Millennial-scale monsoonal climatic change from paleosol sequences on the Chinese western Loess Plateau and Tibetan Plateau: a brief summary and review  

作　　者：FANG Xiao-Min LI Ji-Jun Department of Geography, Lanzhou University, Lanzhou, Gansu 730000, PR China 

出　　处：《Chinese Science Bulletin》1999年第S1期38-52,共15页

摘　　要：This paper summarizes the work from the INQUA 1997 Project "Response of soilformation to short-warm-episodes of Asian summer monsoon" and its seeded related internationaland domestic grants. It reviews the effects of the millennial monsoonal changes on the loess-paleosols of the Chinese Loess and Tibetan Plateaus. High-resolution proxy records ofpedogenesis and monsoons demonstrate that both Asian winter and summer monsoons wereunstable and synchronously and inversely coupled during the last glaciation. During that timerapid episodic cycles of cold surges and warm enhancements spanned only ca. 1-2 ka in high-frequency domain. Sub-Milankovitch cycles (6-8 ka) of progressive cooling or weakening in low-frequency domain generally resembled the pattern of the North Atlantic climatic change. However,during the last interglacial, Asian winter and summer monsoons seemed to vary independently, theformer being stable and the later unstable. Soil formation seems to occur in surprisingly fastresponse to the summer monsoon warm enhancements, resulting in weakly or moderatelydeveloped paleosol sequences. North Atlantic and polar cold air surges though the westerlies andother paths, and the north-south swing of the westerlies beside the Tibetan Plateau, may be thealternative mechanisms for the rapid monsoonal changes during the last glacial. But in the lastinterglacial, the summer monsoons worked largely independently.This paper summarizes the work from the INQUA 1997 Project 'Response of soil formation to short-warm-episodes of Asian summer monsoon' and its seeded related international and domestic grants. It reviews the effects of the millennial monsoonal changes on the loess- paleosols of the Chinese Loess and Tibetan Plateaus. High-resolution proxy records of pedogenesis and monsoons demonstrate that both Asian winter and summer monsoons were unstable and synchronously and inversely coupled during the last glaciation. During that time rapid episodic cycles of cold surges and warm enhancements spanned only ca. 1-2 ka in high- frequency domain. Sub-Milankovitch cycles (6-8 ka) of progressive cooling or weakening in low- frequency domain generally resembled the pattern of the North Atlantic climatic change. However, during the last interglacial, Asian winter and summer monsoons seemed to vary independently, the former being stable and the later unstable. Soil formation seems to occur in surprisingly fast response to the summer monsoon warm enhancements, resulting in weakly or moderately developed paleosol sequences. North Atlantic and polar cold air surges though the westerlies and other paths, and the north-south swing of the westerlies beside the Tibetan Plateau, may be the alternative mechanisms for the rapid monsoonal changes during the last glacial. But in the last interglacial, the summer monsoons worked largely independently.

关 键 词：MONSOON instability LOESS-PALEOSOL sequence PEDOGENESIS Tibetan Plateau 

分 类 号：P532[天文地球—古生物学与地层学]