A contourite depositional system along the Uruguayan continental margin: Sedimentary, oceanographic and paleoceanographic implications

Hernández-Molina, F. Javier; Soto, Matías; Piola, Alberto R.; Tomasini, Juan; Preu, Benedict; Thompson, P.; Badalini, G.; Creaser, A.; Violante, Roberto A.; Morales, Ethel; Paterlini, Marcelo; Ana, Héctor de Santa

doi:10.1016/j.margeo.2015.10.008

Cited by 79 publications

(87 citation statements)

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“…One of these processes may dominate, both spatially and temporally, for instance, periods of intense tectonism may be recorded by repeated deposition of mass‐transport complexes (MTCs) spatially associated with specific structures (Bagguley & Prosser, ; Gee, Gawthorpe, & Friedmann, ; Gee, Uy, Warren, Morley, & Lambiase, ; Hampton, Lee, & Locat, ; Masson, Wynn, & Talling, ; Ortiz‐Karpf, Hodgson, Jackson, & McCaffrey, ; Pérez et al, ; Scarselli, McClay, & Elders, ). In contrast, periods dominated by the activity of intense, along‐slope bottom currents may be recorded by deposition of contourite depositional systems, from which oceanographic and/or palaeo‐oceanographic processes can be inferred (Ercilla et al, ; Hernández‐Molina et al, ; Hernández‐Molina, Llave, et al, ; Pérez et al, ; Pickering et al, ; Uenzelmann‐Neben, ; Viana, Faugères, & Stow, ). Therefore, deep‐marine stratigraphy can record tectonic and oceanographic processes, including periods of continental rifting and collision that may result in the opening and closing of ocean gateways (Faugères & Stow, ; Hernández‐Molina et al, ; Knutz, ; Pérez et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, periods dominated by the activity of intense, along‐slope bottom currents may be recorded by deposition of contourite depositional systems, from which oceanographic and/or palaeo‐oceanographic processes can be inferred (Ercilla et al, ; Hernández‐Molina et al, ; Hernández‐Molina, Llave, et al, ; Pérez et al, ; Pickering et al, ; Uenzelmann‐Neben, ; Viana, Faugères, & Stow, ). Therefore, deep‐marine stratigraphy can record tectonic and oceanographic processes, including periods of continental rifting and collision that may result in the opening and closing of ocean gateways (Faugères & Stow, ; Hernández‐Molina et al, ; Knutz, ; Pérez et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Tectonic and oceanographic process interactions archived in Late Cretaceous to Present deep‐marine stratigraphy on the Exmouth Plateau, offshore NW Australia

et al. 2018

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Deep‐marine deposits provide a valuable archive of process interactions between sediment gravity flows, pelagic sedimentation and thermohaline bottom‐currents. Stratigraphic successions can also record plate‐scale tectonic processes (e.g. continental breakup and shortening) that impact long‐term ocean circulation patterns, including changes in climate and biodiversity. One such setting is the Exmouth Plateau, offshore NW Australia, which has been a relatively stable, fine‐grained carbonate‐dominated continental margin from the Late Cretaceous to Present. We combine extensive 2D (~40,000 km) and 3D (3,627 km2) seismic reflection data with lithologic and biostratigraphic information from wells to reconstruct the tectonic and oceanographic evolution of this margin. We identified three large‐scale seismic units (SUs): (a) SU‐1 (Late Cretaceous)—500 m‐thick, and characterised by NE‐SW‐trending, slope‐normal elongate depocentres (c. 200 km long and 70 km wide), with erosional surfaces at their bases and tops, which are interpreted as the result of contour‐parallel bottom‐currents, coeval with the onset of opening of the Southern Ocean; (b) SU‐2 (Palaeocene—Late Miocene)—800 m‐thick and characterised by: (a) very large (amplitude, c. 40 m and wavelength, c. 3 km), SW‐migrating, NW‐SE‐trending sediment waves, (b) large (4 km‐wide, 100 m‐deep), NE‐trending scours that flank the sediment waves and (c) NW‐trending, 4 km‐wide and 80 m‐deep turbidite channel, infilled by NE‐dipping reflectors, which together may reflect an intensification of NE‐flowing bottom currents during a relative sea‐level fall following the establishment of circumpolar‐ocean current around Antarctica; and (c) SU‐3 (Late Miocene—Present)—1,000 m‐thick and is dominated by large (up to 100 km3) mass‐transport complexes (MTCs) derived from the continental margin (to the east) and the Exmouth Plateau Arch (to the west), and accumulated mainly in the adjacent Kangaroo Syncline. This change in depositional style may be linked to tectonically‐induced seabed tilting and folding caused by collision and subduction along the northern margin of the Australian plate. Hence, the stratigraphic record of the Exmouth Plateau provides a rich archive of plate‐scale regional geological events occurring along the distant southern (2,000 km away) and northern (1,500 km away) margins of the Australian plate.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tectonic and oceanographic process interactions archived in Late Cretaceous to Present deep‐marine stratigraphy on the Exmouth Plateau, offshore NW Australia

et al. 2018

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“…The terrace in the focus of this study represents the shallowest of these contouritic terraces. It discontinuously extends from northern Argentina to the Campos Basin off southeastern Brazil (Viana and Faugéres, 1998;Hernández-Molina et al, 2016). The terrace section in the study area is latitudinally bounded by two major canyons to its north and south (Franco-Fraguas et al, 2014; the Piriápolis and José Ignacio canyon systems: Hernández-Molina et al, 2016).…”

Section: Study Areamentioning

confidence: 99%

“…While Points b-d likewise apply to our study area, an explicit overall along-slope convex seafloor topography is not given. Instead, the upper slope is intersected by canyon structures, which occur at a lateral spacing of about 60 km (Franco-Fraguas et al, 2014;Hernández-Molina et al, 2016). These structures, each about 15 km wide, probably lead to an intense turbulent interaction with the slope-parallel bottom flow (Viana and Faugéres, 1998;Preu et al, 2012;Voigt et al, 2013) of the southward-directed BC.…”

Section: Deposition On the Terrace: Shelf Sediment Export Dynamics Vementioning

confidence: 99%

Sediment Export Dynamics Reflecting the Holocene Hydrodynamic Variability of a High-Energy Continental Shelf System (Southeastern South America)

2019

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This study reconstructs Holocene hydrodynamic changes on the outer shelf off Uruguay by examining deposits from a morphological terrace on the uppermost continental slope (250 m water depth). Seismo-acoustics, litho- and chronostratigraphy, granulometry, and Neodymium isotopy were applied to three sediment cores. The 9.5-m thick terrace sediment record, documenting the past 11.5 cal ka BP, provides exceptional insight into the transport and settling mechanisms of the sand injected from the shelf into the open ocean. The sandy outer shelf is identified as the principal sediment origin. Contouritic bottom currents do not significantly affect deposition on the terrace. Instead, the sandy sediment gets spilled over the shelf edge in the form of suspension clouds, spreading uniformly over the whole terrace. The suspended sand does not transform into high-concentration gravity-driven bottom flows but rains down onto the terrace as a quasi-permanent material supply. This observation suggests that the formation of turbidite beds, as frequently found at the deeper slope in this region, requires first a temporary storage of sediment at deposition-favoring locations on the uppermost continental slope (terraces, canyon heads), before a secondary and episodic process can mobilize the mass.An overall fining-upward trend in silty sand shelf export over Holocene times reflects the deglacial sea-level rise dynamics, leading to overall less effective material mobilization on and transfer across the shelf due to water deepening. The pronounced vertical hydrographic shelf front, as a shallow expression of the regional oceanic confluence zone, acted temporarily as main sediment exporting conveyer, before it shifted further north. The water depth of the terrace coincides with the transition zone between Central Water and Intermediate Water. The pronounced water density gradient might influence sediment distribution twofold, acting as a barrier for sand suspension cloud spreading as well as a medium for incoming internal waves bringing sediment remobilization. DINÂMICA DE EXPORTAÇÃO DE SEDIMENTOS EM FUNÇÃO DA VARIABILIDADE HIDRODINÂMICA DURANTE O HOLOCENO NUM SISTEMA DE PLATAFORMA CONTINENTAL DE ELEVADA ENERGIA (SE DA AMÉRICA DO SUL) ResumoEste estudo pretende ser uma contribuição para a reconstrução das alterações hidrodinâmicas Holocénicas, da plataforma continental externa do Uruguai, a partir de depósitos sedimentares de um terraço do talude continental superior (250 m de profundidade). Três testemunhos de sedimentos foram submetidos a análises geofísicas, lito e cronostratigráficas e granulométricas, tendo também sido obtidos resultados de isótopos de neodímio. O registro sedimentar com 9,5 m de espessura no terraço, documentando os últimos 11,5 ka cal BP, fornece importantes informações sobre os mecanismos de transporte e sedimentação da areia remobilizada da plataforma continental e transportada para o oceano profundo.Os dados obtidos na área de estudo revelaram que o substrato arenoso da plataforma continental externa foi a principal fonte de sedimento para o talude continental superior. As correntes de fundo de contorno não afetaram significativamente a deposição de sedimentos no referido terraço. Em vez disso, o sedimento arenoso remobilizado da plataforma formou nuvens de partículas em suspensão que se espalharam uniformemente por todo o terraço. A areia, uma vez em suspensão, não deu ludar a fluxos gravitacionais de fundo concentrados, mas “choveu” de modo quase continuo por todo o terraço. Esta constatação sugere que a formação de camadas turbidíticas, tais como as que freqüentemente são encontradas no talude continental inferior da região, requerem que primeiramente haja um armazenamento temporário de sedimentos em locais favoráveis à sua deposição na plataforma continental superior (terraços, cabeceiras de cânions), antes da ocorrência de um processo secundário e episódico poder mobilizar os materiais acumulados.Verifica-se, na área de estudo, uma tendência geral de redução da granulometria da areia siltosa ao longo do Holoceno devido à subida do nível do mar após a deglaciação; esta terá levado a uma menor remobilização e a uma transferência menos eficaz de sedimentos da plataforma continental para o talude devido ao aumento da profundidade da coluna de água.A pronunciada frente hidrográfica vertical da plataforma, expressão da zona de confluência oceânica regional, atuou temporariamente como principal processo de transporte e exportação de sedimentos, para norte. A profundidade da água do terraço coincide com a zona de transição entre a Água Central e a Água Intermediária. O pronunciado gradiente de densidade da água poderá ter influenciado de duas maneiras a distribuição de sedimentos, atuando como uma barreira para a propagação da nuvem de areia em suspensão e como meio de propagação de ondas internas que chegam, remobilizando e exportando sedimentos. Palavras-chave: Exportação de sedimentos de plataforma. Margem oceânica de elevada energia. Sudeste da América do Sul. Holoceno.

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“…These younger sediments are generally interpreted as drifts, perhaps associated with the levees of channels, or deposits within channels, where the channels intersect flow along the margin. Drifts are also present farther north along the margin (e.g., Hernández-Molina et al, 2015) with drifts apparently associated with flows of Antarctic Intermediate Water (AAIW), Upper Circumpolar Deep Water (UCDW), North Atlantic Deep Water (NADW), Lower Circumpolar Deep Water (LCDW) and Antarctic Bottom Water (AABW). Violante et al (2010) and Grützner et al (2011Grützner et al ( , 2012Grützner et al ( , 2016 suggested that increased sediment flux to the margin during the Miocene may in part be related to an uplift in the Andes that in turn is due to increased Miocene Pacific Ocean crustal spreading and subduction rates, which peaked at about 10 to 20 Ma (Pardo-Casas and Molnar, 1987;Martinod et al, 2010).…”

Section: Background and Geological Settingmentioning

confidence: 99%

IODP workshop: developing scientific drilling proposals for the Argentina Passive Volcanic Continental Margin (APVCM) – basin evolution, deep biosphere, hydrates, sediment dynamics and ocean evolution

et al. 2017

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Abstract. The Argentine margin contains important sedimentological, paleontological and chemical records of regional and local tectonic evolution, sea level, climate evolution and ocean circulation since the opening of the South Atlantic in the Late Jurassic-Early Cretaceous as well as the present-day results of post-depositional chemical and biological alteration. Despite its important location, which underlies the exchange of southern-and northern-sourced water masses, the Argentine margin has not been investigated in detail using scientific drilling techniques, perhaps because the margin has the reputation of being erosional. However, a number of papers published since 2009 have reported new high-resolution and/or multichannel seismic surveys, often combined with multi-beam bathymetric data, which show the common occurrence of layered sediments and prominent sediment drifts on the Argentine and adjacent Uruguayan margins. There has also been significant progress in studying the climatic records in surficial and near-surface sediments recovered in sediment cores from the Argentine margin. Encouraged by these recent results, our 3.5-day IODP (International Ocean Discovery Program) workshop in Buenos Aires (8-11 September 2015) focused on opportunities for scientific drilling on the Atlantic margin of Argentina, which lies beneath a key portion of the global ocean conveyor belt of thermohaline circulation. Significant opportunities exist to study the tectonic evolution, paleoceanography and stratigraphy, sedimentology, and biosphere and geochemistry of this margin.

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A contourite depositional system along the Uruguayan continental margin: Sedimentary, oceanographic and paleoceanographic implications

Cited by 79 publications

References 42 publications

Tectonic and oceanographic process interactions archived in Late Cretaceous to Present deep‐marine stratigraphy on the Exmouth Plateau, offshore NW Australia

Tectonic and oceanographic process interactions archived in Late Cretaceous to Present deep‐marine stratigraphy on the Exmouth Plateau, offshore NW Australia

Sediment Export Dynamics Reflecting the Holocene Hydrodynamic Variability of a High-Energy Continental Shelf System (Southeastern South America)

IODP workshop: developing scientific drilling proposals for the Argentina Passive Volcanic Continental Margin (APVCM) – basin evolution, deep biosphere, hydrates, sediment dynamics and ocean evolution

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