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新疆和硕县包尔图一带花岗岩LA-ICP-MS锆石U-Pb年龄及其地质意义
引用本文:王行军,王根厚,专少鹏,徐旭明,李广栋,王德强,吴连亨,班长勇,郭晓河,刘玉军.新疆和硕县包尔图一带花岗岩LA-ICP-MS锆石U-Pb年龄及其地质意义[J].中国区域地质,2012(8):1251-1266.
作者姓名:王行军  王根厚  专少鹏  徐旭明  李广栋  王德强  吴连亨  班长勇  郭晓河  刘玉军
作者单位:[1]中国地质大学地球科学与资源学院,北京100083 [2]中国人民武装警察部队黄金地质研究所,河北廊坊065000 [3]河北省区域地质矿产调查研究所,河北廊坊065000
基金项目:新疆国土资源厅项目《新疆和硕县包尔图一带1:5万区域地质矿产调查》(编号:QD200506) 致谢:河北省区域地质矿产调查研究所胡醒明、程洲、孟宪峰、张正平参加了野外工作,在野外地质调查过程中得到新疆地矿局第三地质大队各级领导的大力支持.同位素测试工作由西北大学大陆动力学国家重点实验室完成.河北省区域地质矿产调查研究所朱更新教授级高级工程师提出宝贵的修改意见.在此一并表示衷心的感谢.
摘    要:新疆和硕县包尔图一带地处中天山中段,花岗岩十分发育。包尔图北侧的乌苏通沟岩体属于北天山,为一套中酸性侵入岩,矿物组合显示其为典型的钙碱性火山弧花岗岩,地球化学特征显示富集大离子亲石元素而亏损高场强元素,是洋壳俯冲导致的下地壳物质部分熔融和上地壳同化混染的产物,LA-ICP-MS锆石U-Pb同位素测年结果为(358.9±3.5)Ma,说明乌苏通沟岩体形成于泥盆纪末—早石炭世早期,是北天山洋向中天山陆块之下俯冲的产物,且是泥盆纪俯冲事件的最新地质记录。包尔图南侧的红山岩体属于南天山,是一套酸性侵入岩,矿物共生组合显示出钙碱性同碰撞花岗岩的特征,岩相学特征显示岩浆混合的典型特征,岩石地球化学特征显示Ta、Nb不同程度的贫化,说明该侵入体是陆壳增厚的产物,代表了一次重要的陆壳垂直生长事件,LA-ICP-MS锆石U-Pb同位素测年结果为(295.8±1.2)Ma,说明红山岩体侵位于石炭纪末—早二叠世早期。包尔图一带花岗岩分别记录了南、北天山2次重要的地质事件,为研究天山地区的构造演化提供了重要的依据。

关 键 词:新疆包尔图一带  LA-ICP-MS锆石U-Pb定年  俯冲  碰撞

LA-ICP-MS zircon U-Pb isotope age of granitoids in Baoertu area,Hoxud County,Xinjiang,and its geological significance
WANG Xing-jun,WANG Gen-hou,ZHUAN Shao-peng,XU Xu-ming,LI Guang-dong,WANG De-qiang,WU Lian-heng,BAN Chang-yong,GUO Xiao-he,LIU Yu-jun.LA-ICP-MS zircon U-Pb isotope age of granitoids in Baoertu area,Hoxud County,Xinjiang,and its geological significance[J].Regional Geology of China,2012(8):1251-1266.
Authors:WANG Xing-jun  WANG Gen-hou  ZHUAN Shao-peng  XU Xu-ming  LI Guang-dong  WANG De-qiang  WU Lian-heng  BAN Chang-yong  GUO Xiao-he  LIU Yu-jun
Institution:1.School of Geosciences and Resource,China University of Geology,Beijing 100083,China; 2.Gold Geological Institute of CAPF,Langfang 065000,Hebei,China; 3.Hebei Institute of Regional Geological and Mineral Resource Survey,Langfang 065000,Hebei,China
Abstract:A lot of granitoids exist at Baoertu of Hoxud County in Xinjiang,lying in the middle segment of Middle Tianshan Mountains.Petrologic,mineralogical and geochemical investigations indicate that Wusutonggou pluton,which occurs in northern Baoertu area and belongs to Northern Tianshan Mountains,is composed of a suite of intermediate-acid intrusive rocks showing features of typical calc-alkaline volcanic arc granitoids which are enriched in LILE and depleted in HFSE and have genetic relation with the melting of the lower crust and the assimilation-hybridization of the upper crust resulting from the subduction of the ocean crust.The U-Pb LA-ICP-MS isotope age shows that the Wusutonggou pluton intruded at 358.9±3.5 Ma,belonging to the last stage of Devonian to the early stage of Lower Carboniferous.Wusutonggou granitoids resulted from the southward subduction of northern Tianshan Ocean beneath the middle Tianshan landmass,and could serve as the newest geological record of the subducting events in Devonian.Petrologic,mineralogical and geochemical investigations show that Hongshan pluton,which occurs in southern Baoertu area and belongs to Southern Tianshan Mountains,is a suite of acid intrusive rocks of typical calc-alkaline syn-collision granitoids,having typical characteristics of magma mixing and lower contents of Nb and Ta.Hongshan granitoids resulted from increasing thickness of continual crust and represented an important vertical development of the continual crust.LA-ICP-MS U-Pb isotope age shows that the Hongshan pluton intruded at 295.8±1.2 Ma,belonging to the last stage of Carboniferous to the early stage of Lower Permian.Studies show that granitoids in Baoertu area have recorded two important geological events and offered the important evidence for the tectonic evolution in Tianshan area.
Keywords:Baoertu area of Xinjiang  LA-ICP-MS zircon U-Pb dating  subduction  collision
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