Impact of the Messinian Salinity Crisis and Related Residual Bathymetric Relief on the Structural Evolution of the Nile Deep-Sea Fan, Eastern Mediterranean

Lies Loncke¹, Gaullier Virginie², Mascle Jean³, Vendeville Bruno⁴, and Camera Laurent³. (1) UMR 8110, Université de Picardie Jules Verne, Laboratoire Sciences de la Terre, 33, rue de St Leu, Amiens, 80000, France, phone: (33) 3 22 82 76 39, lies.loncke@u-picardie.fr, (2) LEGEM, Université de Perpignan, 52 avenue Paul Alduy, Perpignan, 66860, France, (3) Géosciences Azur, Observatoire Océanologique de Villefranche-sur-Mer, BP 48, Villefranche-sur-mer, 06235, France, (4) UMR 8110, université de Lille 1, Cité scientifique, bâtiment SN5, Villeneuve d'Ascq, 59655, France

The Messinian salinity crisis had two main consequences on the structural evolution of the Mediterranean basins and margins. First, deposition of large volumes of halite-rich evaporites led to vigorous salt tectonics during Plio-Quaternary times. Second, intense erosion modified the physiography of the margins and introduced rheological contrasts within the sedimentary overburden (mobile evaporites versus non-mobile, clastic evaporites). The Nile deep-sea fan has a complex present-day deformation pattern: this includes structures typical of salt-bearing margins (upslope growth faults, minibasins, diapirs, and contractional folds and thrusts). However, the strike of some of these salt-related structures, and the presence in the eastern province of a 200 km long, NW-SE-trending tectonic corridor suggest that there is some deep-seated controls. Combined analysis of seismic data and physical experiments have shed light on how the Messinian paleobathymetry has influenced the fan's later evolution. First, the paleobathymetry controlled the boundary between a downslope mobile zone (underlain by salt) and an upslope, non-mobile zone (made of Messinian badlands and detrital cones). This boundary, which is partly structurally controlled, is sinuous and is marked presently by the upslope limit of growth-faults, whose traces are parallel to this limit (hence oblique to the slope direction). Second, paleo-Messinian topographic highs located in the basin, such as the Eratosthenes seamount have acted as rigid buttresses that later influenced the pattern and movement directions during gravity spreading and gliding. Therefore, the only deep-seated control acting on the actual physiography, lies in inherited paleo-Messinian relief interfering with salt tectonics.

New Insights into Circum-Mediterranean Basins I
2005 AAPG International Conference and Exhibition (September 11-14, 2005) Technical Program