中国小岩体镍铜(铂族)矿床的区域成矿规律

文章进一步提出中国小岩体镍铜(铂族)矿床产出于三种地质背景,即古大陆内的小侵入体、造山带内小侵入体和与大陆溢流玄武岩有关的小侵入体,分别介绍了金川、喀拉通克和白马寨三个典型矿床的地质情况。从成矿的三个必要条件(①岩浆应达到硫化物饱和;②硫化物与岩浆之间应有足够的质量比;③硫化物聚集到有限的空间成矿)出发,结合矿床实例,阐述了成矿的深部过程和深部熔离-贯入成矿模式。论述了不同尺度的区域成矿规律:①三种地质背景;②邻近深大断裂;③三种岩体-矿床的分布结构形式;④矿集区往往是由一个同源多期次上侵的岩体群组成;⑤矿床由含矿岩浆上侵的终端岩浆房组成;⑥含矿岩浆贯入成矿往往伴随一定的流动分异作用或重力分异作用。

Regional metallogenic controls of small-intrusion-hosted Ni-Cu(PGE) ore de-posits in China

Results of research indicate that Ni-Cu(PGE)ore deposits hosted in small intrusions in China mainly occur in three geologic settings:(1)within paleo-continents,(2)in orogenic belt,and(3)continental rift system such as the Panxi Rift system where a large number of flood basalts and associated mafic-ultramafic intrusive are present.Typical examples of these ore deposits are Jinchuan,Karatungk,Baimazhai,respectively.Based on three controlling factors:(1)sulfide saturation in magma,(2)enough mass ratio between sulfide and magma,(3)sulfide concentration in limited areas,and case studies,we develop a genetic model that emphasizes geological process indicating sulfide segregation at depth before final emplacement.We discuss controls at different scales.These are(1)three geologic settings,(2)close to deep-seated fault,(3)distribution of ore bodies in three different types of intrusions in different tectonic settings,(4)multiple intrusions or injections,(5)distal areas of final chamber,and(6)presence of flow differentiation and gravitational concentration.