岩浆熔离型铜镍矿床硫同位素地球化学特征研究

Study on the geochemical characteristics of sulfur isotope in magma-melting copper-nickel deposits

我国岩浆熔离型铜镍矿床主要分布在大陆边缘裂谷、造山带和峨眉山大火成岩石中,矿床赋存岩体中下部;矿石呈星点状、浸染状、海绵陨铁状和块状,主要矿物为磁黄铁矿、镍黄铁矿、黄铜矿、磁铁矿、橄榄石、石英等;矿床形成温度较高;成矿氧逸度范围受磁黄铁矿-黄铁矿-磁铁矿和橄榄石-石英-磁铁矿矿物组合控制。硫化物硫同位素显示出两种特征,一种为金川、赤柏松、喀拉通克、黄山东、红旗岭、金宝山等矿床,硫化物的硫同位素主要分布在-1.6‰^+3.1‰;另一种为煎茶岭、力马河矿床,硫化物的硫同位素组成为+1.5‰~13.8‰。根据硫同位素组成特征可以得出大多数岩浆熔离型铜镍矿床硫化物的硫主要来自岩浆(金川、赤柏松、喀拉通克、黄山东、红旗岭、金宝山),少数矿床硫的来源较为复杂(煎茶岭和力马河),很可能是两种以上来源。

Magma-melting-type copper-nickel deposits are mainly distributed in the continental margin rift, the orogenic belt and Emeishan igneous rock belt in China. The deposit is in the lower part of the magmatic rock mass. The ore is star-shaped, disseminated, and the main minerals are pyrrhotite, nickel pyrite, chalcopyrite, magnetite, olivine, quartz and so on. The formation temperature is higher. The mineralization oxygen fugacity range is affected and controlled by mineral combination of pyrrhotite-pyrite-magnetite and olivine-quartz-magnetite. The sulfide sulfur isotope shows two kind features, one for Jinchuan, Chibosong, Karatungke, Huangshandong, Hongqiling and Jinbaoshan deposits, whose sulfur isotopic composition is mainly distributed in between -1.6% to ＋3.1%, and the other for Jianchaling and Limahe deposits, whose sulfur isotopic composition is distributed in between ＋1.5% to ＋13.8%. According to the characteristics of sulfur isotopic composition, it can be concluded that the sulfide sulfur sources of most magma-melting type Cu-Ni deposits （Jinchuan, Chibosong, Karatungke, Huangshandong, Hongqiling and Jinbaoshan） are mainly from magma, the sulfide sulfur sources of less deposits （Jianchaling and Limahe） are more complex for more than two sources.