Platinum-group elements for the mantle peridotites in the Dazhuka ophiolite, Tibet, China

The total PGE amounts of mantle peridotites in the Dazhuka ophiolite, Tibet , are 28.37-50.67 ng/g, slightly higher than those of mantle peridotites in the primitive mantle, and typical ophiolites in the world, and the Alps-ty pe mantle peridotites. The PGE distribution patterns in the Dazhuka mantle peridotites are also different from those of the mantle peridotites of part ial melting relict origin. The Dazhuka mantle peridotites have relatively h igh total PGE amounts and are enriched in Pt, Pd, and Ru. Their PGE distrib ution patterns belong to the positively inclined-or swallow-type patterns. The PGE distribution patterns in the mantle peridotites of partial melting relict origin belong to the negative-slope patterns or flat patterns. This reflects the unique features of the upper mantle in this region. Relative e nrichment in Pt and Pd, as well as in the incompatible elements Cu, Au, Cs, Rb, Pa, Th, U and LREE, indicates that the partial melting-derived relict mantle peridotites in the Dazhuka ophiolite had experienced intensive perme ating and mixing processes of the melt and fluid both containing abundant i ncompatible elements.