Submarine landslides on a carbonate platform slope: forward numerical modelling of mechanical stratigraphy and scenarios of failure precondition

Busson, Jean; Télès, Vanessa; Mulder, Thierry; Joseph, Philippe; Guy, Nicolas; Bouziat, Antoine; Danquigny, Charles; Poli, Emmanuelle; Borgomano, Jean

doi:10.1007/s10346-020-01510-7

Cited by 8 publications

(8 citation statements)

References 93 publications

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“…For the carbonate margin, the hydraulic conductivity distribution in Figure 4b is similar to the permeability distribution modeled for the Great Bahamas Bank by Busson et al. (2021). We do not have information on groundwater distribution on the platform, but on the slope the modeled salinity distribution in Figure 6e matches salinity measurements in boreholes from ODP Expedition 166.…”

Section: Discussionsupporting

confidence: 80%

“…The models use a single permeability value for each facies, and, being 2D, do not take into account variability in shore‐parallel sediment and flow regimes. They also ignore cementation, although this was shown to have a second‐order influence on the pore fluid pressure regime and instability in carbonate settings (Busson et al., 2021). The critical yield strength changes with depth, but we have ignored this effect in the slope stability models.…”

Section: Discussionmentioning

confidence: 99%

“…Pore pressure fluctuations and focused fluid flow can lower the consolidation state of sediments and deform them via processes such as creep, liquefaction, fluidization, piping, hydrofracturing, and the development of shear zones (Bull et al., 2009; Kopf et al., 2016; Moernaut et al., 2017; Nardin et al., 1979). In carbonate margins, overpressure development in sub‐seafloor aquifers during a relatively rapid sea‐level fall has been proposed as a trigger of large‐scale failures, which, in low‐angle submarine slopes, are thought to have emplaced megabreccias (Busson et al., 2021; Spence & Tucker, 1997). In volcanic islands (e.g., Hawai'i), Iverson (1995) suggested that topographically controlled meteoric groundwater and sea‐level fluctuations can only generate the groundwater seepage forces required to cause flank collapse in special circumstances (e.g., the occurrence of a buried clay layer under the growing weight of a volcanic edifice).…”

Section: Introductionmentioning

confidence: 99%

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Can Offshore Meteoric Groundwater Generate Mechanical Instabilities in Passive Continental Margins?

et al. 2023

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Offshore meteoric groundwater (OMG) has long been hypothesized to be a driver of seafloor geomorphic processes in continental margins worldwide. Testing this hypothesis has been challenging because of our limited understanding of the distribution and rate of OMG flow and seepage, and their efficacy as erosive/destabilizing agents. Here we carry out numerical simulations of groundwater flow and slope stability using conceptual models and evolving stratigraphy—for passive siliciclastic and carbonate margin cases—to assess whether OMG and its evolution during a late Quaternary glacial cycle can generate the pore pressures required to trigger mechanical instabilities on the seafloor. Conceptual model results show that mechanical instabilities using OMG flow are most likely to occur in the outer shelf to upper slope, at or shortly before the Last Glacial Maximum sea‐level lowstand. Models with evolving stratigraphy show that OMG flow is a key driver of pore pressure development and instability in the carbonate margin case. In the siliciclastic margin case, OMG flow plays a secondary role in preconditioning the slope to failure. The higher degree of spatial/stratigraphic heterogeneity of carbonate margins, lower shear strengths of their sediments, and limited generation of overpressures by sediment loading may explain the higher susceptibility of carbonate margins, in comparison to siliciclastic margins, to mechanical instability by OMG flow. OMG likely played a more significant role in carbonate margin geomorphology (e.g., Bahamas, Maldives) than currently thought.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Can Offshore Meteoric Groundwater Generate Mechanical Instabilities in Passive Continental Margins?

