辽-吉古元古代造山带杉松岗钴镍铜矿床Ni-Co超常富集成矿过程初探  

The processes of ultra-enrichment and mineralization of the Ni-Co in the Shansonggang Co-Ni-Cu deposit from the Liao-Ji Paleoproterozoic orogenic belt

作　　者：王慧宁 刘福来[1] 王舫[1] 田忠华[1] 刘冰[2] WANG HuiNing;LIU FuLai;WANG Fang;TIAN ZhongHua;LIU Bing(Laboratory of Deep Earth Dynamics of MNR,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Liaoning Province Seventh Geological Brigade Co.,Ltd.,Dandong 118003,China)

机构地区：[1]自然资源部深地动力学重点实验室,中国地质科学院地质研究所,北京100037 [2]辽宁省第七地质大队有限责任公司,丹东118003

出　　处：《岩石学报》2024年第10期2971-2987,共17页Acta Petrologica Sinica

基　　金：国家重点研发计划项目(2022YFC2903502);国家自然科学基金重点支持项目(92062214);国家自然科学基金项目(41890833);第九届青托工程项目(2023QNRC001);中国地质科院基本科研业务费-重点攻关项目(JB2304);中国地质调查项目(DD20242528)联合资助.

摘　　要：镍和钴是我国紧缺关键金属矿产,对国民经济和社会发展具有重要战略意义。我国现有镍、钴资源储量匮乏,对外依存度极高。因此,立足国内,加强镍-钴成矿规律研究与找矿战略行动迫在眉睫。吉林省临江市杉松岗变沉积岩容矿型钴镍铜矿床位于辽-吉古元古代造山带东北段。有关该矿床Ni-Co的赋存状态、富集成矿期次与成矿规律等研究十分薄弱。本文通过对杉松岗钴镍铜矿床Ni-Co矿石和赋矿围岩开展显微结构观察、扫描电镜-能谱分析、矿物原位硫同位素分析和电子探针测试等系统研究,发现该矿床Ni-Co的富集成矿经历了多期多阶段复杂的变质变形和热液作用的叠加改造过程。其中,变质变形阶段以辉砷钴矿和黄铜矿等呈微细粒包体赋存于变质矿物中为特点;而热液阶段又可分为早期和晚期。早期热液作用以大量镍钴矿物(辉砷钴矿、硫镍矿和镍黄铁矿)伴生滑石化、白云石化和硅化蚀变为标志,为Ni-Co超常富集成矿的主成矿期,其硫化物的硫同位素分布范围集中(10.92‰~13.67‰),且与珍珠门组白云石大理岩内硫化物的δ^(34) S值接近,推断Ni、Co主要来自深部岩浆热液,即含矿流体向上迁移过程中强烈淋滤并萃取珍珠门组地层内的硫,最终在大栗子组地层发生硫化物沉淀并富集成矿。晚期热液作用主要沉淀铜铁硫化物(黄铜矿、磁黄铁矿和黄铁矿)和极少量钴镍黄铁矿、硫镍钴矿和镍黄铁矿,伴生方解石化、硅化和绿泥石化蚀变,硫化物的δ^(34) S值(6.53‰~8.59‰)与侏罗纪花岗岩体及同期的金等多金属硫化物矿床的硫同位素组成一致,表明晚期岩浆热液可能与古太平洋俯冲事件有关。杉松岗钴镍铜矿床Ni主要以硫镍矿和镍黄铁矿的形式赋存,次为钴镍黄铁矿和硫镍钴矿。Co主要以辉砷钴矿形式赋存,次为硫镍矿、镍黄铁矿、钴镍黄铁矿和硫镍钴矿。有关该矿未来Ni-The nickel and cobalt are critical scarce metal minerals with strategic significance on the national economy and social development in China,however,these two resources are very limited in China and are highly depended on import.In this case,it is necessary to strengthen the study on the metallogenetic regularity of the nickel and cobalt and ore prospection strategic action interiorly.The Shansonggang Co-Ni-Cu Deposit(SCNCD)from Linjiang City,Jilin Province is located at the northeastern part of the Liao-Ji Paleoproterozoic orogenic belt,and it is a typical metasedimentary rock-hosted stratabound-controlled Co-Ni-Cu deposit.However,the occurrence of Ni-Co,the enrichment and metallogenic sequences and regularity of Ni-Co in this deposit are poorly studied.Here,the Ni-Co ores and host rocks from the deposit were selected for an integrated study involving microstructure observations,scanning electron microscope(SEM)-energy spectrum analysis,in-situ S isotopic analysis and electron probe microanalysis of minerals.We proposed that the SCNCD underwent multiple stages of metamorphism and hydrothermal alterations.The metamorphic stage is characterized by the occurrence of cobaltite and chalcopyrite that formed as inclusions within metamorphic minerals.The hydrothermal stage can be divided into two phases:(1)The precipitation of abundant Ni-Co minerals(cobaltite,polydymite and pentlandite)along with tallitization,dolomitization and silicification marks the early-stage hydrotherm,which represents the main metallogenic epoch of the Ni-Co.The Ni-Co minerals exhibit homogeneous S isotope values(10.92‰~13.67‰)that are in line with those of sedimentary strata from the Zhenzhumen Formation.Ni and Co were suggested to be extracted from the deep magmatic hydrotherm.The S from the Zhenzhumen Formation was largely extracted by the upmigrating ore-bearing fluid,which finally resulted to the precipitation and enrichment of Ni-Co minerals in the Dalizi Formation.(2)The late-stage hydrotherm is marked by the precipitation of Cu-Fe s

关 键 词：杉松岗钴镍铜矿床 Ni-Co的赋存状态 变质-热液作用 蚀变类型 找矿标志 

分 类 号：P597.2[天文地球—地球化学] P618.62[天文地球—地质学] P618.63