Magmatic platinum-group element concentrations and hydrothermal upgrading in Shetland ophiolite complex

The Balta Sound area contains a representative and only partially serpentinized vertical section through the sequence of primary rock types that is characteristic of the Shetland ophiolite complex. Here the crustal ultramafic cumulates that overlie mantle tectonites typically contain accessory sulphide. Two stratigraphic zones of chromite enrichment are defined in the basal dunite cumulates by arrays of extracted chromitite pods and discontinuous chromite-rich layers. The distribution of platinum-group element (PGE) concentrations in the igneous rock sequence is described and its bearing on the genesis of precious-metal mineralization elsewhere in Shetland and in other ophiolite complexes is discussed. -from Authors