Литосфера (Oct 2015)
Garnet-glaucophane schists of Tashlinsky block from Maksyutov complex (Southern Urals)
Abstract
On the basis of newest mineralogical, petrological and isotope-geochemical data we have considered the condition and the nature of garnet-glaucophane schists, associated with antigorite serpentinites. This rocks are localized in the lower part of antigorite serpentinites, which was never observed in other areas of the complex. Petrological and geochemical characteristics and mineralogical features of zircons indicate that the garnet-glaucophane schists relate to protolite which had substratum the diopside gabbro with age about 670 Ma. Isotope dating of zircons ((444.9 ± 4.7)-(401.1 ± 5.2) Ma), glaucophanes (406.0 ± 4.6 Ma) and phengites (393.1 ± 3.8 Ma) from garnet-glaucophane schists suggest that blueschist facies metamorphism in the lower part of the Taschlinsky block ( T = 455-544°C, P = 9.5-12 kbar) have been developed before eclogite crystallization in metaterrigene unite of Maksutov complex dated 323 ± 8.8 Ma by the zircon and 333.0 ± 4.6 Ma by the glaucophane. Studies of formation of the metabasite includes in the upper part serpentinites indicate to higher P-T metamorphism, that probably compare with Utarbayevo mafit-ultramafit unite. Recently date evidences that the Taschlinsky block forms the independent part of the Maksyutov complex that have variety specific features indicating to need corrections in the traditional schema of the evolution metamorphism and tectonic event of their generation.
