Platinum-group elements(PGE) in mantle harzburgites from Xigaze ophiolites,Tibet

The harzburgites from Xigaze ophiolites in Tibet are relicts of the partial melting upper mantle. The total w (PGE) amounts of them are (28 37～50 67)×10 -9 , slightly higher than those of mantle peridotites in the primitive mantle, and typical ophiolites in the world, and the Alps-type mantle peridotites. They have relatively high total w (PGE) amounts and are enriched in Pt, Pd, Ru, Ir to Primitive Mantle. Their PGE distribution patterns belong to the positively inclined- or swallow-type patterns different from those of the mantle peridotites of partial melting relict origin. Relative enrichment in Pt and Pd, as well as in the incompatible elements such as Cu, Au, Cs, Rb, Ba, Th, U and LREE, and U-type REE patterns, indicates that the partial melting-derived relict harzburgits from Xigaze ophiolites have experienced intensive permeating and mixing processes of the melt and fluid both containing abundant incompatible elements.