四川丹巴石锅棚子与杨柳坪Cu-Ni-PGE矿区基性——超基性岩PGE地球化学特征对比及其意义

Comparison of PGE Geochemical Characteristics in Basic—Ultrabasic Rock in Shiguopengzi in Danba Area and Yangliuping Cu-Ni-PGE Deposit Area and Its Significance in Danba of Sichuan Province

通过对四川丹巴石锅棚子与杨柳坪基性—超基性岩的PGE地球化学对比分析认为,2处岩体均为S不饱和态,块状铜镍硫化物基性—超基性岩石为铂族元素的主要载体;石锅棚子和杨柳坪侵入岩的铂族元素丰度高于峨眉山玄武岩,表明玄武岩为分异后的玄武质岩浆的喷出物,属于典型的铁质基性—超基性岩的范畴;Cu/(Cu+Ni)、Cu/Pd比值表明,母岩浆经历了硫化物的部分熔离;Pt/Pt~*,Pd/Pt等比值和PGE配分模式图的研究表明,石锅棚子和杨柳坪Cu-Ni-PGE硫化物矿床可能与地幔柱成因或下地幔来源的基性—超基性岩相关,岩体成矿过程中经历了部分硫化物熔离作用,且岩浆在向高位岩浆房侵位过程中发生了地壳物质的混染作用,而石锅棚子岩体相对杨柳坪岩体所受地壳混染作用要强。

Through comparison of PGE geochemical of mafic-ultrabasic rocks in Shiguopengzi and Yangliuping are-a , it is regarded that sulfide is in unsaturated state, and massive Cu-Ni sulfide basic-ultrabasic rocks are main carrier of platinum group elements. The PGE abundance of Shiguopengzi and Yangliuping intrusions is higher than that of Emeishan basalt. 1t is indicated that basalt is the production of basaltic magma ejecta, and these two basic intrusive rocks belong to typical mafic ultrabasic rocks. The ratios of C^^ （ Cu＋ Ni）, Cu/Pd and Ti/Pd show that the parent magma experienced the fusion of sulfide. The ratio of Pt/Pt ＊ and Pd/ P t , and PGE distribution pattern diagram showed that the Cu- Ni-PGE sulfide deposits of Shiguopengzi and Yangliuping is related to the origin of mantle plume or lower mantle magma. During the mineralization process of rock mass, partial sulfide immiscible separation has been experienced; while during the ore-bearing magma tasporting to high crustal level, the crustal contamination occurred. Contamination is relatively higher in Shiguopengzi area than that in Yangliuping area.