东昆仑造山带东段南缘和勒冈希里克特花岗岩体时代、成因及其构造意义  

Geochronology and Genesis of the Helegang Xilikete Granitic Plutons from the Southern Margin of the Eastern East Kunlun Orogenic Belt and Their Tectonic Significance

作　　者：陈国超[1,4] 裴先治[1] 李瑞保[1] 李佐臣[1] 裴磊[2] 刘战庆[3] 陈有炘[1] 刘成军[1] 高景民[1] 魏方辉[1] 

机构地区：[1]西部矿产资源与地质工程教育部重点实验室,长安大学地球科学与资源学院,西安710054 [2]中国地质大学地球科学与资源学院,北京100083 [3]桂林理工大学地球科学学院,广西桂林541004 [4]陕西省煤田地质局勘察研究院,西安710054

出　　处：《地质学报》2013年第10期1525-1541,共17页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41172186、40972136、40572121);中央高校基本科研业务费专项资金项目(编号CHD2011TD020,2013G1271091);青海省国土资源厅-中国铝业公司公益性区域地质矿产调查基金项目(中铝基金200801)共同资助

摘　　要：东昆仑造山带东段出露有较多的晚华力西期-印支期岩浆岩,其岩石成因和源区性质一直是地质学家研究的热点。本文对该区的和勒冈希里克特花岗岩体开展了详细的岩相学、LA-ICP-MS锆石U-Pb同位素年代学及岩石地球化学研究。结果显示,岩体具有高Sr/Y、La/Yb比值和Na2O、Sr含量,轻重稀土元素分馏明显,轻微的Eu负异和正异常,Yb和Y的含量很低,说明岩体具有埃达克质岩石特征;岩体为准铝质到弱过铝质高钾钙碱性花岗岩类,富集大离子亲石元素(LILE)和亏损高场强元素(HFSE),高的Mg#值和Cr、Ni含量,近似于大陆地壳的Nb/Ta比值,并大量发育暗色微粒包体,表明其是以暗色微粒包体为代表的基性岩浆底侵下地壳的产物。岩体的锆石同位素年龄为225±5Ma,代表岩体的形成年龄,结合其地球化学特征表明在这一时期东昆仑造山带东段处于碰撞到后碰撞的转换阶段。There are plenty of Late Paleozoic-Mesozoic plutons outcropped in the southern margin of the eastern part of the East Kunlun Orogenic Belt, and their genesis and features of source region have long been the hot topic among geologists. This study carried out the detailed investigation over petrography, LA-ICP- MS zircon U-Pb chronology and litho-geochemical characteristics for the Helegang Xilikete plutons in the area. The results show that the plutons are characteristic of high Sr/Y and La/Yb ratios, high Na20 and Sr contents, apparent differentiation between LREE and HREE, slight positive and negative anomalies of Eu, and low contents of Yb and Y. All this features indicate that the plutons are similar to adakitie rocks. The rocks are classified to metaluminous or weak peraluminous high-K cale-alkali granitoid and enriched in LILE and depleted in HFSE, with high Mg and Cr, Ni continental crust. In addition, the rocks contain a lot of indicate they were the product of underplating of basaltic of the plutons is about （225 ± 5） Ma, representing their features, the age may imply period from collision to post that the eastern part of East collision at that time. in content, and Nb/Ta value similar to that of mafic enclaves and dark micro-grained enclaves magma into lower crust. The zircon isotopic age forming age. In combination with geochemical Kunlun Orogenic Belt stayed in the transitional

关 键 词：东昆仑造山带 和勒冈希里克特岩体 LA-ICP-MS锆石U-PB年龄 埃达克质岩 晚三叠世 岩浆底侵 后碰撞 

分 类 号：P588.121[天文地球—岩石学]