摘要
吉隆盆地七级阶地和一级山顶剥蚀面的存在说明：本区自早更新世沉积贡巴砾岩后，新构造运动抬升有８次，其中以早更新世Ｑ＿１晚期至中更新世Ｑ＿２抬升最强，共５次，相对于吉隆河河面（盆地基准面）的抬升幅度８９６ｍ；晚更新世Ｑ＿３和全新世Ｑ＿４两者共３次的抬升幅度较小（计７４ｍ）．区内第四纪以来经历过４次冰期：２次发生在Ｑ＿１晚期至Ｑ－２，２次分别出现于Ｑ＿３，Ｑ＿４．从漂砾数量推断，以Ｑ＿３冰期规模最大，Ｑ＿４冰期规模次之．
grade terraces and the peak denudation plane of the Gyirong Basin indicate that , there were8 times of major neotectonic uplift movements since post sedimentary of Gon gba conglomerate inthis region. According to statistics,the strongest uplift occurred in the period from the late ofEarly Pleistocene Q_1 to Middle Pleistocene Q_2. At that time, its relative uplift magnitude was896m, On the contrary,the magnitude was smaller in the period from the Late Pleistocene Q_3 toHoIocene Q_4(74m in total). There were 4 times of major glaciations sinceouaternary in the region,they occurred in Q_1,Q_2,Q_3;and Q_4.respectively。 The quantity of the drift boulder shows that the largest glaciationoccurred in Q_3:,secondly in Q4. The large augen gneiss block at Xiao Gyirong Town illustrates that the former glacier had alarge scale. The blocks should be come from the oceanic glacier of Late Pleistocene。 At that time,the Oceanic glacier had a large scale in the region since the monsoon of the southern BangladeshBay had a dominant position. The ring shape and the arcuate turf hummocks proved that ,the altitude 4 128m in the regionbelongs to seasonal periglacial climate now,but the rock glacier (at altitude 4850m )with creepingphenomenon can be consiuered as a reliable indicator for the permafrost low boundary of theregion.
出处
《山地研究》
CSCD
1995年第4期219-225,T001,共8页
基金
国家科委"八五攀登计划"项目
关键词
西藏
吉隆盆地
新构造运动
第四纪
冰川
Xizang,Gyirong Basin, neotectonism, Quaternary glaciation,periglacial climate
