Interaction of alongslope and downslope processes in the Alentejo Margin (SW Iberia) – Implications on slope stability

Teixeira, Manuel; Terrinha, Pedro; Roque, Cristina; Rosa, Marcos; Ercilla, Gemma; Casas, David

doi:10.1016/j.margeo.2018.12.011

Cited by 24 publications

(17 citation statements)

References 97 publications

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“…The Le Danois CDS shows similar seismic characteristics by comparing with those in the Gulf of Cádiz (Hernández-Molina et al, 2016) (Fig. 3), along the SW Portugues e margin (Teixeira et al, 2019), in the Landes Plateau (Faugères et al, 2002), in Goban Spur (Delivet et al, 2016) and Porcupine Seabight (Van Rooij et al, 2007). These regions are namely located along the pathways of the MOW/AMW from the proximal to distal sites (Hernández -Molina et al, 2011).…”

Section: Chronostratigraphic Frameworkmentioning

confidence: 62%

Sedimentary evolution of the Le Danois contourite drift systems (southern Bay of Biscay, NE Atlantic): A reconstruction of the Atlantic Mediterranean Water circulation since the Pliocene

et al. 2020

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The evolution of the Le D anois contourite depositional systems (CDS) during the Pliocene and Quaternary was investi gated bas ed on high-resolution s eismic reflection data. From old to young, six seismic units (U1 to U6) bounded by major discontinuiti es (H1 to H6) were identified. Regarding variations of the bottomcurrent circul ation, four evolution stages of the Le Danois CD S were identified, includi ng onset (~5.3 to 3.5-3.0 Ma), initial (3.5-3.0 to 2.5-2.1 M a), intermediate (2.5-2.1 to 0.9-0.7 M a) and drift-growth (0.9-0.7 Ma to present day) s tages. The CD S associated wi th the Atlantic Mediterranean Water (AMW) along the middle continental slope initiated at ~3. 5-3 Ma and was widely built after the Mid-Pl eistocene Transition (MPT; 0.9-07 M a). At a s hallower water depth, a second CD S associated with the Eastern North Atl antic Central Water (ENACW) s tarted to develop from the late Quaternary (~0.47 M a) onwards. In the AM Wrelated drift system, the Le Danois Drift was generated both under glaci al and interglacial climatic oscilations. Repeated internal s tructures in uni t 5 that consist of acoustically transparent lower parts, moderate amplitude upper parts and high amplitude erosional surfaces at the top, are compared with interglaci al/glaci al cycles since the middle Pleistocene to the pres ent day. These cyclic features suggest coarsening-upward sequences of the Le Danois Drift and processes rel ated to enhanced AMW duri ng glacial stages. The es timated s edimentation rate of the Le Danois CDS reached a maximum duri ng the MPT (at leas t ~27 cm/ky) and then decreased until present-day (~5 cm/ky). Vari ations of sedimentary stacking patterns and processes of the Le Danois CDS imply full domination of the intermediate water mass along the central Atlantic and southwest European conti nental slopes from the late Pliocene (~3.5-3.0 Ma) onwards.

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Section: Chronostratigraphic Frameworkmentioning

confidence: 62%

Sedimentary evolution of the Le Danois contourite drift systems (southern Bay of Biscay, NE Atlantic): A reconstruction of the Atlantic Mediterranean Water circulation since the Pliocene

et al. 2020

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“…In deep-water settings, submarine canyons can be swept by focused tidal currents with up and down flows and velocities of 25-50 cm/s [142]. Moreover, an increasing number of studies (e.g., [142,[155][156][157][158]) have highlighted that several intermittent oceanographic processes can affect the seabed: eddies, gyres, helical flows, benthic storms, cascading dense shelf water, internal waves, and currents related to extreme, cyclonic, and tsunami waves.…”

Section: Bottom Currentsmentioning

confidence: 99%

“…At small spatial scales, they generate various erosional and depositional bedforms, ranging in size from centimeters to kilometers (see, e.g., [151,159]) (Figure 7c,f-h) and whose identification is particularly relevant for geohazard assessments of seabed infrastructure. At a larger scale, bottom currents with persistent activity on a geological time scale (e.g., thermohaline-induced currents) may form regionally extensive contourite depositional systems [158,[160][161][162][163], including a variety of depositional elements (contourite drifts) (Figure 7a) and erosional elements (contourite channels, furrows, moats, and erosive terraces).…”

Section: Bottom Currentsmentioning

confidence: 99%

“…Recognition of the potential hazard of deep-water bottom currents is increasing because new and large seafloor areas of contourites have intensively eroded during the last 15 years due to mobile seafloors and slope sedimentary instabilities, which have been mapped (e.g., [150,155,158,160,162,177]). The assessment of the role of bottom current activity as a hazardous process is challenging for geoscientists due in part to the need to establish a dialogue with physicist oceanographers (e.g., [162]); as it is necessary to define flow conditions, induced bed shear stress and effects on morpho-sedimentary processes affecting the seabed, as well as their evolution over time.…”

Section: Bottom Currentsmentioning

confidence: 99%

“…The two laser lines are separated 50 cm; (i) diagramshowing the intrinsic and hazardous properties of contourite deposits that may contribute to slope failures. Figure7a-e,iwas adapted with permission from[158]. Copyright 2019, Elsevier.…”

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Offshore geological hazards can occur in any marine domain or environment and represent a serious threat to society, the economy, and the environment. Seismicity, slope sedimentary instabilities, submarine volcanism, fluid flow processes, and bottom currents are considered here because they are the most common hazardous processes; tsunamis are also examined because they are a secondary hazard generated mostly by earthquakes, slope instabilities, or volcanic eruptions. The hazards can co-occur and interact, inducing a cascading sequence of events, especially in certain contexts, such as tectonic indentations, volcanic islands, and canyon heads close to the coast. We analyze the key characteristics and main shortcomings of offshore geological hazards to identify their present and future directions for marine geoscience investigations of their identification and characterization. This review establishes that future research will rely on studies including a high level of multidisciplinarity. This approach, which also involves scientific and technological challenges, will require effective integration and interplay between multiscale analysis, mapping, direct deep-sea observations and testing, modelling, and linking offshore observations with onshore observations.

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Geotechnical properties of Sines Contourite Drift sediments: their contribution to submarine landslide susceptibility

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Interaction of alongslope and downslope processes in the Alentejo Margin (SW Iberia) – Implications on slope stability

Cited by 24 publications

References 97 publications

Sedimentary evolution of the Le Danois contourite drift systems (southern Bay of Biscay, NE Atlantic): A reconstruction of the Atlantic Mediterranean Water circulation since the Pliocene

Sedimentary evolution of the Le Danois contourite drift systems (southern Bay of Biscay, NE Atlantic): A reconstruction of the Atlantic Mediterranean Water circulation since the Pliocene

Offshore Geological Hazards: Charting the Course of Progress and Future Directions

Geotechnical properties of Sines Contourite Drift sediments: their contribution to submarine landslide susceptibility

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