25th International Meeting on Organic Geochemistry IMOG 2011

P-472
Variability of Sea Surface Temperature in the Eastern Equatorial
Pacific Ocean during Last Glacial Cycles
Hasrizal Shaari, Masanobu Yamamoto, Tomohisa Irino
Hokkaido University, Sapporo Shi, Japan (corresponding author:hasrizals@ees.hokudai.ac.jp)
Various marine proxies has been used
intensively in the reconstruction of paleoclimate and
paleoceanography in the Eastern Equatorial Pacific
(EEP). In this study, we discussed the sea surface
temperatures (SSTs) produced by TEX86, U K‘ 37 and
Mg/Ca in Ocean Drilling Program (ODP) Leg 202
sites 1239, 1237 and the nearby core during the last
glacial cycles.
Multi-proxy data show a synchronous SST
variability in the glacial-interglacial cycles, and the
core-top segments were in agreement with the
modern EEP‘s SST (24.4–25.2 o C). The variation
patterns of the proxies were comparable to the global
stack of benthic δ 18 O records by Lisiecki and Raymo
(2005) and the regional δ 18 O records from
Globigerinoides ruber (G.ruber) by Lea et al. (2000),
and the CO2 concentration recorded in Dome Fuji
(Kawamura et al., 2007) they were delayed behind
the variation.
The amplitude of variation was larger in the
TEX86-derived SST record than those in U K‘ 37 and
Mg/Ca-derived SSTs. The average glacial-interglacial
amplitude contrast was ~5.2 o C in TEX86 and ~2.4 o C in
U K‘ 37 at site 1239,~2.4 o C in Mg/Ca at site TR163-19
and ~1.8 o C in U K‘ 37 at site 846.
The low value of TEX86-derived SST than the
U K‘ 37 and Mg/ca especially between MIS 2 and MIS 4
is yet remain puzzle, however there are two posibility
which could explain those condition; (1) the
production of isoprenoid GDGTs by crenarcheota
species within that period likely occured in the
subsurface water, instead of surface water; or (2) the
strengthening of upwelling systems which bring up the
cooler bottom water to the surface and decrease the
SST.
The result of TEX86 also indicated ~4.2 o C
latitudinal temperature gradiant between the EEP (site
1239) and Peruvian upwelling systems (site 1237)
and show the unifrom SST gradient during glacialinterglacial.
This suggests that the upwelling intensity
of the Peruvian Cold Tongue unchanged in glacialinterglacial
contrast.
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