An overview of the PGE concentrations in the Shetland ophiolite complex

Extremely anomalous platinum-group element (PGE) concentrations are known at one site, Cliff, in the Shetland ophiolite complex. Systematic PGE analysis of all the mafic and ultramafic igneous and alteration lithologies in the ophiolite has revealed many lower grade anomalous PGE occurrences throughout the cumulate ultramafic sequence and their distribution is described here. More sites with PGE enrichments as anomalous as those at Cliff have not been found. The PGE concentrations occur in specific primary magmatic lithologies and pathfinder analysis shows that they are associated with Ni, Cu, Au and Cr. PGE have not been found above detection limits in fault zones away from primary PGE mineralization sites and it is concluded that PGE are not significantly hydrothermally reconcentrated. At Cliff, remobilization may have occurred over short distances of only a few metres at most. -from Authors