Enrichment of platinum and associated elements in organic seepage soils of the Tulameen ultramafic complex, southern British Columbia

Abstract

Concentrations of Pt have been determined in seepage waters, organic soil horizons and trees in and upslope from a seepage site on the dunite core of the platiniferous Tulameen ultramafic complex. The concentrations of Pt (together with Sb, Cr, Ni, Br, Co, As and Cu) are enhanced twenty-fold in the organic seepage soils compared to Pt concentration in both the LFH horizons of the upslope soils and Pt concentrations found in the ash of twigs and bark of trees growing on the seep. The seepage waters contain 0.4 to 0.8 ng/L Pt. The study provides evidence that weathering under temperate conditions can release Pt from platinum group minerals and that the released Pt can then be transported, either in solution or a colloidal form, to seepage sites where it is accumulated by organic matter. Organic-rich soils from seepage sites might therefore provide suitable sampling media for geochemical surveys for Pt.