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Sedimentary and Geodynamical 2D-3D Modeling of the Provence Continental Shelf during Mio-Pliocene Eustatic Events

Aurelie Tassy, François Fournier, Jean Borgomano, Bruno Arfib, and Isabelle Thinon

Provence continental shelf is a complex geological domain situated between the Alpine arc and the continental margin of the Liguro-Provençal back-arc basin which was influenced by the high amplitude Neogene eustatic changes, especially during the Messinian Salinity Crisis (MSC). Offshore Cassis Calanques, Cassidaigne Canyon deeply (>1700 m) incises the narrow (7-20 km) Provence continental shelf. Onland, the higher elevation of wave-cut surfaces and marine Miocene deposits matched up to Mio-Pliocene eustatic levels, evidences topographic anomalies suggesting that Provence margin geodynamic was controlled by tectonic processes.

The objectives of the study are to constrain the large wavelength deformation rate of the topography and to constrain the chronology of landscape evolution from land to sea. The topographic variations are estimated by integrating geomorphology, sedimentology and structural geology of the Provence continental shelf. this approach consists in (1) reconstructing the Messinian-Pliocene eustatic signal given by a 2D sismostratigraphic analysis of Messinian incisions sedimentary filling, and (2) paleo-topographic restorations in a 3D model that integrates eustatic signal and large wavelength tectonic deformation.

Cassidaigne Canyon sedimentary functioning study is performed together with the Bandol Canyon that is genetically linked. Two hypothesis of stratigraphic modeling are discussed to explain the sedimentary filling of these canyons using some key newly acquired seismic profiles.

A land to sea 3D topographic model of the Provence continental shelf was performed in the gOcad software, which integrates all sedimentary strata and geomorphologic benchmark levels localized on the continental shelf since the end of the Miocene. Paleo-topographic restorations of the 3D model evidence a tilting of the margin from SW to NE and reliefs rejuvenization (from 300 to 600 m mean Tortonian massifs elevation to 500 to 1100 m at present-day). Since the Miocene, Provence Continental Shelf is localized at the transition zone between the Gulf of Lion subsided margin and the Ligurian uplifted margin. Consequently, the Provence Margin land-sea topography is acquired since the Miocene and is part of the Mediterranean regional geodynamics.

This Bandol-Cassidaigne Canyons sedimentary study has implications on the sedimentary and petroleum geology of the more distal areas in the Gulf of Lion.

AAPG Search and Discovery Article #90161©2013 AAPG European Regional Conference, Barcelona, Spain, 8-10 April 2013