Petrological and geochemical features of the Tashly-Tau ore-bearing massif (Khudolaz complex, South Urals)

Abstract

Petrographic and petrological-geochemical studies of the Tashly-Tau ore-bearing massif rocks of the Khudolaz complex have been carried out. It was revealed that the rocks are rich in hornblende and can be called olivine plagiogornblendites. They are characterized by high concentrations of LILE (Cs, Rb, Sr, Ba) and low concentrations of HFSE (Nb, Ta, Zr, Hf, REE). It was established by geochemical thermometry that the parental magma was a water-saturated, moderate magnesian melt containing olivine phenocrysts in an amount of 16-18 wt.%. Sr-Nd isotopic data (sNd (Т) = + 5.2... + 10.3, sSrUR (Т) = 0... + 3.72) indicate a weak crustal contamination of the parental melt by upper crust. The source of the parental melt could be a PREMA-type mantle reservoir.