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Palaeoclimate Changes Recorded by Loess Deposit around Qinghai Lake (Northeastern Qinghai-Tibetan Plateau) since Last Deglaciation

ZHAO Cun-fa, LU Hua-yu, ZHOU Ya-li, YI Shuang-wen, MASON Joseph   

  1. 1. SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xian 710075, China;2. School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210093, China;3. Department of Geography, University of Wisconsin, Madison, WI 53706, USA;4. Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
  • Received:2009-03-20 Revised:2009-03-20 Online:2009-03-20 Published:2009-03-20

Abstract: Loess and aeolian deposits were found in the area around Qinghai Lake. It is well known that loess is regarded as one of the best terrestrial archives of palaeoclimatic and palaeoenvironmental change. However, investigation on the loess and the aeolian deposits, compared with the lacustrine sediments, is limited and weak in this region. In this paper we dated the loess section by the optically stimulated luminescence (OSL) method, and measured the magnetic susceptibility, Fe/Mg value, grain size distribution and organic matter contents of the Heimahe loess profile. Based on the absolute ages and variations of these climatic proxy indicators, our results show that there are clearly warm/cold and humid/arid alternation in Qinghai Lake area since the late deglaciation. During around 14-9 ka, the palaeolclimate was cold and dry, while the climate was better at about 11 ka. A distinct climate ameliorating occurred from 9 ka to 2.5 ka. Strong disturbance by human activity appeared in loess deposit since 2.5 ka, so it is difficult to analyze the climatic change during the latest Holocene. The environmental changes inferred from the loess deposit are in well comparison with the lacustrine records.