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

PHASE RELATIONS IN OLIVINE-ORTHOPYROXENE-CHLORITE-SPINEL-HORNBLENDE METAULTRAMAFICS FROM THE MALA FATRA MTS., WESTERN CARPATHIANS

Pages: 369 - 376

Authors: SERGEI P. KORIKOVSKY, MARIAN JANAK, BRANISLAV LUPTAK

Abstract: Metaultramafic rocks from the Mala Fatra Mts. (Western Carpathians) preserve mineral assemblages characterized by coexistence of hercynitic spinel, Ca-amphibole (Mg-hornblende), Mg-rich chlorite, olivine (forsterite) and orthopyroxene (enstatite). A large amount of hercynite and Ca-amphibole (up to 30–40 % ) is characteristic. Prograde metamorphism reached P-T conditions close to the equilibrium chlorite = forsterite + enstatite + spinel + H2O and the upper stability of Ca-amphibole which corresponds to the temperature of about 700–800 °C in the model system CMASH. Retrograde reactions lead to the replacement of spinel by secondary chlorite, orthopyroxene by talc and olivine by serpentine. Metaultramafic rocks in the Mala Fatra Mts. reached the conditions of the upper amphibolite facies. They most probably represent the fragments of metaperidotites, attached to the lower continental crust during Variscan tectonometamorphic events.

Keywords: Western Carpathians, Mala Fatra Mts., Variscan orogeny, high-grade metamorphism, phase equilibria, metaultramafic rocks

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