中文摘要：

四川力马河镍矿是峨眉山大火成岩省一个重要的岩浆硫化物矿床。本文通过对其主要岩、矿石类型Re、Os及其同位素组成的分析，综合探讨了成矿岩体原始岩浆性质、矿石硫化物成因、成矿机制及Re-Os同位素等时线年龄。结果表明，力马河镍矿不同类型岩矿石样品初始Os同位素组成是不均一的，富硫化物的网脉状矿石及其选纯硫化物Os同位素组成初始值差异较小，其等时线年龄为265±35Ma，与岩体错石SHRIMP年龄263±3Ma基本相当}硫化物含量较低的岩、矿石样品间初始Os同位素组成差异较大，其表观等时线年龄大于成矿年龄。分析认为。岩矿样品初始Os同位素组成的不均一是由含较高放射成因^187Os丰度的硫化物熔体和含较低放射成因^187Os丰度的硅酸盐熔体不同比例混合造成的。混合模型分析表明，硫化物含量超过30％的矿石样品初始^187Os／^188Os基本接近，硫化物含量低于30％的岩矿石样品初始^187Os／^188Os随硫化物含量上的不同，差异很大，为岩浆硫化物矿床Re-Os等时线年龄出现多组年龄解的现象提供了一种可能的解释。成矿岩体中含放射成因^187Os丰度最低的岩石样品γOs（t=260Ma）在5左右、Cu／Pd比值在7000左右，表明是基本没有受到地壳混染及硫化物熔离影响的原始岩浆结晶分异产物，估计原始岩浆Os含量在1×10^-9左右，为苦橄质岩浆。矿石硫化物Re／Os比值显著高于任何赋矿橄榄岩，γOs（t=260Ma）高达110左右，综合分析揭示了力马河镍矿硫化物为二次熔离成因，模式分析认为，矿石硫化物是由原始岩浆经历R=2000左右的硫化物熔离后，其亏损岩浆再经R=200左右的硫化物熔离形成，与二次熔离相对应，成矿岩浆也经历了两次混染作用，分别为上、下地壳7％左右的混染。

英文摘要：

The Limahe nickel deposit is one of the important PGE-poor Ni-Cu deposit in the Emeishan Large Igneous Province. This paper mainly analyzes Re-Os isotopic composition of various ore and rocks from the Limahe nickel deposit, discusses source magma, genesis of suphide, ore-forming mechanism and Re-Os isoehron. The results show that different rock and rock types of the Limahe deposit are of different initial Os isotopic compositions. The differences of initial Os isotopic composition between sulfide-rich veinlet ores and their ssextracted sulfide are small and their isochron of 265±35 Ma is agreement to the zircon SHRIMP age of 263±3 Ma from the rock. Initial radiogenic Os concentrations between sulfide-poor ore and rock are distinctly different, and its isochron age is larger than metallogenic age. The analysis shows that heterogeneity of initial Os isotopic composition in the ore samples is attributed to the mixture of sulfide melt containing high radiogenic 187Os and silicate melt containing low radiogeneic ^187Os at a different proportion. Mixed modeling suggests that the ore samples containing more than 30 % of sulfide have similar initial ^187Os/^188Os ratios, whilst the samples containing less than 30 % of sulfide have big difference in the initial ^187Os/^188Os depending on the contents of sulfide, providing a possible explanation for several sets of Re-Os isochron ages of the magmatic sulfide deposits. Radigenetic ore-forming rock samples with least abundance of ^187Os has a γOs（t=260Ma） value of 5 and Cu/Pd ratio of 7000, indicating that they were the products of original magmatic crystallization without any crustal contamination and sulfide exsolution. It was estimated that the Os content in primary magma is about 1× 10^-9 , suggesting a picritic magma in origin. Re/Os ratio of sulfide in the ores is higher than those of any ore-hosted peridotite, with γOs （t= 260Ma） up to 110. Comprehensive study reveals that the Limahe deposit originated from a daughter magma which exsolved from deep magma.