wa er
empera
e o
-extens1on
t .
a
mg
different
isotope
compositions
XL mass
spectrometer
were
drill
\
7.0
m Tneste
with
October
.
samples
0.2-mm
growth
top
interval.
Results
European
September
at five
the
The
a
individuaI
the
fixed
isotope
using
dry
y
m
sampled
automated
(Gasbench
mm),
by
summer
respectively.
f~r
265
a 0.3-mm
of
aracterand
and
l prec1p1tatton
we
on-line
to
analysis
axis
lessthanO.l%o.
c
wann
and
annua
ears
.y
h
'
e
and
wet
The
mml
values
Md
temperatures
days/year.
044
l
-conttnenta
long
summers
1
.
(37
isotope
centraI
using
intervals
laterally
relative
b
part
l-mm
C and
O
a Deltap1US
dardo
the
stalagmite
lower
at
stable
along
ofthe
drilled
O
high-resolution
micromilled
28
visible
Each
lamina
jlm/yr),
(Fig.
elongated
with
4).
to
jlm/yr
another
columnar
growth
consists
sublayer,
and
a
portion.
The
growth
and
some
optical
of precise
laminae
lamina
0.5
are
microscopy,
counting.
then
calcite
laminae
calcite
by
and
3).
luminescent
low,
penod
1 to
of a thicker,
to
4 jlm
rate
too
which
These
thin,
is
thin
relato
hinders
groups
be
the
of
.
'.
448
Silvia Frisia et al.
.I
BOREAS
34(2005)
.
.
Table J. Results of Urrh ana~ses (errors are quoted as 20-standarddeviations). Ages were corrected far detrita! thorium by utilizing the
2~232Th va!ue of 1.34 +0 1/-0.25(20- errars).
U
234Uf38U
2~238U
23~23~
234U/238U(t = O)
Age
Age COlf
kyr
kyr
.
i
Dist.
Sample
mm
SVI-BI
SVI-21
SVI-22
SVI-B4
SVI-23
SVI-B5
SV1122
SVI-B6r
SV1-172
SVI-207
SVI-24
SVl-25
SVI-26
SVI-238
SVI-27
SVI-249
SVl-28
SVI-258
14.5
18.5
27.5
52.5
62.3
83.8
103.0
127.0
172.0
207.0
214.0
215.0
230.0
238.0
239.2
249.0
250.0
257.5
Ppb
Activity ratio
172.5:t0.49
178.9:t0.46
195.9:t0.56
176.5:t0.46
163.3:t0.41
220.8:t0.56
192.4:t0.54
168.5:t0.84
154.9:t0.48
168.6:t0.49
160.4:t0.42
175.9:t0.46
151.1:t0.40
179.5:t0.47
193.2:t0.50
159.6:t0.40
188.1:t0.48
146.3:t0.40
0.9735:t0.0034
0.9729:t0.0034
0.9690:t0.0039
0.9732:t0.0030
0.9745:t0.OO28
0.9870:t0.0018
0.9856:t0.OO55
1.0103:t0.Oll0
1.0002:t0.0070
1.0020:t0.OO53
0.9835:t0.0042
0.9883:t0.0044
0.9895:t0.0039
1.0039:t0.0032
0.9971 :t 0.0036
1.0130:t0.0036
1.0076:t0.0027
1.0184:t0.0041
0.0139:t0.00ll
0.0178:t0.0009
0.0258:t0.0008
0.0406:t0.0015
0.0431:t0.00ll
0.0523:t0.0012
0.0704:t0.0014
0.0771:t0.0020
0.0859:t0.0016
0.0959:t0.0014
0.0926:t0.0018
0.0940:t0.0017
0.1196:t0.0020
0.1282:t0.0015
0.1266:t0.0017
0.1469:t0.0020
0.1331:t0.0015
0.1589:t0.0028
from c. 10.6 to 2.5 kyr BP it is 23 to 95 years (mean
resolution=28 years), and from 2.5kyr BP to the
present it is 18 to 25 years. The O180cvalues show a
tendency toward lower values during the Lateglacial,
from 16.6 to 10.6kyr BP (-4.45%0 at 16.6kyr to
-6.65%0 at 10.6kyr). The Lateglacial is characterized
by O180c minima at c. 15.4, 14.5 and 12.3kyr BP
7.5:t0.57
13.1:t0.64
7.6:t0.25
27.4:tl.02
39.2:tl.03
28.2:t0.65
18.1:t0.38
29.6:tl.62
25.9:t0.51
30.9:t0.50
69.7:tl.51
50.0:t1.08
27.0:t0.58
53.9:t0.71
86.3:tl.32
11.6:t0.17
103.3:t2.24
11.8:t0.22
0.9735:t0.003
0.9728:t0.003
0.9688:t0.004
0.9729:t0.003
0.9742:t0.003
0.9868:t0.002
0.9853:t0.006
1.0110:t0.Ol1
1.0002:t0.OO7
1.0021:t 0.006
0.9829:t0.004
0.9879:t0.005
0.9890:t0.004
1.0040:t0.003
0.9969:t0.004
1.0136:t0.004
1.0080:t0.003
1.0194:t0.004
1.57:t0.13
2.02:t0.l0
2.95:t0.l0
4.65:t0.17
4.94:t0.13
5.95:t0.13
8.10:t0.17
8.67:t0.26
9.80:t0.19
10.98:t0.18
10.80:t0.23
10.92:t0.21
14.07:t0.26
14.92:t0.19
14.83:t0.22
17.11:t 0.26
15.47:t0.20
18.51:t0.37
1.29+0.17-0.19
1.81+0.14-0.14
2.43+0.21-0.24
4.43+0.21-0.24
4.78+0.16-0.17
5.66+0.21-0.19
7.52+0.30-0.33
8.28+0.33-0.33
9.32+0.29-0.32
10.53+0.27-0.30
10.66+0.25-0.25
10.64+0.26-0.28
13.41+0.40-0.43
14.57+0.26-0.28
14.62+0.25-0.27
15.26+0.69-0.85
15.33+0.22-0.22
16.57+0.79-0.96
(Fig. 5). In the Lateglacial, the interval from c. 12.0 to
c. 11.4kyr BP is marked by higher O180cvalues, and
there is a drop of about 1%0from c. 11.4kyr to c.
