High pressure alpine metamorphism of the Pelagonian allochthon in the Kastania area (Southern Vermion), Greece
(EN)
MPOSKOS, E.
PERRAKI, M.
The Pelagonian allochthon in the Kastania area (Southern Vermion) consists of pre-alpine and alpine rocks that underwent two episodes of Alpine HP/LT metamorphism. The first episode, of Lower Cretaceous age, is represented by the mineral assemblages: Quartz-albite-microcline-phengite±garnet-clinozoisite± biotite±rutiletitanite in orthogneisses and the Kastania metagranite and garnet-chloritoid-chlorite±kyanite-white K-micaparagonite- rutile in high alumina metapelites. Pressures, were estimated at TO kbar at 500 °C, applying the phengite geobarometry and more than 22 Kbar, calculating the reaction Grt+Rt+Qtz+W®Ttn-l-Czo, occurred in the Kastania metagranite during decompression. Recrystallization at albite-epidote-amphibolite facies conditions accompanied by penetrative deformation defines the dominant mineral assemblages and textures in orthogneisses, metapelites and metabasites. The second metamorphic episode of a probable Eocene age occurred under blueschist/greenschist facies conditions and produced fine-grained phengite, stilpnomelane, green biotite and blue amphibole in orthogneisses and amphibolites.
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