东昆仑五龙沟花岗岩特征及其构造背景  

Characteristics and tectonic setting of granite in Wulonggou area,East Kunlun Mountains

作　　者：李希[1,2] 袁万明[1] 郝娜娜[1] 段宏伟[1] 陈小宁[1] 莫宣学[1] 张爱奎 

机构地区：[1]中国地质大学科学研究院,北京100083 [2]重庆市市政设计研究院,重庆400020 [3]青海省第三地质矿产勘察院,西宁810029

出　　处：《世界地质》2014年第2期275-288,共14页World Geology

基　　金：中国地质调查局地质调查工作项目(基2011-03-04-06);国家自然科学基金项目(41172088和40872141)联合资助

摘　　要：根据岩石学、地球化学等特征及MC-ICP-MS锆石U-Pb定年,对东昆仑五龙沟地区花岗岩进行了构造环境研究。黄龙沟中粒正长花岗岩具有高硅、高碱、相对富铝、高FeOt/MgO和104Ga/Al值、富集轻稀土、明显的Eu负异常、相对原始地幔明显富集Zr、Ga、Y和Hf等高场强元素并强烈亏损Ba、Sr、P和Ti元素的特征,为A型花岗岩。锆石U-Pb法获得206Pb/238U值加权平均年龄为416.9±1.3 Ma,是早古生代晚志留世造山旋回末后造山碰撞产物,标志晚志留世东昆仑造山旋回进入造山后碰撞阶段。岩金沟矿区东花岗闪长岩为典型准铝质钙碱性花岗岩,具有I型花岗岩稀土元素特征,为I型花岗岩,形成年龄为258.9±2.1 Ma,属于昆南断裂结束后、于晚二叠世开始南区巴颜喀拉地体与昆中区南昆仑地体间发生强烈的壳幔剪切作用的产物。According to the characteristics of petrology,geochemistry and MC-ICP-MS zircon U-Pb dating,the tectonic setting of granite in Wulonggou of East Kunlun had been studied.It was shown that the Huanglonggou granite had high content of silicon,alkaline,aluminum,FeOt/MgO,l04 Ga/Al and LREE with apparent negative Eu anomalies.There were obvious enrichment of high field strength elements （Zr,Ga,Y,and Hf） and strong losses of Ba,Sr,P,and Ti,comparing with primitive mantle.These features were consistented with geochemical characteristics of A-type granitoids.By using LA-ICP-MS zircon U-Pb method,a weighted average age of 416.9 ± 1.3 Ma （MSWD =3.6） was obtained,which indicates that the rocks were the post-orogenic collision product in Late Silurian of Early Palezoic,marking the East Kunlun orogenic cycle entering the post-collision stage in that time.The granodiorite metaluminous calc-alkaline granite of the east Yanjingou mine had the characteristics of the granite type I in rare earth elements,and formed in 258.9 ± 2.1 Ma,which was the product of intense magmatism resulted by strong crust-mantle shearing between southern Bayan Har terrane and central queensland of South Kunlun terrane,began in Late Permian.

关 键 词：五龙沟 花岗岩 岩石地球化学特征 锆石U-PB 

分 类 号：P588.121[天文地球—岩石学]