Geochemical and isotopic characterisation of mafic intrusions in the Fraser Zone, Western Australia

The Albany-Fraser Orogen records widespread mafic/ultramafic magmatism in the Fraser Zone, which hosts the magmatic Ni-Cu deposit, Nova-Bollinger. Seven prospects containing mafic/ultramafic intrusives in the Fraser Zone were analysed to determine how they compare to Nova-Bollinger and if they are prospective for magmatic sulfide deposits. Broadly, similar trace element data suggest these intrusions are formed from a similar source which may be consistent with subduction modified mantle intruding into a back-arc/rift environment. Negative ENd suggest varying degrees of crustal contamination, whilst S isotopes also display some crustal signatures and possible incorporation of Archean MIF bearing Δ33S. The greatest difference between regional prospects and Nova-Bollinger is in the olivine chemistry with differences in partial melting and sulfide segregation. These differences potentially being responsible for Nova's economic sulfides and the relatively barren intrusions studied regionally.