西昆仑东段宿营地晚三叠世中性脉岩的锆石U-Pb定年、岩石地球化学特征及其意义

发布时间：2018-04-22 08:06

  本文选题：中性脉岩 + 锆石U-Pb定年　； 参考：《地球科学》2017年06期

【摘要】：为了研究西昆仑造山带东段古特提斯构造-岩浆演化,提升区域研究程度,对宿营地脉岩进行系统的野外地质调查、岩相学、LA-ICP-MS锆石U-Pb定年、岩石地球化学研究.脉岩呈NE向成群成带分布;岩石类型为(含石榴)闪长玢岩、角闪安山玢岩及闪斜煌斑岩;获得(含石榴)闪长玢岩LA-ICP-MS锆石U-Pb加权平均年龄(214±1)~(219±1)Ma,形成于晚三叠世,是印支晚期构造-岩浆活动产物;脉岩主要为钙碱性系列岩石,表现出中Si(SiO_2=53.92%~62.95%)、高Al(Al_2O_3=15.99%~17.69%)、富Na(Na_2O=2.63%~6.09%、Na_2O/K_2O=1.09~8.30)、低Ti(Ti_2O=0.50%~0.76%)、低P(P_2O_5=0.14%~0.23%)、Mg(Mg~#=37.73~59.32)变化大等主量元素特征,铝饱和指数(A/CNK)为0.92~1.36;脉岩富集LREE、Rb、Th、U、K,亏损HREE、Nb、Ta、P、Ti,(La/Yb)N=7.24~20.02,Ce、Eu异常不明显.结果表明,宿营地中性脉岩是西昆仑东段南缘晚三叠世古特提斯弧后拉张作用引起的壳-幔混合作用的产物.
[Abstract]:In order to study the evolution of Paleotectonic-magma in the eastern part of the West Kunlun orogenic belt and to enhance the regional study degree, systematic field geological survey of the Suzhang dike rocks, U-Pb dating of zircon from the lithofacies and geochemistry of the rocks were carried out. The dike rocks are distributed in NE direction in groups of diorite porphyrite, hornblende porphyrite and diorite lamprophyre, and the LA-ICP-MS zircon U-Pb weighted mean age of diorite porphyrite (including pomegranate) is obtained, which was formed in the late Triassic. 鏄�鍗版敮鏅氭湡鏋勯�，

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