内蒙古巴彦都兰铜矿地质特征及矿床成因——岩石地球化学、锆石U-Pb年代学及Hf同位素证据

发布时间：2018-04-25 13:41

本文选题：巴彦都兰铜矿 + 锆石U-Pb年代学　；参考：《现代地质》2017年06期

【摘要】：巴彦都兰铜矿是内蒙古二连浩特—东乌旗成矿带近年来新发现的一处中—高温热液脉型铜多金属矿床。通过对矿区内与成矿关系密切的花岗岩岩体开展同位素年代学、岩石地球化学和Hf同位素测试,据此探讨了该矿床的成因机制。分析结果显示,黑云母二长花岗岩LA-ICP-MS锆石U-Pb年龄为(300.2±2.2)Ma和(300.0±2.0)Ma;具有富硅、高钾钙碱性、弱过铝质,富集轻稀土元素及Rb、K等大离子亲石元素,亏损Sr、Nb、Ta等高场强元素的特征;锆石Hf同位素εHf(t)=6.1~10.7,TDM2=632~924 Ma,表现出洋壳俯冲形成的新生下地壳部分熔融的特征。综合研究认为,巴彦都兰铜矿形成的大地构造背景处于晚石炭世—早二叠世二连—贺根山洋盆闭合、区域构造环境逐渐由挤压转为后碰撞的伸展环境,在此期间碰撞后的岩石圈拆沉作用以及拉张机制下上涌的地幔物质使得新生下地壳得到再活化,产生的混合有基性幔源物质的酸性岩浆体系为成矿系统提供了主要成矿物质与流体。
[Abstract]:Bayan Dulan copper deposit is a newly discovered middle-high temperature hydrothermal vein copper polymetallic deposit in the Erlianhaot-Donwuqi metallogenic belt of Inner Mongolia in recent years. Based on the isotopic geochronology, geochemistry and HF isotopic measurements of granitic rock bodies closely related to mineralization in the ore area, the genetic mechanism of the deposit is discussed. The results show that the LA-ICP-MS zircon U-Pb age of biotite monzogranites is 300.2 卤2.2)Ma and 300.0 卤2.0Ma.The zircon is characterized by rich silicon, high potassium calc-alkaline, weak peraluminous, rich in light rare earth elements and large ion lithophile elements such as RB K, and depletion of high field strength elements, such as Sr, NB, Ta, etc. Zircon HF isotope 蔚 HF isotopic 蔚 HflT ~ (10. 7) TDM2 / 632 ~ (2 +) 924 Ma. shows the characteristics of partial melting of the new lower crust formed by the subduction of the oceanic crust. It is considered that the tectonic setting of Bayan Dulan copper deposit is closed in the late Carboniferous to early Permian, and the regional tectonic environment has gradually changed from compression to post-collision extensional environment. During this period the lithospheric delamination after the collision and the upwelling of mantle material under the extensional mechanism reactivated the new lower crust. The acid magmatic system mixed with basic mantle-derived materials provides the main ore-forming materials and fluids for the ore-forming system.
【作者单位】：中国地质大学(北京)地球科学与资源学院;锡林郭勒盟同仁矿业有限责任公司;内蒙古自治区地质调查院;
【基金】：内蒙古自治区地质勘查基金项目(2014-01-YS01) 中国地质调查局地质矿产资源调查评价专项(1212011220923);中国地质调查局新兴产业资源战略调查评价专项工程项目(1212011220673)
【分类号】：P618.41

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