【作者】 田彬；

【导师】 胡建中；

【作者基本信息】 中国地质大学（北京） ， 自然地理学， 2008， 硕士

【摘要】 新生代以来,印度板块与欧亚板块的碰撞导致了青藏高原的隆升及其西北缘西昆仑的活化隆升,并在塔西南坳陷内堆积了巨厚的沉积物。这些沉积物是青藏高原西北缘晚新生代强烈隆升的产物,良好地记录了高原的隆升过程。本论文将通过分析其在坳陷内留下的沉积物记录反演青藏高原西北缘晚新生代隆升的性质和特征。塔西南坳陷的沉降与西昆仑及青藏高原的隆升存在着良好的耦合关系,相关性主要表现在塔西南地区的沉积作用与西昆仑的造山作用之间在时间、空间、成因机制、物源供应等方面。通过对塔西南地层的层序及不整合分析,塔西南坳陷新生代以来主要发生了古近纪与前古近纪,新近纪与古近纪及中—晚更新世与早更新世之间的不整合,这三次不整合面反映了三次剧烈的构造运动,均导致了西昆仑的强烈隆升剥蚀及塔西南沉降速率的加快和沉积物的快速充填。通过对沉积物厚度、岩性、颜色、成分的对比及粒度、重矿物、年代的分析,得出磨拉石建造分为4个阶段:阿图什组下部为第一阶段,上部为第二阶段,西域组为第三阶段,中晚更新世和全新世为第四阶段。通过对磨拉石沉积岩石学的分析,并结合裂变径迹及磁性分析,我们将西昆仑的隆升历史划分为5个阶段:(1)上新世以前,无磨拉石建造特征,说明西昆仑隆升速率较慢;(2)上新世早期,西昆仑山前开始出现砾岩沉积,即西昆仑隆升速率加快;(3)上新世晚期,岩性变化明显,西域砾岩出现,反映西昆仑隆升速率更快;(4)早更新世时期,底部局部出现了一次不整合,表明塔西南出现了一次构造运动。此后岩性更粗,表明西昆仑隆升速率继续加快;(5)早更新世末期的构造运动使更新世以前的地层全部卷入,说明此次运动非常剧烈,西昆仑处于强烈隆升状态。此后磨拉石沉积持续,西昆仑仍然维持高速隆升的状态。更多还原

【Abstract】 Since Cenozoic, the collide of India plate and Eurasian plate have caused the uplift of Qinghai-Tibet plateau and the uplift of The West Kunlun, which lies in Qinghai-Tibet’s northwestern margin , and have deposited massive sediments in the southwest depression of Tarim basin. These sediments were the result of the uplift of the northwest of Qinghai-Tibet plateau in late Cenozoic, and to a large extent, well documented the uplifting of the plateau .This thesis is to recover some of the qualities and characteristics of the uplift of the northwest of Qinghai-Tibet plateau in late Cenozoic through analyzing the sediment record in the southwest depression of Tarim basin.The subsidence of the southwest depression of Tarim basin is relatively well coupled with the uplifting of the Qinghai-Tibet plateau. The relative of the couple lies is in time ,space, mechanism and the sediment supply between the sediment of the southwest depression of Tarim and the orogeny of the West Kunlun. After analysising the sequence and unconformities of the southwest depression of Tarim basin, in Cenozoic, we found there were three times of unconformities in the southwest depression of Tarim: Paleogene and pre-Paleogene, Neogene and Paleogene, late Pleistcene and early Pleistocene. These three times of unconformities showed three times vialent tectonic movement, caused highly uplift and denudation of the West Kunlun, rapidely the subsidence rate and the sediment of the southwest depression of Tarim.By contrasting the thickness, lithology , colour , ingredient of the sediments, and analyzing the size, heavy mineral ,chronology ,the molasses formation can be divided into 4 period: the lower Atushi formation is the first stage, the upper Atushi formation is the second period ,Xiyu formation is the third stage ,later Pleistocene and Holocene is the forth stage.By analyzing the sedimentology character of the molasses, and with combining the characteristics of fission track and magnetic, the uplift history of the West Kunlun can be divided into 5 stage:①Before Pliocene, there is no molasses formation, which shows slow uplift of the West Kunlun ;②Early Pliocene, there is conglomerate sediment in the foreland of the West Kunlun, which shows rapid uplift of the West Kunlun in the late Miocene;③Late Pliocene, the lithology changed obviously and Xiyu Conglomerate occured, which shows that more rapid uplift of the West Kunlun;④Eatly Pleistocene, there is unconformities at some places and shows violent tectonic movement in the southwest depression of Tarim. After that, the lithology more and more thicker ,the uplift rate of the West Kunlun continuously rapid;⑤One tectonic movement evoled the former formation into it in the early Pleistocene, shows that this movement is violent, the West Kunlun is still at the stage of rapidly uplifting.after this movement, the molasses sediment is still on the rapidly uplifting stage.更多还原