Regional Metallogenic Controls of Small-intrusion-hosted Ni-Cu (PGE) Ore Deposits 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, Kalatongke, 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.