新疆库地北中三叠世斑状二长花岗岩锆石U-Pb年龄、地球化学特征及其构造意义  

Zircon U-Pb age and geochemistry of Middle Triassic porphyritic granite in the north of Kudi, Xinjiang

作　　者：白春东 王金贵[1] 李典[1] 专少鹏 陈圆圆[1] 张新征[1] 张子轩[1] BAI Chundong;WANG Jingui;LI Dian;ZHUAN SHAOpeng;CHEN Yuanyuan;ZHANG Xinzheng;ZHANG Zixuan(Regional Geology and Mineral Resources Research Institute of Hebei Province, Langfang 065000, Hebei, China)

机构地区：[1]河北省区域地质矿产调查研究所

出　　处：《地质通报》2019年第5期802-809,共8页Geological Bulletin of China

基　　金：新疆维吾尔自治区地质勘查基金项目管理中心招标项目《新疆叶城县库地东一带1:5万区域地质矿产调查》(编号:XJDKJJZ2011-4)

摘　　要：西昆仑山是塔里木地块和羌塘地块在晚中生代碰撞造山的产物,古特提斯洋分支库尔良-阿羌裂谷闭合时限亦存在争议。以库地北斑状二长花岗岩为研究对象,进行岩石学、地球化学和年代学研究。获得LA-ICP-MS锆石U-Pb年龄244.42±0.87Ma,时代为中三叠世。斑状二长花岗岩的SiO2含量为65.57%~67.70%,Mg^#值为35~38,A/CNK值为0.90~1.01,属于偏铝质高钾钙碱性岩石。稀土元素总量为193×10^-6~339×10^-6,δEu =0.72~0.78,具弱负Eu异常。微量元素Rb、K、Th、U、La、Ce、Zr富集,Nb、Ti、P中等-强亏损。斑状二长花岗岩属于I型花岗岩,源岩为安山岩,形成于俯冲的大陆岛弧环境。结合区域资料和前人研究成果表明,斑状二长花岗岩形成于中三叠世大陆岛弧环境,中三叠世库地一带存在古特提斯洋壳俯冲活动,库尔良-阿羌裂谷尚未消减闭合。The West Kunlun Mountains is the product of the Tarim block and the Qiangtang plots in the Late Mesozoic collision orogeny. The closing time of the Kurdish- Aqiang rift valley is also controversial. In this paper, we studied the petrology, geochemistry and chronology of prophyritic monzonitic granite of the Kudi northern. In this paper, the LA-ICP-MS zircon U-Pb age is 244.42±0.87Ma, and the age is Middle Triassic. The SiO2 content of the porphyritic granite is 65.57%~67.70%, Mg^#=35~38, A/CNK=.90~1.01, belonging to the aluminum-alkali high-potassium calc-alkaline rock. The total amount of rare earth elements is 193×10^-6~339×10^-6,δEu=0.72~0.78, with weak negative anomaly.Trace elements Rb, K, Th, U, La, Ce, Zr are enriched, Nb, Ti, P medium-strong loss. The porphyritic granite belongs to the I-type granite, and the source rock is the Andesite, which is formed in the subduction continental island arc environment. Regional data, previous achievements and research in this paper indicate that the porphyritic granite was formed in the continental arc environment of the Middle Triassic, and that the ancient Tethys oceanic crust subduction activity existed in the reservoir area of the Middle Triassic, Kulliag- A Rift Valley has not yet reduced closure.

关 键 词：西昆仑 库地 中三叠世 花岗岩 古特提斯洋 LA-ICP-MS锆石U-PB测年 斑状二长花岗岩 

分 类 号：P597.3[天文地球—地球化学] P588.121[天文地球—地质学]