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abstracts
An absolute-dated and high-resolution Indian Monsoon record over the past 245 ka from Xiaobailong Cave, southwest China
Yanjun Cai, Liangcheng Tan, Hai Cheng, Zhisheng An, R. Lawrence Edwards, Chuan-Chou Shen
An absolute-dated δ18O record from Xiaobailong Cave, southwest China, completes a Chinese speleothem-based record of the Indian Monsoon (IM) over the past 245,000 years. The record is dominated by 23-ka precessional cycles that are synchronous within dating errors with that of East Asian Monsoon (EAM) records from Sanbao Cave. The synchronicity of precessional cycles of both records with summer insolation at 65°N supports the idea that Asian monsoon respond dominantly and directly to changes in N-Hemisphere summer insolation on orbital timescales. The Xiaobailong record, similar to EAM records, demonstrates a remarkable resemblance to δ18O records from Greenland ice-core, suggesting that IM intensity changed in concert with Greenland temperature as well. This, in turn, suggests that the meridional thermal gradients in N-Hemisphere may be the main driving force behind the millennial-scale oscillations in intensities of both IM and EAM. However, there are also a number of notable differences in detailed features and amplitudes of variations between EAM and IM δ18O records. This might be mainly because of the different geographical conditions that result in different responses of these two monsoon systems to global climatic change. For example, the “continental-effect” on amplitudes in δ18O variations could be quite different as the coastline shift during the glacial and interglacial cycles was far more significant in western Pacific Ocean than in northern Indian Ocean. Furthermore, the IM record bears certain features that are likely to be linked to climatic changes in S-Hemisphere where significant amount of moisture of the IM originated from.
Yanjun Cai, Institute of Earth Environment, Chinese Academy of Sciences,#10 Fenghui South Road, Xi'an High-Tech Zone, Xi'an 710075, China, yanjun_cai@ieecas.cn
Liangcheng Tan, Chinese Academy of Sciences, Institute of Earth Environment, Xi'an 710075, China
Hai Cheng, University of Minnesota, Department of Geology and Geophysics, Minneapolis, 55455, United States
Zhisheng An, Chinese Academy of Sciences, Institute of Earth Environment, Xi'an 710075, China
R. Lawrence Edwards, University of Minnesota, Department of Geology and Geophysics, Minneapolis, 55455, United States
Chuan-Chou Shen, National Taiwan University, Department of Geosciences, Taipei 106, China
Session: F3: Global Earth-System Dynamics
Download Talk:
> YSM09_OralF_YanjunCai.pdf
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