10.6kyr BP (Fig. 5). During the Holocene tl\~O180C
trendisaslow,steadyriseofvalues.o180cmirlimaare
recorded from c. 6.4 to 6.0kyr BP, at c. 4.5kyr BP,
from c. 3.0 to 2.5kyr BP and from 0.2 to 0.6kyr BP.
200
O
un(X)rrected
15 ~
-0-1.340
_1.646
i
O
30 ~
~
45 ~
30
220
c:5
--60
E
~
g
E
.9 230
~
g
.,g 120
Cl.
E
.c
90
E
o
8
i
~
f
-'-1.092
210
I
.:= 150
240
G)
-g
~
S
180
1/1
5
250
210
240
A
260
210
10
11
12
13
14
15
U/Th age (kyr)
16
17
18
19
O
2
4
6
8
10
12
14
16
18
20
UfTh age (kyr)
Fig. 3. A. Age mode1 far SVI. Triang1es= uncorrectedages; dots, open circ1esand asterisks indicate the corrected ages ca1culatedwith a
23"Thf232Thactivity ratio far the detrital component of 1.092, 1.340and 1.646,respective1y.The 20- errar bars afe p1ottedonly far the 1.34
corrected series. B. Age mode1and mean annua! extension rate far SVI. Triangles=uncorrected ages; open circ1es=ages corrected far
23~h/232Th activity ratio ofthe detrital component of 1.34 +0.31/-0.25'The corrected ages afe plotted with 20- errar bars.
.",
",,'.".c'-
..I
450
Silvia Frisia et al.
BOREAS
34(2005)
...+-
+-
+-
+-
-+-.-
-]
#o
I
-4
~
I
-5
>
--
Q
Q.
O
~: ~60
-9 ~J~\~~vvJJ\V'l/'~f\JV~~V--t-~~~~
# -10
.8
G
Q -11
A.
~
=U -12
A
eo
-13
O
1
2
3
4
5
I
6
7
8
9
Age[kyfBP]
10
11
12
13
14
15
L
16
17
~
.5
\ .I~N
j,.j.rAl\.
1-10 ~Vl"f
'\Al' vr'
,...
G
,lI..
V\f'J
A
\l'V
, AI ..AA- A~.
~\JV~'~.
-V
~
J.ti.
#
B,...
J -6 l
'-\J '--'L"'\r~\"\I~r"~'
-7 =.o
"'
.~.ll ~
~
-8
eo -12
O
1
2
3
4
5
6
7
8
9
10
Age [kyr BP]
Fig. 5. A. Carbon and oxygen isotopic variability far the past c. 17 kyr measuredalong the growth axis of SVI with the position ?f the
um ages shown with 20" error bars (top). The grey area between 12.1 and Il.3 kyr HP corresponds to a honey-coloured layer in the
stalagmite. The Holocene portion of the stable isotope profiles shows muted variability with respect to the Lateglacial. B. Enlargement
showing the muted stable isotopes variability far the Holocene.
annual temperature (over 25 years) COlTesponds
to a
2.85%0 increase of the SVI &180c (over 25 years).
Because the Holocene portion of the stalagmite has
formed in quasi-isotopic equilibrium it is reasonableto
assume that the present-day relationship between
&lSOc and &lSOw remained similar throughout the
Holocene. A shift toward higher &lSOcvaluestherefore
indicates warmer mean annual temperatures, as
already observed in an Alpine speleothem from NE
Italy (McDermott et al. 1999). By coupling the modero
relationship between &lSOp and mean annual air temperature of 0.60/ooI°Cfor mid-Europe (Rozanski et al.
1993) with the calcite/water fractionati°n.' which, at
the mean annual temperature of the cave 1S-0.220/00/
°C (O'Neil et al. 1969), a net positive shift of &1Soc of
c. 0.38%o1°Cis obtained. This theoretical value is
lower than that obtained throu~ the calibration. The
dampened sensitivity of SVI & Oc with respectto the
theoretical &lSOc-temperature relationships depends
on several factors. One is the resolution of the &lSOc
data, which, for the past 500 years in SVI is 25 years.
An improved resolution would allow &lSOc peaks to
be detected that are smoothed (see, for exampIe,
McDermott et al. 2001). We were, however, at the
limit of the present state of our analytical technique.
The second factor is the damping effect of the
MeditelTaneanon rainfall oxygen isotope composition
with respectto the Alpine and CentraI Europeanvalues
(Darling 2004). Proximity to the sea seems to
bave protected the karst area of Trieste from much
temperaturechange.
Holocene temperature variability in the SE Alps
Although we are not fully confident of the accuracy
of temperature estimates based on the present day
calibration, which does not account for changes in
storm tracks and 'amount etfect', we reconstruct a
slow temperaturerise of c. 0.5°C since IOkyr BP. The
trend indicates close agreement with the temperature
..
BOREAS34 (2005)
Climate variability
in SE Alps
451
.
!
0.8
.5
-A
~
O4
E
>.
.:
0.8
I
cJ
Y
-6 i3'
\
9:
~
pq
Ò
0.3371x
(j
()
~\/~j~
=
1.9782
B
R2 = 0.3776
:-
~
+
I
0.4
i
O
O
§
~
I-i
0.0
\
tI
r~
-0.4
.W
\~
~
.7
~
il
lì.
M
~O
-8
g
0.0
;;::-::-:~
O!-
~-O.4
citU
iO
O
O
O
00 O
O
O00
O
O
-0.8
-0.8
2000
1800
1600
1400
1200
-1.5
-7.0
-6.5
Age (years AD)
I
~
-6.0
-5.5
6180 (VPDB) ~
-10,5
"I
C
-11.5
~~~"""""'/'"-I'\
~~hJ"~i\.-"",
'00
LlA
-12.
5
MW2
\
~
~
~
MC2
MW1
~
"~
/~
,
MC1
-5
RWP
~1\;fI
~vJ~y-'~,-.I\/
-6
~
òJ
~
\
-7 G
O
,
..
..-r()
...
2000
1500
-8
1000
500
O
~500
-1000
Age (years AD)
r:ig.
6.
R~construction
cm1es)
Wlth
1ine).
B.
each
loC
for
of
the
Co1d
3
(time
Periods;
RWP
MW
=
1
and
reconstruction
for
inferred
rise
could
local
climate
throughout
the
pollen
et
Holocene
RWP
in
or
in
Fig.
RWP
6C).
slightly
of
past
McDennott
structure
for
Fig.
from
Carolingian
6C),
c.
and
AD
medieval
c.
450
700
values
afe
to
c.
AD
(MWl
.
c.
850
in
the
BC
ofthe
the
to
the
&
Jones
complex
warming
been
6C).
the
second
McDennott
as
by
Northern
(MW2
in
structure
is
(McDennott
et
speleothem
'Medieval'
Mann
al.
data
interval
about
&
climate
c.
seem
of
AD
Jones
800
(2003),
instability
(at
to
was
least
in
Hemisphere).
records
from
(Mann
from
today
from
by
respect
temperatures
Regional
reconstructed
characterized
records
occurred
of
single
conditions
for
period
stalagmite
the
record
1000,
with
temperature
Irish
recorded
AD
-0.2°C
those
2004).
that
warm
SVI
years
the
The
temperature
which
complex
by
indicate
actually
to
similar
bottom.
reconstructions
warming
for
Medieva1
0180
year
of
1400,
the
was
reference
similar
A
recorded
2001;
the
AD
=
SVI
proxy
instrumental
c.
at
temperature
second
ofSVl
MC2
6C)
the
anomaly
The
whereby
records
1100.
about
high-resolution
to
bave
at
(2004),
and
Fig.
AD
surface
2003).
1400,
in
spell
open
continuous
detai1s).
in
to
al.
bars
for
with
years;
isotope
error
text
900
temperature
moderately
phase
cold
O
(line
25
et
and
20"
(see
Sl80c
=
MCl
(MC2
AD
1961-1990
1150
with
years
mean
a
thus
(MCl
The
on
also
with
6C).
a
C
Periods;
p1otted
c.
SV1
mean
erbacher
C.
Period
from
based
to
afe
Cold
SVI
Lu
Warm
100
of
rng
S180c.
Medieval
past
iO~
from
in
ages
the
global
RWP
2001;
cool
first
of
which
Fig.
to
al.
a
700
Uffh
today
similar
first
AD
=
:E
2004;
anoma1y
MW2
AD
in
of
(coinciding
Fig.
400
those
also
The
by
the
Period,
shows
c.
of
and
those
Ca1ib
al.
of2.85%o
indicate
et
record
followed
most
temperature
identifies
distant
A.
et
Medieval
the
in
(McDennott
to
km
record.
enrichment
by
reconstruction,
0180c
climate.
AD
was
Empire)
our
to
SVI
the
This
Warm
similar
Ireland
years
The
the
from
(Roman
to
SW
100
2004).
occurred
between
The
from
the
reached
AD
to
on
the
an
corrected
intracontinental
temperatures
were
warmer.
to
afe
the
isotope
(Luterbacher
MWl
but
20
warmest
O
of
effect
respect
According
stalagmite
those
c.
temperatures
even
a
and
Age;
lower.
