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Parize, Olivier1, Gerard Friès2, Jean-Loup Rubino3, Luc-Georges Bulot4, Patrice Imbert5, Nicolas Fiet6, Jean-Louis Latil7
(1) Ecole des Mines de Paris, Fontainebleau, France
(2) Institut Français du Pétrole, Rueil Malmaison, France 
(3) Total, Pau, France 
(4) Université de Montpellier-Languedoc, Montpellier, Georgia
(5) Total, Houston, TX 
(6) Université d'Orsay - Paris Sud, Orsay, France
(7) -, Lazer, France

ABSTRACT: Middle Cretaceous Deep-Water Vocontian Deposits (SE France): an Alternative Upper Slope Sedimentation Model

The Vocontian Domain - external part of Western Alps, South-eastern France - is the preserved and well-exposed upper slope domain of the Tethysian palaeomargin. Aptian and Albian series consist of marl and marly calcareous pelagic facies with a wide range of gravity-driven deposits: marly to sandy slumps, numerous debris flow deposits, turbidite packages and massive sandstones. These are followed over 80 km down slope from the shelf edge and are up to 100 metres thick. Thus we can propose an upper slope sedimentation model on the ground of intensive field work and robust biostratigraphic knowledge. This model is an alternative to (i) passive margin, delta-fed, mud-rich models or (ii) compressive foreland basins, sand rich models. Key elements of this Vocontian model are: - an emphasis on lowstand slope erosion and complex morphologies controlled by contemporaneous tectonics and salt or shale diapirism, - slope deposition in confined erosional and structurally-controlled conduits, - large mud-dominated slumps and transitional debris flow deposits, with their correlative sandy turbidites, - sandstone facies derived from shelf/upper slope well sorted sand stores, resulting of the shelf or contour currents reworking, - per ascensum or per descensum sandy injectites (sills and dykes) genetically linked with massive sandstone facies, - slight down-slope evolution of flows with the nature of the source sediment determining flow behaviour and deposit characteristics, - sequence boundaries on the slope which may be associated with the base of either large muddy debris flows or sandy turbidite packages or even black shale horizons.


AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.