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西藏措勤晚白垩世英安岩的厘定与地球化学特征
引用本文:王伟,曾令森,刘静,肖萍,高利娥.西藏措勤晚白垩世英安岩的厘定与地球化学特征[J].地质科学,2013,48(2):484-500.
作者姓名:王伟  曾令森  刘静  肖萍  高利娥
作者单位:1. 中国科学院青藏高原研究所大陆碰撞与高原隆升重点实验室 北京 100101; 2. 中国科学院大学 北京 100049; 3. 中国地质科学院地质研究所大陆构造与动力学国家重点实验室 北京 100037; 4. 中国地震局地质研究所 北京 100029
基金项目:国家重点基础研究发展计划"973"项目,国家自然科学基金项目
摘    要:野外地质调查和SHRIMP锆石U/Pb地质年代学研究表明,拉萨地块中带措勤地区发育一套形成于晚白垩世中期的英安岩(88.5±1.2 Ma)。该套火山岩具有岛弧火山岩的地球化学特征,为地壳深部岩浆岩部分熔融形成的Ⅰ型岩浆岩,经历了明显的斜长石分离结晶作用。与同时代的侵入岩相比,该套火山岩为高度演化的岩浆,Rb/Sr比值较高,但Sr/Y比值较低。在拉萨地块内部,广泛发育的90~85 Ma的岩浆作用与新特提斯洋的北向俯冲作用相关。

关 键 词:岛弧岩浆作用  火山岩  拉萨地块  锆石U/Pb定年  Hf同位素地球化学
收稿时间:2012-11-13
修稿时间:2012-11-13;

Geochemical characteristics of the Late-Cretaceous dacite in Coqen,western Gangdese batholith, Tibet
Wang Wei , Zeng Lingsen , Liu Jing , Xiao Ping , Gao Li'e.Geochemical characteristics of the Late-Cretaceous dacite in Coqen,western Gangdese batholith, Tibet[J].Chinese Journal of Geology,2013,48(2):484-500.
Authors:Wang Wei  Zeng Lingsen  Liu Jing  Xiao Ping  Gao Li'e
Institution:1. Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101; 2. University of Chinese Academy of Sciences, Beijing 100049; 3. State Key Laboratory of Continental Tectoincs and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037; 4. Institute of Geology, China Earthquake Administration, Beijing 100029
Abstract:Field investigations and zircon SHRIMP U-Pb dating show that a suite of dacite formed at Late Cretaceous(88.5±1.2 Ma) occurred in the southeast of Coqen,western Gangdese Batholith,Tibet.This suite of volcanic rocks is characterized by trace element geochemistry similar to those formed in the arc environment.Geochmical and isotopic data indicate that they are Ⅰ-type igneous rocks and have experienced high degrees of plagioclase fractional crystallization.As compared to those intrusive rocks of similar ages,this suite of rocks represents highly evolved magmas drieved from partial melting of deep crustal mafic rocks and is characterized by elevated Rb/Sr but lower Sr/Y ratios.Our new data as well as those from the literature further indicate that the Lhasa terrane had experinecd extensive magmatism at 90~85 Ma due to northward subduction the Neo-Tethyan oceanic lithosphere beneath the Lhasa terrane.
Keywords:Island arc magmatism  Volcanic rocks  Lhasa terrane  Zircon U-Pb age  Hf isotope geochemistry
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