Abstract
In Central Mediterranean, Sicily is known for its intense volcanic activity (Mount Etna, Aeolian Islands) and its major historical earthquakes (Noto, 1693, M 7.4 ; Messina, 1908, M 7.1). These events reflect a particularly active geodynamic context, controlled by deformation mechanisms and interactions between deep tectonics and surface processes (erosion, sedimentation) that are still poorly understood.During the Mesozoic, the opening of the Neo-Tethys, between the future Europe and Africa plates, shaped the geometry of the surrounding continental margins, particularly in the North African domain. The Alpine Tethys, the western branch of this ancient ocean, closed during the Cenozoic through a system of fast subductions and collisions developing in a context of slow convergence between the Africa and Eurasia plates. The Calabro-Sicilian Arc, and more generally the Apennines-Maghreb system, result from the retreat of the Alpine Tethys, followed by the continental subduction of the African and Apulian margins under the AlKaPeCa continental blocks (Alboran, Kabylia, Peloritan and Calabria) with the African and Apulian margins. These micro-continental blocks, derived from the European margin, accompanied the slab rollback towards the South-East, localizing at their front the accretion of the Alpine Tethys sedimentary cover and opening in their wakes a series of back-arc basins (Algerian-Provençal and Tyrrhenian basins). From North to South, Eastern Sicily is divided into four tectono-stratigraphic domains : 1) the Peloritain-Calabria block, detached from the Corso-Sardinian micro-continent since the opening of the Tyrrhenian 15 Ma ago, 2) the pelagic sediments of the Alpine Tethys, remnants of the oceanic accretionary prism, 3) the Meso-Cenozoic cover of the African margin accreted since the Middle Miocene, and 4) the present day foreland represented by a thick carbonate platform (Hyblean Plateau), separated from the Ionian domain by the Malta Escarpment.This thesis focuses on the crustal deformation processes and their interactions with deep dynamics based on the analysis of geological, geophysical and morpho-structural data, coupled with analytical and analogue modeling. My work first led to a new interpretation of the origin of the Hyblean Plateau (SE of Sicily). This sub-circular topographic anomaly, 1000 m high and 80 km in diameter, is inherited from an uplift phase that started in the Late Miocene, simultaneously with major magmatic episodes in this region. Unlike the commonly evoked flexural model, most of the uplift is probably related to magmatic intrusions deforming the thick Meso-Cenozoic carbonate cover. Analogue models mechanically validated the hypothesis of a tectono-magmatic scenario at the origin of the present day morphology and outlined the major effect of structural inheritance in the localization of the subsurface deformation. Based on a critical review of the available geological data, I also proposed a new tectono-stratigraphic reconstruction of the Sicilian Fold-and-Thrust Belt. Once again, analogue modeling provided strong constraints on the African margin paleogeography and mechano-stratigraphy, as well as the dynamics of the deformation and the tectonic-erosion-sedimentation interactions involved in the building of the Sicilian orogenic prism. Finally, I studied the transition zone between the Sicilian Belt and the Calabrian Prism, in its four dimensions, in order to specify the current kinematics of this potentially highly seismogenic region. Based on bathymetric and seismic data, the mechanisms of the deformation at the origin of the onshore and offshore fault networks are explained by the dynamics imposed by the lower plate and those resulting from the migration of the Calabrian Arc and the oceanic accretionary prism towards the Southeast.