ENVIRONMENTAL EVOLUTION OF ORDOS DESERT IN CHINA SINCE 1.1MA B. P. AS INDICATED BY YULIN STRATIGRAPHICAL SECTION AND ITS

Yulin section is a typical sedimentary record for reflecting the environmental evolution of OrdosDesert, China in the past 1.1Ma. By analyzing its sequence and grain-size composition some views have been put for-ward in this paper as follows. The layers of sand, loess and palaeosol in Yulin section were respectively formed bywind and the pedogenesis on parent material of the sand and loess. Since 1.1Ma B. P., Ordos Desert has alternately ex-perienced 11 stages of shifting dunes under extreme cold-dry climatic environment, 7 stages of fixed and semi-fixeddunes and 8 stages of dust (loess) under cold-dry climatic condition; and the pedogenesis environment under 15 timesof warm-humid climate and 3 times of temperate-humid climate (brownish-drab soils and black soils formed respec-tively). The aeolian sand had already existed in Ordos Desert at latest by 1.1Ma B. P., and from that time on it has un-dergone a series of alternative processes of shifting sands, fixed and semi-fixed dunes, loess and soils. Ordos Deserthas been situated in the transitional belt of the Mongolian High Pressure and margin of the southeast summer mon-soon since 1.1Ma B. P., and influenced repeatedly by migration of the lithofacies belts of shifting sands, fixed andsemi-fixed dunes, loess and soils, which have been caused by the climatic fluctuations of glacial and interglacial periods.

作 者： LI Bao-sheng GAO Shang-yu DONG Guang-rong JIN He-ling   作者單位： LI Bao-sheng(Department of Geography, South China Normal University, Guangzhou 510631, P. R. China;State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Acaderny of Sciences, Xi'an 710075, P. R. China)

GAO Shang-yu(Institute of Resources Sciences, Beijing Normal University, Beijing 100875, P. R. China)

DONG Guang-rong,JIN He-ling(Cold and A rid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, P. R. China) 

刊 名： 中國地理科學(xué)（英文版）  SCI 英文刊名： CHINESE GEOGRAPHICAL SCIENCE  年，卷(期)： 2005 15(1)  分類號： P534.63  關(guān)鍵詞： Ordos Desert   Yulin stratigraphical section   past 1.1 Ma   grain-size composition   environment evolution  

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