吉林省蛟河市新安屯钨钼矿流体包裹体、氢氧同位素及成矿时代研究

Fluid Inclusions,H-O Isotope and Metallogenic Epoch of the Xin’antun W-Mo Deposit in Jiaohe City,Jilin Province

吉林省蛟河市新安屯钨钼矿位于小兴安岭-张广才岭成矿带内,矿体呈细脉浸染状产于似斑状花岗闪长岩内,严格受北东向压扭性断裂构造控制。本文系统阐述了新安屯钨钼矿的区域地质背景、成矿地质特征,重点开展了流体包裹体、氢氧同位素及成矿时代等方面研究。结果表明,矿床成矿期流体均一温度180~235℃,流体盐度(3.23~13.82)wt%NaCleqv,密度0.875~0.975 g/cm^3 ,成矿深度0.05~1.1km;成矿流体中δ^18O为9.0‰~9.8‰,δD为-106.2‰^-116.3‰;采用LA-ICP-MS锆石U-Pb法获得含矿似斑状花岗闪长岩成岩年龄为195.4±1.2Ma;通过辉钼矿Re-Os 同位素法获得成矿年龄为180.5±3.9Ma。综合分析认为,该矿床成矿物质来自壳源,矿床类型属于断裂构造控制的浅成中低温岩浆热液型,成矿时代为早侏罗世,属于太平洋板块俯冲作用下的活动大陆边缘构造环境下的产物。

The Xin antun W-Mo deposit of Jiaohe City,Jilin Province is situated in the Xiaoxinganling-Zhangguangcailing metallogenic belt,where the ore body occurs in byporphyroid granodiorite with veinlet-disseminated shape,controlled by northeast-east trending compression-shear fault structure. This article elucidates the regional geologic background and metallogenic characteristics of this deposit,focusing on the study of fluid inclusions,H-O isotope and metallogenic epoch. Results show that the homogeneous temperature of fluids was 180~235℃,the salinity of fluids was (3.23~13.82)wt%NaCleqv,fluid density was 0.875~0.975 g/cm^3 ,metallogenic depth was 0.05~1.1km,and δ^18O was 9.0‰~9.8‰ and δD is-106.2‰^-116.3‰ in ore-forming fluid. The LA-ICP-MS zircon U-Pb age of ore-bearing byporphyroid granodiorite is 195.4±1.2Ma. The Re-Os isotopic dating yields an isochron age of 180.5±3.9Ma. Comprehensive analysis suggests that the mineralization material was originated from the crust. The deposit is of a meso- epithermal magmatic type controlled by fault structure. It was formed in the Early Jurassic along an active continental margin under the subduction of the Paleo-Pacific Plate.