甘肃省金川超大型铜镍硫化物矿床富铂钯矿石成因研究

Pt-Pd Rich Ores Genesis Research of Jinchuan Giant Ni-Cu Sulfide Deposit,in Gansu Province

金川铜镍硫化物矿床的成因及侵位机制尤其是块状矿石和铂钯富集体成因一直存在较大争议,本文通过对金川矿石的空间关系、地球化学特征研究,指出金川矿床遭受构造及热液蚀变作用影响明显,块状矿石相对富集Os、Ir、Ru、Rh,铂钯富集体相对富集Pt、Pd、Au、Cu。研究认为,块状矿石是晚期纯硫化物矿浆上升贯入后经单硫化物固溶体结晶堆积而成,残余熔浆形成初始铂族矿物,后期矿体遭受热液蚀变及构造剪切-热液作用,使Pt、Pd、Cu、Au进一步富集形成铂钯富集体,并在有利于成矿的空间聚集成矿。块状矿石与铂钯富集体关系密切,据此推测2#矿体、24#矿体深边部裂隙中具有良好的勘探前景。

The Jinchuan deposit understandings of the sulfide ore genesis and the magma intrusion and emplacement history of it remains limited.On the basis of the spatial relationships and the geochemistry of magmatic sulfide ores,this paper suggests that the Jinchuan deposit was affected obviously by tectonization and hydrothermal alterations,and that the massive ores are relatively enriched in Os,Ir,Ru,Rh comparing with other ore-forming elements,whereas Pt-Pd-rich sulfide ores are relatively rich of Pt,Pd,Au,Cu.It is concluded that platinum group minerals（PGMs） are the relic liquid of monosulfide solid solution segregation,and that the massive ore represents the accumulation of monosulfide solid solution,and that the late stage of pure sulfide liquid injection evolves both massive ore and PGM.The ore bodies underwent hydrothermal and tectonic-hydrothermal alterations,thus Pt,Pd,Cu,Au are concentrated in Pt-Pd-rich sulfide ores which have deposited in the certain restricted localities.It is concluded that the Jinchuan deposit was formed as a result of primary magmatic crystallization followed by hydrothermal remobilization,transport,and deposition of PGE.Based on special relationships of massive ores and Pt-Pdrich zones,we expect that the prospect of seeking new ore bodies in deep and border fractures in the footwalls of orebody-2and orebody-24appears to be justified.