广西金牙金矿毒砂 Re-O s同位素测年和硫同位素示踪  

Re-Os dating and sulfur isotope tracing of arsenopyrites from Jinya gold deposit in Guangxi

作　　者：刘苏桥[1,2] 陈懋弘[3] 杨锋[1,2] 戴昱[1,2] 张延[4] 

机构地区：[1]桂林理工大学 广西矿冶与环境科学实验中心 [2]桂林理工大学 广西隐伏金属矿产勘查重点实验室,广西桂林541004 [3]中国地质科学院矿产资源研究所,北京100037 [4]广西第一地质队,广西桂林541100

出　　处：《桂林理工大学学报》2014年第3期423-430,共8页Journal of Guilin University of Technology

基　　金：国家重点基础研究发展计划(973)项目(2014CB440902);广西自然科学基金项目(2012GXNSFAA053184)

摘　　要：金牙金矿的载金矿物主要为毒砂,次为含砷黄铁矿。毒砂矿物结构均一,为主成矿阶段热液成因,相较于成因复杂的环带状含砷黄铁矿更适合于同位素测年和示踪。通过对该矿床毒砂的单矿物Re-Os同位素测年和S同位素分析,获得Re-Os等时线年龄为(206±22)Ma,反映金矿形成于晚三叠世末期,大致相当于印支期挤压造山向燕山期拉伸的构造转换期。毒砂δ34S值为-9‰^-3.9‰,平均值为-5.3‰,具有沉积硫的特征,推断硫来自地层,成矿流体为盆地建造水。由此认为金牙金矿是一个与盆地流体和沉积物有关的后生热液矿床。Jinya gold deposit,located in Fengshan county,is an important Carlin-type gold deposits in Guan-gxi.Arsenopyrite is one of major gold-bearing minerals in the deposit.The simple texture and hydrothermal ge-netic type that arsenopyrite would be more suitable for isotopic dating and tracing compared with the zoned py-rite.Re-Os isotopic dating and the S isotopic composition of arsenopyrite were undertaken,in order to better constrain the mineralization age and trace metallogenic material and ore-forming fluid.Re-Os isotopic analysis of arsenopyrite yielded isochronal ages of 206 ±22 Ma,indicating the metallogenic epoch of Jinya gold deposit is terminal later Triassic,consistent with the tectonic setting of the structural transition from collisional compression to extension tectonics.The δ34 S value of arsenopyrites ranges from-9‰ to-3.9‰,with the average value of-5.3‰.The sulfur isotopic composition with the sedimentary feature indicates that the sulfur originates from the strata,and ore-forming fluid comes from basin formation water.It can be inferred that Jinya gold deposit is an epigenetic hydrothermal deposit related with basin liquid and sedimentary.

关 键 词：毒砂 RE-OS 测年 硫同位素示踪 盆地流体 金牙金矿 广西 

分 类 号：P618.51[天文地球—矿床学]