云南兰坪-思茅盆地新发现中排富钴矿点中钴的富集特征及其地质意义  

Cobalt enrichment characteristics and geological significance of the new discovered Zhongpai Co-rich mineralization occurrence in the Lanping-Simao Basin,Yunnan Province,China

作　　者：李丽清 周家喜 杨昌华 姜永果 沈良 陶永林 罗开 LI LiQing;ZHOU JiaXi;YANG ChangHua;JIANG YongGuo;SHEN Liang;TAO YongLin;LUO Kai(Key Laboratory of Critical Minerals Metallogeny in Universities of Yunnan Province,School of Earth Sciences,Yunnan University,Kunming 650500,China;Key Laboratory of Sanjiang Metallogeny and Resources Exploration&Utilization,MNR,Yunnan University,Kunming 650500,China;Institute of Geology,Geophysics and Geochemistry Exploration,Yunnan Nonferrous Geological Bureau,Kunming 650051,China)

机构地区：[1]云南大学地球科学学院,云南省高校关键矿产成矿学重点实验室,昆明650500 [2]自然资源部三江成矿作用及资源勘查利用重点实验室,昆明650500 [3]云南省有色地质局地质地球物理化学勘查院,昆明650051

出　　处：《岩石学报》2025年第2期510-525,共16页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(U2444206);云南省重大科技专项计划项目(202402AB080006);云南省新一轮找矿突破战略行动暨地质勘查基金项目(Y202403);云南大学科研启动项目(YJRC4201804);云南大学关键金属成矿与找矿预测创新团队(2021-3);云南省关键金属成矿与找矿预测硕士生导师团队(2023-5);云南省教育厅科学研究基金项目(2023Y0189)联合资助.

摘　　要：云南兰坪-思茅盆地已发现如水泄、厂街、白秧坪、金满等富钴矿床/点,且钴异常广泛发育,具有较大的钴找矿潜力。本次工作在兰坪-思茅盆地新发现中排钴超常富集矿点,初步研究显示矿石钴平均品位达到0.46%,但钴的赋存状态和富集规律尚不清晰。本文通过详细的野外地质调查,结合黄铁矿的EMPA、LA-ICPMS微量元素和Mapping分析,试图查明该富钴矿点中钴的富集特征。富钴矿点含矿地层为中侏罗统花开佐组(J_(2)h),赋矿围岩为泥岩、砂岩夹泥灰岩,矿体呈层状、似层状、透镜状,受构造控制。矿石矿物主要为黄铁矿,其次是黄铜矿等硫化物,脉石矿物有石英、白云石、方解石、沥青等。按矿物共生组合和生成顺序,将成矿期划分为黄铁矿-石英-沥青(Ⅰ)、黄铁矿-黄铜矿-(砷)黝铜矿-毒砂(Ⅱ)和黄铁矿-白云石-方解石-石英(Ⅲ)三个阶段。电子探针分析结果表明,Co主要富集在黄铁矿中(平均0.584%),含量远高于黄铜矿(平均0.003%)和(砷)黝铜矿(平均0.009%)。黄铁矿LA-ICPMS原位微量分析结果显示,Co含量变化范围为3.24×10^(-6)~76766×10^(-6),平均14941×10^(-6)。与石英、沥青共生的Ⅰ期黄铁矿中Co含量为3207×10^(-6)~76766×10^(-6),远高于其他期次黄铁矿,显示Co的超常富集。LA-ICPMS时间分辨率深度剖面图和电子探针面扫结果进一步显示,黄铁矿中Co元素在亚微米尺度上均匀分布,暗示Co主要以类质同象替代Fe进入黄铁矿晶格。第一阶段黄铁矿(Py1)中的Co/Ni比值和Se含量高于第二(Py2)和第三阶段(Py3)黄铁矿,As含量则变化趋势相反,暗示富钴黄铁矿较贫钴黄铁矿形成于更高温度和更低的pH条件。综上,本文认为中排富钴矿点中钴具有时空分布不均一特征,钴的超常富集与特殊的流体成分和成矿物理化学条件有关,兰坪-思茅盆地具有良好的钴找矿前景。There are several cobalt(Co)deposits have been found in the Lanping-Simao Basin,western Yunnan Province,China,such as Shuixie,Changjie,Baiyangping,and Jinman,together with widely developed Co geochemical anomalies,indicating significant cobalt exploration potential in this basin.This study focusses on the newly discovered Zhongpai Co super-enriching occurrence in the Lanping-Simao Basin.Preliminary research shows that the average Co ore grade reaches 0.46%,but the occurrence and enrichment of Co are still unclear.This study attempts to identify the enrichment characteristics of Co through detailed field geological investigation,combined with EMPA,and LA-ICPMS trace elements and Mapping analyses.The Co-rich occurrence is hosted by mudstone and sandstone intercalated with limestone of the Middle Jurassic Huakaizuo Formation.The ore body shows stratiform,stratiform-like,or lens-like shapes,and is controlled by the structures.The primary ore mineral is pyrite,followed by sulfides such as chalcopyrite.Gangue minerals include quartz,dolomite,calcite,and bitumen.According to the mineral assemblage relationship and generation sequence,the mineralization period can be divided into three stages:pyrite-quartz-bitumen(Ⅰ),pyrite-chalcopyrite-tetrahedrite-arsenopyrite(Ⅱ),and pyrite-dolomite-calcite-quartz(Ⅲ).EMPA results indicate that Co is mainly enriched in pyrite(mean 0.584%),much higher than in chalcopyrite(mean 0.003%)and in tetrahedrite(mean 0.009%).LA-ICPMS trace elements analysis of pyrite shows that Co contents range from 3207×10^(-6) to 76766×10^(-6),average 14941×10^(-6).The Co contents in Py1 coexisting with quartz and asphalt are 3.24×10^(-6)~76766×10^(-6),much higher than those in Py2 and Py3.LA-ICPMS time-resolved depth profiles and EMPA maps indicate a homogeneous Co in pyrite on the sub-micron scale,suggesting that Co mainly replace Fe in the pyrite lattice.The Co/Ni ratios and Se contents in Py1 are higher than those of Py2 and Py3,despite of opposite trend for the variation of As contents.This ind

关 键 词：钴 赋存状态 富集规律 黄铁矿 兰坪-思茅盆地 

分 类 号：P575.1[天文地球—矿物学] P612[天文地球—地质学] P618.62