Abstract:

The western Sichuan Plateau is located on the transitional zone of plateau climate and monsoon climate. Climatic characteristics of this region are very important for understanding of the Tibetan Plateau impacting on the surrounding climate.¹⁴C dating, stratigraphic correlation and grain size vs. age model were used to calculate ages for all sampling stratigraphic levels. Multi-proxy including grain size, color, magnetic susceptibility, and carbonate content analysis of Zhangla loess section at western Sichuan Plateau revealed a detailed history of climate changes since 104 ka B.P. The long-term trend of increasing grain size, middle grain sizes are 17.6 and 17.7 μm in MIS(marine isotope stage)3 and 4, may be explained in part by a rapid uplift of the Tibetan Plateau events. The climate showed suborbital scale fluctuations similarity to millennial-scale climatic changes recorded in Nanjing stalagmite. The strength of H(heinrich)2 significantly higher than H1. It may indicate that the climate system at high latitudes in the Northern Hemisphere had played an important role. There were two distinct weakening aridification recorded in MIS3, during 28-31 ka and 42-45 ka. They may suggest that the climate system also controlled by factors at low latitudes.

Key words: loess, last glaciation, climate change, sub-orbital scale fluctuations, western Sichuan Plateau