HR: 1330h
AN: PP32B-0295    [PDF]
TI: A High Resolution, Absolute-Dated Holocene and Deglacial Asian Monsoon Record From Dongge Cave, China
AU: * Dykoski, C A
EM: dyko0008@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Hall, Minneapolis, MN 55455 United States
AU: Edwards, R L
EM: edwar001@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Hall, Minneapolis, MN 55455 United States
AU: Cheng, H
EM: cheng021@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Hall, Minneapolis, MN 55455 United States
AU: Yuan, D
EM: dxyuan@karst.edu.cn
AF: Karst Dynamic Laboratory, The Ministry of Land Resources, 40 Qixing Road, Guilin, 541004 China
AU: Cai, Y
EM: caiyjelle@263.net
AF: State Key Lab of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Science, Xi'an, 710075 China
AU: Zhang, M
EM: mlzh@karst.edu.cn
AF: Karst Dynamic Laboratory, The Ministry of Land Resources, 40 Qixing Road, Guilin, 541004 China
AU: Lin, Y
EM: yslin@karst.edu.cn
AF: Karst Dynamic Laboratory, The Ministry of Land Resources, 40 Qixing Road, Guilin, 541004 China
AU: An, Z
EM: anzs@loess.llqg.ac.cn
AF: State Key Lab of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Science, Xi'an, 710075 China
AU: Revenaugh, J
EM: justinr@umn.edu
AF: Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Hall, Minneapolis, MN 55455 United States
AB: Previous work on speleothems from Hulu Cave, China, demonstrated a link between last glacial period and deglacial East Asian monsoon intensity and millennial-scale events in the North Atlantic as well as orbitally induced insolation variations (Wang et al., 2001, Science, 294, 2345-2348). The East Asian monsoon originates from the tropical Pacific thereby connecting this specific site in the tropics to the processes creating these millennial-scale events. Recently these events have been observed to extend into the Holocene (Bond et al., 2001, Science, 278, 1257-1266), challenging the idea of fairly stable climatic conditions observed in Greenland ice cores during the Holocene. Here we present a continuous record of the Asian monsoon over the last 16,000 years from stalagmite calcite to further extend the link between Asian monsoon intensity and millennial-scale events into the Holocene. This time range overlaps the Hulu stalagmites by $\sim$6,000 years and a strong correlation is observed between the two records suggesting the same mechanisms affecting the East Asian monsoon affect a broader region of the Asian monsoon system. 808 oxygen isotopic measurements providing information on shifts in monsoon precipitation are combined with a chronology from 45 precise $^{230}$Th dates. Monsoon intensity increased dramatically ($\sim$3$\permil$) during the start of the Holocene ($\sim$11.5 ka) and remained high for $\sim$6 ka. In the middle-late Holocene, two abrupt positive shifts in $\delta$$^{18}$O occur at 5457$\pm$75 years (0.75$\permil$ in 170 y) and 3614$\pm$50 years (1.1$\permil$ in 15 y) corresponding to a stepwise decrease in Asian monsoon intensity at these times. In addition, several other smaller intervals of decreased Asian monsoon activity occur suggesting millennial-scale features are present in the Holocene. Whereas one period of decreased activity occurs at 8085 years BP within error of the "8200-year event" seen in Greenland ice cores, similar events ($\sim$1.1$\permil$) are present throughout the record. Therefore the "8200 year event" is not clearly evident in the monsoon record. Spectral analyses of the $\delta$$^{18}$O record show significant peaks at 205- and 88- year cycles, which are also present in records of solar activity (Stuiver and Braziunas, 1993, Holocene, 3, 289-305), suggesting monsoon variation is influenced by solar forcing. However, there are numerous significant peaks at periods not present in the solar spectra. Thus, there are additional features besides insolation and solar variations, which affect the Asian monsoon.
DE: 3344 Paleoclimatology
DE: 4215 Climate and interannual variability (3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting