Alluvial Fan to Gilbert-type Fan Delta Dynamics of the Corinth Rift (Greece): Field Studies and Numerical Modeling

Sebastien Rohais, Geology-Geochemistry-Geophysics, Institut Français du Pétrole, 92852 Rueil Malmaison Cedex, France, phone: 00 33 1 47 52 52 79, sebastien.rohais@ifp.fr, François Guillocheau, Geosciences Rennes, Rennes University, Campus de Beaulieu, Rennes, 35042, France, Rémi Eschard, Geology-Geochemistry-Geophysics, IFP, 1 & 4, avenue de Bois-Préau, Rueil Malmaison, 92852, France, and Mary Ford, Centre de Recherches Petrographiques et Geochimiques, ENSG-CRPG, 15 rue Notre-Dame des Pauvres, B.P. 20, VANDOEUVRE-LES-NANCY Cedex, Nancy, 54501, France.

The architecture of Gilbert-type fan deltas exposed along the uplifted southern coast of the Gulf of Corinth has been reviewed using an integrated approach based on field observations and numerical modelling. Previous numerical modelling has concentreted on geometries developed at the offlap break. Based on studies of the Evrostini and the Ilias fan deltas (Akrata-Derveni region), we consider the whole delta from topsets to distal turbidites. Stratigraphic simulations using DIONISOS software are used to define the relative role of five controlling factors on stratigraphic architecture (sediment supply, water supply, subsidence, eustasy, lithologic ratio).

Three main types of depositional system are defined based on internal geometry and relation with bounding basal surfaces. The first system type is characterised by continuous vertically aggrading topsets that laterally pass to aggrading-prograding foresets. Bottomsets and distal turbiditic systems are poorly developed. The second system type is characterised by a lack of topsets and the development instead of a by-pass surface, thick foresets and bottomsets, and thick, distal turbiditic systems. The third system is characterised by small-scale (2 to 10 m) deltas prograding above stacked topsets. The offshore is characterised by the development of thinly bedded fine-grained sandy turbiditic systems.

Restoration of the stratigraphic geometry using DIONISOS suggests that eustasy to subsidence rate ratio is the first order controlling parameter on stratigraphic architecture at this scale. Sediment supply variations induce finer scale geometries but cannot be responsible for large-scale depositional system types. Water supply, and lithologic ratio variations can cause very fine geometric variations.

New and Emerging Plays from the Circum Mediterranean Region I
AAPG & AAPG European Region Energy Conference and Exhibition (November 18-21, 2007) Technical Program