Ice-wedge Pseudomorphs Showing Climatic Change Since the Late Pleistocene in the Source Area of the Yellow River, Northeast Tibet  

作　　者：CHENG Jie ZHANG Xujiao TIAN Mingzhong YU Wenyang YU Jiangkuan TANG Dexiang YUE Jianwei 

机构地区：[1]China University of Geosciences, Beijing 100083, China [2]Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080, China [3]Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China

出　　处：《Journal of Mountain Science》2005年第3期193-201,共9页山地科学学报（英文）

基　　金：the Ministry of Land and Resource of P.R.China ; the National Natural Science Foundation of China(No.40172062).

摘　　要：The source area of the Yellow River is located in the northeastern Tibetan Plateau, and is a high-elevation region with the annual mean temperature of -3.9℃. The ice-wedge pseudomorphs discovered in this region are recognized as two types. One was found in sandy gravel beds of the second terrace of the Yellow River. This ice-wedge pseudomorph is characterized by higher ratio of breadth/depth, and are 1-1.4 m wide and about 1 m deep. The bottom border of the ice-wedge pseudomorph is round arc in section. Another discovered in the pedestal of the second terrace has lower ratio of width/depth, and is o.3-1.0 m wide and 1-2 m deep. Its bottom border is sharp. Based on the TL dating, the former was formed at the middleHolocene （5.69±0.43 ka BP and 5.43±0.41 ka BP）, that is, the Megathermal, and the latter was formed at the late Last Glacial Maximum （13.49±1.43 ka BP）. Additionally, the thawing-freezing folders discovered in the late Late Pleistocene proluvium are 39.83±3.84 ka BP in age. The study on the ice-wedge pseudomorphs showed that the air temperature was lowered by up to 6-7℃ in the source area of the Yellow River when the ice-wedge pseudomorphs and thawing-freezing folds developed.

关 键 词：Ice-wedge pseudomorph PALEOCLIMATE Last Glacial Age MEGATHERMAL the source area of the Yellow River Tibetan Plateau 

分 类 号：P343.6[天文地球—水文科学]