中国西部山岳冰川MIS3b冰进的初步探讨

对横断山的沙鲁里山、祁连山东段的冷龙岭、天山西段托木尔峰南麓的阿特奥依纳克河流域等3个地区7个研究点的第四纪冰川作用开展了深入研究,应用ESR测年技术在7个研究点特定的地貌部位共获得12个对应于MIS3(56~36 ka BP)的测年结果,且年龄基本上都对应于MIS3b(54~44 kaBP).结合已有的研究资料,并对MIS3气候特征进行综合分析,研究表明:MIS3强大的季风环流带来的丰富降水与MIS3b冷阶段的组合是川西高原的沙鲁里山与祁连山东段冷龙岭MIS3b冰进的主要原因,而天山西段阿特奥依纳克河流域MIS3b冰进则是不稳定的西风波动带来的丰富降水所致.这3个地区沉积有该次冰进的冰碛物.

A Preliminary Study of the Glacier Advance in MIS3b in the Western Regions of China

Environmental variations in the Late Pleistocene are hot topics in the research fields of Quaternary environment and global change,including difficulties about the glaciations since the Late Pleistocene.In recent years,the Quaternary glaciations research has entered an accurate dating stage owing to the development and application of dating techniques and a new academic theory that a great glacier advance occurred in marine isotopic stage 3(MIS 3) has been proposed.In the last several years,a research group has carried out further studies in relation to glaciations in Shaluli Mountains which belongs to the Hengduan Mountains,Lenglongling in the eastern segment of the Qilian Mountains and the Ateaoyinake River Valley on the south slopes of the Tomur Peak in the western segment of the Tianshan Mountains,including 3 different areas and 7 sites.ESR dating technique was applied to determine these glacial tills that were collected from above areas and Ge centers in quartz grains were chosen.12 dating results(33~56 ka) dealing with MIS 3 were obtained and ten of these ages are corresponding to MIS 3b(54～44 ka BP).Combining the previous studies and analyzing the climate characteristics of the MIS 3 synthetically,a preliminary conclusion could be drawn: the MIS 3b glacier advance in Shaluli Mountains and Lenglongling was caused by the abundant precipitation carried by the strong monsoon circulation in MIS 3 and cold period of MIS 3b,the glacier advance in the Tianshan Mountains was also a result of the abundant precipitation produced by the unstable westerly and cold period of MIS 3b.The glacial tills formed in MIS 3b were reserved in the three areas.