东昆仑东段新生代高原隆升重大事件的沉积响应

根据新生代沉积盆地的地层序列、环境演变及地貌和水系变迁分析将研究区新生代高原隆升过程划分为5个重大事件.首次在研究区内海拔5400m的主夷平面上发现古土壤、岩溶角砾岩及钟乳石等, 认为沱沱河组上段细碎屑沉积及五道梁组石膏沉积(中新世) 是主夷平面形成期的沉积响应, 提出了主夷平面的高程具有东西向排列的盆岭地貌特点, 这种高程差异反映了后期构造隆升的不均衡, 应该是上新世以来差异断块抬升的结果; 早更新世中期(1525.5ka后) 一套河流砂砾卵石沉积是青藏运动C幕的沉积响应, 体现在布尔汗布达山的强烈上升和成山; 早更新世晚期(1113.9~836.3ka) 先湖滨砾石沉积, 后转为河流砂砾卵石沉积, 是昆黄运动在研究区的沉积响应, 并体现在马尔争-布青山的强烈上升和成山, 中更新世早期冰碛物的发育说明昆黄运动后研究区已隆升达到"水汽冻结高度"; 研究区T5阶地沉积前的强烈下蚀, 柴达木盆地内陆水系溯源侵蚀切过布尔汗布达山主分水岭, 袭夺了昆南断裂带原由西向东流向共和古湖的东西向水系并到达阿拉克湖一带, 晚更新世洪冲积角度不整合于中更新世洪冲积之上等是共和运动的具体表现. 

Deposit Response to Important Tectonic Events of Cenozoic Plateau Uplift, East Segment of Eastern Kunlun Mountains

Five important tectonic events in Cenozoic can be divided according to the study of its stratigraphic sequences and relief, drainage system and environment change in the east of the eastern Kunlun Mountains. The first discovery of the paleosoil and paleokarst, including karst breccia and stalactite, on the main planation surface about 5 400 m high in the area suggests that the fine clastic deposits of the upper Tuotuohe Formation and the gypsum deposits of the Wudaoliang Formation are the response to the forming period of the main planation surface in Miocene epoch. The distribution of the main planation surface nowadays shows a range and basin relief style with E-W extension. This elevation differentia reflects disequilibrium in the post-tectonic uplift, which should be the result of differentiated block uplifting since Miocene. While a series of alluvial sand and gravel deposits in middle Early Pleistocene, about 1 525.5 ka, can be regarded as the deposit response to the C episode of the Qinghai-Xizang tectonic movement, reflected in the intensive relief uplifting and formation of the Buerhanbud a Mountain near the Alake Lake. However, in the late Early Pleistocene, about 1 113.9-836.3 ka, lakeshore gravel deposits were deposited first and then they changed into alluvial gravel and sand deposits at the Chahaxili area. This could be regarded as the deposit responsing to the Kunlun-Yellow River movement, indicated in the intensive uplifting and formation of the Maerzheng-Buqing Mountains. The development of the moraine deposits in the early Middle Pleistocene suggested that the elevation in the study area could have reached a hydrosphere frozen altitude after the Kunlun-Yellow River tectonic movement. Whereas the Gonghe tectonic movement is represented by the strong erosion of the Qaidam drainage system before the terrace T₅ deposition along the main river, cutting through the main Buerhanbuda Mountain divide, capturing the Gonghe paleolake drainage system, and the unconformity of the Late Pleistocene pluvial and alluvial deposits over the Middle Pleistocene pluvial and alluvial deposits.