Sediment properties, flow characteristics, and depositional environment of submarine mudflows, Bear Island Fan

Bowles, Frederick A.; Faas, Richard W.; Vogt, Peter R.; Sawyer, William; Stephens, Kevin P.

doi:10.1016/s0025-3227(03)00089-6

Cited by 21 publications

(13 citation statements)

References 31 publications

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“…4) resembles that of trough- mouth fans described from the Norwegian and Antarctic margins (e.g., Laberg and Vorren 1995;Passchier et al 2003). This poorly sorted diamicton resembles deposits termed glacigenic debris flows from the Norwegian margin (Bowles et al 2003;Dahlgren and Vorren 2003) and eastern Canadian margin (Tripsanas et al 2005) that are interpreted to result from direct flow of glacial till down the continental slope (Nygård et al 2005). 7b), the base of which penetrated the mass-transport deposit and recovered a carbonate-rich diamicton.…”

Section: Character and Age Of Glacigenic Debris Flows On The Continenmentioning

confidence: 91%

The extent of ice on the continental shelf off Hudson Strait during Heinrich events 1-3

Rashid¹,

Piper²

2007

Can. J. Earth Sci.

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North Atlantic Heinrich events, which dispersed widespread sediment plumes and icebergs, originated principally from Hudson Strait ice streams of the Laurentide Ice Sheet. The dynamics and extent of these ice streams across the wide continental shelf seaward of Hudson Strait are not well understood. High-resolution airgun seismic reflection profiles from the outer shelf and slope show an acoustically incoherent, prograded unit at least 30 m thick. This unit has been sampled by piston cores and corresponds to a carbonate-rich diamicton unit interpreted as a glacigenic debris flow, locally overlain by carbonate-rich mud turbidites, dated as corresponding to Heinrich event 3 (H3). Younger glacigenic debris flow deposits are lacking. These data are compared with the seismic-stratigraphic record on the continental shelf, where a regional erosion surface at 10-200 m depth below the sea floor truncates Tertiary strata and is overlain by a 50 m thick diamicton (?subglacial till) sheet and is correlated with the H3 glacigenic debris flows. Above this unit, at least two distinct diamicton sheets terminate on the inner continental shelf. These data imply that grounded Laurentide ice crossed the continental shelf during H3, delivering large amounts of diamicton to the continental slope, but during the younger Heinrich events H1 and H2, no detectable record of diamicton was left on the outer shelf or slope. These findings account for observed differences between H3 and younger Heinrich events in the Labrador Sea.Résumé : Dans l'Atlantique Nord, les événements Heinrich, qui ont dispersé de vastes panaches de sédiments et des icebergs, ont surtout débuté à partir de langues glaciaires dans le détroit d'Hudson, lesquelles faisaient partie de l'inlandsis laurentidien. La dynamique et l'étendue de ces langues glaciaires à travers la large plate-forme continentale au large du détroit d'Hudson ne sont pas bien comprises. Obtenus par des tirs d'air comprimé, des profils de sismique réflexion à grande précision de la plate-forme externe et de la pente montrent une unité de progradation, acoustiquement incohérente, d'une épaisseur minimale de 30 m. Cette unité a été échantillonnée par du carottage par piston et elle correspond à une unité de diamictons riche en carbonates, interprétée en tant qu'une coulée de débris glaciogéniques, par endroits recouverte de turbidites boueuses riches en carbonates, lesquelles ont été datées en tant qu'un événement Heinrich 3 (H3). Il manque des coulées de débris glaciogéniques plus jeunes. Ces données sont comparées aux enregistrements sismiquesstratigraphiques de la plate-forme continentale, où une surface d'érosion régionale, à une profondeur 10-200 m sous le plancher océanique, recoupe des strates du Tertiaire et est recouverte par un feuillet de diamicton (till sous-glaciaire?) d'une épaisseur de 50 m; cette surface est corrélée aux coulées de débris glaciogéniques. Au-dessus de cette unité, au moins deux feuillets distincts de diamictons prennent fin sur la partie interne de la plate-forme contin...

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Section: Character and Age Of Glacigenic Debris Flows On The Continenmentioning

confidence: 91%

The extent of ice on the continental shelf off Hudson Strait during Heinrich events 1-3

Rashid¹,

Piper²

2007

Can. J. Earth Sci.

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“…9). Rheological analysis of submarine debrite samples, which are progressively diluted, suggests that such low yield strengths may indeed characterize debris mixtures with densities up to 1500 kg −3 or ≈ 40% volume sediment (Bowles et al ., 2003). Alternative explanations for such long run‐out include hydroplaning (Mohrig et al ., 1998) and elevated pore‐fluid pressure at the base of the debris flow (Gee et al ., 1999).…”

Section: Debris Flow Rheology and Extreme Mobilitymentioning

confidence: 99%

Beds comprising debrite sandwiched within co‐genetic turbidite: origin and widespread occurrence in distal depositional environments

Talling¹,

Amy²,

Wynn³

et al. 2004

Sedimentology

215

317

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Co‐genetic debrite–turbidite beds occur in a variety of modern and ancient turbidite systems. Their basic character is distinctive. An ungraded muddy sandstone interval is encased within mud‐poor graded sandstone, siltstone and mudstone. The muddy sandstone interval preserves evidence of en masse deposition and is thus termed a debrite. The mud‐poor sandstone, siltstone and mudstone show features indicating progressive layer‐by‐layer deposition and are thus called a turbidite. Palaeocurrent indicators, ubiquitous stratigraphic association and the position of hemipelagic intervals demonstrate that debrite and enclosing turbidite originate in the same event. Detailed field observations are presented for co‐genetic debrite–turbidite beds in three widespread sequences of variable age: the Miocene Marnoso Arenacea Formation in the Italian Apennines; the Silurian Aberystwyth Grits in Wales; and Quaternary deposits of the Agadir Basin, offshore Morocco. Deposition of these sequences occurred in similar unchannellized basin‐plain settings. Co‐genetic debrite–turbidite beds were deposited from longitudinally segregated flow events, comprising both debris flow and forerunning turbidity current. It is most likely that the debris flow was generated by relatively shallow (few tens of centimetres) erosion of mud‐rich sea‐floor sediment. Changes in the settling behaviour of sand grains from a muddy fluid as flows decelerated may also have contributed to debrite deposition. The association with distal settings results from the ubiquitous presence of muddy deposits in such locations, which may be eroded and disaggregated to form a cohesive debris flow. Debrite intervals may be extensive (> 26 × 10 km in the Marnoso Arenacea Formation) and are not restricted to basin margins. Such long debris flow run‐out on low‐gradient sea floor (< 0·1°) may simply be due to low yield strength (≪ 50 Pa) of the debris–water mixture. This study emphasizes that multiple flow types, and transformations between flow types, can occur within the distal parts of submarine flow events.

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“…As the results show, in our model solutions θ never exceeds 0.68 while the flow is turbulent so that this is not a significant issue. An expression for the yield strength,  y , for turbulent flow, even up to very high solid fractions, can be derived from a curve fitted to the empirical data of Huang and Garcia (1998), Parsons et al (2001) and Bowles et al (2003) for fine-grained sediments (Fig. 3); we find: σ y = 0 .1341exp 10 .14 ϕ (30).…”

Section: Yield Strength and Viscosity Of Flowmentioning

confidence: 98%

Erosive flood events on the surface of Mars: Application to Mangala and Athabasca Valles

Bargery

Wilson

2011

Icarus

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We address key factors involved in determining water flow conditions in outflow channels on Mars, including the temperature of the sub-surface water being released and the environmental conditions of low temperature, low atmospheric pressure, and low acceleration due to gravity. We suggest how some of the assumptions made in previous work may be improved. Our model considers the thermodynamic effects of simultaneous evaporation and freezing of water, and fluid dynamical processes including changes in flow rheology caused by assimilation of cold rock and ice eroded at the channel bed, and ice crystal growth due to water freezing. We model how far initially turbulent water could flow in a channel before it erodes and entrains enough material to become laminar, and subsequently ceases to erode the bed. An ice raft will begin to form on the flood while transition occurs between turbulent and laminar flow.Estimates are given for water transit times, ~17 to ~19 hours, initial water depths, 50 to 62 m, and average flow speeds, 5 to 12 m s -1 , in the Mangala and Athabasca Valles.We show that these two outflow channels, and by implication others like them, could plausibly have been formed in single water release events. Resulting mean erosion rates are approximately 0.7 mm s -1 , a factor of three greater than previous estimates based on combinations of estimates of flood duration and required water volumes. This is explained by the consideration of the effects of eroded ice and the physics of thermal erosion in the present study.

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Sediment properties, flow characteristics, and depositional environment of submarine mudflows, Bear Island Fan

Cited by 21 publications

References 31 publications

The extent of ice on the continental shelf off Hudson Strait during Heinrich events 1-3

The extent of ice on the continental shelf off Hudson Strait during Heinrich events 1-3

Beds comprising debrite sandwiched within co‐genetic turbidite: origin and widespread occurrence in distal depositional environments

Erosive flood events on the surface of Mars: Application to Mangala and Athabasca Valles

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