Mafite-ultramafites (Peridotitovy stream, Polar Urals): mineralogy, estimation of P-T-parameters of formation

The petrographic features and conditions of the formation of metamorphosed mafic-ultramafic rocks of the Ampelshor complex, which are part of a small massif in the southern part of the Marunke u block of the Polar Urals (Peridotitovyi stream) and are controlled by tectonic thrust faults, have been studied. Muscovite-albite-clinozoisite-amphibole rocks (metabasites) and pyroxene-amphibole-chlorite (metautramafic) rocks are described. Structural, textural, and mineralogical features of metamagmatites indicate the hypabyssal nature of metabasite and plutonic nature of metaultramaphite. In metabasites, primary minerals are represented by relics of amphiboles (pargasite, edenite), and in metaultramaphites - by olivine and, possibly, clinopyroxene (augite, diopside). Magnesiohastingsite and chermakite in metautramafite were formed either at the late magmatic or metamorphic stages of rock transformation. The studied rocks underwent low-temperature changes (t - 468-380 °C, P - 2-3 kbar), corresponding to the greenschist metamorphic facies.