| Paleoclimate and Environment Evolution |
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| Evolution Process of Land Desertification around Qinghai Lake since 32 ka BP Reflected by Sediment Grain-size Features |
| HU Meng-jun1, LI Sen1, GAO Shang-yu2, ZHANG Deng-shan2 |
1.College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, China;
2.Ministry of Education Key Laboratory of Environmental Change and Natural Disaster, Beijing Normal University, Beijing 100875, China |
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Abstract Land desertification in the east coast is the most serious and has the largest area among areas around the Qinghai Lake. In this paper we took an aeolian sediment section at Dashuitang (QDST section) in the east coast of the Qinghai Lake as the research object to reconstruct the evolution process of land desertification around Qinghai Lake during the last 32 ka by the environment evolution information extracted from grain size composition, grain size parameters and grain size sensitive index. Results show that the evolution process of land desertification in the study area can be divided into four stages since 32 ka BP. In the interglacial period of the Last Glacial Stage from 32 ka BP to 23.4 ka BP, the climate was humid with weak wind, and sand dunes experienced being fixed and pedogenic process. So the area of land desertification land during this period was the smallest. From 23.4 ka BP to 15.2 ka BP, the climate was cold-dry with strong wind, and the intense aeolian activities activated sand dunes. Land desertification area during this period was the biggest in the past 32 ka. In 15~10.4 ka BP, land desertification area slowly decreased under the background of increasing temperature and humidity. Since 10.4 ka BP, aeolian activities weakened with the climate changed from cool-dry to wet-warm, sand dunes were fixed and consolidated into soil, and the land desertification area significantly decreased.
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Received: 16 May 2012
Published: 20 September 2012
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2012, Vol. 32 
