朋曲组——西藏南部最高海相层位一个新的地层单元  

The Pengqu Formation: a New Eocene Stratigraphical Unit in Tingri Area, Tibet

作　　者：李祥辉[1] 王成善[1] 胡修棉[1] 万晓樵[2] 徐钰林[2] 赵文金 

机构地区：[1]成都理工学院沉积地质研究所,四川成都610059 [2]中国地质大学,北京10083

出　　处：《地层学杂志》2000年第3期243-248,共6页Journal of Stratigraphy

基　　金：国家杰出青年科学基金"特提斯喜马拉雅中新生代古海洋与生烃环境"( No.4962 5 2 0 3 )资助

摘　　要：西藏南部定日地区遮普惹山向斜核部近来发现一套非碳酸盐型海相沉积 ,由黄绿色页岩含砂岩、紫红色砂页岩组成 ,总厚约 180 m,产丰富的钙质超微化石 ,时代属始新世中—晚期 (路特中晚期—巴顿早期 ) ,延时约 10个Ma(5 0～ 40 Ma B.P.)。这套地层显然与过去在该区命名的碳酸盐型最高海相层位不同 ,本文命名为朋曲组 ,包括两个段 :下部恩巴段 ,黄绿色页岩夹砂岩 ,含超微化石带 NP15 ,限时路特中—晚期 ,属残留海浊流沉积 ;上部扎果段 ,紫红色砂、页岩 ,含超微化石带 NP16 ,局限于路特末期—巴顿早期 ,系入海三角洲相。这套非碳酸盐型最高海相层的发现有三点重要意义 :1)第一次在研究区建立了始新统的较为精确的化石、年代地层 ;　 2 )在西藏特提斯喜马拉雅发现了真正碰撞型残留海沉积建造 ;　 3)为新特提斯洋在西藏南部最后关闭和西藏南部早期隆升的时间确定提供了直接依据。A sequence of non carbonate sediments totalling 180m thick was recently found at Qumiba on the northwestern flank of the Zhepure Shan Syncline, in western Tingri, southern Tibet, which are composed of gray and purple shale, fine lithoclastic sandstone, and siltstone. Here we name it Pengqu Formation. It can be divided into in two members, the upper member (Zhaguo Member) in purple and reddish and the lower member (Enba Member) is gray and greenish gray. Nonnofossils and foraminiferal fossils indicate that it may range in age from mid-late Lutetian to early Bartonian. The non carbonate sediments provide the basis the interpretation of the last closure time of the Neo Tethys Ocean, and the process of the collision between the India Subcontinent and Asia Continent, and the primary uplift of the Himalayas and Gangdise.

关 键 词：朋曲组 最高海相层位 西藏 第三纪 

分 类 号：P534.6[天文地球—古生物学与地层学]