俄罗斯诺里尔斯克铜镍硫化物矿床研究进展

    The progress in the study of the Noril’sk Cu-Ni-PGE sulfide deposit in Russia

    • 摘要: 诺里尔斯克铜镍硫化物矿床赋存于西伯利亚大火成岩省,是全球最大的镍-铜-铂族元素硫化物矿集区。研究表明:①该矿床形成于二叠纪—三叠纪之交,与溢流玄武岩在时空上紧密相关,但由于未发现含矿岩体和矿体与溢流玄武岩之间直接接触,尚无法确定其成因联系;②幔源岩浆遭受过壳源物质的混染,但这种混染作用何时发生,混染程度如何,是否是成矿的必要条件?存在诸多争论;③成矿金属元素是从岩浆中沉淀出来的,但究竟是来自地幔还是地壳,有不同认识;④硫化物的熔离作用至关重要,在深部岩浆房曾发生过,但在浅部岩浆房中是否也曾发生过?还存在明显的分歧。尽管在矿床成因方面存在一定的分歧,但某些控矿因素对于诺里尔斯克铜-镍-铂族元素矿集区而言是有效的。

       

      Abstract: The Noril’sk Cu-Ni sulfide deposit, existing in the Siberia Trap, is located at the northwest corner of Russian Siberia. As the largest Cu-Ni sulfide ore district, it consists of two orefields, i.e., Noril’sk and Talnakh. The flood basalts, Noril’sk type, Lower Talnakh type and the later intrusions constitute the four magmatic rock types in the ore district. Both the Noril’sk intrusion and the Lower Talnakh intrusion have been mineralized, but only the former one is of economic value. There are three main ore types, i.e., massive ores, breccia ores and disseminated ores. The existence or nonexistence of massive ores is one of the most important differences between the Noril’sk intrusion and the Lower Talnakh intrusion. Although there are four common opinions among the numerous published papers, many debates remain existent: ①The age data of the P-T time of magmatic rocks and ore deposition reveal that these ore deposits are related to the flood basalts in time and space; nevertheless, due to lack of direct geological evidence, it is hardly possible to know the relations between the orebodies and the flood balsalts. ②The mantle source magma underwent a crustal contamination in the ore-forming process, and disputes focus on three aspects, namely, at which magmatic stage did the contamination happen? What was the degree of the contamination? What was the contamination essential for the ore deposit? ③The ore elements (eg., Cu, Ni and PGE) were precipitated from the magma, but where did these elements come from? Did they come from crust or from mantle? All the publications hold that the mantle source of the ore elements played the leading role; nevertheless, no one can exclude the opinion that the Proterozoic sediments and the Siberia basement might have supplied the ore elements. ④Sulfide segregation played an important role in the ore-forming process. Up till now, all the reseachers have agreed that there was one sulfide segregation in the deep magma chamber as the granitic lower-most crustal contamination. The most hot debate is that whether there existed another sulfide segregation in the shallow magma chamber near the ore-bearing magmatic rocks. Although there are no ultimate common opinion on the ore genesis, the authors still believe that some ore-controlling factors are valid in Noril’sk area.

       

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