摘要
湘东北地区热液型钴多金属矿床赋存于长沙—平江断裂带下盘的构造热液蚀变岩带内,目前对带内钴的赋存形式及含钴矿物的认识并不充分,因此制约了对该带钴成矿机制的理解。详细的矿相学观察、TIMA和电子探针分析结果表明:黄铁矿是横洞矿区重要的含钴矿物,具有复杂的结构特征,表现为富钴黄铁矿呈环带状或不规则状交代核部贫钴黄铁矿,富钴黄铁矿Co含量高达3.52%,Ni含量低于0.09%,富钴黄铁矿的形成与流体耦合的溶解再沉淀机制有关。辉砷钴矿是金塘钴多金属矿区最主要的载钴矿物,呈他形粒状产出或被包裹在毒砂内,颗粒大小为3~45μm,Co含量为9.51%~23.21%,Ni含量为5.52%~15.24%。结合井冲矿区已有工作,提出在连云山地区从控矿断裂带南西到北东方向,含钴矿物存在由辉砷钴矿向黄铁矿转变,且辉砷钴矿中Co含量升高、Ni含量降低,而黄铁矿中Co含量降低,这一变化趋势可能与成矿流体的运移方向和物理化学条件(如pH值和硫逸度等)有关。结合湘东北地区钴(多金属)矿床(点)严格受长沙—平江断裂带控矿,提出连云山地区深大断裂的南西侧可作为今后湘东北钴矿勘查的重点方向。
A series of hydrothermal cobalt polymetallic deposits in northeastern Hunan Province occurr along the Changsha-Pingjiang fault zone,the middle section of the Jiangnan orogen belt.These deposits are hosted in the tectonic-hydrothermal alteration belt at the footwall of the Changsha-Pingjiang fault zone,and controlled by the fault zone and its secondary structures.However,the occurrence state of cobalt and cobalt-containing minerals in the whole belt isn’t sufficient,which restricts the understanding of the metallogenic process of cobalt in the belt.The detailed mineralogical observation,TIMA analysis and EPMA showed that the pyrite is the main sulfide and also an important cobalt-containing mineral in the Hengdong deposit.It exhibits a complex textural characteristics,that is,the cobalt-rich pyrite with silk-shaped,ring-shaped or irregularly at the edge replaced by the cobalt-poor pyrite at the core.The cobalt-rich pyrite has a clear oscillating zone exhibits high Co(up to 3.52%)but low Ni contents(≤0.09%).The complex zoning indicated that fluid-coupled dissolution and precipitation mechanism was responsible for the formation of Co-rich pyrite.In comparison,cobaltite ore is the most important cobalt-bearing mineral in the Jintang cobalt polymetallic deposit,which is closely related to pyrite,marcasite,and arsenopyrite,and occurs as an isolated granular form or wrapped in arsenopyrite particles.The particle size of cobaltite is between 3μm and 45μm.The contents of Co,Fe,and Ni of cobalt vary from 9.51%to 23.21%(average is 15.50%),4.33%to 17.66%(average is 9.46%),and 5.52%to 15.24%(average is 9.31%),respectively.Combied with the occurrence form of cobalt in the Jingchong cobalt-copper polymetallic deposit,it could be concluded that the cobalt-containing minerals vary from cobaltite to pyrite along the Changsha-Pingjiang fault zone from southwest to northeast.Furthermore,the Co contents in cobaltite increases tend to while Ni contents decreases,and the high content of Co in pyrite decreases.The mineralizing dis
作者
宁钧陶
黄宝亮
董国军
周岳强
高卓龙
康博
NING Juntao;HUANG Baoliang;DONG Guojun;ZHOU Yueqiang;GAO Zhuolong;KANG Bo(Hunan Institute of Geological Disaster Investigation and Monitoring,Changsha 410004,Hunan,China)
出处
《黄金科学技术》
CSCD
2023年第4期531-545,共15页
Gold Science and Technology
基金
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)
湖南省自然资源厅科技项目“湘东北钴矿成矿规律与找矿方向研究”(编号:2021-20)联合资助。
关键词
黄铁矿
辉砷钴矿
TIMA分析
热液型钴矿床
金塘矿区
横洞矿区
湘东北
pyrite
arsenopyrite cobalt ore
TIMA analysis
hydrothermal cobalt deposit
Jintang mining area
Hengdong mining area
northeastern Hunan
