Mauritania Slide Complex: morphology, seismic characterisation and processes of formation

Abstract

Recently acquired Parasound and high resolution multi-channel seismic reflection data have afforded a more detailed investigation of the Mauritania Slide Complex. The slide is more complex than previously reported, and has affected an area in the order of 34,000 km 2 between~600 and > 3,500 m water depths. The ovate-shaped slide displays a long run-out distance > 300 km. Slide formation was pre-conditioned mainly by uninterrupted deposition of upwelling-induced organic-rich sediment in an open slope environment which gave rise to rapid accumulation of poorly consolidated bedded sediment intercalated with thin weak layers. The stages of slide development were characterised by multiple failure events probably occurring mainly as retrogressive sliding which exploited widespread weak layers as glide planes. The study suggests excess pore pressures as being the most important trigger mechanism for slide formation. Earthquakes associated with nearby Cape Verde Islands may have played a mostly complementary or, at one time, a leading role in triggering sediment failures. Diapiric growths have locally triggered minor instability events which resulted in remobilizing of preexisting debris flows as well as translational sliding. The combined activities of all these triggering factors are the most like cause of the complex morphology of the Mauritania Slide Complex.

Cold-water coral banks and submarine landslides: a review

“…As no large failures are observed upslope of the coral bank ridge (Antobreh and Krastel 2007), as the mounds are rooted on a lower reflector than the slide plane, and as the headwall scarp and the mound ridge are closely related in shape and location, it is suggested here that the mound ridge may have stopped the retrogression of the complex landslide (Fig. 7).…”

“…These failures deposited huge debris flow units towards the Gambia Abyssal Plain and adjacent fracture zone valley . In general, the central Mauritanian margin is not affected by sliding at water depths shallower than 600 m. To the south of the study area, a stretch of the coral bank province coincides with the MSC headwall scarp at this depth (Antobreh and Krastel 2007). Where this occurs, the seafloor is characterised by an intricate morphology composed of slide scars, detached blocks and gullies.…”

“…Where this occurs, the seafloor is characterised by an intricate morphology composed of slide scars, detached blocks and gullies. Upslope of the mound ridge, several local bathymetric features form an arc-shaped feature indicative of seabed crown cracking that might correspond to the initial stages of a new retrogressive slide phase (Antobreh and Krastel 2007;Colman et al 2005). …”

“…The inset shows a detailed shaded relief map illustrating mound shapes, associated moats and slope failures. Locally, the mounds developed in two parallel ridges (modified from Colman et al 2005) diapiric uplift (Antobreh and Krastel 2007). These failures deposited huge debris flow units towards the Gambia Abyssal Plain and adjacent fracture zone valley .…”

Architecture and sediment dynamics of the Mauritania Slide Complex

“…Top: sedimentary features in the area of the Mauritania Slide Complex (modified after Antobreh and Krastel, 2007).…”