辽东五龙金矿区成矿期构造过程与岩脉就位机制  

Structural processes and dike emplacement mechanism in the Wulong gold field, eastern Liaoning

作　　者：肖世椰 朱光[1] 张帅[1] 刘程[1] 苏楠 尹浩 吴晓冬 李云剑[1] Shiye Xiao;Guang Zhu;Shuai Zhang;Cheng Liu;Nan Su;Hao Yin;Xiaodong Wu;Yunjian Li(School of Resource and Environmental Engineering,Hefei University of Technology,ttefei 230009,China)

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009

出　　处：《科学通报》2018年第28期3022-3036,共15页Chinese Science Bulletin

基　　金：国家重点研发计划重点专项(2016YFC0600102);国家自然科学基金(41472186)资助

摘　　要：五龙金矿是华北克拉通东部辽东矿集区的典型代表,属于石英脉型金矿.但是,对于其构造控矿机制长期没有明确的认识.本次构造与年代学研究表明,该区在早白垩世初经历了近南北向挤压,形成了多条北东走向左行平移断裂,及其派生的共轭剪破裂.在随后的早白垩世期间(约131～113Ma),该区遭受了西北西-东南东向拉张,形成了北东至北北东走向正断层,并且使得前期构造复活.在此早白垩世伸展期,五龙金矿区南部侵位了三股流岩体(131～120 Ma),北部侵位了五龙背岩体(127～126 Ma),而矿区内侵位了一系列闪长岩脉、花岗岩脉、花岗伟晶岩脉、煌斑岩脉、辉绿岩脉等,前两者与含金石英脉紧密伴生.本次锆石U-Pb定年,指示区内闪长岩脉与花岗岩脉的侵位时间为127～113Ma,属于伸展活动中的同构造侵位岩脉.这些早白垩世岩脉,一方面沿着新生的北东至北北东向张裂面就位,另一方面沿着复活的早期构造就位,从而导致了区内多方位岩脉的共生现象.五龙金矿含金石英脉与这些同期岩脉具有类似的形成机制,两者常呈伴生关系,推断区内金成矿发生127～113Ma期间,属于华北克拉通破坏峰期形成的金矿.但是,五龙金矿具体成矿时间还需矿石矿物直接定年的证据.The Wulong gold deposits are typical representative of deposits in the Liaodong ore concentration area in the eastern North China Craton. The gold deposits occur as the quartz-vein type. However, gold mineralization time of the Wulong gold deposits was uncertain, and structural controlling mechanism for them remains unclear. We present structural and geochronological data to constrain structural evolution and dike emplacement mechanism before and during the gold mineralization. The Wulong monzonitic granite pluton, the host intrusion for the gold deposits, was dated at 173-163 Ma （Middle Jurassic）. The pluton suffered WNW-ESE shortening probably at the beginning of Late Jurassic, as shown by penetrative, ductile deformation and local ductile reverse shear belts in the pluton. The Wulong pluton was then subjected to nearly N-S compression that led to formation of several NE-striking sinistral faults and associated conjugate fractures at the beginning of Early Cretaceous. The compression was followed by WNW-ESE extension during the Early Creta- ceous （ca. 131-113 Ma）. The Early Cretaceous extension caused a series of NE- to NNE-striking normal faults and reac- tivated previous faults or fractures with varied orientations. Our fault-slip data gave reliable constraints on the stress fields during the compression and extension. The extension was also associated with emplacement of the Sangouliu plu- ton （131-120 Ma） in the south, the Wulongbei pluton （127-126 Ma） in the south and a series of diorite, granite, granitic pegmatite, lamprophyre and diabase dikes in the gold mine field. Previous work demonstrates that the diorite and granite dikes often coexist with the auriferous quartz veins. Our zircon U-Pb dating gave 127-113 Ma intrusion ages for the dated diorite dikes, 126-113 Ma ages for the granite dikes and a 121 Ma age for the granitic pegmatite dike. These demonstrate that the diorite and granite dikes in the Wulong gold field are synchronous and their emplacement of 127-113 Ma happened during t

关 键 词：五龙金矿 伸展活动 岩脉就位 锆石U-Pb年龄 早白垩世 

分 类 号：P618.51[天文地球—矿床学]