More than 100 basic-ultrabasic small intrusions outcrop in the southwest of Jinchuan Ni-Cu mining area. They mainly distribute in the Lower Proterozoic stratum nearby Tamazi ditch and in the Sininan stratum along Baierquan ditch . Small intrusions are small size, shallow buried in the form of, vein, stock and dike. The attitude in general tends to southwest with a dip angle of about 70 degrees. Base on the characteristics of microscopy and X-ray powder diffraction, these intrusions are roughly divided into two kinds, there are the basic diabase and the ultrabasic josefite. The analysis results of petrochemistry show that the content of Ni and Cr of these intrusions are 58 × l0-6-l900. 8 × l0-6 and 65. 1 × 10-6-4518. 2 × l0-6, and the content of REE ranges from 22. 57×l0-6 to 308. 20× 10-6. The enichment of LREE is a typical characteristic of these intrusions, and the differentiation of the HREE is weak. Compared study results show that the josefite in the research area have similar mineral composition, similar content of trace elements and the similar distribution of REE with the ore bearing intrusions, indicating that they are evolved from the same magma activity.%金川铜镍矿南延地区出露基性-超基性小岩体(群)近百处,主要分布在塔马子沟附近的下元古界及白儿泉沟附近的震旦系中,小岩体规模小,形态多为脉状、岩株状、岩墙状,产状总体倾向南西,倾角70°左右.根据镜下特征及X射线粉晶衍射分析结果,将这些岩体分为基性的变辉绿岩类和超基性的变辉橄岩类两大类.岩石化学分析结果显示,这些岩体Ni含量为58×10-6～1 900.8×10-6,Cr含量为65.1×10-6～4 518.2×10-6,ΣREE含量变化于22.57×10-6～308.20×10-6,具轻稀土富集而重稀土分异较弱的特征.与含矿岩体对比研究结果表明,研究区出露的变辉橄岩与金川矿区含矿岩体具有相似的稀土配分形式,AFM图上投影点都落入镁铁-超镁铁堆积岩区,且同具高Cr富Ni的地球化学特征,认为它们为同源岩浆异地侵入形成.
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