The genetic relationship between the Jinchuan Cu-Ni sulfide deposit and the near-by mafic-ultramafic intrusions is important for further exploration. The zircon U-Pb age (832.5 ±1.5) Ma of the Maocaoqun mafic intrusion is consistent with the zircon U-Pb age (831.8±0.6) Ma of the Jinchuan ultramafic intrusion. Petrogeo-chemical compositions indicate that both intrusions belong to sub-alkaline tholeiitic basalts, and chondrite-normalized REE and primitive-mantle normalized micro-elements diagrams show parallel patterns, displaying LREE enrichment and Nb, Ta negative anomalies. Primitive-mantle normalized PGE patterns show parallel distribution between Maocaoqun and Jinchuan ultramafic intrusions. Isotopic geochemical data display high εsr(t). low εNd( t) and fairly low 206Pb/204Pb values for both intrusions, which implies that the magma forming the intrusions came from the enrichment mantle source like EM I -type mantle. The above features suggest that the Jinchuan and Maocaoquan intrusions were derived from the same magma source with the same age. Maocaoquan mafic-ultramafic intrusions were possibly formed by earlier stage magma from the Jinchuan magma chamber, which contributed siderophile elements and olivine for later stage magma, thus forming the Jinchuan Cu-Ni sul-fide deposit.%金川铜镍硫化物矿床及其与附近的镁铁-超镁铁质岩体的成因关系对成岩成矿理论研究及找矿具有重要意义.通过对镁铁-超镁铁质岩体的岩石学、年代学、岩石地球化学、同位素地球化学研究,获得金川附近的茅草泉镁铁-超镁铁质岩体中单颗粒锆石U-Pb年龄为(832.5±1.5) Ma,与金川超镁铁质岩体中锆石U-Pb年龄(831.8±0.6) Ma在误差范围内一致.岩石地球化学数据显示,金川岩体与茅草泉岩体都属于亚碱性拉斑玄武岩系列,微量及稀土元素配分曲线平行,变化趋势相似,属于右倾型,具有Nb、Ta负异常；Cu/Zr比值显示过渡变化特征,Cu/Ni比值都小于1,原始地幔标准化的铂族元素配分曲线平行过渡.同位素地球化学数据显示,样品具有高正εSr(t)值,低的εNd(t)值,较低的206Pb/204Pb值,指示岩浆源区为EMI型富集岩石圈地幔.多种方法证明了金川、茅草泉岩体具有同期同源岩浆演化特征,茅草泉小岩体群可能是金川母岩浆先期侵入岩相,为金川矿床的形成贡献了亲铁元素与橄榄石成分.
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