青海湖东岸末次冰期冰盛期和早全新世沙漠范围重建

The Reconstruction of the Desert Area during Last Glacial Maximum and Early Holocene in the East side of QingHai Lake

中文关键词:  青海湖  风成沉积  古沙丘  末次冰期冰盛期  早全新世

英文关键词:Qinghai Lake  Aeolian deposits  Paleo-dunes  Last Glacial Maximum  Lake level variation

中文摘要:

      本文基于野外沉积物调查、已报道的风成沉积物年代和重建的湖泊水位波动曲线，初步绘制了末次冰期冰盛期和全新世早期青海湖东岸的沙漠范围。结果认为：末次冰期冰盛期时青海湖大幅度萎缩，湖底沉积物暴露并遭受风蚀，在偏西风的搬运下，近岸粗颗粒砂堆积在日月山西侧和倒淌河谷，形成流动沙丘，细颗粒沉积物被向东搬运沉积在河湟谷地和黄土高原。倒淌河源头的沙丘至少也是在末次冰期盛冰期（23-16 ka BP）沙漠扩张时形成并残留至今的；青海湖东部日月山西侧山麓地带和倒淌河河谷中、晚全新世黄土、古土壤下部普遍沉积的风成砂是末次冰期冰盛期和全新世早期（11-9 ka BP）青海湖东岸地区大范围沙化的证据。

英文摘要:

      Based on the Geomorphologic surveys, remote sensing image, reported aeolian deposit chronologies and lake level variations, we reconstruct the desert areas during Last Glacial Maximum and early Holocene for the eastern shore regions of Qinghai Lake. We conclude that with the decline of lake level and expose of lake sediments in the time of Last Glacial Maximum and early Holocene, yearly round westerly wind eroded and carried the fine grain lake sediments to eastern Hehuang valley basin and Chinese Loess Plateau, the coarse sands deposited in the Daotang River valley and the west?piedmont of Riyue mountain. Dunes preserved in the head area of Daotang River were formed at least in the time of Last Glacial Maximum when massive desert existed around Qinghai Lake. The aeolian sands covered by loess and paleosol in the Daotang River valley and the west piedmont of Riyue mountain are the proof of massive desertification during Last Glacial Maximum and early Holocene.