C-axis fabrics of quartz-ribbons during high-temperature deformation of syn-tectonic granitoids (Sila Massif, Calabria, Italy) |
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Authors: | Vincenzo Festa |
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Institution: | aDipartimento Geomineralogico, Università degli Studi di Bari, Via E. Orabona 4, 70125 Bari, Italy |
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Abstract: | Late-Hercynian, high temperature (HT) shear deformation affected the zone straddling the contact between the Sila Massif batholith (above) and the host migmatitic paragneisses (below). A segment of the regional HT shear zone was investigated close to the town of Mesoraca, where a natural section allows one to analyse the solidus deformation of syn-tectonic granitoids. Shearing favoured the formation of polycrystalline quartz ribbons in deformed granodiorite and tonalite. Two main c-axis fabrics were found in the quartz-ribbons, different from each other by opening angles around Z between strong point maxima, in accordance with deformation under granulite to amphibolite facies conditions. These fabrics, along with microstructural observations, suggest that temperature of deformation played a key role and that ribboning was accompanied by the activation of (i) prism c] slip and prism c] + prism <a> slips, under granulite facies conditions, followed by (ii) basal <a> and prism <a> slips under amphibolite facies conditions. |
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Keywords: | Quartz Ribbons c-axis fabrics Granitoids Shearing Granulite facies Amphibolite faciesMots clé s: Quartz Rubans Fabrique des axes c Granitoï des Cisaillement Faciè s granulite Faciè s amphibolite |
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