(about
that
lce
data,
SVI
years
in
simi1ar
damping
Europe
The
ago)
the
500
and
positions
0.5°C
with
SE
Litt1e
pollen
Sea
probably
years
the
to
Adriatic
2003).
were
(2400
due
the
for
al.
from
from
past
resu1ts
temperatures
about
kyr
variations
=
The
by
is
Holocene)
archives
(Davis
be
of
LlA
Periodo
the
mean
years):
Europe
SVI
3
S.80c
present-day
characterized
SE
from
discrepancy
25
Warm
were
SV1
the
=
Roman
2
1ast
for
between
from
reso1ution
RWP
and
the
reconstrucl1on
re1ationship
deviation
kyr
ove~
anoma1y
temperature
1ast
variabi1ity
temperature
Reconstructed
the
c1imate
the
AD
1450
coldest
to
period
1800,
which
of
coincides
the
past
2000
with
the
..
452
Si/via Frisia et a/.
Little Ice Age (LIA). In the period AD 1650 to 1750,
which broadly coincides with the Maunder Minimum
(MM; 1645-1715) coldest phaseofthe LIA in Europe
and in the Alps (Wanner et al. 2000; Luterbacheret al.
2004), the estimated temperature anomaly with respect
to the presentis c. -1°C for the extremes.Becauseof
the resolution (25 years) and the damping effect of
the Mediterranean, SVI does not record the extreme
temperature anomaly of -3.7°C reconstructed by
Luterbacher (2001) for the coldest years of the MM in
CentraI Europe. In SVI, the decade centred at AD
1840 is the last coldest phase of the LIA. In the past
100 years, temperature rose sharply (Fig. 6A) and
followed the Northem Hemisphere temperature trend
reconstructed by Mann et al. (1999), which is also
recorded by a stalagmite from Alps ofNE Italy (Frisia
et SV
al 12003)
h
S ows H o locene mean u~13Cc va lues o f
-11.44:.t 0.22%0, which afe typical of continental
carbonates and speleothernsdeposited in equilibrium
with the C3 vegetation of temperate regions (Cerling
et al. 1991; Baker et al. 1997).
Stalagmite growth rate in temperate settingsis controlled by temperature, the amount of CO2 available
in the soil and drip rate (Kaufrnann 2003; Kaufrnann
& Dreybrodt 2004). Drip rate can limit growth at
slow dripping sites. In our experience, however, we
observed that changes in drip rates in Alpine
stalagmites commonly resulted in fabric changes
(Frisia et al. 2000). In particular,' columnar fabric,
which is typical of constant drip rate, is replaced by
microcrystalline or dendritic fabric if drips show
strong seasonalvariability. SVI consists of the same
elongated columnar fabric. We, therefore, assumethat
drip rate variability was not a limiting factor.
In recent Alpine stalagmites, temperature controls
growth rate via the duration of winter ftozen soil
conditions (Frisia et al. 2003). SVI records its highest
extension rate in the time period c. 10.6 to c. 7.5 kyr
BP, when the Ò180cvalues were lighter than today
and, ifthe ò180c-temperaturerelationship observed for
the past 500 years stili held, mean annualtemperatures
could have been lower than at the present day, but
winter temperatures may bave been relatively mild.
The Early Holocene winter temperatures reconstruction for SW Europe based on pollen data indicates
temperature anomalies up to c. + 2°C with respectto
present-day (Davis et al. 2003). Bar-Matthews et al.
(2003) showed that in the Early Holocene the annual
rainfall in the Eastem Mediterranean was higher than
today, and therefore we do not exclude influence of the
amount effect on both Ò180c and growth rate ftom
c. 10.6 to c. 7.5kyr BP. In SVI, growth rate slowed
to c. 11 J.lmlyr after 4.4kyr BP, when Holocene
temperature reconstruction based on the Ò180ctemperature calibration indicates warmer conditions. Early
Holocene extension rates were high in stalagmites
from the NE Italian Alps, SW Ireland and Sauerland
.
.
BOREAS
34(2005)
(McDennott et al. 1999; Niggemann et al. 2003) in
a period for which pollen data indicate cooler temperaturesthan after 6kyr BP (Guiot et al. 1993; Davis
et al. 2003). It is, therefore, possible that the extension
rate-temperature relationship did not hold for the
Early Holocene, when the Mediterranean region was
characterized by wetter conditions (Bar-Matthews
et al. 2003). Orbital variations may be a fundamental
cause of this phenomenon.Higher summer insolation
in the Alps may bave resulted in enhancedrainfall and
stronger seasonalcontrast than today (Crucifix et al.
2002; Bradley et al. 2003), which shifted the
stalagmite growth season.Extension rate in the Early
Holocene might bave been controlled by summer
temperaturesand rainfall.
Al.
l . l l ..
ateg acla c Imate m the s'v
L pS
L
The calibration with the presentmay not hold true for
the Lateglacial, when climate was stili in a 'gIaci al
mode' (Kolodny et al. 2003), the cave was located 500
to 300km north ofthe coastline (Lambeck et al. 2004)
in a more continental setting, and speleothemdeposition may not have occurred in isotopic equilibrium
(Fig. 2). SVI extension rate was very slow up to c.
