International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

METAMORPHIC PETROLOGY OF METABASITES FROM THE BRANISKO AND CIERNA HORA MOUNTAINS (WESTERN CARPATHIANS, SLOVAKIA)

Pages: 3 - 16

Authors: SHAH WALI FARYAD, PETER IVAN, STANISLAV JACKO

Abstract: Mineral assemblages in metabasites were used to estimate P-T conditions of pre-Alpine metamorphism in the Branisko and Cierna Hora Mountains which represent the easternmost exposure of the Tatric and Veporic Units. Garnet-pyroxene-bearing metabasites of the Branisko Mountains indicate high-grade metamorphism close to the boundary of amphibolite and eclogite facies conditions. They contain Ca- and Mg-rich garnet (Grs20–32, Py18–20), diopside and plagioclase (An10–40). Garnet contains inclusions of clinopyroxene, plagioclase, ilmenite and K-feldspar. P-T conditions of 732±24 °C and 1.26±0.12 GPa were estimated using various exchange thermometers and equilibrium reactions. Pyroxene forms symplectite with plagioclase and amphibole in the matrix. The high-grade metamorphism was followed by amphibolite facies metamorphism at 650 °C and 0.7–0.8 GPa. Lower temperature and pressure of 610±20 °C and 0.9±0.1 GPa for Variscan metamorphism were calculated from garnet amphibolites in the neighbouring Cierna Hora Mountains. Metamorphic conditions for Alpine metamorphism in the Cierna Hora Mountains were obtained using the mineral assemblages in Permian diorite of the Choc Nappe. They contain prehnite, pumpellyite, epidote, chlorite, albite and white mica, and yield temperature and pressure of 250±25 °C and 0.3±0.02 GPa.

Keywords: Variscan, Alpine metamorphism, Western Carpathians, Branisko, Cierna Hora

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