西藏阿里地区古近纪沉积记录及其与印度-亚洲大陆碰撞的关系

Syncollisional sedimentary strata preserved within the Indus-Yarlung Zangbo suture zone recorded important information for the India-Asia collision. In the past decades, our knowledge about the collision process and the Himalayan orogenesis has been greatly improved by investigating these rocks. However, previous studies are mainly focused on the Zanskar area in the western Himalaya and the Xigaze area in the eastern Himalaya. The sedimentary records in the Ngari area of the middle part of the Himalayan orogen are poorly studied, despite that they are critical for regional comparison between the eastern and western Himalayas..Several Paleogene sedimentary suites, including the Dajiweng Formation, the Liuqu Conglomerate, the Dajin Formation and the Qiuwu Formation, have been reported from the Ngari area, southwestern Tibet. In this program, a combination of stratigraphic, sedimentologic, petrologic and geochemical approaches will be carried out to indentify their sedimentary environments, depositional ages and provenances. On the basis of the geological data and regional comparison, we will discuss the characteristics and evolution of the sedimentary basin and try to provide more details for the India-Asia collision process. We believe that this program will improve our knowledge about the geology in the Ngari area, and also will help us in understanding the Himalayan orogen.

保存在印度河-雅鲁藏布缝合带中的同碰撞沉积地层记录了印度-亚洲大陆碰撞的重要信息。在过去几十年中，通过对这些沉积记录进行研究，取得了大量的研究成果。然而，前人的研究主要集中在西部Zanskar地区和东部日喀则地区，对阿里地区同碰撞沉积记录的研究几乎为空白。阿里地区位于喜马拉雅造山带中段，是进行喜马拉雅东部和西部对比、全面了解印度-亚洲大陆碰撞和喜马拉雅早期造山作用的重要地区，因此对阿里地区同碰撞沉积记录进行研究，具有重要的地质意义。.区域地质调查发现，阿里地区发育多套古近纪同碰撞沉积地层，包括达机翁组、柳区砾岩、达金组和秋乌组。本项目拟以这些古近纪沉积记录为研究对象，运用地层学、沉积学、岩石学和地球化学等手段进行深入研究，查清这些地层的沉积环境、形成时代、物源区特征。在此基础上，探讨沉积盆地性质及其演化，以期为深入了解印度-亚洲大陆的碰撞过程提供更多依据。

本项目利用野外地层学、沉积学观察和室内岩石学、单矿物地球化学、同位素年代学分析等多种方法，对西藏阿里地区古近纪地层记录，包括达机翁组、达金组和柳区砾岩进行了系统研究。研究工作基本查明了这些地层的沉积时代、物源区和地球动力学背景，初步建立了阿里地区古近纪沉积地层与印度-亚洲大陆碰撞及喜马拉雅造山过程的关系。