黑龙江宁安英城子热液金矿床流体包裹体的氩同位素激光探针定年与成矿时代讨论

^(40)Ar/^(39)Ar laser probe dating of fluid inclusions and discussion on metallogenic epoch of Yingchengzi epithemal Au deposit in Ning'an area of Heilongjiang

英城子金矿床产于张广才岭岩浆构造带内早古生代花岗岩岩体内部的韧脆性剪切带中,矿体由花岗质糜棱片岩、含硫化物石英脉和纯硫化物脉组成,赋矿围岩为晚奥陶世黑云母二长花岗岩。对含金石英脉中石英流体包裹体进行的40Ar/39Ar激光探针定年结果表明:实验室给定的等时线年龄为207±5.5Ma(40Ar/36Ar Int.=410±11,MSWD=44,n=31),剔除相对误差较大的数据点,运用Isoplot程序拟合的等时线年龄为248±39Ma(40Ar/36Ar Int.=344±54,MSWD=0.37,Probability=0.99)。结合区域构造热事件的发育状况,初步确定该矿床的成矿作用发生在晚二叠世末向早三叠世转化阶段或东段的兴蒙造山运动过程。

Yingchengzi Au deposit is located in ductile-brittle shear zone of Early Paleozoic granite which emplaced at Zhangguangcailing magma structural zone. The orebody is composed of granitic mylonite schist, sulfidequartz vein and pure sulfide vein, and the ore-hosting rock is Late Ordovician biotite monzonite granite. ^40Ar/^39Ar isochron age of quartz fluid inclusion in auric quartz vein is 207 ±5.5 Ma （^40Ar/^36Ar Int. =410 ± 11, MSWD = 44, n = 31 ）. Rejecting some data points with major relative errors and using Isoplot process fit, the isochron age is 248 ±39 Ma （4^40Ar/^36Ar Int. =344 ±54, MSWD =0. 37, Probability =0. 99）. According to the development situation of regional structural thermal event, the authors preliminarily confirm that the mineralization occurs in the conversion phase from Late Permian to Early Triassic or in the course of eastern Xingmeng orogeny process.