东昆仑浪木日铜多金属矿床成矿特征及找矿启示

Metallogenic Characteristics of Langmuri Copper Polymetallic Deposit in East Kunlun and Its Ore Prospecting Enlightenment

位于东昆仑造山带东段的浪木日铜镍钴多金属矿床,在新近勘查工作中又圈出独立的铂矿体,对该矿床成矿特征的进一步研究有助于指导勘查找矿.通过矿床地质特征分析,结合含矿橄辉岩主微量元素、Sr‐Nd同位素及其中橄榄石、云母主量元素测试,以及黑云母花岗岩锆石U‐Pb年代学及岩石地球化学特征研究,探讨了浪木日矿床成矿特征、成矿时代及矿床成因.含矿橄辉岩中橄榄石属贵橄榄石(Fo值为86.72~88.39),云母为金云母,其均为幔源岩浆作用产物;含矿橄辉岩稀土元素具右倾型的配分模式,富集Cs、Rb、U等元素,ε_(Nd)(t)值为0.66~2.66,暗示其形成过程中经历了地壳混染.获得黑云母花岗岩U-Pb年龄为414.5±8.8 Ma,其具弧岩浆地球化学特征,(87Sr/86Sr)i(0.718609~0.719177)、ε_(Nd)(t)值(1.28~5.36)显示其为壳幔岩浆混合作用产物.本研究认为浪木日铜多金属矿床具叠加成矿特征,在450~439 Ma形成与橄辉岩有关的铜镍钴铂钯矿体的基础上,叠加了415 Ma的与黑云母花岗岩有关的热液脉型铜矿化;本矿床以早期与橄辉岩有关的硫化物成矿为主,岩浆演化过程中的地壳混染及岩浆期后热液活动对成矿具积极贡献.本矿区基性-超基性杂岩体底部及顶部、黑云母花岗岩与之接触部位均为有利找矿空间.

The Langmuri Cu-Ni-Co polymetallic deposit,located in the eastern segment of the eastern Kunlun orogenic belt,has recently delineated an independent platinum group element orebody.Further study on the metallogenic characteristics of the deposit is helpful to guide the further exploration work.Based on the analysis of the geological characteristics of the deposit,combined the analysis of the major and trace elements,Sr-Nd isotopes of the ore-bearing olivine pyroxenolite and the electronprobe microanalysis of major elements in olivine and mica from the ore-bearing olivine pyroxenolite,as well as the zircon U-Pb chronology and geochemistry of the biotite granite,In this paper it discusses the metallogenic characteristics,metallogenic age and genesis of the Langmuri deposit.Olivine in ore-bearing olivine pyroxenolite belongs to chrysolite series(Fo value is^(86).72-88.39),and mica is phlogopite,which are all products of mantle-derived magmatism.The geochemical characters of the orebearing olivine pyroxene show a right-dipping REE distribution patterns,enriched with LILE elements such as Cs,Rb,U,etc.,and with positiveε_(Nd)(t)values of 0.66-2.66,suggest that the parent magma of olivine pyroxene experienced crustal contamination during its formation.The age of biotite granite is 414.5±8.8 Ma,which shows the geochemical characteristics of arc magma.(^(87)Sr/^(86)Sr)i(0.718609-0.719177)andε_(Nd)(t)values(1.28-5.36)show that the biotite granite is the product of crust-mantle magma mixing.In this paper it proposes that Langmuri copper-polymetallic deposit underwent multi-period of superimposed mineralization.The Cu-Ni-Co-Pt-Pd sulfide orebodies hosted in olivine pyroxenolite were formed at 450-439 Ma,and the hydrothermal vein-type copper mineralization related to biotite granite with 415 Ma was superimposed upon it.The deposit is dominated by early sulfide mineralization related to olivine pyroxene.Crustal contamination in the process of magmatic evolution and post-magmatic hydrothermal activities have important contributions to mineralization.The bottom and top of the basicultrabasic complex in Langmuri mining area and the contact zone between biotite granite and it are all favorable prospecting areas.