金川超大型铜镍矿床与超基性小岩体的同源分异关系

The Homologous Differentiation Relationship between Jinchuan Super-Large Cu-Ni Sulfide Deposit and Small Ultrabasic Intrusion

世界级的金川超大型硫化铜镍矿床具有小岩体容大矿之特点,根据地质地球化学信息论述了其分异关系:①成矿大地构造环境为中元古代长城纪龙首山-祁连山裂谷带。②成矿岩浆性质为拉斑玄武系列苦橄质岩浆,是地幔岩较高程度部分熔融的产物。③成矿岩浆源区为富S地幔,岩浆起源时就富含成矿物质。④岩浆演化过程进一步浓集成矿物质,在地壳过渡岩浆房经深部分异再多次脉动侵入。现存的含矿岩体包括4次侵入,第一、二次侵入携带硫化物液滴与橄榄石晶体的硅酸盐熔浆,局部形成贫矿体;第三次侵入携带大量橄榄石晶体的硫化物矿浆,全部构成富矿体;第四次侵入杂质很少的硫化物矿浆,全部构成特富矿体。

The Jinehuan super-large Cu-Ni sulfide characteristic that small intrusion formed large deposit is a world famous deposit, it has the deposit. Based on the geological and geochemical information, the authors discuss the differentiation relation of this deposit- （1）The Jinehuan Cu-Ni sulfide deposit was formed in the Mesoproterozoie Changchengian Longshoushan-Qilianshan rift zone. （2） The met- allogenic magma was picritic magma, it belong to the tholeiite series, and it was the product of partial melting of mantle rock. （3）The metallogenic magma derived from sulfur rich mantle, and the magma was rich in minerals at the beginning. （4） The metaltogenic substance were further concentrated during the magma evolution process, and the magma occurred many pulsatile intrusion after deep differentiation in the crust transition magma chamber. There was four times invasion to formed the existent ore-bearing rock bodies. The first and second invasion carried sulfide droplet and peridot crystal in the silicate magma, and formed the low grad ore bodies in local place. The third invasion carried a large quantity of olivine crystals and sulfide droplets, and formed rich ore bodies. The fourth invasion carried more magma sulfide, and all the magma formed special rich ore bodies.