10.6kyr. The drop in Ò180csince 16.5kyr BP ,correlates with the sharp drop observed in spel8~ems
from Soreq cave (Israel) starting at c. 17kyr BP
(Bar-Matthews et al. 2003), which were attributed to a
temperatureincrease and ice-sheetmelting during the
last deglaciation (Bar-Matthews et al. 1999). The
structure of the last deglaciation differs ftom that in
Greenland,however, where it is characterized by two
major abrupt wanning spells at 14.6 (B0l1ing) and
11.6kyr BP (Blunier et al. 1998), and Antarctica,
where temperatureincreasedfrom at least 18.5kyr BP
(Blunier et al. 1998). The last interglacial palaeoclimate changes in the SE margin of the Alps appear
compatible with both the early ending of fuIl glacial
conditions in Antarctica and the steps toward full
interglacial climates recorded in Greenland. By contrast, a composite speleothem record ftom NW
Germany spanningthe last 17.6kyr shows connections
with Greenland, i.e. no deposition during the cold
phasesGS-2 and GS-1 (YD) and a very short depositional stage in GI-Ia (B0l1ing-AlIer0d) (Niggemann
et al. 2003).
The extension rates and Ò180crecord for the late
deglaciation in SVI afe interpreted here as a combination of temperature and rainfall, with rainfall
exerting the dominant effect (Bar-Matthews et al.
1997, 1999). According to the model proposed by
Bar-Matthews et al. (1997), the Ò180cdepletion at
c. 14.5kyr BP is interpreted as reflecting warm and
wet conditions. The GS-I (YD) is characterized by a
shift toward higher Ò180cvalues, coinciding with
Ò13Ccenrichment of up to + I %o(Fig. 7) ftom 12.0
and 11.4kyr BP, while the extensionrate is extremely
..I
BOREAS34 (2005)
Climate variability
+.-+-
+-
in SE Alps
453
+-
I
I YDI B-A I
-44~
I
-42 o
~
-40!
r
'I
AI
8 -4
~
lJJ.. J.
~5
~
~~M1a,1~1-""~'~'~'~v~
"""
-38
~It{v:
N
~
.r.hl
8
I
~\,Nr'
-36~o
I
1-34
~
.
984-6
>
N
Q.
CI)
o
mO-7
...
2
00
~
~
-~
Q
Do
-8
~
-4 r
..
-6
O
'"
O
m
-8 "'00
O
1
2
3
4
5
6
7
8
9
lO
Age
(kyrBP)
Il
12
13
14
15
16
17
18
..~
Fig. 7. Comparison between the SVI oxygen isotope record, the Greenland GISP2 ice care 0180(note inverted scale -Grootes et al. 1993)
and the 0]80c speleothemrecord from Soreq Cave in lsrael (Bar-Matthews et al. 2003). The position of the Urrh ages of SVI are plotted
with 2a error bars at the top. YD = Younger Dryas; B-A = B011ing-Allernd interstadial. (Last Glacial and lnterglacial Greenland
event-stratigraphy from Lowe et al. 2001).
low «8~m/yr). These characteristicsindicate that the
YD was most probably characterizedby cool and arid
conditions, which is consistentwith pollen data (Guiot
et al. 1993). Lake level records in the Jura mountains
provide evidence far climatic drying during the late
GS-I and the GS-I to Preboreal transition (Magny
et al. 2003). By contrast, the relatively high lake levels
in the YD at Gerzensee(Switzerland) were interpreted
as due to reduced percolation ofwater into the shallow
groundwater as a result of frozen soil conditions,
which increased direct runofI in the lake (von
Grafenstein et al. 2000). Similarly, reduced percolation
due to prolonged frozen soil conditions, associated
with decreasedprecipitation may bave diminished the
recharge of the karst aquifer in the Savi cave area
during the YD. The 013C~~eak far the YD, which is
better defined than the O Oc, can be interpreted as
reflecting cold and arid climate, which yielded a short
duration of active soil condition and the related
decreaseof soil COl production (cf. Frisia et al. 2003;
Genty et al. 2003). The 0180cpeak recorded by SVI in
the YD broadly coincides with a similar 0180c peak at
Soreq Cave (Bar-Matthews et al. 2003), supporting a
connection betweenthe SE margin of the Alps and the
Eastem Mediterranean. Bar-Matthews et al. (2003)
calculated high 0180 values ofrainwater far the YD, at
c. 5kyr and far the last 3.5kyr. They did not provide
palaeo-annual rainfall calculations far the YD, but
associatedthe high 0180 at c. 5.1 kyr with an abrupt
drop in average rainfall amount and, similarly,
estimated low average rainfall amounts far the past
3kyr. The high 0180cvalues recorded in the YD may,
therefore, reflect a combination of low rainfall amount
and high rainfall 0180. A comparison with the 0180
record of GISP2 ice care (Grootes et al. 1993) shows
that shifts to depleted oxygen in Greenland (cold)
correspondto high 0180cvalues in the SVI and Soreq
0180c profiles (dry) (Fig. 7). Bar-Matthews et al.
(1999) hypothesizedthat the higher 0180 values ofthe
Lateglacial portion of the Soreq cave record indicate a
major change in the way the Mediterranean Sea
affected rainfall. Similarly, in SVI the 0180c values
afe higher in the Lateglacial and may reflect a close
connection betweenthe SE margin of the Alps and the
Mediterraneanregion.
The isotope record of SVI indicates that the Lateglacial climate in the SE Alpine region was dominated
by shifts from arid to humid periods. The marked
glacial climate instability observed in the SVI
speleothem supportsthe hypothesis that Late Palaeolithic Alpine alt was a consequence of these harsh
conditions, which required a deep knowledge of the
",.,~.'.=-:
.454
Silvia Frisia et al.
environment
need
proposed
for
C
to
be
BOREAS34 (2005)
transmitted
by
paintings
such
by Mithen
knowledge
(2003). anyAfter
more.the YD
there
as
was no
SVI
. d
prOVI
th
fu
es
.
e
st
E
cont~uous
l .B.,
uropean
c
Stocker,
Imate
C.
proxy
record
&om a stalagmite
for the past c. 17 kyr
BP, and the first evidence
for the different
effects
of
the glacial
and the Holocene
climate
modes
in the SE
Alpine
region.
