缅甸Wunto-Popa岩浆弧Shangalon铜金矿床辉钼矿Re-Os同位素测年及其地质意义  

Re-Os isotope dating of molybdenite from Shangalon Cu-Au deposit in the Wunto-Popa magmatic arc,Myanmar and its geological significance

作　　者：冷秋锋 吴松洋 刘书生 聂飞[3] 张彬 LENG Qiufeng;WU Songyang;LIU Shusheng;NIE Fei;ZHANG Bin(Chengdu Center,China Geological Survey(Geosciences Innovation Center of Southwest China),Chengdu 610218,China;Chengdu Institute of Environmental Geology and Resources Development Co.,Ltd.,Chengdu 610218,China;Applied Geological Survey Center,China Geological Survey,Chengdu 610036,China)

机构地区：[1]中国地质调查局成都地质调查中心(西南地质科技创新中心),四川成都610218 [2]成都环境地质与资源开发研究所有限责任公司,四川成都610218 [3]中国地质调查局应用地质调查中心,四川省成都610036

出　　处：《沉积与特提斯地质》2024年第2期411-420,共10页Sedimentary Geology and Tethyan Geology

基　　金：国家自然科学基金重点基金(92055314);东南亚和南亚国际合作地质调查(DD20230127);四川省“天府万人计划”杰出科学家项目(川万人第023号);云南省科学技术奖-杰出贡献奖项目(2017001)。

摘　　要：Shangalon铜金矿床位于缅甸Wunto-Popa岩浆弧北段,研究工作薄弱,其成矿地质背景和矿床成因尚缺乏高精度同位素成矿年代学数据的制约。本文选取典型矿石中5件辉钼矿样品通过Re-Os同位素定年方法厘定成矿时代,获得的模式年龄集中变化于38.5±0.6至38.3±0.5 Ma,加权平均年龄为38.4±0.2 Ma,对应的等时线年龄为38.0±1.6 Ma(MSWD=0.17),二者在误差范围内基本保持一致,指示Shangalon铜金矿床的成矿时限为始新世,该年龄数据与矿区的含矿闪长岩和花岗闪长岩锆石U-Pb年龄38~40 Ma相吻合,表明Shangalon Cu-Au-Mo成矿作用与始新世闪长岩–花岗闪长岩侵入体密切相关,为始新世岩浆活动的产物。Shangalon铜金矿床辉钼矿样品的Re含量为82.4~111.2μg·g-1,平均值为98.88μg·g-1,指示成矿物质具有壳幔混源的特征。通过综合分析区域成矿动力学背景,认为Shangalon地区始新世铜金成矿作用可能形成于印度与欧亚大陆碰撞背景下的新特提斯洋板片撕裂和断裂,诱发软流圈上涌,新生下地壳部分熔融。The Shangalon copper-gold deposit is located in the northern segment of the Wunto-Popa magmatic arc in Myanmar.The research on this deposit is limited,and there is a lack of high-precision isotopic geochronological data regarding its ore-forming geological background and deposit genesis.In this study,five molybdenite samples from typical ores were selected to determine the mineralization age using the Re-Os isochron dating method.The obtained model ages range from 38.3±0.6 to 38.5±0.5 million years ago(Ma),with a weighted average age of 38.4±0.2 Ma.The corresponding isochron age is 38.0±1.6 Ma(MSWD=0.17).Both ages are in good agreement within the error range,indicating that the mineralization timing of the Shangalon copper-gold deposit is in the Eocene epoch.This age data corresponds well with the zircon U-Pb ages of 38 to 40 million years for the mineralized syenogranite and granodiorite in the mining area,suggesting a close relationship between the Shangalon Cu-Au-Mo mineralization and Eocene syenogranite-granodiorite intrusions,which are products of Eocene magmatic activity.The Re contents of molybdenite samples from the Shangalon copper-gold deposit range from 82.4 to 111.2µg·g^(-1),with an average value of 98.88µg·g^(-1),indicating a mixed source from the crust and mantle for the mineralizing fluids.Based on a comprehensive analysis of the regional metallogenic dynamics,it is suggested that the Eocene copper-gold mineralization in the Shangalon region possibly formed as a result of the fragmentation and faulting of the Neo-Tethys oceanic plate,triggered by the collision between the Indian and Eurasian continents,leading to upwelling of the asthenosphere and partial melting of the lower crust.

关 键 词：辉钼矿 RE-OS同位素定年 Shangalon铜金矿床 Wunto-Popa岩浆弧 缅甸 

分 类 号：P618.51[天文地球—矿床学] P618.41[天文地球—地质学]