Characteristics of Early Eocene radiolarian assemblages of the Saga area,southern Tibet and their constraint on the closure history of the Tethys  

作　　者：LI YaLin WANG ChengShan HU XiuMian M. Bak WANG JinJun CHEN Lei 

机构地区：[1]Research Center for Tibetan Plateau Geology, China University of Geosciences, Beijing 100083, China [2]School of Earth Sciences, Nanjing University, Nanjing 210093, China [3]Institute of Geological Sciences, Jagiellonian University, Krakow, Poland [4]Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China

出　　处：《Chinese Science Bulletin》2007年第15期2108-2114,共7页

基　　金：the National Natural Science Foundation of China (Grant No.40672086);the National Key Basic Research Program of China (Grant No.2006CB701400)

摘　　要：Quantitative analysis of Early Eocene radiolarian assemblages discovered in the sedimentary mélange (accretionary prism) of the Saga area,southern Tibet provides new information to constrain the timing of Tethys closure and the initial collision of India and Eurasia. The radiolarian species of Saga include Amphisphaera coronata (Ehrenberg),Buryella hannae Bak & Barwicz-Piskorz,Buryella clinata Foreman,Buryella tetradica Foreman,Calocycloma ampulla (Ehrenberg),Lamptonium fabaeforme constrictum Riedel and Sanfilippo,Lamptonium pennatum Foreman,Lithomespilus coronatus Squinabol and Lamptonium (?) colymbus Foreman. The adequate and reliable correlation of these radiolarians specimens indicates that the assemblage is of Early Eocene in age. The age and depositional envi-ronment of these radiolarians testify that deep ocean basins existed between India Plate and Asia Plate during the Early Eocene. The complete closure of Tethys must have taken place at least after the Early Eocene.Quantitative analysis of Early Eocene radiolarian assemblages discovered in the sedimentary melange （accretionary prism） of the Saga area, southern Tibet provides new information to constrain the timing of Tethys closure and the initial collision of India and Eurasia. The radiolarian species of Saga include Amphisphaera coronata （Ehrenberg）, Buryella hannae Bak ＆ Barwicz-Piskorz, Buryella clinata Foreman, Buryella tetradica Foreman, Calocycloma ampulla （Ehrenberg）, Lamptonium fabaeforme constrictum Riedel and Sanfilippo, Lamptonium pennatum Foreman, Lithomespilus coronatus Squinabol and Lamptonium （？） colymbus Foreman. The adequate and reliable correlation of these radiolarians specimens indicates that the assemblage is of Early Eocene in age. The age and depositional environment of these radiolarians testify that deep ocean basins existed between India Plate and Asia Plate during the Early Eocene. The complete closure of Tethys must have taken place at least after the Early Eocene.

关 键 词：西藏 放射虫 深海沉积 古地中海 地球运动 

分 类 号：P54[天文地球—构造地质学]