阿尔金北缘尧勒萨依片麻岩锆石LA-ICP-MS U-Pb年龄、地球化学特征及其地质意义  

Zircon LA-ICP-MS U-Pb ages,geochemical features and their geological implications of Yaolesayi gneiss in north Altyn Tagh

作　　者：何鹏[1] 杨睿娜 陈培伟[1] 张焕 芦西战 贺晓天 翁红波 裴玉华[3] 杨毅明 HE Peng;YANG Ruina;CHEN Peiwei;ZHANG Huan;LU Xizhan;HE Xiaotian;WENG Hongbo;PEI Yuhua;YANG Yiming(No.2 Institute of Geological Exploration of Henan Province,Zhengzhou,450001;No.2 Institute of Geological and Mineral Resources Survey of Henan Province,Zhengzhou,450001;Henan Institute of Geological Survey,Zhengzhou,450001)

机构地区：[1]河南省地质矿产勘查开发局第二地质勘查院,郑州450001 [2]河南省地质矿产勘查开发局第二地质矿产调查院,郑州450001 [3]河南省地质调查院,郑州450001

出　　处：《地质论评》2021年第3期803-815,共13页Geological Review

基　　金：新疆维吾尔自治区地质勘查基金项目管理中心项目(编号:K16-1-LQ12)的成果。

摘　　要：阿尔金北缘尧勒萨依片麻岩分布于尧勒萨依河中下游,主要岩性为黑云二长花岗片麻岩。为确定该地区侵入岩形成时代、成因和构造背景,本文对其进行了岩石学、锆石U-Pb年代学和地球化学研究。研究区花岗岩LA-ICP-MS锆石U-Pb测年显示,其形成年龄为927±3 Ma,时代为新元古代早期青白口纪。其具高硅(SiO2=71%~73.96%)、富碱[(Na2O+K2O)=6.61%~8.00%]的特征,岩石里特曼指数σ=1.41~2.09,属钙碱性系列;铝过饱和指数(A/CNK)=1.01~1.25,为过铝质系列岩石;富集Rb、K、Th、U等大离子亲石元素,相对亏损Nb、Ti、P、Ta等高场强元素,具有典型的大陆碰撞型花岗岩特征;稀土总量高,其中轻稀土元素富集,轻、重稀土元素分馏较明显((La/Yb)N=7.53~8.13),Eu负异常明显(δEu=0.40~0.68),总体呈"右倾海鸥型"稀土配分模式,具典型地壳重熔型花岗岩特征。根据原岩判别图,推测其为变质砂岩部分熔融的产物。结合区域资料,认为尧勒萨依片麻岩应该形成于同碰撞晚期的构造地质环境。Objectives:The gneiss from Yaolesayi in north Altyn Tagh is mainly composed of biotite monzonitic granitic gneiss.In order to find out the origin,formation age and tectonic setting of intrusive rocks in this area,studies of petrology,zircon U-Pb chronology and geochemistry were carried out.LA-ICP-MS U-Pb dating obtains the age of 927±3 Ma,corresponding to Qingbaikou period of early Neoproterozoic.We have learnt that the granite in research area is riched in silicon(SiO2=71%~73.96%)and alkali[(Na2O+K2O)=6.61%~8.00%].The Rittman index of the granite is 1.41~2.09,which shows a characteristic of calc-alkaline series.The aluminum oversaturated index(A/CNK)is 1.01~1.25,which is a peraluminous series.The granite is rich in LILEs such as Rb,K,Th and U and depleted in HFSEs such as Nb,Ti,P and Ta,corresponding to the features of continental collision granite.The granite is also characterized by high∑REE,LREE enrichment,notable light and heavy REE fractionation[(La/Yb)N=7.53~8.13]and apparent negative Eu anomaly(δEu=0.40~0.68),which shows a right-leaning REE pattern in the shape of a seagull,corresponding to the features of crustal remelting granite.The granite in research area may be produced by partial melting of metamorphic sandstone.According to the regional geological data,the granite magma is proved to be a product in the late stage of syn-collision.

关 键 词：锆石LA-ICP-MS U-Pb年龄 岩石地球化学 花岗片麻岩 阿尔金北缘 新元古代 

分 类 号：P588.345[天文地球—岩石学] P597.3[天文地球—地质学]