滇西南墨江金厂金镍矿床金、镍赋存状态及成矿过程探讨  

Metallogenic process in Jinchang gold-nickel deposit,Mojiang County,SW Yunnan,China: Constraints from occurrence of gold and nickel

作　　者：熊伊曲 杨立强[2] 邵拥军[1] 赵凯[2] 李坡[2] 卢宜冠 杜达洋 

机构地区：[1]中南大学有色金属成矿预测与地质环境监测教育部重点实验室,长沙410083 [2]中国地质大学地质过程与矿产资源国家重点实验室,北京100083

出　　处：《岩石学报》2015年第11期3309-3330,共22页Acta Petrologica Sinica

基　　金：国家重点基础研究发展规划(2015CB452605);高等学校学科创新引智计划(B07011);中国地质调查局地质调查项目(12120114013501);中南大学"创新驱动计划"项目(2015CX008)联合资助

摘　　要：墨江金厂金镍矿床位于滇西南哀牢山造山带中段,是西南三江地区一个独特的金镍共生矿床。笔者通过野外地矿物主要为针镍矿、辉砷镍矿、锑硫镍矿、黄铁矿等。依据矿（化）脉切割关系、矿石结构构造及矿物共生组合,墨江金厂金镍矿床成岩-成矿期共发育4个世代黄铁矿。沉积变质期以草莓状黄铁矿和胶状黄铁矿为主,热液成矿期可划分为：早阶段石英-针镍矿-辉砷镍矿-锑硫镍矿-黄铁矿;主阶段石英-黄铁矿-毒砂-硫锑铜银矿-自然金;晚阶段方解石-石英-黄铁矿。对矿区赋金镍贯通性矿物黄铁矿进行详细的电子探针分析,结果显示4个世代黄铁矿微量元素有所差异。其中热液主阶段黄铁矿中含有Au、As、Sb、Pb、Zn、Cu、Co、Ni和Te,显示其流体成分复杂。不同阶段黄铁矿Ni含量不同,沉积变质期黄铁矿中Ni含量较低,为0.00%~0.82%,平均0.26%;热液早阶段黄铁矿中Ni含量最高,为0.43%~3.15%,平均1.38%;热液主阶段黄铁矿中Ni含量降低,为0.00%~0.99%,平均0.22%;热液晚阶段黄铁矿中Ni含量最低,为0.00%~0.09%,平均0.03%。研究结果表明墨江金厂金镍矿床中主要含金矿物和含镍矿物形成于热液期,含金矿物形成晚于含镍矿物。Ni在热液流体中的迁移能力与流体温度正相关,温度越高,Ni进入黄铁矿晶格的能力越强。基于上述金、镍成矿过程研究成果,并对比国内外热液镍矿床的地质-地球化学特征,推断墨江金厂金镍矿床是一个受岩浆热液改造的中-低温热液金镍矿床。The Jinchang gold-nickel deposit is an unique gold-nickel paragenetic deposit,located in the middle section of the Ailaoshan orogenic belt,southwestern Yunnan Province,China. The ore petrography,gold and nickel mineralogy and minerals chemistry were studied based on detail field work,petrography and electron probe micro-analyzer（ EPMA） research. The results show that there are two occurrences of gold in this deposit： visible gold and invisible gold. Furthermore,visible gold could be subdivided two occurrences：（ 1） intergranular gold,hosted between the quartz particles as native gold; and（ 2） inclusion gold,enclosed by polybasite. Invisible gold is mainly hosted in the lattice of pyrites as Au＋. The native gold,pyrite and arsenopyrite are the main goldbearing minerals. There are two occurrences of nickel：（ 1） independent minerals,such as millerite,gersdorffite and ullmannite; and（ 2） hosted in lattice of pyrite and arsenopyrite as ionic form. The millerite,gersdorffite,ullmannite and pyrite are the main nickelbearing minerals. Four generations of pyrite have been identified in diagenetic-metallogenic process,based on the crosscutting relationships of different auriferous veins,ore textures,and mineral paragenesis. The sedimentary-metamorphic episode is mainly characterized by framboidal pyrite and colloid pyrite,and hydrothermal gold-nickel mineralization episode could be further subdivided into three stages： with a quartz-millerite-gersdorffite-ullmannite-pyrite assemblage at the early stage; quartz-pyrite-polybasite-native gold at the main stage; calcite-quartz-pyrite at the late stage. According to the results of EPMA,the content of trace elements is different in four generations of pyrite. The pyrite of the main stage is enriched in Au,As,Sb,Pb,Zn,Cu,Co,Ni and Te,which indicates the complexity of the ore-forming fluid. Nickel contents are also variable in different mineralization episodes and stages. The pyrite of sedimentary-metamorphic episode contains low Ni（ 0. 00% ~ 0. 82%,

关 键 词：金镍矿物 微量元素 成矿过程 墨江金厂 滇西南 

分 类 号：P595[天文地球—地球化学] P618.51[天文地球—地质学]