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西藏羌塘南缘热那错早白垩世流纹岩锆石U-Pb年代学和Hf同位素及其意义
引用本文:常青松,朱弟成,赵志丹,董国臣,莫宣学,刘勇胜,胡兆初. 西藏羌塘南缘热那错早白垩世流纹岩锆石U-Pb年代学和Hf同位素及其意义[J]. 岩石学报, 2011, 27(7): 2034-2044
作者姓名:常青松  朱弟成  赵志丹  董国臣  莫宣学  刘勇胜  胡兆初
作者单位:1. 地质过程与矿产资源国家重点实验室,中国地质大学地球科学与资源学院,北京100083
2. 地质过程与矿产资源国家重点实验室,中国地质大学地球科学学院,武汉430074
基金项目:本文受国家973项目(2011CB403102、2009CB421002)、国家自然科学基金项目(40830317、40973062、40973026)、中央高校基本科研业务费专项资金项目(2010ZD02)、教育部新世纪优秀人才项目(NCET-10-0711)和中国地质调查局项目(1212011121260)联合资助.
摘    要:在青藏高原的演化历史中,班公湖-怒江洋的俯冲方向一直存在争议。现有的岩浆作用时空展布表明,大量早白垩的岩浆作用分布在班公湖-怒江缝合带(以下简称为班怒带)以南,但是近年来在该缝合带以北也发现了少量同时代的岩浆作用。本文研究了靠近班公湖-怒江蛇绿岩带以北、改则县北部热那错地区的流纹岩,获得了岩石的锆石U-Pb年龄和Hf同位素成分。热那错流纹岩年龄为~110Ma,与相邻地区报道的岩浆岩活动和缝合带以南的北拉萨地体地区大范围出露的早白垩世岩浆岩同期产出。岩石具有不均一且偏正的εHf(t)特征,与北拉萨地体同期岩浆岩Hf同位素成分相似。本文综合考虑了班怒带两侧发育同期岩浆活动、且南侧极大量而北侧很少量发育的特征,认为热那错流纹岩的成因可以置于班公湖-怒江洋向南俯冲的总体模式中,南向俯冲的班公湖怒江岩石圈在~110Ma发生板片断离,可以同时解释分布于缝合带两侧的早白垩世岩浆活动。

关 键 词:热那错流纹岩  锆石U-Pb年龄  Hf同位素  班公湖-怒江洋  南向俯冲  早白垩世
收稿时间:2011-05-01
修稿时间:2011-06-30

Zircon U-Pb geochonology and Hf isotopes of the Early Cretaceous Rena-Co rhyolites from southern margin of Qiangtang, Tibet, and their implications
CHANG QingSong,ZHU DiCheng,ZHAO ZhiDan,DONG GuoChen,MO XuanXue,LIU YongSheng and HU ZhaoChu. Zircon U-Pb geochonology and Hf isotopes of the Early Cretaceous Rena-Co rhyolites from southern margin of Qiangtang, Tibet, and their implications[J]. Acta Petrologica Sinica, 2011, 27(7): 2034-2044
Authors:CHANG QingSong  ZHU DiCheng  ZHAO ZhiDan  DONG GuoChen  MO XuanXue  LIU YongSheng  HU ZhaoChu
Affiliation:State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, and School of Earth Sciences and Mineral Resources, China University of Geosciences, Beijing 100083, China;State Key Laboratory of Geological Processes and Mineral Resources, and Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China;State Key Laboratory of Geological Processes and Mineral Resources, and Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China
Abstract:The direction of subduction of Bangong Lake-Nujiang oceanic crust has long been a debate in the topic of geological evolution history of Tibetan Plateau. Informed research shows that large amount of Cretaceous igneous activity spreads widely on northern Lhasa terrane, south of Bangong Lake-Nujiang suture zone. However, small magmatic activity of the same era was discovered on the north side of the suture zone. An isotopic and geochronologic study of this paper presents zircon LA-ICP-MS U-Pb data and Hf isot...
Keywords:Rena-Co rhyolites  Zircon U-Pb geochronology  Hf isotope  Bangong Lake-Nujiang Ocean  South-trending subduction  Early-Cretaceous
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