金川铜镍硫化物矿床铂族元素地球化学特征及成矿作用研究

【作者】 苏昌学；

【导师】 燕永锋； 李石磊；

【作者基本信息】 昆明理工大学 ， 矿产普查与勘探， 2009， 硕士

【摘要】 金川矿床作为一个世界级超大型矿床,是我国最大的铂族元素生产基地,不仅是铜、镍、铂族等多种金属元素超常富集的产物,也是典型的地质条件和完整的成矿机制长期作用的结果。随着金川矿床勘探的不断深入,坑道及钻探揭露大量的地质信息,提供了大量新的矿床地质信息。随着成矿理论和测试技术的不断快速发展,为系统深入研究金川矿床铂族元素的富集机理及成矿作用奠定了基础。在成矿环境、成岩成矿时代、岩石特征方面,通过与全球硫化镍矿床的对比分析,认同金川矿床产出环境为地台边缘裂谷环境,具有地台区地质特征；根据K—Ar法和Sm-Nd法同位素测定,推测金川岩体形成于长城纪晚期；岩石化学、稀土元素特征,表明金川原始的含矿岩浆属于高镁质拉斑玄武岩浆。在前人总结提出的深部熔离一分期贯入的金川矿床成矿模式基础上,应用液态硫化物结晶分异理论,紧密联系岩浆成因、演化及地幔源区性质和构造环境；同时开展稀土元素、硫同位素、矿物流体包裹体成分和温度的测定,研究铂族元素赋存状态、矿物学特征、成矿地质条件：着重研究岩浆形成和演化过程中铂族元素结晶分异过程中的地球化学行为,探讨铂族元素的富集机制及成矿作用,建立铂族元素成矿模式。金川铂族元素成矿模式包括岩浆源特征、岩浆上侵动力、岩浆上侵方式、岩浆的深部熔离作用、同化作用、结晶分异作用、重力滞后作用等,导致在岩浆房中产生贫PGE+Au的含矿岩浆、含PGE+Au的含矿岩浆、富PGE+Au的富矿岩浆和硫化物残余岩浆的分层体系。经历了早期岩浆喷发、三期岩浆上侵定位,含矿岩浆上侵就位后就地熔离和聚集,以及后期的气化热液、热液叠加成矿作用和矿床的后期改造等,导致产生一个完整的、动态的成矿模式,形成复式超基性岩体和复式矿体,这就是深部熔离一脉动侵入一多次贯入成矿模式。正是这一个成矿模式致使在一个面积1.34km2的小岩体中,赋存了世界级的超大型矿床。正是这一成矿机制,可能是唯一能够使“小岩体成大矿”的机制。更多还原

【Abstract】 Jinchuan deposit, as a world-class super-large deposit, it is the largest production base of platinum group elements in China, not only copper, nickel, platinum group elements metals and other extraordinary metals’product of enrichment, it is also the long-term result of a typical geological conditions and complete ore-forming mechanism. With the continuous deepening of the Jinchuan deposit exploration, tunnel and drilling exposed a lot of geological information, Provided a large number of new deposit geological information. With the rapid development of ore-forming theory and testing techniques, which laid a solid foundation for systematic in-depth study of Jinchuan copper-nickel sulfide deposit platinum group elements’enrichment mechanism and mineralization.In terms of ore-forming environment, diagenetic ore-forming epoch, rock characteristics, by making a comparative analysis of global nickel sulfide deposit, they agreed with the Jinchuan deposit, output environment for platform marginal rift, with the geological features of the platform. According to K-Ar method and Sm-Nd isotopic method, Speculated that Jinchuan rock formed in the late changchengian, of which rock chemistry, rare earth elements’feature, showed that the original ore in Jinchuan is a high magnesian tholeiitic basaltic magma.On the basis of the jinchuan deposit metallogenic model of predecessors summarized and proposed, application of the theory of liquid sulfide fractionation, closely contacted with magmatic origin, evolution and mantle source region, property and the tectonic setting; at the same time, carry out the measurement of rare earth elements, sulfur isotope, Fluid fluid inclusion composition and temperature, research the occurrence of platinum group elements, mineralogical characteristics, ore-forming geological conditions, focused on the geochemical behavior of magma formation and evolution of which platinum-group elements crystallization differentiation,research enrichment mechanism and mineralization of platinum group elements.Jinchuan ore-forming model, including igneous rocks’characteristics, power on the magma intrusion, mode on the magma intrusion, molten magma from the role of the deep, assimilation, crystallization differentiation, gravity hysteresis, bring about magma chamber generate layered System which is poor PGE+Au ore magma, with PGE+Au ore magma, rich PGE+Au ore magma and residual magmatic sulfide. Experienced early magmatic eruption, three periods’location magma intrusion, ore magma’ invasion, liquation, aggregation, as well as the late hydrothermal gasification, superimposed hydrothermal mineralization and post-transformation etc. which lead to generate a complete, dynamic model of mineralization, formed double-ultrabasic rock and multiple orebody, this is metallogenic model of deep segregation-pulse invasive-repeated penetration. It is this leading to in a 1.34km2 small rock, ccurrenced the world-class super-large deposits. It is this ore-forming mechanism may be the only one to make "little rock becomes large ore" mechanism.更多还原