Evolution of the arid climate in High Asia since～ 1 Ma: Evidence from loess deposits on the surface and rims of the Tibetan Plateau

摘要

The formation and development of the arid climate in High Asia remain controversial. This is largely because of the scarcity of continuous high-resolution geological records from the Asian interior region. Thick loess sequences deposited on the surface of the Tibetan Plateau and its rims provide great potential to reconstruct a high-resolution history of the formation and evolution of High Asia arid climate. Based on detailed investigations of the grain size and carbonate content of representative loess sequences in High Asia, a persistent drying of High Asia occurred in the past 1 Ma, and two major rapid drying events occurred at about 0.9-0.8 Ma and 0.5 Ma. Persistent and rapid stepwise uplifts of the Tibetan Plateau since the Mid-Pleistocene might play a dominant role in the drying of High Asia, although the Mid-Pleistocene global cooling may partially contribute to the event.