High-pressure-low-temperature metamorphism and polyphase alpine deformation at Sant'Andrea di cotone (eastern corsica, france)

Abstract

Abstract A quarry, located in the “Schistes lustres” of eastern Corsica, has been studied in detail for both structural geology and metamorphic petrology. The superimposed structures belong to three successive generations. For each generation, folds, foliations, lineations and behaviour of metamorphic minerals are briefly described. Attention is devoted to the connection between deformation—recrystallization processes of minerals in thin section and macroscopic contrasts in ductility. Typical HP—LT metamorphic minerals were developed during the two first generations of structures and were little transformed during the third, Clinopyroxenes, garnets, blue amphiboles, phengites, chlorites, stilpnomelane, piemontite, lawsonite, pumpellyite and deerite occur in different lithologies. P—T conditions of metamorphism are estimated to 8 kbar and 300°C. fO2 and XCO2 in metamorphic fluids are specified. Furthermore, evolution and behaviour of metamorphic fluids are described in this example of HP—LT metamorphism, with emphasis on interactions between these fluids, deformation processes and mineral assemblages.