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引用本文:邱瑞照1 周 肃2,3 邓晋福3 李金发4 肖庆辉1,3 蔡志勇5. 西藏班公湖—怒江西段舍马拉沟蛇绿岩中辉长岩年龄测定——兼论班公湖—怒江蛇绿岩带形成时代[J]. 中国地质, 2004, 31(3): 262-268.
QIU Rui-zhao1, ZHOU Su2,3, DENG Jin-fu3, LI Jin-fa4, XIAO Qing-hui1,3, CAI Zhi-yong5. Dating of gabbro in the Shemalagou ophiolite in the western segment of the Bangong Co-Nujiang ophiolite belt, Tibet—with a discussion of the age of the Bangong Co-Nujiang ophiolite belt[J]. Geology in China, 2004, 31(3): 262-268(in Chinese with English abstract).
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西藏班公湖—怒江西段舍马拉沟蛇绿岩中辉长岩年龄测定——兼论班公湖—怒江蛇绿岩带形成时代
邱瑞照1 周 肃2,3 邓晋福3 李金发4 肖庆辉1,3 蔡志勇51,2,3,4,5
1. 中国地质科学院地质研究所,北京 100037;2.岩石圈构造、深部过程及探测技术教育部重点实验室, 中国地质大学,北京 100083;3. 中国地质大学,北京 100083;4. 中国地质大学,湖北 武汉 430074;5.中国科学院广州地球化学研究所,广东 广州 510640
摘要:
提要:对班公湖—怒江西段舍马拉沟蛇绿岩中层状辉长岩的Sm-Nd、K-Ar同位素测定结果表明, Sm-Nd内部等时线年龄为(191±22) Ma, K-Ar年龄为(140±4.07) Ma和(152.30±3.60) Ma, 结合地质资料分析,认为前者代表了洋盆张开年龄为早侏罗世,后者代表受到洋壳俯冲影响的时间; 根据中段、东段蛇绿岩带已有的资料, 讨论了班公湖―怒江蛇绿岩带的洋盆张开时代、俯冲时间及闭合时代, 认为班公湖―怒江洋盆可能在早侏罗世自东向西同时张开, 中侏罗世开始极性向南的俯冲, 洋盆最终在早侏罗世末封闭。
关键词:  班公湖—怒江蛇绿岩带  Sm-Nd和K-Ar同位素定年  西藏
DOI:
分类号:
基金项目:国家自然科学重点基金(NSFC40234048);国土资源部国际合作与科技司专项计划(200010103);中国地质调查局国土资源地质大调查项目(200113900018)和中国地质大学“岩石圈构造、深部过程及探测技术”教育部重点实验室开放课题(2003009、2003010)联合资助。
Dating of gabbro in the Shemalagou ophiolite in the western segment of the Bangong Co-Nujiang ophiolite belt, Tibet—with a discussion of the age of the Bangong Co-Nujiang ophiolite belt
QIU Rui-zhao1, ZHOU Su2,3, DENG Jin-fu3, LI Jin-fa4, XIAO Qing-hui1,3, CAI Zhi-yong51,2,3,4,5
1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;2. Key Laboratory of Lithospheric Tectonics, Deep Process and Exploration, Ministry of Education, Beijing, 100083, China;3. China University of Geosciences, Beijing 100083, China;4. China University of Geosciences, Wuhan 430074, Hubei, China;5. Guangzhou Institute of Geochemistry,Chinese Acadeng of Science Guangzhou 510640, Guangdong, China
Abstract:
Abstract: Sm-Nd and K-Ar dating of layered gabbro in the Shemalagou ophiolite in the western segment of the Bangong Co-Nujiang ophiolite belt indicates a combined internal and whole-rock Sm-Nd isochron age of 191±22 Ma and K-Ar ages of 140±4.07 Ma and 152.30±3.60 Ma. According to the dating results, combined with geological data, it is suggested that the Sm-Nd age represents the age of ocean basin opening, i.e. Early Jurassic, while the latter is the time of alteration influenced by the subduction of oceanic crust. Based on the available data in the central and eastern segments of the Bangong Co-Nujiang ophiolite belt, the ages of opening, subduction and closing of the ocean basin are discussed. The authors think that the Bangong Co-Nujiang ocean basin probably opened from east to west simultaneously in the Early Jurassic, began to be subducted southward in the Middle Jurassic and finally closed at the end of the Early Cretaceous.
Key words:  Bangong Co-Nujiang ophiolite belt  Sm-Nd and K-Ar dating  Tibet