During
the Lateglacial,
the oxygen
..
b' l'
Isotope
vana
Ilty
speleothem
record
and
is
instability
con
d
rate,
Th
.,
hIgh
e
and
tur
empera
'
e.
presento
nse
This
area-average
reconstructed
data.
The
ifi
In
b
d
the
Eastern
O lsotopes
th
f
Raynaud,
lohnsen,
Bradley,
Change
e
Mediterranean,
D.,
S.
l,
louzel,
l.,
1998:
Clausen,
Asynchfony
H.
of
B.,
Hammer,
Antarctic
and
R
S.
and
& Pedersen,
the
Future,
T. F. (eds.):
105-141.
Paleocllmate,
Global
Springer,
Berlin
and
Heidelberg.
We
05
~.
°
cold
identified
C
~
a slow,
10
1,
..uom
IS m
and
and
of the Alps.
In the
relationship
between
broad
t
Wlth
'
W:mn
Pen
ods
d
an
two
M
Asmeron,
Y.
2000:
The
half-lives
17~2-1703.
th
,o
agreement
&
of
uranium-234
and
thorium-230. Chemical Geology 169,17-33.
Craig, H. 1961: Isotopic variations in meteoric waters. Science 133,
steady
BP
AJ'
.
Crucifix,M.,Loutre,M.-F.,Tulkens,P.,Flchefet,T.&Berger,A.
e
2002:
the
mean
annual
temperature
anomalies
for the SE European
region
&om pollen
high-resolution
record
far the past 3 kyr
e Roman
T.,
&
Greenland climate change during the last glacial periodo Nature
394, 39-743,
Bradley, R S., ~riffa, K. R, Cole, l:, Hug.es, M. K. & Osbom, T. l.
2003: The cllmate of the last mlllennium. 1n A1~erson, K. D.,
th
Wl
Indlcatmg
SE margin
a positive
O180c.
trend
agreement
U,
being
record
.
YD
o
'
roa
th
es,
of p~s-
dominated
by greater
Cerling, T. E., Quade, l., Solomon, D. K. & Bowman, l. R 1991:
under glacial boundary
On the carbon isotopic composition of soil calbon dioxide.
h
'
ed b l
.Geochimic'a
et Co.\'moc'himic.'aActa 55, 3403-3405.
~s c arac~en~
.y
ow extensl~n
Cheng, H., Edwards, R L., Hoff, l., Gallup, C. D., Richards, D. A.
for the
there
is
temperature
l.d ent
.
&om
C and
conditions
Holocene
t
,
IS
interpreted
as
of the rainfall
lti.ons.
intervals. Geochimic'a et Cosmochimica Acta
sure, temperature and molsture and changes m the typlcal
weather pattems in the Alpine region in response to the behaviour of tbe North Atlantic Oscillation.
Theoretica/ and App/ied
Climatology 71, 29-42.
Blunier, T., Chappellaz, I., Schwander, l., Dallenbach, A., Stauffer,
l.
USIOnS
onc
during interglacial
Beruston,
6:,3181-3199.
M. & lungo, P. 200.2: Shifts m the distn~utlon
Climate
Earth
evolution
system
during
model
of
the
Holocene:
intermediate
a
study
with
complexity.
an
Climate
DynamiL:1' 19, 43-60.
Dalmeri, G., Cusinato, A., Bassetti, M:, Ko~patsche~,. K. &
Hromy-Kompat.scher, M. 2004: The Eplgravettlan Moblllary art
ed .of
levaI
the
national
Dalmen
rock-shelter
(Trento,
Northem
News/etter
on Rock Art 40, 15-24.
Italy)
..'~
1nter-
Warm
Penods
charactenzed
by temperatures
that were
similar
to the presento The LIA stands out as ODe ofthe
coldest
periods
of the Holocene,
with estimated
mean
annual temperatures
of c. 1°C cooler relative
to today.
Darling, W. G. 2004: Hydrological factors in the interpretation of
stable isotopic proxy data presentand past: a European perspecti~e. Quaternary Science Review 23,743-770.
.
DavIs,~.
A. S., Brewer, S., Stevenson, A. C., Gwot, l..& Data
contributors 2003: The temperature of Europe durmg tbe
Holocene reconstructed from pollen data. Quaternary Science
Reviews 22,1701-1716.
Acknowledgement.l'.
-We
are very grateful
to P. Tuccimei
for
pe.rr?rming
siX; Urrb
analy~es, R ~iorandi
for ~icromilling
and
drilling;M. Wlmmer
for a~s~stance Wlth the stable I.so~ope analyses,
P. Forti, M. Potleca, L. Z~
.and U. Sauro for loglstlcs.
