Geomorphological analysis on the Alentejo Margin: features and processes

IX Simpósio sobre a Margem Ibérica Atlântica (MIA 2018) - IX Simposio sobre el Margen Ibérico Atlántico - IX Symposium on the Iberian Atlantic Margin, 4-7 September de 2018, Coimbra.-- 2 pageThe Alentejo Margin is a geomorphological complex area, where the interaction of bottom-currents with the irregular seafloor and gravitational processes creates a set of different along-slope and downslope-driven sedimentary features, such as drifts, moats, sediment waves, gullies and landslides scars and debris flow deposits. These features have been identified through the analysis of multibeam bathymetry and multichannel seismic data. Several landslide scars appear in the area, mostly in the western side of the contourite drift near the steep-slope Pereira de Sousa Fault scarp, with areas ranging from 0.15 to 40.3 km2, and volumes ranging from 0.01 to 6.34 km3. Thick debris flow deposits accumulate in the Lebre Basin (LB), downstream the scars, being fed by gullies coming from upstream with ~30 to ~120 m depth and ~2 km to ~20 km length. A ~2311-km2 contourite drift, with a ~84-km length moat, eastwards, is deposited by the Mediterranean Outflow Water (MOW), which creates sediment waves with varied extensions (~9 to 32 km) on this drift. The geomorphology of the Alentejo margin reflects a complex multi-process interaction, including bottom-current circulation, gravity-driven processes and tectonics. The interac tion between these processes favoured active slope instabilityThis work was supported by Fundação para a Ciência e Tecnologia through project CONDRIBER (FCT – PTDC/GEO GEO/4430/2012) and by Ciencia y Tecnologías Marinas through project MOWER (CTM (2012)-39599-C03-02). Manuel Teixeira benefits from a Ph.D. scholarship provided by FCT - Fundação para a Ciência e Tecnologia (SFRH/BD/110674/2015). Sara Rodrigues benefits from a Ph.D. scholarship provided by BP to the Joint Industry Project of “The Drifters Research Group” at Royal Holloway, University of London (UK). Manuel Teixeira thanks the Commission of Marine Geology of the Geological Society of Spain for funding the inscription in the Symposium on the Iberian Continen tal Margin - MIA2018. Publication supported by FCT- project UID/GEO/50019/2013 - Instituto Dom LuizPeer reviewe