HR: 15:10h
AN: PP13D-05    [Abstracts]
TI: 15-ky Peat Paleo-Monsoon Reconstructions from Lipid Biomarker Contents of Three Bogs in China
AU: Zhou, W
EM: weijian@loess.llqg.ac.cn
AF: State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Science, Xi'an, 710075, China
AU: Zheng, Y
AF: State Key Laboratory of Continental Dynamics, Northwest Universiy, Xi'an, 710069, China
AU: * Meyers, P A
EM: pameyers@umich.edu
AF: Department of Geological Sciences, The University of Michigan, 1100 North University, Ann Arbor, MI 48109-1005, United States
AU: Xie, S
AF: Faculty of Earth Sciences, China University of Geosciences, Wuhan, 430074, China
AB: Paleoclimate reconstructions based on lipid biomarkers from peat bogs are relatively uncommon, although this approach has been widely applied to lake sediments where it yields important histories of climate-related changes in types of vegetation and organic matter preservation. We describe stratigraphic patterns in peat lipid biomarker distributions extracted from three well-dated peat cores. One core is from the Dingnan bog on the border of Guangdong and Jiangxi Provinces of southeastern China. A second core is from the Zoige-Hongyuan bog, which is on the Qinghai-Xizang Plateau of west China on the northeast edge of the Tibetan Plateau. The third peat core is from a shallow lake that is the source of the Hani River in Jiling Province of northeastern China. The combination of the three locations provides a broad regional history of the evolution of monsoon-influenced climate in China from the late-glacial through the Holocene. The start of peat accumulation in these locations at about 15 ka indicates the onset of wetter post-glacial climate. A period of warmer climate corresponding to the Holocene Optimum between 9 ka to 5 ka is evident in greater alterations of n-alkanoic acids and n-alkanols and in the appearance of biomarkers diagnostic of greater microbial activity. Changes in local precipitation that raised the water level of the Zoige-Hongyuan bog are indicated by increases in the proportions of C23 and C25 n- alkanes that are mainly derived from submerged/floating plants and by conversion of the Dingnan bog to a lake. Alternations in submergent and emergent plant n-alkane proxies reveal millennial scale rises and falls of the water level in these bogs, thereby reflecting variations in East Asian and Indian Ocean monsoon precipitation during the Holocene. These events correlate well with cold-dry events recorded in same regions by other climatic proxies. Our results reflect Holocene instability in the Asian monsoon system and indicate that millennial-scale changes in precipitation are more sensitive than temperature in reflecting the paleo-monsoon history of China.
DE: 1055 Organic and biogenic geochemistry
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1637 Regional climate change
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 4914 Continental climate records
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting