Gabbroic rocks Central Dunite Pyroxenite Mining sequence 200 m Ultramatic fragments Country rock Metavolcanics and sedimentary Marginal (ol) websterite & gabbro Footwall Dunite Mainly three types of ores Normal Ni-PGE ore Whole-rock Ni 2.30 wt%, Cu 0.17 wt% NiO in olivine 1.5 wt% Ni in sulfide 43.3 wt% Normal ore Whole-rock Ni 0.27 wt%, Cu 0.68 wt% NiO in olivine 0.25 wt% Ni in sulfide 4.7 wt% False ore Whole-rock Ni 0.038 wt%, Cu 0.024 wt% NiO in olivine 0.02 wt% Ni in sulfide 0.29 wt% Serpentinite Gabbro Ni-PGE ore Dunite Websterite Olivine pyroxenite Normal ore Schists Mafic volcanic rocks Santaguida et al. (2013) Key questions • Magma emplacement and differentiation history of the intrusion • Ore-forming processes • Origin of Ni-PGE ores Multiple magma emplacement in a dynamic system Luolavirta et al., 2014 Normal ore • The mineralized zone has higher initial Sr isotope ratios than non-mineralized zone, indicating crustal contamination is stronger in the mineralized part. • Crustal sulfur is critical in triggering sulfur saturation False ore Olivine composition KV 297, KV280 – False ore • Very depleted in Ni, sulfide saturation may have occurred at depth Luolavirta et al., 2014 Two contrasting aspects of the Ni-PGE ore • High Ni-PGE => a primitive signature • On the other hand, very rich in LREE, high Sri and negative eNd => strong enriched component
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