阿尔金北缘尧勒萨依河口Ⅰ型花岗岩岩石地球化学、锆石U-Pb年代学研究  

Petrogeochemistry,zircon U-Pb chronology of Ⅰ type granite from Yaolesayi estuary,Northern Altun

作　　者：何鹏[1] 芦西战 杨睿娜 陈培伟[1] 刘晓[1] 张焕 贺晓天 李福斌 HE Peng;LU Xizhan;YANG Ruina;CHEN Peiwei;LIU Xiao;ZHANG Huan;HE Xiaotian;LI Fubin(No.2 Institute cf Geological Exploration of Henan,Zhengzhou 450001,Henan,China;No.2 Institute of Geological and Mineral Resources Survey of Henan,Zhengzhou 450001,Henan,China)

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

出　　处：《矿产勘查》2020年第9期1822-1830,共9页Mineral Exploration

基　　金：新疆维吾尔自治区地质勘查基金项目(编号:K16-1-LQ12)资助。

摘　　要：阿尔金北缘尧勒萨依河口花岗岩主要由黑云二长花岗岩组成。为确定该地区侵入岩源区性质、形成时代和地质背景,对其进行了地球化学、构造环境及锆石U-Pb年代学研究,认为研究区花岗岩为高硅(SiO 2=67.48%~70.75%)、高钾(K2O=5.03%~7.66%)、富碱(Na_2O+K_2O=8.45%~11.32%)的特征,岩石里特曼指数δ=2.92~5.08,属碱性系列;铝过饱和指数(A/CNK)=0.8~1.15,基本为准铝质系列岩石;稀土总量偏高,轻稀土元素富集,(La/Yb)N=24.67~117.33,轻、重稀土元素分馏明显,Eu有弱负异常(δEu=0.59~0.97),无明显Ce异常(δCe=0.99~1.05)。富集轻稀土和大离子亲石元素(Rb、K、Th、U),Nb、Ta、P、Ti等高场强元素相对亏损,具有弧形岩浆岩的地球化学特征。花岗岩锆石U-Pb加权平均年龄为(237.3±2) Ma,为中三叠世岩浆活动产物。研究表明,该区侵入岩属I型花岗岩,具有陆陆碰撞型花岗岩的特征,属同碰撞阶段,为壳幔混合源花岗岩类型。The granite from Yaolesayi estuary in north Altyn-Tagh is mainly composed of biotite monzogranite.In order to find out the origin,formation age and tectonic setting of granites in this area,studies of zircon U-Pb chronology,tectonic environment and geochemistry were carried out.We have learnt that granite in research area is rich in silicon(SiO2=67.48%-70.75%),potassium(K2O=5.03%-7.66%),and alkali(Na2O+K2O=8.45%-11.32%).The Rittmann index of granite is 2.92-5.08 which shows a characteristics of alkaline series.The aluminum oversaturated index(A/CNK)of granite is 0.8-1.15,which is a metaluminous series.The granite is characterized by high∑REE(∑REE 161.23×10-6-1217.10×10-6),LREE enrichment,notable light and heavy REE fractionation((La/Yb)N=24.67-17.33),negative Eu anomaly(δEu=0.59-0.97),inapparent positive Ce anomaly(δCe=0.99-1.05),rich LILEs such as Rb,K,Th and U and depleted HFSEs such as Nb,Ta,P and Ti.LA-ICP-MS U-Pb dating obtains the age of(237.3±2)Ma,which is Middle Triassic.These characteristics suggest that the granite in research area is typical I-type granite and may be continent-continent collisional granite,which is produced during the stage of syn-collision.The granite magma is proved to be a crust-mantle mixing origin.

关 键 词：岩石地球化学 花岗岩 锆石U-PB年代学 构造 北阿尔金 

分 类 号：P597.3[天文地球—地球化学]