新疆西天山可克萨拉-艾木斯呆依铁铜矿床成岩成矿年代学及其地质意义  

Geochronology of intrusive rocks and associated ores of the Kekesala-Aimusidaiyi Fe-Cu deposit in the West Tianshan,Xinjiang and its geologic significance

作　　者：顾雪祥[1,2] 章永梅[1,2] 王新利[1,2] 张力强[1,2] 董连慧[3] 涂其军[3] 刘瑞萍[1,2] 高虎[1,2] 

机构地区：[1]地质过程与矿产资源国家重点实验室 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]新疆维吾尔自治区地质矿产勘查开发局,新疆乌鲁木齐830000

出　　处：《地学前缘》2013年第6期195-209,共15页Earth Science Frontiers

基　　金：国家科技支撑计划项目(2011BAB06B02-02);国家自然科学基金重点项目(40930423);国家重点基础研究发展计划(2009CB421003-01);长江学者和创新团队发展计划项目;高等学校学科创新引智计划项目(B07011)

摘　　要：可克萨拉-艾木斯呆依铁铜矿床是新疆西天山北缘博罗科努多金属成矿带上的一个典型夕卡岩矿床,产于海西期呼斯特中酸性侵入体与上奥陶统碳酸盐岩的接触带,其成岩成矿时代此前尚无确切的年代学资料。文中通过对矿区呼斯特岩体二长花岗岩中锆石的LA-ICP-MS U-Pb同位素测定,获得等时线年龄为(368.0±3.6)Ma,加权平均年龄为(365.6±3.2)Ma,表明其侵入时代为晚泥盆世晚期,代表了晚古生代北天山洋向南俯冲于伊犁板块之下诱发的岩浆作用产物。夕卡岩矿石中辉钼矿Re-Os同位素等时线年龄为(295±11)Ma,加权平均年龄为(288.3±1.5)Ma,指示矿化作用可能发生于早二叠世早期碰撞后的陆内伸展构造背景。成岩、成矿的时间跨度大,约为80Ma,可能的原因包括:(1)呼斯特岩体是个多期次侵入的复式岩体,辉钼矿化和夕卡岩型铁铜矿化均与该杂岩体于早二叠世的一次岩浆侵入和接触交代作用有关;(2)两期成矿作用叠加,即在早期(晚泥盆世)与中酸性岩浆接触交代有关的夕卡岩型铁铜矿化基础上,后期(早二叠世)又叠加了一次钼的矿化作用。As a typical skarn-type deposit,the Kekesala-Aimusidaiyi Fe-Cu deposit is located in the Boluokenu polymetallic belt in the northern West Tianshan,Xinjiang Province.It occurred at the contact zone between the Husite intermediate-acidic intrusive rocks of Hercynian age and Upper Ordovician carbonate rocks.The timing of host rock intrusion and mineralization is unclear yet up to this study.LA-ICP-MS U-Pb dating of this study on zircon in monzogranite from the Husite intrusive body gave a concordia age of 368.0±3.6Ma and a weighted average age of 365.6±3.2 Ma,indicating its intrusion in the latest Devonian during the southward subduction of the North Tianshan ocean under the Yili plate.Re-Os dating on molybdenite from the skarn ore gave an isochron age of 295±11 Ma and a weighted average age of 288.3±1.5 Ma,indicating the earliest Permian mineralization during the post-collisional extension.Possibilities for the wide range of the timing between host rock intrusion and mineralization include that（1）the Husite intrusive body is a complex with multiple-stage intrusions,and the Mo mineralization as well as the skarn-type Fe-Cu mineralization were associated with the contact metasomatism of magmatic rocks intruded in the early Permian,and that（2）the skarn-type Fe-Cu mineralization was associated with the intrusion and metasomatism of the intermediate-acidic rocks in the late Devonian and,later in the early Permian,was superimposed by the Mo mineralization.

关 键 词：U-PB年龄 RE-OS年龄 成岩成矿时差 夕卡岩型铁铜矿床 可克萨拉-艾木斯呆依 西天山 

分 类 号：P618.31[天文地球—矿床学] P618.41[天文地球—地质学]