We thank
Frisia,
S., Borsato, A., Fairchild,
I. l. &
cite fabrics,
growth mechanisms,
and
in speleothems
from the ltalian
Alps
Journal
o/ Sedimentary'
Research
70,
M: .Bar-Ma~~ews for provldmg .tbe updated Soreq record and for
cntlcal revision of the ~anuscnpt. The res~h.
was funded b~
MIUR-COFI.N 2~
project ~d. by the Provmcla ~utonoma. di
Trento
(Uruverslty
and Sclentific
Research Servlce, prolect
AQUAPAST).
Frisia, S., Borsato, A., Preto, N. & McDermott, F. 2003: Late
Holocene annual growth in three Alpine stalagmites records tbe
influence of solar activity and the North Atlantic Oscil1ation
on winter c1imate. Earth and Planetary Science Letter,\' 216,
411-424.
McDennott,
F. 2000: Calenvironments
of formation
and Southwestem
Ireland.
1183-1196.
Genty, D., B1amart, D., Ouahdi, R, Gilmour, M., Baker, A., louzel
l. & Van-Exeter, S. 2003: Precise dating ofDansgaard-Oeschger
climate oscillations in western Europe from stalagmite data.
Nature 421,833-837.
References
von
Grafenstein,
Schwander,
Baker, A., Ito, E., Smart, P. L. & McEwan, R. F. 1997: Elevated
and variab1e OJ3C in speleothems in a British cave system.
Chemical Geology 136, 263-270.
Bar-Matthews,
M., Ayalon, A. & Kaufman, A. 1997: Late
Quatemary paleoclimate in the Eastem Mediterranean Region
from stable isotope analysis of speleothems in Soreq Cave Israel.
Quaternary Re.\'earch 47, 155-168.
Bar-Matthews, M., Ayalon, A., Kaufman, A. & Wasserburg, G. l.
1999: The eastem Mediterranean palaeoclimate as a reflection of
regional events: Soreq cave, Israel. Earth and Planetary Science
Lette~' 166, 85-95.
Bar-Matthews,
M., Aya1on, A., Gilmour, M., Matthews, A. &
Hawkesworth, C. 2003: Sea--1and oxygen isotopic relationships
from planktonic foraminifera and spelothems in the Eastem
Mediterranean region and their imp1ication for palaeorainfall
U.,
l.
&
Eicher,
Amman,
U.,
B.
Erlenkeuser,
2000:
lsotope
H.,
signature
Ruch,
P.,
of
tbe
Younger Dryas and two minor oscillations
at Gerzensee
(Switzerland):
pa1aeoclimatic and palaeo1imnologic interpretation based on bulk and biogenic carbonates. Palaeogeography,
Palaeoc'limatolog)', Palaeoecology 159, 215-229.
Grootes, P. M., Stuiver, M., White, l. W. C., lohnsen, S. & louzel
l. l. 1993: Comparison of oxygen isotope records from tbe
GISP2 and GRlP Greenland ice cores. Nature 366, 552-554.
Guiot, l., de Beaulieu, l. L., Cheddadi, R, David, F., Ponel P. &
Reille, M. 1993: Climate in Western Europe during tbe last
Glacial/lnterglacial
cycle derived
from pollen and insect
remains. Pa/aeoceanography, Palaeoc'limatology, Palaeoecolog)'
103,73-93.
Hendy, C. H. 1971: The isotopic composition of speleotbems. -I.
The calculations of the effects of different modes of formation on
the isotopic composition of speleothems and their applicability as
.,'
, .
BOREAS
34(2005)
Climatevariability in SEAlps
455
paleoclimatic indicators. Geochimica Cosmochimica Acta 35, Magny, M., Thew, N. & Hadom, P. 2003: Late-glacial and early
801-824.
Holocene changes in vegetation and lake-level at Hauterivel
Kaufmann, G. 2003: Stalagmite growth and palaeo-climate: a
Rouges Terres, Lake Neuchatel (Switzerland). Journal o/
numerical perspective. Earth and Planetary &oience Lettero'o
214,
Quaternary Science 18, 31-40.
251-266.
Mann, M. E., Bradley, R. S. & Huges, M. K. 1999: Northem
Kaufmann, G. & Dreybrodt, W. 2004: Stalagmite growth and
Hemisphere temperaturesduring the pastmillennium: inferences,
palaeoclimate: an inverse approach. Earth and Planetary Science
uncertainties and limitations. Geophy.,oicalRe.\'earchLetters 26,
Letters 224,529-5450
759-762.
Kolodny, Y., Bar-Matthews, M., Ayalon, A. & McKeegan, K. D.
Mann, M. E. & lones, P. D. 2003: Global surface temperature
2003: A high spatial resolution 0180 profile of a speleothem
over the past two millennia. Geophysical Research Letters 30,
using an ion microprobe. Chemical Geology 97, 21-28.
1820-1824.
o
.
Lambeck, K., Antonioli, F., Purcell, A. & Silenzi, S. 2004: Sea McDerm~tt, F. 2~0~: ~alaeo-cllmate reco~tructlon
from
level change along the Italian coast for the past 10,000yrs.
sta~le lsot°p'e varlatlons m speleothems:a revlew. Quaternary
Quaternary Science Reviews 23, 1567-1598.
Sclence Revlews.2.3,901-9:18:
...
Lauritzen, S. E. & Lundberg, 1.1999: Calibration ofthe speleothem McDermott, F., Fnsla, S., Ylmmg, H., Longmelll, A., SpirO, B.,
delta function: an absolute temperaturerecord for the Holocene
He.ato~,T. H. E., Hawkesworth, C. 1., Borsato, A., Keppens, E.,
in northem Norway. The Holocene 9, 659--669.
