A Craton-margin Model for the Genesis of Magmatic Ni-Cu-PGE Sulfide Deposits

Basing on the global distribution of magmatic Ni-Cu-PGE sulfide deposits and the relationship between this type deposits and large igneous provinces(LIPs),we suggested that the location of magmatic Ni-Cu-PGE sulfide deposits is related to lithospheric architecture.At crustal levels,this relationship is manifested by a close proximity to craton and paleocraton margins.Deposits are associated with mafic-ultramafic rocks and many show a close spatial and temporal relationship with coeval igneous magmation.A craton-margin model for the genesis of magmatic Ni-Cu-PGE sulfide deposits is proposed,and there are five steps for the formation of this type deposits:①The generation of high-volume ultramafic melts in the mantle.②The flowage of hot mantle or magma towards the craton margin.③The passage of magma through the lithosphere.④The tectonics and interaction between magma and crustal rocks.⑤The eruption of magma and the deposition of minerals.The advantages of the craton margin for the formation of magmatic Ni-Cu-PGE sulfide deposits were summarized:①Zones of thinner lithosphere are more likely adjacent to and along the cratonic margins,this provides a natural focus for mantle plume flow along the base of the SCLM,followed by localized decompression melting of the plume in the zones of thinner lithosphere.②Margins of cratons are prone to focusing strain during regional tectonism,providing points of dilation along active structures in the craton margins area.③ Deposits along or slightly internal to paleocraton margins internal to a continent may be better protected from uplift and erosion during subsequent orogenesis.