摘要
矽卡岩型矿床是全球最具经济价值且研究最为深入的矿床类型之一。其矿物分带、金属矿化机制、流体演化特征均已获得共识性的结论,但其矽卡岩的成岩作用时限一致是困扰成矿作用机理研究的难题。桑日铜矿是青藏高原班公湖-怒江成矿带中段新发现的重要斑岩-矽卡岩型矿床。金属矿物主要为黄铜矿、黄铁矿和少量辉钼矿,呈细脉状、块状、浸染状产于斑岩和矽卡岩中。文章以西藏班戈县桑日铜矿为实例,利用飞秒激光剥蚀系统高分辨率电感耦合等离子体质谱仪,对矿区内矽卡岩中的石榴子石进行U-Pb精确定年,获得其结晶时代为83.2±2.3Ma(MSWD=1.2,n=26),有效限定矽卡岩成岩作用时代为晚白垩世。同时,将其与含矿斑岩锆石U-Pb年龄和辉钼矿Re-Os年龄对比,发现三者在误差范围内基本一致,说明三者属于同一成岩成矿作用事件的产物。因此,石榴子石U-Pb精确测年能够有效厘定矽卡岩矿床或斑岩-矽卡岩成矿系统中矽卡岩成岩作用时限,也为诸多矽卡岩矿床成矿机理研究提供了新的测试手段和数据支撑,具有良好的应用前景。
Skarn deposits,as one of the most economically viable and highly studied deposits,is famous and commonly identified by its mineral zone,metal mineralization,and ore-forming fluid evolution.However,determining the diagenesis age of skarn is a challenge for the mineralization study of skarn deposit in the past decades.The Sangri copper deposit is a newly discovered porphyry-skarn deposit in the middle of the Bangong Co-Nujiang metallogenic belt,located in the Qinghai-Tibet Plateau.Chalcopyrite,pyrite,and molybdenite are the common metal minerals,occurring as veinlet,massive,and disseminated in the porphyry and skarn.The U-Pb age of garnet in the skarn dated by femtosecond laser erosion system with high-resolution inductively coupled plasma mass spectrometer is 83.2±2.3 Ma(MSWD=1.2,n=26),from the Sangri copper deposit in the Bangion county,Tibet.These data showed that diagenesis age of skarn was late Cretaceous.At the same time,compared with the U-Pb age of zircon from the ore-bearing porphyry and the Re-Os age of molybdenite,U-Pb age of garnet was consistent with them within the error range,indicating that they were the products of the same mineralization event.Therefore,the accurate U-Pb dating of garnet can effectively confirm the diagenesis age of skarn deposit or porphyry-skarn deposit.It is a new geochronology method and provides useful support for the metallogenic mechanism study of skarn deposits.
作者
林彬
陈蕾
刘振宇
唐菊兴
邹兵
贺文
LIN Bin;CHEN Lei;LIU Zhenyu;TANG Juxing;ZOU bin;HE Wen(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing,100037;Université Laval,Quebec,G1V0A6,Canada;Geological Survey Institute of Jilin Province,Changchun,130102)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2020年第10期2883-2892,共10页
Acta Geologica Sinica
基金
中国地质科学院基本科研业务费专项经费项目(编号SYSCR2019-02)
国家自然科学基金项目(编号41902097)
国家重点研发计划-深地专项(编号2018YFC0604101)
西藏自治区科技计划项目(编号XZ201901-GB-24)联合资助。
