新疆中天山乔霍特铜矿区Ⅰ型花岗岩锆石LA-ICP-MS U-Pb年龄及其地质意义  

Zircon LA-ICP-MS U-Pb age of I type granitoids from Qiaohuote copper deposit in Central Tianshan of Xinjiang and its geological implications

作　　者：张喜[1,2] 高俊[1] 董连慧[3] 李继磊[1,2] 江拓[1,2] 钱青[1] 苏文[1] 

机构地区：[1]中国科学院地质与地球物理研究所,矿产资源研究重点实验室,北京100029 [2]中国科学院研究生院,北京100049 [3]新疆维吾尔自治区地质矿产勘查开发局,乌鲁木齐830000

出　　处：《岩石学报》2011年第6期1637-1648,共12页Acta Petrologica Sinica

基　　金：自然科学国家重点基础发展规划项目(2007CB411302);国家自然科学基金项目(40672153、40872057、40872059、40721003)联合资助

摘　　要：新疆中天山乔霍特铜矿位于中天山南缘,毗邻南天山缝合带。矿区南侧出露有1个花岗闪长岩岩体,该岩体与包裹于赋矿火山岩中的钾长花岗岩均属钙碱性弱过铝质I型花岗岩,具有相似的地球化学特征,富集LILE、亏损HFSE,具显著的Eu、Ta、Nb、Ti负异常,其形成可能与南天山洋的北向俯冲密切相关。LA-ICP-MS锆石U-Pb定年获得花岗闪长岩年龄为450.4±1.1Ma,钾长花岗岩年龄为430.8±4.1Ma,指示晚奥陶世时期,乔霍特地区存在南天山洋向中天山复合弧地体之下的俯冲;早志留世晚期,俯冲作用依然持续,此时,天山地区岩浆活动强烈。乔霍特铜矿赋矿火山岩的形成时代晚于431Ma,矿区南侧出露的花岗闪长岩早于赋矿火山岩形成,成矿作用可能与花岗闪长岩的侵位无直接关系。Two kinds of granitoids with the similar geochemical characteristics outcrop in Qiaohuote copper deposit which lies on the north side of South Tianshan Suture Zone.The granodiorite outcropping on the south side of Qiaohuote copper deposit and the moylite occurring as an enclave in the volcanic rocks belong to I type granite.They both have calc-alkaline composition,and are characterized by enriched LILE and depleted HFSE and negative anomalies in Eu,Ta,Nb,and Ti.Tectonically,they are related to the northward subduction of South Tianshan Ocean beneath the southern margin of Central Tianshan terrane.LA-ICP-MS zircon ages of 450.4±1.1Ma and 430.8±4.1Ma were obtained from these granitoids.The geochemical and age dating data reported in this paper indicate that these granitoids were formed in a subduction environment,the northward subduction of South Tianshan Ocean may start at Late Ordovician （450Ma） and still be active during Early Silurian （431Ma） in Qiaohuote region.The age of granodiorite is earlier than the ore-host volcanic rocks,therefore,the metallization of Qiaohute copper deposit is independent of the granodiorite.

关 键 词：乔霍特铜矿 花岗岩类 地球化学 锆石U-Pb年龄 中天山 

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