HR: 1330h
AN: PP32A-0279    [PDF]
TI: High Resolution Characterization of the Asian Monsoon Climate During MIS 5 and 6, Dongge Cave, China
AU: * Kelly, M J
EM: kell0738@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Drive SE, Minneapolis, MN 55455 United States
AU: Edwards, R L
EM: edwar001@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Drive SE, Minneapolis, MN 55455 United States
AU: Cheng, H
EM: cheng021@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Drive SE, Minneapolis, MN 55455 United States
AU: Yuan, D
EM: dxyuan@karst.edu.cn
AF: Karst Dynamics Laboratory, The Ministry of Land and Resources, 40 Qixing Road, Guilin, 541004 China
AU: Cai, Y
EM: ycai@loess.llqg.ac.cn
AF: State Key Lab of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710075 China
AU: Zhang, M
EM: mlzh@karst.edu.cn
AF: Karst Dynamics Laboratory, The Ministry of Land and Resources, 40 Qixing Road, Guilin, 541004 China
AU: Lin, Y
EM: ysln@karst.edu.cn
AF: Karst Dynamics Laboratory, The Ministry of Land and Resources, 40 Qixing Road, Guilin, 541004 China
AU: An, Z
EM: anzs@loess.llqg.cn
AF: State Key Lab of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710075 China
AB: Speleothem samples from Hulu (eastern China, $32\deg$30'N, $119\deg$10'E) and Dongge (southern China, $25\deg$17'N $108\deg$5'E) caves provide a nearly continuous record of the Asian monsoon over the last 160 ka. Based on the $\delta$$^{18}$O records of two stalagmites from Dongge Cave (D3 and D4), we have shown that Termination II was an abrupt climatic transition occurring at 129.3 $\pm$ 0.9 ka marking the onset of the Last Interglacial Asian Monsoon (Yuan et al., in review). This earlier work had relatively coarse resolution with Termination II bracketed by a single pair of $\delta$$^{18}$O measurements $\sim$200 years apart in age, providing an upper limit for the rapidity of the climate transition. The Last Interglacial Asian Monsoon lasted 9.7 $\pm$ 1.1 ky, also ending abruptly ($<$300 y, limited by sample resolution) at 119.6 $\pm$ 0.6 ka. The full glacial-interglacial amplitude is $\sim$5%, with the abrupt transitions into and out of the Last Interglacial having a range of approximately 3$\permil$. Higher resolution isotope sampling (averaging $\sim$30 y, with $\sim$10 y resolution over Termination II) from stalagmites D3 and D4 has provided a more detailed account of $\delta$$^{18}$O variations over much of MIS 5 and 6. Precise $^{230}$Th dating has replicated the chronology of the samples within error. The higher resolution data set confirms the timing of Termination II, placing it at 128.9 $\pm$ 0.9 ka, BP. The bulk of this transition ($\sim$1.7$\permil$) took place within 60 years, with the total range of the transition being $\sim$3$\permil$. A major issue is climate stability during interglacial periods. There were some early indications of major instability of the Last Interglacial climate (GRIP members, 1993, Nature 364, 203-207). Whereas our record shows no evidence for instability with glacial-interglacial $\delta$$^{18}$O amplitudes, there is clear evidence for abrupt $\sim$1$\permil$ shifts with periods on the order of several hundred years during the Last Interglacial (supporting some earlier work, An and Porter, 1997, Geology 25, 603-606). Similar to the features found by Dykoski et al. (this meeting) during the Holocene in the Hulu/Dongge record (see also Bond et al., 2001, Science 294, 2130-2136), these shifts cover approximately « of the amplitude of millennial-scale events during the Last Glacial Period in China (Wang et al., 2001, Science 294, 2345-2348). Thus, it appears that abrupt centennial or millennial-scale changes are a general feature of interglacial periods, albeit with significantly smaller amplitudes than events during glacial periods.
DE: 1600 GLOBAL CHANGE (New category)
DE: 3344 Paleoclimatology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting