Mass Wasting Along Atlantic Continental Margins: A Comparison Between NW-Africa and the de la Plata River Region (Northern Argentina and Uruguay)

Krastel, Sebastian; Lehr, Johanna; Winkelmann, Daniel; Schwenk, Tilmann; Preu, Benedict; Strasser, Michael; Wynn, Russell B.; Georgiopoulou, Aggeliki; Hanebuth, Till J J

doi:10.1007/978-3-319-00972-8_41

Cited by 7 publications

(5 citation statements)

References 20 publications

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“…The northern Argentine margin is part of the passive-volcanic rifted continental margin of South America ranging from southern Brazil to northern Patagonia (Franke et al, 2007). It is characterized by highly dynamic depositional conditions due to a complex interaction of alongslope and downslope processes (e.g., Hensen et al, 2003;Riedinger et al, 2005Riedinger et al, , 2014Riedinger et al, , 2017Henkel et al, 2011Henkel et al, , 2012Krastel et al, 2011Krastel et al, , 2013Preu et al, 2012Preu et al, , 2013Voigt et al, 2013Voigt et al, , 2016Warratz et al, 2017Warratz et al, , 2019. The tectono-volcanic crust is covered by a thick tectonically undisturbed sedimentary succession of Cretaceous to Cenozoic age (Hinz et al, 1999a(Hinz et al, , 1999bFranke et al, 2007).…”

Section: Geological and Morphological Contextmentioning

confidence: 99%

Discovery of a giant cold-water coral mound province along the northern Argentine margin and its link to the regional Contourite Depositional System and oceanographic setting

et al. 2020

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Section: Geological and Morphological Contextmentioning

confidence: 99%

Discovery of a giant cold-water coral mound province along the northern Argentine margin and its link to the regional Contourite Depositional System and oceanographic setting

et al. 2020

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“…Shielded from sulfidic conditions in the upper sediment column due to rapid burial-and in the presence of mostly reworked, unreactive organic matter-those oxidized reactive iron phases are then preserved in deeper subsurface sediments März et al, 2008;Riedinger et al, 2014). The continental margin off Uruguay and Argentina is characterized by such highly dynamic depositional conditions (e.g., Riedinger et al, 2005;Henkel et al, 2011Henkel et al, , 2012Krastel et al, , 2013, and these locations are likely to be representative of environments that are common throughout the world along continental margins.…”

Section: Introductionmentioning

confidence: 99%

Sulfur Cycling in an Iron Oxide-Dominated, Dynamic Marine Depositional System: The Argentine Continental Margin

Riedinger

Brunner

Krastel³

et al. 2017

Front. Earth Sci.

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The interplay between sediment deposition patterns, organic matter type and the quantity and quality of reactive mineral phases determines the accumulation, speciation, and isotope composition of pore water and solid phase sulfur constituents in marine sediments. Here, we present the sulfur geochemistry of siliciclastic sediments from two sites along the Argentine continental slope-a system characterized by dynamic deposition and reworking, which result in non-steady state conditions. The two investigated sites have different depositional histories but have in common that reactive iron phases are abundant and that organic matter is refractory-conditions that result in low organoclastic sulfate reduction rates (SRR). Deposition of reworked, isotopically light pyrite and sulfurized organic matter appear to be important contributors to the sulfur inventory, with only minor addition of pyrite from organoclastic sulfate reduction above the sulfate-methane transition (SMT). Pore-water sulfide is limited to a narrow zone at the SMT. The core of that zone is dominated by pyrite accumulation. Iron monosulfide and elemental sulfur accumulate above and below this zone. Iron monosulfide precipitation is driven by the reaction of low amounts of hydrogen sulfide with ferrous iron and is in competition with the oxidation of sulfide by iron (oxyhydr)oxides to form elemental sulfur. The intervals marked by precipitation of intermediate sulfur phases at the margin of the zone with free sulfide are bordered by two distinct peaks in total organic sulfur (TOS).Organic matter sulfurization appears to precede pyrite formation in the iron-dominated margins of the sulfide zone, potentially linked to the presence of polysulfides formed by reaction between dissolved sulfide and elemental sulfur. Thus, SMTs can be hotspots for organic matter sulfurization in sulfide-limited, reactive iron-rich marine sedimentary systems. Furthermore, existence of elemental sulfur and iron monosulfide phases meters below the SMT demonstrates that in sulfide-limited systems metastable sulfur constituents are not readily converted to pyrite but can be buried to deeper Riedinger et al.Non-steady State Subsurface Sulfur Cycling sediment depths. Our data show that in non-steady state systems, redox zones do not occur in sequence but can reappear or proceed in inverse sequence throughout the sediment column, causing similar mineral alteration processes to occur at the same time at different sediment depths.

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“…2a) reveal deeply buried MTDs associated with scar S1 on the lower slope, scar S2 with younger MTDs upslope of S1, and seaward-dipping discontinuities even further upslope, possible indicating incipient fronts of future slope failures. This geometry is interpreted to represent a retrogressive slope failure system in which successive landslides are dislocated progressively farther upslope (Krastel et al 2014). The slope stability analyses of this article suggest that the NS area is today stable and unlikely to experience repeated small-scale failures in the foreseeable future.…”

Section: Triggering Mechanismsmentioning

confidence: 86%

“…The strong currents control the sedimentation pattern which, in turn, exerts a key control on the slope stability precondition. The influence of contour currents on mass wasting processes and the shaping of continental margins has also been highlighted by a recent comparison between submarine landslides off NE Africa and Uruguay/Argentina (Krastel et al 2014), showing that contouritic depositional systems feature smaller but more frequent landslides.…”

Section: Triggering Mechanismsmentioning

confidence: 92%

New constraints on oceanographic vs. seismic control on submarine landslide initiation: a geotechnical approach off Uruguay and northern Argentina

Strasser

Preu

et al. 2014

Geo-Mar Lett

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Submarine landslides are common along the Uruguayan and Argentinean continental margin, but size, type and frequency of events differ significantly between distinct settings. Previous studies have proposed sedimentary and oceanographic processes as factors controlling slope instability, but also episodic earthquakes have been postulated as possible triggers. However, quantitative geotechnical slope stability evaluations for this region and, for that matter, elsewhere in the South Atlantic realm are lacking. This study quantitatively assesses continental slope stability for various scenarios including overpressure and earthquake activity, based on sedimentological and geotechnical analyses on three up to 36 m long cores collected on the Uruguayan slope, characterized by muddy contourite deposits and a locus of landslides (up to 2 km 3), and in a canyon-dominated area on the northern Argentinean slope characterized by sandy contourite deposits. The results of shear and consolidation tests reveal that these distinct lithologies govern different stability conditions and failure modes. The slope sectors are stable under present-day conditions (factor of safety >5), implying that additional triggers would be required to initiate failure. In the canyon area, current-induced oversteepening of weaker sandy contourite deposits would account for frequent, small-scale slope instabilities. By contrast, static vs. seismic slope stability calculations reveal that a peak ground acceleration of at least 2 m/s 2 would be required to cause failure of mechanically stronger muddy contourite deposits. This implies that, also along the western South Atlantic passive margin, submarine landslides on open gentle slopes require episodic large earthquakes as ultimate trigger, as previously postulated for other, northern hemisphere passive margins.

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Mass Wasting Along Atlantic Continental Margins: A Comparison Between NW-Africa and the de la Plata River Region (Northern Argentina and Uruguay)

Cited by 7 publications

References 20 publications

Discovery of a giant cold-water coral mound province along the northern Argentine margin and its link to the regional Contourite Depositional System and oceanographic setting

Discovery of a giant cold-water coral mound province along the northern Argentine margin and its link to the regional Contourite Depositional System and oceanographic setting

Sulfur Cycling in an Iron Oxide-Dominated, Dynamic Marine Depositional System: The Argentine Continental Margin

New constraints on oceanographic vs. seismic control on submarine landslide initiation: a geotechnical approach off Uruguay and northern Argentina

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