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

Eclogites overprinted in the granulite facies from the Dumbier Crystalline Complex (Low Tatra Mountains, Western Carpathians)

Pages: 193 - 204

Authors: MARIAN JANAK, TOMAS MIKUS, PAVEL PITONAK, JAN SPISIAK

Abstract: Metabasites with evidence for breakdown of former eclogites and recrystallization under granulite facies conditions occur in the Dumbier Crystalline Complex of the Low Tatra Mountains, Central Western Carpathains. Textural relationships, phase equilibrium modelling and thermobarometry have been used to determine the P-T evolution of these rocks. Omphacite diagnostic for the eclogites facies stage is absent but its former presence is inferred from the symplectitic intergrowths of clinopyroxene+plagioclase. The re-equilibration in high-pressure granulite facies conditions is demonstrated by the assemblage garnet+clinopyroxene (<10 % Jd)+plagioclase+quartz. The phase equilibrium modelling using THERIAK-DOMINO program and conventional geothermobarometry suggest the P-T conditions of 750–760 °C and 1.1–1.5 GPa for the high-pressure granulite stage. Orthopyroxene formed in the clinopyroxene + plagioclase symplectites and kelyphites and coronas around garnet at P-T conditions of ca. 0.7–1.0 GPa and 650–700 °C. P-T evolution of granulitized eclogites is interpreted as the result of two metamorphic events; early Variscan eclogite facies metamorphism was followed by granulite facies thermal overprint in the Carboniferous time. The second metamorphic event was crucial for breakdown of eclogites, these are only seldom preserved in the pre-Alpine basement of the Western Carpathians.

Keywords: Western Carpathians, Low Tatra Mountains, geothermobarometry, phase equilibrium, modelling, granulites, eclogites

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