【作者】 徐刚；

【导师】 钱壮志；

【作者基本信息】 长安大学 ， 构造地质学， 2010， 硕士

【摘要】 金川矿床在铜镍硫化物矿床中具有特殊地位,近年来,众多的国内外地质学家对其进行了大量的研究。本文在系统地总结和提取前人的地质资料基础之上,通过野外地质观察、系统采样、室内光、薄片鉴定以及岩石学矿物学、岩石地球化学和铂族元素地球化学等方面进行系统的研究,取得了以下主要认识：(1)Ⅰ、Ⅱ号岩体较为相似的铂族元素配分模式,与主量元素、微量稀土元素等地球化学特征显示的信息一致,均表明二者具有相同的母岩浆成分,为同源岩浆演化的产物。(2)金川Ⅰ、Ⅱ号岩体岩石和矿石具有相似的PGE分配模式(Pt-Pd配分型),PPGE与IPGE分异明显,以PPGE (Pt、Pd)为主,IPGE (Ir、Os、Ru、Rh)含量较低。(3)PGE特征进一步佐证了金川成矿母岩浆为高镁拉斑玄武质岩浆。金川矿床成矿岩石及矿石Cu/Pd、Ni/Ir比值(岩石42.59×103,7.87×105；矿石152.71×103,3.62×106)远高于原始地幔的Cu/Pd、Ni/Ir(7.7×103；6.12×105)比值(McDonough and Sun,1995)这些特征表明原始岩浆在侵入岩浆房之前存在少量硫化物熔离作用。通过进一步模拟计算初步得出大约有0.013%的硫化物早期发生预先熔离。(4)主量、微量稀土以及铂族元素特征一致显示的橄榄石、辉石及铬铁矿的分离结晶作用为促使岩浆中的硫化物达到饱和而发生熔离提供了良好的条件；部分熔融程度低不应是金川铜镍矿床PGE亏损的原因,而少量硫化物预先熔离是造成金川母岩浆PGE亏损的主要控制因素。(5)通过对块状矿石成因的模拟计算,表明块状矿石主要由10%～40%分离结晶后的MSS冷却固结形成,这与其相对富IPGE而贫PPGE特征相吻合；富Cu、Pt和Pd的特富块状矿石和脉状矿石可能与固溶体结晶分离后富集Cu、Pt和Pd的残余硫化物熔体固结形成有关。更多还原

【Abstract】 In past years, many Geologists that is at home and abroad have done a lot of research about Jinchuan deposit because of its special status in magmatic Ni-Cu-PGE sulfide deposits. Before writing paper, I try to summarize and extract the previous geological basic data systematically, do the field geological observations and collect the typical samples. The paper study on mineralogy, petrology, geochemistry and platinum group elements geochemistry of the Jinchuan nickel-copper sulfide deposit systematically and concluded the following points:(1) SegmentⅠand segmentⅡintrusions of Jinchuan have the Similar distribution patterns of platinum-group elements, and the geochemistry characteristic of major elements and trace element state clearly that they have the same primary magma composition.(2) The PGE distribution patterns of segmentⅠand segmentⅡintrusions belong to the Pt-Pd type, and the differentiation between IPGE and PPGE is clear, the high content in PPGE and low in IPGE.(3) The PGE characteristic support that the primary magma of Jinchuan is high MgO tholeiitic magma. The Cu/Pd, Ni/Ir ratio (rock 42.59×103,7.87×105; ore 152.71×103, 3.62×106) of rock and ore is much higher than the original mantle (Cu/Pd=7.7×103, Ni/Ir =6.12×105). All of these data suggest the basaltic magma had experienced minor suifide segregation, whose amount is about 0.013% attained by means of quantitative simulation, prior to emplacing the staging magma chamber.(4) The characteristic of major elements, trace element and platinum-group elements show that the fractional crystallization of Olivine, pyroxene and chromite provide suited conditions for the sulfide segregation. A small quantity of sulfide segregation is the main controlling factor lead to the lossing of PGE in primary magma of Jinchuan rather than the low degree of partial melting.(5) The amount of 10% to 40% fractional crystallization of MSS cooled to form the massive ore by means of quantitative simulation. It is consistent with the massive ore characteristic rich in IPGE and poor in PPGE. The formation of other type of massive ore and veined ore which rich in Cu, Pt and Pd relate to the consolidation of the residual sulfide melts that experienced MSS fractional crystallization.更多还原