Quaternary Turbidite Systems Along the Algerian Margin: Morphology and Structure of the Kramis and Algiers Deep-Sea Fans (Maradja Project)

Nathalie Babonneau¹, Bruno Savoye², Antonio Cattaneo², Audrey Nougues¹, Karim Yelles³, and Jacques Déverchère^1
1Domaines océaniques, Brest University, Brest, France
²Géosciences Marines, IFREMER, Brest, France
³CRAAG, Alger, Algeria

The Algerian margin is located along the Eurasia-Africa plate boundary, presently reactivated in compression. Since 2003, high-resolution bathymetric and backscatter images are available over an area of 1200 km along the margin and complemented by HR seismic reflection profiles.

The submarine slope morphology is characterised by numerous deep canyons and gullies, indicating highly efficient sediment transport by gravity processes, from the shelf break to the deep basin. Morphological and sedimentological studies of the margin suggest that several types of gravity deposits occur: slump and debris-flow characterised by sediment motion of a few kms and large turbidity currents flowing over hundreds of kms and building large deep-sea fans.

The Kramis and Algiers fans are two examples of turbidite systems of the Algerian margin. They have both a complex structure resulting from the interaction between turbidity sedimentation, compressive tectonic structures and salt tectonic.

In the Boumerdes-Algiers area, the Algiers canyon feeds a 30 km long submarine valley, spreading westward along the foot of the slope. The valley is bordered on its right side by a well developed sedimentary ridge. The morphology of the Algiers canyon and upper fan is strongly controlled by inverse faults creating morphological highs and scarps. In the distal part, the seafloor morphology is highly deformed by salt diaprism, which control the paths of active sediment transport and the location of deposition area (mini-basins).

In the western part of the Algerian margin, the Kramis fan is fed by two perpendicular canyons merging into a submarine valley. This westward flowing valley is bordered on its right side by a sedimentary ridge displaying spectacular sediment wave fields. Distally, sediment waves are very erosional suggesting the occurrence of strong overflow turbidity currents.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas