青海祁漫塔格虎头崖矿区花岗岩地球化学特征及构造意义  

Geochemical Characteristics of Granite in Hutouya Mining Area of Qimantag,Qinghai and Its Constraints on Tectonic Setting

作　　者：马圣钞[1] 丰成友[2] 李大新[2] 赵一鸣[2] 刘建楠[2] 

机构地区：[1]中国冶金地质总局山东正元地质勘查院,济南250101 [2]中国地质科学院矿产资源研究所,北京100037

出　　处：《地质学报》2014年第1期72-82,共11页Acta Geologica Sinica

基　　金：中国地质调查局地质调查项目(编号1212011085528);国家自然科学基金项目(编号41172076);中国地质调查局高层次地质人才培养计划(编号201309);青年地质英才计划(编号201112)的联合资助结果

摘　　要：位于青海东昆仑祁漫塔格构造带内的虎头崖矿区花岗岩形成于中-晚三叠世，岩性主要由黑云母二长花岗岩、正长花岗岩组成，局部含闪长质暗色包体。岩石高硅、高钾、富碱，SiO2含量为70．71％～77．67％；K2O含量平均为4．7％；Na2O＋K2O为7．86％～9．10,4；K2O／Na2O平均为1．36。A／CNK比为1．01，KN／A比为0．86，属于高钾钙碱性系列的微过铝质I型花岗岩类。∑REE含量中等，平均为120．10×10；δEu值0．04～0．47；（La／Yb）N值为1．52～8．06。稀土元素球粒陨石标准化曲线显示Eu负异常、HREE较平坦的右倾“V”型特征。岩体富集LIL和HFS元素，而Ba、Sr、Nb、Ti、P元素明显的负异常。微量元素蛛网图和稀土元素球粒陨石标准化图解显示各花岗岩体具有相同的岩浆源区。结合区域地层岩性特征、A／MF-C／MF图解和岩体微量元素蛛网图，认为虎头崖矿区花岗岩是基性源区部分熔融和地壳物质混合的产物。结合地质特征、构造演化背景、元素判别图解等，认为该地区花岗岩类形成的构造环境为碰撞造山期后阶段。The granite of Hutouya mining area is a middle-late Triassic （Late Indosinian） granitic body in THE Qimantage tectonic belts, which is mainly composed by biotite-monzonitic granite, syenogranite and a small scale of granite with diorite inclusion. The rocks contain high silicon （70. 71%- 77. 67%）, high potassium （4.7% in average） and are rich in alkali （Na2O＋K2O=7.86%-9.1%）, and the average value of K2O/Na2O （1.36）, the value of A/CNK spread within the limits of 0.91-1.05. The rocks belong to high-K, cala-alkaline series peraluminous granitoids. The rocks have medium ∑ REE values with an average of 120. 10 × 10 6 values of δEu within the limits of 0. 04-0. 47, values of （La/Yb）N spread among 1. 5248.06, the rare earth patterns of rocks/chondrite show the right deviation of ＂V＂ type with the character of negative Eu and flat HREE. The rocks are rich in LIL and HFS, and evident negative anomalies of Ba, Sr, Nb, Ti, P. According to the character of regional geology, the diagram of A/FM-C/ FM and the spider pattern of trace elements, the author infers that the Hutouya granite is the production of partly fusion of original resource and participation of crust. Based on tectonic history and the diagram of structure environment, the Indosinian granitoids （including Hutouya pluton） formed in post-collisional tectonic setting of syn-orogenic stage

关 键 词：I型花岗岩 地球化学 后碰撞 虎头崖 祁漫塔格 

分 类 号：P588.121[天文地球—岩石学]