The Alpine Corsica ophiolites from Inzecca Valley and the Pineto Massif

The Inzecca Zone is located in central-eastern Corsica, at the southern end of the "Alpine Corsica". Along the Inzecca gorge, thanks to the incision produced by the Fium'Orbo River, a good and continuous outcrop is visible. In this area, the tectonic pile is formed by three tectonic units, superposed to each other, from East to West: the Schistes Lustres (Inzecca series: Amaudric du Chaffaut et al., 1972; Caron and Delcey, 1979), the Parautocthonous Unit (Netelbeek, 1951) and the Variscan Basement Unit (Hercynian Corsica). These distinguished tectonic units differ from each other in lithology and petrography and for the metamorphic-deformative Alpine evolution. The tectonic contacts between the different units are subvertical, show strike about N-S and are concordant with the internal attitude in all the studied area. - Schistes Lustres: it comprises meta-ophiolites and their meta-sedimentary cover, whose age ranges from Late Jurassic to Late Cretatceous. In the Inzecca area a complete succession is visible; it includes (from bottom to top): serpentinites, ophicalcites, ophiolitic sandstones, pillow basalts and pillow breccias with intercalations of ophiolitic sandstones, meta-radiolarites, the Erbajolo Formation made by phyillites and marbles of Early Cretaceous age (Amaudric du Chaffaut et al., 1972). They are affected by low HP-LT retrogressed in Green Schistes facies. - Parautocthonous Unit (roches brunesAuctt.): it is constituted by Variscan garnet-biotite-muscovite-plagioclase micaschists (Netelbeek, 1951) of pre- Carboniferous age, (Netelbeek, 1951) with a HP-LT metamorphic imprint, transformed by the Alpine metamorphic-deformative events into sericite-chlorite-pumpellyite-lawsonite schists (Fig. 7). Their texture varies from porphyroclastic to mylonitic towards East, approaching the contact with the Schistes Lustres, but also within local shear zones. The contact between these rocks and the Variscan granite was affected by polyphased transpositive deformation phenomena, which produced a tectonic alternance of the two lithologies. - Variscan Basement Unit: it is represented by a biotite-amphibole Carboniferous monzogranite (Durand-Delga, 1978; Amaudric du Chaffaut et al., 1985). Where local shear zones occur, the rock shows a porphyroclastic to mylonitic texture. The Alpine metamorphic imprint determined the blastesis of stilpnomelane, pumpellyite and white mica and the alteration of the feldspar into sericite. The crystallization of sodic amphibole has locally been observed. The granite is here associated to Permian meta-rhyolites and meta-conglomerates with rhyolitic and granitic clasts. As a result of the Alpine transpositive phenomena, these lithologies appear as plurimetric and pluridecamentric tectonic intercalations in the granite itself.