HR: 14:40h
AN: PP33C-05 INVITED    [Abstracts]
TI: Rapid Amazonian Moisture Oscillations Correlated with Dansgaard-Oeschger Cycles
AU: * Wang, X
EM: wang0452@umn.edu
AF: Department of Geology & Geophysics, University of Minnesota, 310 Pillsbury Dr. SE, Minneapolis, MN 55455, United States
AU: Auler, A S
EM: aauler@terra.com.br
AF: Instituto do Carste, Rua Kepler 385/04, Belo Horizonte, MG 30360-240, Brazil
AU: Edwards, R
EM: edwar001@umn.edu
AF: Department of Geology & Geophysics, University of Minnesota, 310 Pillsbury Dr. SE, Minneapolis, MN 55455, United States
AU: Cheng, H
EM: cheng021@umn.edu
AF: Department of Geology & Geophysics, University of Minnesota, 310 Pillsbury Dr. SE, Minneapolis, MN 55455, United States
AU: Ito, E
EM: eito@umn.edu
AF: Department of Geology & Geophysics, University of Minnesota, 310 Pillsbury Dr. SE, Minneapolis, MN 55455, United States
AU: Dorale, J A
EM: jeffrey-dorale@uiowa.edu
AF: Department of Geoscience, University of Iowa, North Capitol St., Iowa City, IA 52242, United States
AB: Terrestrial paleoclimate records on abrupt climate events from the tropics, e.g. Dansgaard-Oeschger (D-O) oscillations, are still rare, in particular, from Amazonia, which contains the largest tropical rainforest in the world. We have obtained a high-resolution oxygen isotopic record of cave calcite from Caverna Paraíso (PAR, 04o04'S, 55o27'W), Amazonia, Brazil. The chronology was determined by 69 U-Th ages from 4 stalagmites. Tests for equilibrium conditions show that their oxygen isotopic variations are primarily caused by climate change. We thus interpret the Paraíso record, spanning the last 50 thousand years, in terms of meteoric precipitation changes at this equatorial location. The oxygen isotopic profile shows significant abrupt millennial-scale variations during Marine Isotope Stage (MIS) 3, with amplitudes as large as 2 per mil. Using independent age scales, we compare the record to contemporaneous records from caves in eastern China and high-latitude ice cores. During MIS 3, the PAR calcite oxygen isotopic profile correlates remarkably with the Hulu Cave record (Wang Y.J. et al., 2001, Science), indicating that precipitation histories at the two sites are asynchronous, similar to our previous observations from northeastern and southern Brazil speleothems (Wang X.F. et al., 2004, Nature; Wang X.F. et al., 2006, Quat. Sci. Rev.). During MIS 3, Paraíso precipitation also broadly anti-correlates with Greenland D-O events (NGRIP members, 2004, Nature) and positively correlates with Antarctic warm events (EPICA community members, 2006, Nature). Our record adds further support to the idea that abrupt climate events have a worldwide distribution during MIS 3 (Voelker et al., 2002, Quat. Sci. Rev.). The observed correlations between the records support an oceanic meridional overturning circulation mechanism for driving the abrupt millennial-scale events of the last glacial period, coupled with strong air-sea feedbacks from the tropics. In combination with Andean ice core and lake records (e.g. Thompson et al., 2006, PNAS), knowledge of the meteoric precipitation oxygen isotope and moisture history of the central Amazon may shed new light on the role of the tropics in abrupt climate change.
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4914 Continental climate records
DE: 4938 Interhemispheric phasing
DE: 4958 Speleothems
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting