东昆仑祁漫塔格晚志留世——早泥盆世花岗岩:年代学、地球化学及形成环境  

Late Silurian to Early Devonian Granitoids in the Qimantage Area, East Kunlun Mountains: LA-ICP-MS zircon U-Pb Ages, Geochemical Features and Geological Setting

作　　者：郝娜娜[1] 袁万明[1] 张爱奎[1] 曹建辉[1] 陈小宁[1] 冯云磊 李希[1] 

机构地区：[1]中国地质大学(北京)科学研究院,北京100083

出　　处：《地质论评》2014年第1期201-215,共15页Geological Review

基　　金：中国地质调查局地质调查工作项目(编号基2011-03-04-06);国家自然科学基金资助项目(编号41172088;40872141)的成果

摘　　要：东昆仑祁漫塔格构造—岩浆岩带发育大量与加里东期造山有关的花岗岩,对其进行研究不仅能为祁漫塔格早古生代构造演化提供新信息,而且对探讨整个东昆仑造山带的动力学演化过程具有重要的意义。本文报道祁漫塔格东部那棱郭勒河东黑云母二长花岗岩及祁漫塔格乌兰乌珠尔钾长花岗岩的锆石U-Pb年龄和地球化学数据,并对研究区晚志留世—早泥盆世花岗岩成因及其构造意义进行探讨。本区的黑云母二长花岗岩、钾长花岗岩的LA-ICP-MS锆石U-Pb年龄分别为420.6±2.6Ma、421.2±1.9Ma。祁漫塔格晚志留世—早泥盆世花岗岩类整体属高钾钙碱性准铝—过铝质花岗岩,稀土配分曲线为轻稀土元素相对富集、重稀土元素相对平坦、中等负铕异常,微量元素表现为大离子亲石元素Rb、Th相对富集,高场强元素Nb、Sr、P、Ti亏损的特征;该时期为后碰撞构造环境,岩石成因类型以高钾钙碱性I型花岗岩为主,但同时出露同时期S型花岗岩,推测在同碰撞挤压造山作用向后碰撞区域拉伸构造体制(约420Ma)的转换时期,产生了具有A型花岗岩特征的花岗岩、高钾钙碱性I型花岗岩及过铝质花岗岩。Qimantage tectonic--magamatic belt in East Kunlun Mountains develops a large number of granitoids associated with the caledonian orogency. Researching these can provide new informations for the tectonic evolution of Qimantage in Early Paleozoic, and also has great significances for investigating the geodynamic evolution characteristics of the whole East Kunlun orogenic belt. In this paper, writers report the new zircon U-Pb ages and geochemical datas of the biotite monzogranite in East Nalinggele River and the potash-feldspar granite in Wulanwuzhuer, and discussed the petrogenesis and tectonic significance of Late Silurian to Early Devonian granitoids in studied area. The LA-ICP-MS zircon U-Pb ages of the biotite monzogranite and the potash-feldspar granite are 420. 6 ± 2. 6Ma and 421.2 ± 1.9Ma, respectively. Late Silurian to Early Devonian granitoids in studied area belong to high-K calc-alkaline metaluminous to peraluminous rocks, with REE patterns displaying enriched-LREE, fiat HREE and moderate negative Eu anomalities, and trace elements showing relative enrichment of large iron lithophile elements Rb, Th and depletement of high field strength elements Nb, St, P, Ti ; the tectonic setting is post-collision, and the petrogenetic type gives priority to high-K calc-alkaline I-type granites, meanwhile, the study area exposures some S-type granites. It is inferred that tectonic regime transformation from compressive tectonic setting of syn-collision to stretching tectonic setting of post-collision produces the granites having some traits of A-type granites, high-K calc-alkaline I-type granites and peraluminous granites.

关 键 词：花岗岩 年代学 地球化学 构造环境 晚志留一早泥盆世 祁漫塔格 东昆仑 

分 类 号：P597.3[天文地球—地球化学] P588.121[天文地球—地质学]