Falrchild, I. 1., v~ der Bo~, ~:' V~rheyden, S. B:- Selmo, E.
Longinelli, A. & Selmo E. 2003: lsotopic composition of
1999: Holocene cllmate. vanablilty. ~ Ew:ope: evldence from
'.
..'
0180, textural and extenslon-ratevanatlons m three speleothems.
270
preclpltatlon
75-88 m ltaly: a first overall map. Journal o/ Hydrology
Quat emary sclence
o
Revlews,
o
18 1021-. 1038
l
1
H
.
L
'
Int
.
I
McDermott,
F.,
Mattey,
D.
P.
C. 1. 2001:
k W..group.
Z & INTIMATE
2001'
Ce t . I al H l
l. &t Hawkesworth,
. b.l .ty
l d b h.
owe, ..,
oe,
er-reglona
n ennla -sc e o ocene c Ima e varia I I revea e y a Ig-h
correlatl~n of pa~e.ocllmatlc records for. the Last Gla~I~Iresolution speleothem 0180 record from SW lreland. Science
Interglaclal Transltlon: a protocol for Improved prec!slon
294, 1328-1331.
rec°.mmended by the INTIMATE group. Quatemary Sclence Mithen, S. 2003: After the Ice. 622 pp. Phoenix, Londono
Re~'ews 20, 1175-11~7..
Niggemann, S., Mangini, A., Richter, D. K. & Wurth, G. 2003: A
Ludw~g,K. R. 1.999: Us~g IsoplotlEx, Verslon 2.01: A geochronopalaeoclimaterecord of the last 17,600years in stalagmites from
loglcal toolkit for Microsoft Excel. Berkeley Geochronology
the B7 cave Sauerland,Germany. Quatemary Science Reviews
Center Special Publication la, I-55.
22 555-567'.
Ludwig, K. R. 20~~: Mathematical-statistical ~atmen~ of data O'N~il, 1. R., Clayton, R. N. & Mayeda, T. K. 1969: Oxygen
and errors for
~U
geochronology. Revlews Mmeralogy
isotope fractionation in divalent metal carbonates. Journal o/
Geochemistry 52,631--636.
ChemicalPhysic.v51,5547-5558.
0..-'
Lute~acher, 1. 200..: The Late ~aunder Minimum (1675-1?1~).
Rozanski, K., Araguas-Araguas,L. & Gonfiantini, R. 1993: lsotopic
Cllmax of the Llttle Ice Age m Europe. 1n lones, P., Ogllvle,
patterns in modero precipitation. In Swart, P. K., Lohmann,
A. E.I., Davies, T. D. & Briffa, K. R. (eds.): Hi.vtory and
K. C., McKenzie, 1. A. & Savin, S. (eds.): Climate Change in
Climate Memorie.v o/ the Future? 29-54. Kluwer Academicl
Continental1.votopicRecordv,1-36. Geophysical Monograph 78.
Plenum Publishers, New York.
American Geophysical Union, Washington DC.
Luterbacher, 1., Dietrich, D., Xoplaki, E., Grosjean,M. & Wanner, Wanner, H., Holzhauser, H. P., Pfister, C. & Zumbiihl, H. 2000:
H. 2004: European seasonaland annual temperature variability,
Interannual to century scale climate variability in the European
trends, and extremes since 1500. Science 303, 1499-1503.
Alps. Erdkunde (Earth Science) 54, 167-175.
Appendix
For the present study, we applied a Dovei strategy for therefore the sensitivity of the correction is mostly
U/Th dating when stalagmites show detrital contami- tuned bJ the discrepancy of this pair. The calculated
nation. In SVl, detrital Th contaminationcharacterized 23~2
Th activity ratio of the detrital component
alI the samples, even though high Th contamination that eliminates the age discrepancy for the SVI-249/was detected in only two specimens at the bottom of 28 pair is 1.34+0.31/_0.25
(95% confidencelimits). The
the stalagmite. We used the ISOPLOT code calculation accounts for the fact that SVl-249 was
Th-correction function (Ludwig 1999) on three pairs of taken 1 rom above SVI-28: this distance coJTesponds
quasi co-genetic specimens (SVI-24/-25; SVI-238/- to 60 years at the estimatedgrowth rate of 17 ~m/year.
27; and SVI-249/-28) to calculate the 230Th/232Th The calculated ages, which coJTesponded
to the 95%
activity ratio of the detrital component that minimizes confidence limits of + 0.31 and -0.25, were utilized to
the age discrepancy of the two cogenetic samples ~ropa~ate the eJTors in the corrected ages. The
within each pair by successive iterations. The pairs
30J1J32Th activity ratio of 1.34+0.31/_0.25
optimizes
SVI-24/-25 and SVI-238/-27 bave a high and similar
230Th/232Thactivity ratio. By contrast, the ~air SVI249/-28 is characterized by very different 2 Th/23~
the age agreementfor the SVI-24/-25 and SVI-238/27 pairs, and eliminates the age inversion for the
SVI-207. This value falls within the range ofthe mean
activity ratios (11.8 and 103.3, respectively), and
bulk Earth value of 0.8:t0.8 (see Ludwig 2003).
4
";.;:"'.,.::~-
I
I