DAVYDOVSKII DUNITE-CLINOPYROXENITE-GABBRO MASSIF: AN EXAMPLE OF THE PLATINUM-BEARING ASSOCIATION IN THE EASTERN URALS

Abstract

The Davydovskii ultramafic-gabbro massif in the eastern Central Urals (about 100 km east of the Platinum-bearing belt) has been studied in detail. The rock suite (dunite, clinopyroxenite, and gabbro) and chemical characteristics (elevated contents of such indicator elements as Sr and Sc, concentrations and distribution of platinum-group elements, etc.) suggests its affiliation with the dunite-clinopyroxenite-gabbro association of orogenic regions, which are represented by the massifs of the Ural platinum-bearing belt. This provides evidence for the occurrence of massifs of such a type east of the Platinum-bearing belt over the entire width of the Ural orogenic region. In addition to distinct features common with those of the Platinum-bearing belt rocks, the rocks of the Davydovskii massif show some specific characteristics including lower alkali, vanadium, and light REE and higher nickel and, especially, chromium contents. Titanomagnetite-rich (ore) clinopyroxenite varieties, which are widespread in the Platinum-bearing belt, are missing in the Davydovskii massif. These differences mirror a lateral geochemical zoning, which was probably related to an increase in the degree of depletion of mantle magma sources beneath the eastern part of the Urals.