et al. 2023

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“…In addition, the amphitheatre‐shaped scarps on the south Al Wajh slope did not evolve into gullies or smaller canyons as a result of retrogressive erosion driven by shallow‐water sediment export from the platform top, as observed for the slope at the Great Barrier Reef (Webster et al ., 2012; Puga‐Bernabéu et al ., 2013) and Little Bahama Bank (Tournadour et al ., 2017). Typically, sea‐level fluctuations, sediment influx from shallow water (Wunsch et al ., 2017) and a steepening stratigraphic trend (Busson et al ., 2021) are mechanisms controlling slope failures. However, the non‐retrogressive trend combined with the other observations suggests tectonic processes triggering slope failures on the southern Al Wajh slope.…”

Section: Interpretation and Discussionmentioning

confidence: 99%

Sediment dynamics and geomorphology of a submarine carbonate platform canyon system situated in an arid climate setting

Petrovic,

Reijmer,

Alsaihati

et al. 2023

Sedimentology

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Changes in neritic carbonate production and sediment transport off platforms are related to climate variations, sea‐level fluctuations and tectonic processes. Canyon systems marking the platform slopes represent critical source‐to‐sink pathways transporting shallow‐water sediments basinward. However, these export systems and related processes are primarily studied on platform slopes in humid to tropical climate settings. A newly discovered canyon system on the leeward margin of the Al Wajh platform (north‐east Red Sea) represents the ideal laboratory to investigate source‐to‐sink pathway dynamics in an arid climate that prevailed since the Late Pleistocene. A high‐resolution bathymetry map was established to characterize the slope morphology. The system displays a U‐shaped, 10 km long main channel dominantly sourced by the north‐west/south‐east running outer channel and two smaller 2 to 3 km long canyons. The latter are positioned perpendicular to the main canyon. A 4 km wide head scarp at the reef edge and dozens of amphitheatre‐shaped scarps along the mid to lower slope suggest significant slope failures over time. The analysis of four sediment cores collected on a profile down the canyon revealed sedimentation rates of 26 cm/ka at the mid‐slope to 9.4 cm/ka in the basin. Three main sediment‐export processes were identified: (i) sandy and neritic component‐poor turbidites; (ii) winnowing of strontium‐rich carbonate fines through surface currents; and (iii) remobilized carbonate fines on the upper slope. As of the Last Glacial, turbidites are predominantly deposited during times of significant sea‐level instability, both rises and falls, whereas their flat‐topped‐tropical counterparts show a higher turbidite frequency during highstands. Strontium‐rich carbonate fines are exported similarly through time in both climate settings. Overall, sediment export is controlled by: (i) the platform morphology (flat‐topped versus rimmed lagoon); (ii) variations in sediment production; (iii) sea‐level variations (exposure or flooding of sediment production areas); and (iv) the interaction between the sedimentary system and atmospheric changes (sediment production and delivery).

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“…Therefore, Spence and Tucker (1997) highlighted the importance of pore-water overpressure of confined aquifer horizons associated with karstification beneath the seafloor as the dominant factor of destabilization during sea-level falls. This process was also proposed in the modelling study of Busson et al (2021) to explain the occurrence of platform margin collapses and associated MTD deposits, marking the western margin of GBB during sea-level falls. The pore-water overpressure scenario and associated platform margin sediment overloading were confirmed through the analysis of the debris-flow facies constituents by Reijmer et al (2012Reijmer et al ( , 2015aReijmer et al ( , 2015b, which explained the occurrence of debris-flow deposits at glacial to interglacial and interglacial to glacial transitions for Exuma Sound.…”

Section: The Mis 5 Eventmentioning

confidence: 91%

Quaternary sedimentary processes on the Bahamas: From platform to abyss

et al. 2023

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Submarine landslides on a carbonate platform slope: forward numerical modelling of mechanical stratigraphy and scenarios of failure precondition

Cited by 8 publications

References 93 publications

Can Offshore Meteoric Groundwater Generate Mechanical Instabilities in Passive Continental Margins?

Can Offshore Meteoric Groundwater Generate Mechanical Instabilities in Passive Continental Margins?

Sediment dynamics and geomorphology of a submarine carbonate platform canyon system situated in an arid climate setting

Quaternary sedimentary processes on the Bahamas: From platform to abyss

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