东昆仑它温查汉西花岗岩地质地球化学特征及其构造意义  

Geological and Geochemical Characteristics of the Tawenchahanxi Granites in East Kunlun and Its Tectonic Significance

作　　者：杨涛[1] 李智明[1] 张乐[2] 宋忠宝[1] 张洲远 杜亚龙 赵辛敏 张斌[2] 李金超[1] 陈向阳[1] 王宇[1] 

机构地区：[1]中国地质调查局西安地质调查中心,西安710054 [2]长安大学地球科学与资源学院,西安710064

出　　处：《高校地质学报》2017年第3期452-464,共13页Geological Journal of China Universities

基　　金：中国地质调查局青海省岩浆岩时空分布与成矿作用研究项目(1212011121089);青海省都兰县察汗乌苏河地区1:5万地质矿产综合调查子项目(12120115022101)

摘　　要：它温查汉西铁多金属矿床是东昆仑祁漫塔格成矿带新发现的又一典型矽卡岩型矿床,与成矿密切相关的花岗闪长斑岩和二长花岗斑岩成岩时代分别为236.0±2.3 Ma和229.9±2.0 Ma。二者均为弱过铝质高钾钙碱性系列,成因类型分别属于Ⅰ型和A型;二者稀土元素配分表现为富LREE、贫HREE以及中等Eu负异常的特征,微量元素具有Th、U、K、Zr、Hf相对富集和Nb、Ta、Ti、Sr、Ba相对亏损的特征。花岗闪长斑岩和二长花岗斑岩形成于晚古生代—早中生代构造—岩浆旋回的碰撞—后碰撞转化阶段,与区域上的大规模幔源岩浆底侵及壳—幔岩浆混合作用有关,从形成花岗闪长斑岩到二长花岗斑岩过程中地壳具有由厚减薄的趋势。The Tawenchahanxi Fe-polymetallic deposit is a typical skarn type deposit newly discovered in the Qimantage metallogenic belt of East Kunlun. The mineralization is related to the granodiorite porphyry and monzogranite porphyry with ages of 236. 0 ± 2. 3 Ma and of 229. 9 ± 2. 0 Ma,respectively. Both the granodiorite porphyry and monzogranite porphyry show weakly peraluminous and high-K calc-alkaline signature, and genetically can be ascribed to I-and A-type granites, respectively. They are enriched in LREE and depleted in HREE, and display right-inclined REE distribution patterns with medium negative europium anomalies. These rocks are also enriched in Th,U,K,Zr,Hf, and depleted in Nb, Ta, Ti, Sr, Ba on the primitive mantle-normalized spidergrams. Based on a synthesis of petrography, geochronology, elemental geochemistry and tectonics, we suggest that the granodiorite porphyry and monzogranite porphyry were formed in a conversion stage from collisional to post collisional setting during Late Paleozoic to Early Mesozoic, and their generation were likely related to large-scale underplating of mantle-derived magma and crust-mantle magma mixing process. Investigation also shows that there is a crustal thinning tendency from the formation of the granodiorite porphyry to the generation of the monzogranite porphyry.

关 键 词：矽卡岩 I型和A型花岗岩 碰撞-后碰撞转化阶段 壳-幔岩浆混合 它温查汉西铁多金属矿床 东昆仑 

分 类 号：P588.12[天文地球—岩石学]