岩浆镍铜铂族矿床成矿过程中流体的作用——对小岩体超大型矿床的启示  

The roles of volatiles in mineralizations of magmatic Ni-Cu-PGE sulfide deposits——Implications for potential metallogenic mechanism of super-large scale magmatic deposits in small magma

作　　者：张铭杰[1] 汤庆艳[1] 李文渊[1,2] 余明[1] 胡沛青[1] 李建平[1] 

机构地区：[1]兰州大学地质科学与矿产资源学院,兰州730000 [2]中国地质调查局西安地质调查中心,西安710054

出　　处：《中国工程科学》2015年第2期40-49,84,共11页Strategic Study of CAE

基　　金：国家自然科学基金项目(41372095;41472070;41072056);高等学校博士学科点专项科研基金项目(20120211110023);中国地质调查局项目(12120114044401)

摘　　要：超大型岩浆镍、铂族元素(PGE)硫化物矿床控制了Ni-PGE的资源量,本文根据地幔岩浆事件中Ni、Cu和PGE等在部分熔融、岩浆结晶和硫化物熔离过程的行为,讨论了岩浆Ni-Cu-PGE硫化物矿床的成矿岩浆类型与规模、成矿金属元素聚集的方式、岩浆演化过程中硫饱和度与硫化物液相不混溶的控制因素,探讨了流体对成矿金属的运移聚集作用等。认为地幔大规模的高度部分熔融(即要求高Mg岩浆)促使地幔硫化物及橄榄石中巨量的Ni和PGE进入岩浆,硫化物熔离富集成矿金属形成大型层状(或通道)岩体赋存的超大型Ni-Cu-PGE硫化物矿床;地幔超临界流体可能大范围内搬运聚集大量Ni-PGE金属元素,对岩浆硫化物矿床成矿可能有重要贡献,是小规模岩浆(小岩体)成矿的可能机制。The resources of nickel and platinum group element （PGE） are contributed by super-large scale magmatic Ni-PGE sulfide deposits in the world. In this paper, on the basis of the behaviors of Ni, Cu and PGE in the processes of partial melting, magma crystallization and sulfide segregation etc. mantle magmatic events, we summarized the types and scales of ore- forming magma, the gathering way of ore-forming metal elements, the controlling factors of sulfur saturation and the immiscibility of the sulfide liquid phase during the magmatism of Ni- Cu-PGE sulfide deposits, and discussed the role of volatiles in the transport and enrichment of ore-forming metals. It is concluded that the high degree of partial melting （i.e., magma with high Mg content） in mantle is crucial to gather the huge amounts of Ni and PGE from mantle sulfide and olivine into ore-forming magma, and the sulfide segregation will form super-large scale Ni-PGE sulfide deposits in a large scale layered （or conduit） intrusion. It is inferred that the supercritical fluid （volatile） in mantle can carry and aggregate a large number of Ni-PGE metals from a large volume of mantle, and make a great contribution to the formation of Ni- PGE sulfide deposits. It is possible to be the metallogenic mechanism of magmatic Ni-PGE sul- fide deposits by small mantle derived magma （i.e., small intrusion）.

关 键 词：流体 小岩体 幔源岩浆 超大型岩浆矿床 成矿作用 

分 类 号：O35[理学—流体力学] P611[理学—力学]