摘要
东昆仑是我国西部重要的金、铜、铁、钴、镍多金属成矿带,其中,驼路沟钴(金)矿床是西北地区发现的首例大型独立钴矿床,目前关于该矿床中钴的成矿过程尚存在争议。在详细野外地质调查和岩(矿)相学观察的基础上,结合EPMA和EBSD分析,将驼路沟钴成矿过程划分为喷流沉积期和叠加改造期,喷流沉积期形成了细粒富钴黄铁矿(PyⅠ),叠加改造期包括细粒富钴黄铁矿(PyⅡ)+辉砷钴矿—辉砷镍矿+硫镍钴矿+磁黄铁矿+少量黄铜矿阶段和半自形—他形粗粒贫钴黄铁矿(PyⅢ)+自然金阶段。其中,PyⅠ中钴含量为0.03%~4.86%,PyⅡ中钴含量为0.38%~2.74%,PyⅢ中钴含量为0.03%~0.58%,流体耦合的溶解再沉淀机制是黄铁矿复杂环带的重要形成机制。上述矿物学研究表明:钴在驼路沟矿床中以独立矿物和富钴黄铁矿2种形式赋存,喷流沉积成矿作用和后期构造变形叠加改造作用是驼路沟矿床中钴富集成矿的2个重要过程。
The demand for cobalt metals has accelerated due to the increased use of cobalt in high-technology industries,thus the security supply of cobalt ore resources has attracted attention worldwide.Cobalt,as one of the critical metals,is in an acute shortage in China.The East Kunlun Orogen is a significant Au-Cu-Fe-Co-Ni-Pb-Zn polymetallic metallogenic belt in western China.The Tuolugou Co(Au)deposit has great reputation as the first large independent cobalt deposit discovered in the northwestern China,whereas the understanding of the metallogenic process of Co is controversial.By combining EPMA and EBSD analyses,together with the field investigation and detailed microscopic observation,the paper revealed the sedimentary exhalative mineralization and superimposed reworking process responsible for the formation of the Tuolugou deposit.The sedimentary exhalative mineralization formed the fine-grained pyrite(PyⅠ),and the superimposed reworking process consists of two mineralizing stages,i.e.,fine-grained pyrite(PyⅡ)+cobaltite+gersdorffite+siegenite+pyrrhotite+minor chalcopyrite stage and coarse-grained pyrite(PyⅢ)+native Au stage.The three generations of pyrite have different chemical compositions,of which PyⅠhas Co contents ranging from 0.03%to 4.86%,PyⅡranging from 0.38%to 2.74%and PyⅢranging from 0.03%to 0.58%.The obvious negative correlations of Co with Fe uncover that Co exists in the pyrite lattice by stoichiometric substitution of Fe.These results concluded that Co occurs as either independent minerals(e.g.,cobaltite,gersdorffite and siegenite)or cobaltiferous pyrite in the Tuolugou deposit.The EMPA mappings depict that pyrite has complicated textural and chemical compositions,which suggest that the composite pyrite grains were formed by fluid-mediated coupled dissolution-reprecipitation reactions according to the sharp contact boundaries,the distinct chemical compositions,and the consistent morphology and crystallographic orientation among different generations ofpyrite in EBSD inverse maps. In combination with the previous work,it is deduced that both the sedimentaryexhalative mineralization and subsequent reworking process contributed Co mineralization in the Tuolugoudeposit.This study provides a useful guide for the Co mineral exploration and efficient metallurgy in the easternKunlun Orogenic Belt.
作者
王智琳
张凯
许德如
邹少浩
王宇非
WANG Zhilin;ZHANG Kai;XU Deru;ZOU Shaohao;WANG Yufei(Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring,Ministry of Education,School of Geosciences and Info-Physics,Central South University,Changsha 410083,Hunan,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,Jiangxi,China)
出处
《黄金科学技术》
CSCD
2023年第2期175-189,共15页
Gold Science and Technology
基金
国家自然科学基金项目“湘东北地区钴铜多金属成矿作用研究”(编号:41672077)
湖南省自然科学基金项目“长沙—平江钴矿带钴的精细成矿过程与富集机制”(编号:2021JJ30817)联合资助。
关键词
钴
黄铁矿
辉砷钴矿
富集成矿
驼路沟矿床
东昆仑成矿带
cobalt
pyrite
cobaltite
enrichment and mineralization
Tuolugou deposit
east Kunlun Orogen
