黄铜矿微量元素对矿床成因类型的指示

金属矿物微量元素对矿床形成过程和成因类型具有重要指示作用，目前对黄铁矿、磁铁矿及闪锌矿研究较多，黄铜矿微量元素特征鲜有报道。根据收集的斑岩型铜矿床(PCD)、岩浆型铜镍硫化物矿床(MSD)、沉积岩型层状铜矿床(SSC)、铁氧化物铜金矿床(IOCG)、喷流沉积型矿床(SEDEX)及火山成因块状硫化物矿床(VMS)铜精矿样品，结合资料，对黄铜矿开展了详细矿相学和LA-ICP-MS微量元素研究，揭示黄铜矿微量元素特征及其与矿床成因类型的关系。黄铜矿中Mn，Co，Ni，Se，Ag，Sn，Pb及Bi质量分数可达1 000×10-6以上，Ga，Ge，Mo，Cd，In，Sb，Te，Au及Tl质量分数可达100×10-6以上，说明黄铜矿是很多微量元素的重要载体。黄铜矿Sb-Tl，In-Sn，Pb-Bi及Mn-Ni呈明显的正相关关系，其中Sb，Tl，In及Sn主要以固溶体的形式赋存于黄铜矿，Pb与Bi以方铅矿包裹体的形式赋存于黄铜矿，Mn，Co，As，Te，Ag及Ni 2种赋存状态均有发育。PCD型和VMS型黄铜矿微量元素变化大，MSD型黄铜矿中Ni质量分数高，In质量分数较低，SSC型黄铜矿Ge质量分数高，Sn质量分数较低。Se在MSD型和VMS型黄铜矿中质量分数较高，在SEDEX型和SSC型黄铜矿中质量分数较低。Ni，In，Sn元素差异主要与不同类型岩浆作用有关，Se元素质量分数差异主要受温度控制，SSC型黄铜矿Ge元素质量分数高可能与成矿温度和赋矿围岩有关。因此，基于上述微量元素特征，Ni-Co和Ni-In图解可区分MSD型和其他类型，Ni-Se图解可区分SEDEX型，SSC型及VMS型，Ge-Sn图解可进一步区分SSC型和SEDEX型，Co/Ni-Ag/Bi图解可区分MSD型和PCD型，Zn-Sn/In在一定程度上可区分IOCG型和其他类型。这些首次系统地提出的图解将为判别矿床成因类型提供新的参考。 

Genesis type of ore deposits indicated by trace elements of chalcopyrite

Trace elements of metallic minerals are important to constrain the formation processes and genetic types of ore deposits. Trace elements have been mainly focused on pyrite, magnetite, and sphalerite but have rarely been applied to chalcopyrite. To reveal the relationships between chalcopyrite trace elements and ore deposit types, ore petrography and LA-ICP-MS trace element of chalcopyrite in collected copper concentrate samples from porphyry copper deposits (PCD), magmatic copper-nickel sulfide deposits (MSD), sedimentary rock-hosted stratiform copperdeposits (SSC), iron oxide copper-gold deposits (IOCG), sedimentary exhalative deposits (SEDEX) and volcanogenic massive sulfide deposits (VMS) have been carried out. In chalcopyrite, Mn, Co, Ni, Se, Ag, Sn, Pb, and Bi contents are more than 1 000×10-6, and Ga, Ge, Mo, Cd, In, Sb, Te, Au and Tl contents are up to 100×10-6, which together indicate chalcopyrite is an important carrier for many trace elements. Antimony-Tl, In-Sn, Pb-Bi, and Mn-Ni in the chalcopyrite are positively correlated.Meanwhile, in chalcopyrite, Sb, Tl, In, and Sn mainly occur in the form of solid solution, Pb and Bi in the form of galena inclusions, and Mn, Co, As, Te, Ag, and Ni are both developed. Trace elements of chalcopyrite from PCD and VMS are variable. The concentrations of Ni and In in chalcopyrite from MSD are high and low, and Ge and Sn from SSC are higher and lower than other types, respectively. Moreover, the concentration of Se in chalcopyrite is higher from MSD and VMS, but is lower from SEDEX and SSC. Different concentrations of Ni, In, and Sn in the chalcopyrite are mainly related to different magmatism, and Se is principally controlled by temperature. The high concentrations of Ge in chalcopyrite from SSC may be related to ore-forming temperature and host rocks.Therefore, based on the above trace elements characteristics, Ni-Co and Ni-In diagrams can distinguish MSD from other deposit types, the diagram of Ni-Se can differentiate SEDEX, SSC from VMS, and the diagram of Ge-Sn is used to isolate SSC from SEDEX. In addition, the diagram of Co/Ni-Ag/Bi can differentiate between MSD and PCD, while Zn-Sn/In can discriminate IOCG from others to some extent.These first systematically proposed diagrams will provide a new reference for distinguishing the genetic types of deposits.