【作者】 王瑞廷；

【导师】 赫英；

【作者基本信息】 西北大学 ， 地球化学， 2002， 博士

【摘要】 我国西北地区有着丰富的镍、钴、铜等金属的矿产资源，尤其是甘肃省金川超大型铜镍硫化物岩浆矿床，以其超大规模及其典型的成矿特征而闻名于世，是我国重要的镍、铜金属矿产基地，而相比之下，陕西省煎茶岭大型镍(钴)矿床规模较小且未开采，但因其独特的地质背景和成矿特征而具有重要的研究意义。本次工作依据比较矿床学的研究思路，在重点剖析煎茶岭镍矿床成矿地质、地球化学特征的基础上，采用新的分析测试技术手段，对这两个岩浆硫化镍矿床从成矿地质背景、岩体及矿床地质特征、地球化学及成矿作用年代学等角度进行系统分析、比较和研究，找出二者的共同性和差异性，进一步更深刻地认识其成因并探讨该类矿床形成与分布的规律性以指导找矿。 通过对煎茶岭和金川镍矿床地质、地球化学的系统分析与比较研究，取得以下新的认识和进展： (1)Re—Os同位素地质年代学研究表明，煎茶岭硫化镍矿床形成于～878Ma前的新元古代，成矿作用和成岩作用基本上是同时进行的，属岩浆矿床。并佐证了煎茶岭岩体确为新元古代形成的超基性岩体。 (2)通过铂族元素地球化学研究，比较论证了金川超大型镍铜硫化物矿床的多次成岩成矿作用。而与赋存超大型镍铜硫化物矿床的金川岩体相比，煎茶岭超基性岩体为岩浆一次侵位形成，分异程度小，镍、硫含量较低。 (3)证实煎茶岭超基性岩体为含铁的镁质超基性单式岩体，空间上与扬子地块关系密切，形成于新元古代由元古宙活动带向显生宙造山带过渡时期。与之有关的煎茶岭镍矿床成因上属岩浆矿床，其成矿作用有岩浆分结作用、硫化作用、岩浆熔离作用及热液作用等，但岩浆熔离成矿作用不发育，热液作用仅占次要地位，富硫围岩的同化混染对矿床的形成有特殊的意义。 (4)比较研究表明，不同地质环境产出的不同类型超基性—基性岩及其不同的侵入机制可以导致形成不同类型的镍矿床。与煎茶岭镍矿床相比，金川超大型镍铜硫化物矿床主要与多次侵入的镁铁—超镁铁质杂岩有关，空间上与时代相对较老的华北地块关系密切，形成于中—新元古代的边缘裂谷。其成矿作用有岩浆分结作用、硫化作用、岩浆熔离作用及热液作用等，以岩浆熔离成矿作用为主，热液作用亦仅占次要地位。金川和煎茶岭镍矿床的成岩成矿物质均主要源于地幔，但后者更为亏损；二者中均有地壳物质的混入，但前者混染较弱且主要为深部混染。 (5)通过对煎茶岭和金川镍矿床的比较研究，结合对国内外有关岩浆镍矿床的比较分析，根据我国的地质特点，提出沿较老地块边缘分布的特别是沿华北地块北缘分布的基性—超基性小杂岩体，是找寻大而富的硫化镍矿床之有利找矿方向；而对较老地块内部的镁铁质侵入体，亦应给予高度注意。更多还原

【Abstract】 There are plentiful mineral resources of nickel, cobalt, and copper in the northwest region of China, specially Jinchuan superlarge copper-nickel sulflde magmatic deposit in Gansu province, known for its large scale and typical metallogenetic feature in the world, is an important source of Ni-Cu metal mineral resource in our country. In contrast, Jianchaling large cobalt-bearing nickel sulflde deposit in Shannxi province is not famous and unmined, but many problems about the deposit are researched because of its special geologic settings and mineralization characteristic. According to the theory and study methods of comparative economic geology, the ore-forming geological background, geological feature, the elements geochemistry, the metallogenic geochronology about the two ore deposits and rock-bodys are systematic analysed, compared, and researched by means of new measure and assay technique. Jianchaling nickel sulflde deposit is stress investigated in order to study similarities and differences between the two deposits in mineralization background, geochimistry, and metallogenesis, also to find the reasons for these, discuss the regularity of formation and distribution for the type deposit, and guide its exploration.On the basis of systematic analysis and comparative research on Jianchaling and Jinchuan nickel sulflde deposit in geology and geochemistry, some conclusions can be drawn as follow:(1) Re-Os isotopic geochronology data define an precise 878 ?6 Ma isochon, suggest Jianchaling nickel sulflde deposit would form in new Proterozoic. The rock-forming process and metal logenesis happened on the whole, this deposit subordinates to magmatic deposit. At the same time, it is proved again that Jianchaling rock-body intruded in new Proterozoic.(2 ) The comparative study on PGE geochemistry indicated that it exists multiple diagenesis and mineralization in Jinchuan superlarge copper-nickel sulflde deposit. However, compared with Jinchuan ore-bearing intrusion, Jianchaling ultrabasic intrusion formed by magma simple emplacement, and magma fractionated weakly with lower content of nickel and sulphur.(3) Jianchaling ultrabasic intrusion belongs to magnesian ultrabasic simple rock-body, close related with Yangzi block in space, which formed in the interim of Proterozoic active tectonic zone to Phanerozoic orgenic belt. Jianchaling nickel deposit that respected with it is originally devided into magma type deposit, its metallogenesis include magma differrentiation-crystalization, sulfurization process, magma melt-segregated, and hydrothermal process. But melt-separated ore-forming poorly developed, and hydrothermal process is subordinate, the assimilation and contamination of country rocks have special significance to the formation of this ore deposit.(4) The comparative research suggests that various types of ultrabasic-basic rocks occurred different geological environment and different intruded mechanism can bring on different types of nickel sulflde deposit. Compared with Jianchaling nickel sulflde deposit, Jinchuan superlarge copper-nickel sulflde deposit mostly related with mafic-ultramafic complex that multiple intruded, spatially respected with old Huabei block, which formed in marginal rift in middle-new Proterozoic. Its metallogenesis also include magma differrentiation-crystalization, sulfurization process, magma melt-segregated, and hydrothermal process, whereas magma melt-segregated ore-forming process played an important role, and hydrothermal process is secondary, too. Substance of rock-forming and ore-forming in both Jianchaling and Jinchuan nickel deposit mainly derived from the upper mantle, but the former source is relatively depleted mantle. On the other hand, there exsisted the crustal contamination during the formation of the two mineral deposits, the later contaminated poorly and gave priority to deep contamination.(5) By the comparative study of Jianchaling with Jinchuan nickel sulflde deposit, it is pointed that small basic-ultralbasic complexes whi更多还原