中文摘要：

古近纪是印度板块和亚欧板块拼合的最后阶段,也是东特提斯的消亡时期,形成了最年轻的海相沉积即最高海相层。对西藏境内最高海相层的相关研究进行了综合评述,认为东特提斯在西藏境内最终消亡的时间应该在始新世Priabonian早期以后。通过与喜马拉雅各地区和塔里木盆地最高海相层进行区域对比,初步总结出东特提斯洋的宏观演化特征：Lutetian初期,东特提斯在西部印度克哈特（Kohat）、赞斯卡尔（Zanskar）等地区开始关闭,之后向东海退至西姆拉（Simla）-坦森（Tansen）一带;Priabonian期在藏南定日-亚东一带关闭,直至渐新世在东部缅甸西昂（Siang）、那嘎兰（Nagaland）地区完全退出。由于印度板块向亚欧大陆楔入产生的远程效应,东特提斯洋分支的残留海水在渐新世末期（23 Ma）从塔里木盆地退出,标志着东特提斯洋在该区的最后关闭。对藏南及邻区最高海相层的综合研究和对比,不仅有助于了解东特提斯的晚期演化特征及封闭时限,也能为印度-亚欧板块碰撞时间的厘定提供直接证据。

英文摘要：

Paleogene is final stage during which the Indian and Eurasian plates collided completely together and Neo-Tethys was demised in southern Tibet. Therefore, the youngest marine sedimentary, namely the highest marine layer, have been formed. This paper reviews the the age of highest marine layer in Himalaya and concludes that the closing of Neo-Tethys in Tibet should be later than early Priabonian. In addition, compared with Tarim basin and Himalaya areas to discuss the regression ways of Neo-Tethys： the initial retreat oecured at the beginning of Lutetian in Kohat to Zansker, then the retreat moved to Simla to Tans- en. In Priabonian, the retreat migrated to Gamba, Tingri and Yadong of southern Tibet, finally afterwards to Slang to Nagaland in Oligocene. As remote effect of collision of the Indian-Eurasian plates, Neo-Theys has retreated at the latest Oligocene in Tarim basin. The age of highest marine layer should represent the demise time of the residual sea basin, it stands for the closing age of Neo-Tethys and provides direct infor- mation about the late evolutionary collision process of two plates .