HR: 0800h
AN: H41F-0840    [Abstracts]
TI: Morphology and Structure of the Algiers Deep-Sea Fan and Possible Sedimentary Record of the 2003 Boumerdès Earthquake (Maradja Project)
AU: Babonneau, N
EM: nathalie.babonneau@univ-brest.fr
AF: Universite de Brest, IUEM UMR6538 Place N. Copernic, Plouzane, 29280, France
AU: Cattaneo, A
EM: antonio.cattaneo@ifremer.fr
AF: IFREMER, Geosciences Marines BP 70, Plouzane, 29280, France
AU: Harster, M
EM: marine.harster@gmail.fr
AF: Universite de Brest, IUEM UMR6538 Place N. Copernic, Plouzane, 29280, France
AU: Deverchere, J
EM: jacques.deverchere@univ-brest.fr
AF: Universite de Brest, IUEM UMR6538 Place N. Copernic, Plouzane, 29280, France
AU: Yelles, K
EM: kyelles@yahoo.fr
AF: CRAAG, Route de l'Observatoire, Bouzareah - BP63, ALGER, 16340, Algeria
AU: Savoye, B
EM: bruno.savoye@ifremer.fr
AF: IFREMER, Geosciences Marines BP 70, Plouzane, 29280, France
AU: * Domzig, A
EM: anne.domzig@univ-nantes.fr
AF: Universite de Nantes, LPG 2 rue de la Houssinière B.P. 92208, Nantes, 44322, France
AB: The Algerian margin is a Cenozoic passive margin along the plate boundary between Eurasia and Africa, presently reactivated in compression. The deformation is expressed by ESE-WNW-aligned inverse faults associated with moderate to large earthquakes. Earthquakes can generate sediment instabilities on the continental slope; for instance, strong turbidity currents are likely responsible of submarine cable breaks observed at the foot of the continental slope, after the Boumerdes earthquake in may 2003. In the Boumerdes-Algiers area, the Algiers canyon is the main sediment pathway from the shelf to the deep sea environment. Since Maradja surveys in 2003 and 2005, high-resolution bathymetric and backscatter images are available over an area of 1200 km along the margin. The morpho-bathymetric interpretation supported by seismic reflection data allowed to identify the Quaternary Algiers deep-sea fan and its main morphological features: the canyon, the main valley, the sedimentary ridge, and the distal deposits confined in mini-basins. The Algiers canyon is characterised by two tributary paths in the upper slope. The maximum incision is about 600 m deep. The canyon fed a 30 km long turbidity valley, spreading westward along the foot of the slope and bordered by the sedimentary ridge on the right side. The sedimentary ridge is covered by large sediment wave features, probably generated by turbidity overflow currents. The Algiers deep-sea fan has a complex structure resulting from the interaction between turbidity sedimentation, compressive tectonic structures and salt tectonic. In the upper part, the morphology of the Algiers canyon and fan is strongly controlled by inverse faults creating morphological highs and scarps. In the distal part, the sea floor morphology is highly deformed by salt diaprism, which control the paths of active sediment transport and the location of deposition area (mini-basins). Sediment gravity cores collected on the deep-sea fan show recent sedimentation in distinct morphological areas. The valley and the ridge present successions of thin-bedded turbidites. In the submarine valley, we collected the most recent turbidite sequences (younger than 100 years, based on 210Pb isotope analyses) in order to evaluate the impact of the 2003 event on the Algiers Fan.
DE: 1810 Debris flow and landslides
DE: 1815 Erosion
DE: 1824 Geomorphology: general (1625)
DE: 1861 Sedimentation (4863)
DE: 1862 Sediment transport (4558)
SC: Hydrology [H]
MN: 2007 Fall Meeting