Sardinia and the Alpine cycle: A tectono-sedimentary history at the Western Tethys edge

Luca Giacomo Costamagna

Primo

In corso di stampa

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Abstract

A tectono-stratigraphic and paleoenvironmental comparison between Sardinia and the coeval surrounding chains allowed to identify and characterize several Alpine-age tectonic events in Sardinia developing from Late Cretaceous to Early Miocene times. This was accomplished through the analysis of new data and the reinterpretation of old ones. Sedimentation and paleogeography were considered. During the development of the Alpine deformations, Sardinia, belonging to the Eastern part of the Grand Iberian Microplate, was on the outskirts of a complex deformation belt. Despite this, Sardinia was involved in significant tectonic events due to the pre-Eocene shift of Iberia and to the following Eocene counterclockwise rotation of a developing independent CorsicaSardinia-Provence-Brianconnais (CSPB) Microplate. The relationships of this Microplate with the close AlKaPeKa Microplate (made of the Alpujarride Domain, the Kabylies, and the Calabrian-Peloritan Arc) remain controversial. During the Paleogene, while Pyrenean piggy-back basins developed in the SW of Sardinia, an early Alpine (Apenninic)-related flexural basin developed close to the NE. Particularly during the Eocene, tectonic movements affecting sedimentation were caused by separate kinematic interactions of the Corsica-Sardinia area with the European Plate to NW, to the Alpine W-verging contraction (E-dipping subduction) area in the NE, and to the Iberian Plate to SW. The several Eocene Pyrenean compressive and Alpine (Apenninic) transpressional phases were almost coeval in the different sectors of Sardinia. Still, while in the Western sector of the Island, only the Pyrenean Phase took place, in the NE sector, the Alpine(Apenninic) phase superposed over the previous Pyrenean Phase. These deformations conditioned the CSPB Microplate evolution of the NW Mediterranean area. Thus, the destiny of Sardinia first intertwined with Iberia and then, after Eocene times, with S Europe. This last connection was terminated during Late Oligocene - Early Miocene times by the opening of the Algero-Provencal basin and the following separation of the Corsica-Sardinia block from the European plate.