攀西地区镁铁-超镁铁岩地球化学与岩浆型Cu-Ni-(PGE)硫化物矿床成矿

Geochemistry of Mafic-ultramafic Intrusions and Cu-Ni-(PGE)Sulfide Deposits in Panxi Region,China

中国攀西地区沿南北向断裂带内分布着一系列镁铁-超镁铁质岩体及岩浆型Cu-Ni-(PGE)矿床,它们具有一定的含矿差异性。年代学及地球化学对比表明:除新远古时期形成的冷水箐CuNi-PGE矿床以外,杨柳坪、力马河、白马寨、朱布、金宝山矿床均与峨眉山低钛(LT)玄武岩具有密切亲缘关系,同为峨眉山地幔柱的产物;Sr-Nd、Re-Os、S同位素对比表明攀西地区含矿镁铁-超镁铁质岩体的母岩浆均遭受了地壳物质的混染,;PGE元素变化特征表明,母岩浆在演化过程中发生了硫化物熔离进而导致成矿。不同程度的地壳混染作用以及不同的硫化物熔离进程最终导致该地区具有相同地幔柱源区的镁铁-超镁铁质岩体具有不同的含矿性,金宝山、朱布PGE矿床为母岩浆演化早期阶段的产物,杨柳坪Cu-Ni-PGE矿床为母岩浆演化中期阶段的产物,而力马河、白马寨铜-镍矿床为母岩浆演化至晚期阶段的产物。

A series of mafic-ultramafic intrusions with Cu-Ni-（PGE） sulfide deposits are occurred along the NS-trending fault zone in Panxi region of China, which have different ore-bearing feature. The comparison in geochronology and geochemistry indicate that, there is a close geneticrelationship among Yangliuping, Limahe, Baimazhai, Zhubu and Jinbaoshan deposits, which serve as the products of Emeishan mantle plume. Sr-Nd, Re-Os and S isotopic characteristics show that the parental magma of ore-bearing mafic-ultramafic intrusions in Panxi region have suffered the contamination of crustal materials; PGE elements variation features make it clear that the parental magma of intrusions has experienced the separation of sulfide, which lead to the formation of mineral deposit. Different degrees of crustal contamination and different progress of sulfide separationfinally result in the disparate ore-bearing features of mafic-ultramafic intrusions that sourced from the samemantle plume.Furthermore, the intrusions respectively represent the product of different stages（early, middle, later stage） in the evolutionary process of parental magma. Jinbaoshan and Zhubu PGE deposits serve as the products of early evolution stage：Yangliuping Cu-Ni-PGE deposit is formed by theparental magma in middlestage, while Limahe and Baimazhai Cu-Ni deposits are formed in later stage of parental magma.