Distribution of Te, As, Bi, Sb, and Se in Mid-Ocean Ridge Basalt and Komatiites and in Picrites and Basalts from Large Igneous Provinces: Implications for the Formation of Magmatic Ni-Cu-Platinum Group Element Deposits

Abstract In magmatic nickel-copper-platinum-group element (PGE) deposits, the PGEs are found both in solid solution base metal sulfides and as platinum group minerals (PGMs). Apart from S, most common elements that combine with to form PGMs Te, As, Bi, Sb, Sn (TABS). Whether TABS play a role collecting or simply partition into sulfide liquid along later when phase becomes saturated is not currently clear. This part because concentrations of magmas (picrites basalts large igneous province komatiites) these types deposits well established, hence it evident whether contain sufficient control PGEs. order establish Se (TABS+) rock document processes affecting concentrations, we have determined TABS+ komatiites, mid-ocean ridge basalt, picrites provinces. Using mantle-normalized diagrams, affects different mantle sources, crystal fractionation, crustal assimilation, degassing, alteration considered. We estimate komatiites be approximately twice primitive values. vary: 10 times values for As Sb decreasing through Bi Te 7 2 mantle. Assimilation S-bearing sedimentary rocks thought important triggering saturation leading formation Ni-Cu-PGE deposits. such sediments would enrich magma Th over Nb Bi. Evidence assimilation enrichment clear PGE reef Bushveld Stillwater Complexes, but do also true Norilsk-Talnakh However, at Norilsk degassing has resulted loss TABS, which results negative Se, anomalies on plots.