新疆西天山萨瓦亚尔顿金成矿过程:来自硫化物矿物世代及其EMPA、LA-ICP-MS和FESEM分析的约束  

The ore-forming process of the Sawayaerdun gold deposit,western Tianshan,Xinjiang:Contraints from the generation relationship and EMPA,LA-ICP-MS and FESEM analysis of the Pyrite and Arsenopyrite

作　　者：张国震 薛春纪[3] 刘家瑛[3] 赵晓波[3] 冯昌荣 孟宝东 ZHANG Guozhen;XUE Chunji;LIU Jiaying;ZHAO Xiaobo;FENG Changrong;MENG Baodong(Tianjin Center,China Geological Survey(CGS),Tianjin 300170,China;North China Center for Geoscience Innovation,Tianjin 300170,China;State Key Laboratory of Geological Processes and Mineral Resources,School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;Geological Team No.2,Xinjiang Bureau of Geology and Mineral Resources,Kashi 844000,Xinjiang,China)

机构地区：[1]中国地质调查局天津地质调查中心,天津300170 [2]华北地质科技创新中心,天津300170 [3]地质过程与矿产资源国家重点实验室,中国地质大学地球科学与资源学院,北京100083 [4]新疆地质矿产局第二地质大队,新疆喀什844000

出　　处：《中国地质》2022年第1期16-35,共20页Geology in China

基　　金：中国地质调查局项目(DD20211339、DD20190038);国家自然科学基金(U1303292)联合资助。

摘　　要：【研究目的】为确定硫化物中金的赋存状态及元素含量特征。【研究方法】本文选取西天山萨瓦亚尔顿造山型金矿床(探明金储量127 t,远景资源量350 t),针对矿石矿物黄铁矿、毒砂开展系统显微岩/矿相学观测、电子探针、LAICP-MS和扫描电镜分析。【研究结果】结果表明萨瓦亚尔顿矿石中除可见金外,还有“不可见金”主要以固溶体(Au+)形式赋存于黄铁矿、毒砂中。矿石中载金黄铁矿发育3期:球丛状黄铁矿(Py0)呈浸染状分布于围岩中,局部富含金,同时富集Ag、As、Bi、Ni、Cu、Pb、Sb等微量元素;他形黄铁矿(Py1),分布于硅化围岩及强烈变形石英脉中,与他形毒砂(Apy1)伴生,电子探针得到的平均金含量为0.050%,富集Co、Mn、Zn等微量元素;自形—半自形黄铁矿(Py2),在矿体中分布最为广泛,与未变形石英脉密切共生,伴生自形毒砂(Apy2),电子探针分析得到的平均金含量为0.052%,微量元素相对Py1、Py2较为亏损。【结论】推测Py0形成于沉积成岩期;Py1形成于同碰撞期,与塔里木板块与中天山地块在晚石炭世碰撞事件有关;Py2形成于晚/后碰撞阶段。赋矿地层可能是金的初始矿源层,同时提供了部分微量元素,地层变质脱水作用形成的变质流体是主要的成矿流体。研究表明萨瓦亚尔顿金矿发育多期成矿作用,相似成矿过程在西天山同类型矿床中可能也有发生。This paper is the result of mineral exploration engineering.[Objective]To determine the occurrence of Au and elements feature of the sulfide.[Methods]The Sawayaerdun orogenic gold deposit(explored Au:127 t,prospective Au:350 t)in the western Tianshan is chosen and the microscopic petrography study,EMPA,LA-ICP-MS and FESEM analysis have been applied.[Results]Except for“visible gold”,the result indicate that“invisible gold”is likely present as solid soluation(Au+)in the pyrite and arsenopyrite in the Sawayaerdun deposit.Three generations of auriferous pyrite have been recognized.The pyrite with framboidal texture(Py0)are disseminated in the host rock,and are locally enriched in gold.They have relatively high values of Ag、As、Bi、Ni、Cu、Pb、Sb.The anhedral pyrite(Py1),associated with silicified rocks and quartz veins that experienced strong deformation,have an average Au content of 0.050%.They have high contents of Co、Mn、Zn.The euhedral-subhedral pyrite(Py2)are best developed in the main orebodies,and have an average Au content of 0.052%.Comparing to Py1,Py2,they have lower contents of trace elements.[Conclusions]The Py0 are interpreted to have formed contemporaneously with the ore-bearing rocks.Py1 are interpreted to have formed in the syn-tectonic stage,during the collision between the Tarim craton and the Central Tianshan terrane in the Late Carboniferous,whereas Py2 were formed in a later mineralization event,during the late-to post-tectonic stage in the Early Permian.Ore-bearing strata could be the initial source bed of gold,meantime provides the trace elements when forming gold-bearing sulfides.The ore-forming fluids were probably metamorphic fluids deriving from dehydration of the sedimentary strata.The study results suggest that multi-stage of gold mineralization have developed in the Sawayaerdun deposit,similar metallogenic process may exist in other homogeneous deposits in theWestern Tianshan Orogen.

关 键 词：造山型金矿 黄铁矿 微量元素 矿产勘查工程 萨瓦亚尔顿 西天山 

分 类 号：P618.51[天文地球—矿床学]