Deep segregation-injection ore-forming process and metallogenetic model for magmatic Cu-Ni(PGE) sulfide deposits—Geological comparative study on two deposits exemplified by Voisey′s Bay (Canada) and Jinchuan(China)

In this paper,geological and mineralization characteristics and metallogenetic model of Jinchuan Cu-Ni(PGE) magmatic sulfide deposit are systematically analysed and compared with Voisey`s Bay Cu-Ni(PGE) deposit(Canada),and the results show that the two world-class Cu-Ni(PGE) deposits have some common geological characteristics,and so,there are similarity and comparability on ore-forming and evaluation of the deposit.That means ore-bearing magma at depth pulsating invasion along the magma flow conduit results in a large deposit in upper magmatic room which appears it was generated from a small rock mass.Several key aspects of the characteristics on ore-forming process and metallogenetic model emerged as follows: i) ore-bearing magma pulsating invasion in sequence reveals that segregation and differentiation has occurred during primitive magma staying at a lower magmatic room and resulted in layering structure of magma,ore-bearing magma,sulfide-enriched magma and sulfide mass;ii)ore forming process occurs in a dynamic magma flow during pulsating invasion,melted magma mass contains volatile composition,acutely invasion results in brecciated wall rocks;iii) ore bearing magma invades along the same conduit or overpass to access to the bottom or upper part of the previous invasions to form ore body;ⅳ) magma interacts with wall rocks,exchanges some components and enrich metallogenetic materials during transportation.It is clarified that ore-bearing magma pulsating invasion and subsequent magma re-supply are very important ore-forming mechanism through which sulfide-bearing mafic-ultramafic magma assembles along the magma flowing conduit at depth to form super-larger Cu-Ni(PGE) magmatic sulfide deposits during the process of magmatic Ni-Cu sulfide deposits forming by injecting of sulfide-bearing magma segregated at depth.