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青藏高原东北缘的武威黄羊镇及高原东南缘的川西甘孜黄土剖面同时记录了250kaBP前后一次显著的干旱化事件,前者表现为风尘粒度变粗,后者表现为C4植被的扩张和古土壤化学风化强度的降低.这次事件在我国北部干旱区及北太平洋风尘记录中均有强烈表现,而在东南季风控制的黄土高原中南部及西风带控制的中亚地区的现有记录中没有明显反映.由于川西甘孜剖面位于典型的西南季风区,中国北方这次重要的干旱化事件主要是来自西南季风的水汽减少所致.青藏高原东南缘在该时期的强烈隆升可能是水汽输送减少的直接原因。
A significant aridification event was recorded before and after 250 kaBP in Huangyang town, Wuwei, northeastern Qinghai-Tibet Plateau, and in western Sichuan, Sichuan Province, in the western part of the Yellow River, in the western part of Sichuan Province, in the western Sichuan Basin. The former appeared as coarse dust particles and the latter showed C4 vegetation expansion and paleosol chemistry The intensity of weathering decreased.These events were strongly observed in both the arid and North Pacific dust records in the north of China, but not in the existing records in the central and southern part of the Loess Plateau controlled by the southeast monsoon and the Central Asia controlled by the westerly zone Due to the fact that the western part of the Tibetan Plateau is located in the typical southwesterly monsoon region and this major aridification event in northern China is mainly caused by a decrease in the water vapor from the southwest monsoon.The intense uplift of the southeastern margin of the Tibetan Plateau during this period may be a direct reduction in water vapor transport the reason.