摘要
喜集钴金矿床是西秦岭造山带南带首次发现的新型钴金矿床,由于其发现时间短,勘探与研究程度低,对矿床成因与流体来源的认识还有待加强。在野外地质调查、室内岩相学研究及Nano-SIMS微量元素扫描的基础上,利用LA-ICP-MS原位微区分析与成矿有关硫化物的微量元素特征,结合原位S同位素分析成矿流体来源,为进一步了解矿床成因提供制约。黄铁矿可划分为3种类型:PyⅠ产在沉积期,主要为自形—半自形结构,部分呈脉状分布,几乎不含As、Co,w(Co)/w(Ni)值远小于1,显示沉积成因;PyⅡ产在石英-黄铁矿阶段,主要呈环带状产出,Co质量分数很高,w(Co)/w(Ni)值为0.94~2.21,显示沉积改造-岩浆成因;PyⅢ产于石英-黄铁矿-毒砂阶段,As质量分数很高,Co质量分数较PyⅡ大幅下降,w(Co)/w(Ni)值大于1,显示岩浆成因。含钴环带状黄铁矿边部向核部δ34 S值逐渐升高,δ34 S值呈现出较高的离散程度,表明S来源较为复杂。Co元素异常位于环带状黄铁矿边缘部位,S来源为深部岩浆硫和地层硫的混合流体。综合野外地质特征、室内岩相学研究、硫化物原位微区微量元素及S同位素分析,认为喜集钴金矿床为沉积-热液叠加改造型矿床。
Xiji Cobalt-Gold Deposit is a new type of cobalt-gold deposit discovered for the first time in the south of West Qinling orogenic belt.Due to its short discovery time and low degree of exploration and research,the genesis and fluid source of the deposit need to be further understood.On the basis of field geological survey,indoor petrographic study and Nano-SIMS trace element surface scanning,LA-ICP-MS in-situ micro area analysis is used to analyze the trace element characteristics of sulfide minerals related to mineralization,the results of which,combined with in-situ sulfur isotope analysis of ore-forming fluid source,provide constraints for further understanding the genesis of the deposit.The pyrite can be divided into three types:PyI occurs in the sedimentary period,mainly in the form of euhedral and hypidiomorphic structure,partly in vein distribution,almost has no As,Co,and w(Co)/w(Ni)is far less than 1,indicating sedimentary genesis;PyⅡoccurs in quartz-pyrite stage,mainly in annular belt,with high Co content,with w(Co)/w(Ni)between 0.94 and 2.21,indicating sedimentary transformation magmatic origin;PyⅢmainly occurs in quartz-pyrite-arsenopyrite stage,the content of As is very high,and the content of Co is much lower than that of PyⅡ,and the w(Co)/w(Ni)is greater than 1,indicating magmatic origin.The value ofδ34 S increases gradually from the edge to the core of the cobalt-bearing annular pyrite,and theδ34 S value shows a high degree of dispersion,indicating that the source of S is complex.The anomaly of Co element is located at the edge of zonal pyrite,and the source of S is the mixed fluid of deep magmatic rock and formation sulfur.Based on the field geological characteristics,laboratory petrography,in-situ trace sulfide and sulfur isotope analysis,this paper considers that the Xiji Cobalt-Gold Deposit is a sedimentary-hydrothermal fluid superimposition altered deposit.
作者
王旺
贾文彬
杨言辰
李永胜
公凡影
Wang Wang;Jia Wenbin;Yang Yanchen;Li Yongsheng;Gong Fanying(College of Earth Sciences,Jilin University;Development Research Center of China Geological Survey)
出处
《黄金》
CAS
2020年第12期14-22,共9页
Gold
基金
中国地质调查局发展研究中心项目(DD20190159)。
关键词
硫化物成分特征
原位硫同位素
原位微区微量元素分析
矿床成因
喜集钴金矿床
sulfide composition characteristics
in-situ sulfur isotope
in-situ micro area trace element analysis
deposit genesis
Xiji Cobalt-Gold Deposit
