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柴达木盆地西部昆北断阶带基底花岗岩锆石U-Pb年龄、地球化学特征及其地质意义
引用本文:刘桂珍,张玉修,薛建勤,吴光大,陈琰.柴达木盆地西部昆北断阶带基底花岗岩锆石U-Pb年龄、地球化学特征及其地质意义[J].岩石学报,2014,30(6):1615-1627.
作者姓名:刘桂珍  张玉修  薛建勤  吴光大  陈琰
作者单位:西安石油大学地球科学与工程学院, 西安 710065;中国科学院计算地球动力学重点实验室, 北京 100049;中国科学院大学地球科学学院, 北京 100049;中国石油青海油田公司勘探开发研究院, 敦煌 736202;中国石油青海油田公司勘探开发研究院, 敦煌 736202;中国石油青海油田公司勘探开发研究院, 敦煌 736202
基金项目:本文受大陆动力学国家重点实验室开放基金(09LCD07)、中国科学院优秀博士学位论文和院长特别奖获得者科研启动专项(Y129012EA2)、国家自然科学基金项目(40802048、41010104041、40910104050)和中国石油天然气股份有限公司科研项目(2009-81-05)联合资助.
摘    要:柴达木盆地西部基底分布有大量的有花岗岩类岩石。通过对柴达木盆地西部昆北断阶带钻遇的基底花岗岩样品开展详细的岩石学、锆石激光探针等离子体质谱U-Pb同位素年代学及岩石地球化学研究表明,锆石U-Pb同位素年龄为467~450Ma,显示基底花岗岩的结晶年龄为中-晚奥陶世,属于加里东期岩浆侵入旋回。详细的岩石地球化学分析表明,昆北断阶带基底花岗岩属过铝高钾钙碱性系列,其稀土元素配分模式为具有Eu负异常的轻稀土元素富集型,昆北断阶带中南部基底花岗岩属上地壳物质熔融,同碰撞环境下形成的花岗岩。综合区域上的研究成果,昆北断阶带及其以西地区存在中奥陶世-早志留世的加里东期构造-岩浆事件,这对探讨柴达木盆地西部基底花岗岩成因类型及岩浆演化具有重要的意义。

关 键 词:花岗岩  锆石LA-ICPMS定年  加里东期  基底  昆北断阶带  柴达木盆地
收稿时间:1/4/2013 12:00:00 AM
修稿时间:2013/7/26 0:00:00

Zircon LA-ICPMS U-Pb dating and geochemistry of basement granites from north Kunlun faults zone, western Qaidam Basin and their geological implications
LIU GuiZhen,ZHANG YuXiu,XUE JianQin,WU GuangDa and CHEN Yan.Zircon LA-ICPMS U-Pb dating and geochemistry of basement granites from north Kunlun faults zone, western Qaidam Basin and their geological implications[J].Acta Petrologica Sinica,2014,30(6):1615-1627.
Authors:LIU GuiZhen  ZHANG YuXiu  XUE JianQin  WU GuangDa and CHEN Yan
Institution:School of Earth Science and Engineering, Xi'an Shiyou University, Xi'an 710065, China;Key Laboratory of Computational Geodynamics, Chinese Academy of Sciences, Beijing 100049, China;College of Earth Science, University of Chinese Academy of Sciences, Beijing 100049, China;Research Institute of Petroleum Exploration and Development, PetroChina Qinghai Oilfield Company, Dunhuang 736202, China;Research Institute of Petroleum Exploration and Development, PetroChina Qinghai Oilfield Company, Dunhuang 736202, China;Research Institute of Petroleum Exploration and Development, PetroChina Qinghai Oilfield Company, Dunhuang 736202, China
Abstract:Lots of granitoids occur in north Kunlun faults zone of western Qaidam Basin. Comprehensive petrology, laser ablation ICPMS zircon U-Pb geochronology (LA-ICPMS U-Pb) and geochemistry of drilling basement granites were carried out from north Kunlun faults zone, western Qaidam Basin. Zircon U-Pb isotopic ages of 467~450Ma, i.e. Middle-Late Ordovician, show the crystallization age of the basement granites which belong to the Caledonian magmatic cycles. Detailed geochemical analyses show that the basement granites are per-aluminous and high-K calc-alkaline series, characterized by obvious LREE enrichment with medium to strong negative Eu anomalies. These geochemical features indicate that the basement granites probably resulted from crustal remelting of syn-collision setting. There exist Middle Ordovician-Early Silurian Caledonian tectonic-magmatic events, which provide important information for the researches on magmatic and tectonic evolution in north Kunlun faults zone and its west.
Keywords:Granite  Zircon LA-ICPMS dating  Caledonian  Basement  North Kunlun faults zone  Qaidam Basin
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