Foraminiferal and lithologic indicators of depositional processes in Wilmington and South Heyes submarine canyons, U. S. Atlantic continental slope

1997 ◽  
Vol 27 (3) ◽  
pp. 209-231 ◽  
Author(s):  
J. J. Lundquist ◽  
S. J. Culver ◽  
D. J. Stanley
Keyword(s):  
Continental Slope ◽  
Submarine Canyons ◽  
Depositional Processes

scholarly journals Influence of the summer deep-sea circulations on passive drifts among the submarine canyons in the northwestern Mediterranean Sea

Ocean Science ◽  
2019 ◽  
Vol 15 (6) ◽  
pp. 1745-1759 ◽  
Author(s):  
Morane Clavel-Henry ◽  
Jordi Solé ◽  
Miguel-Ángel Ahumada-Sempoal ◽  
Nixon Bahamon ◽  
Florence Briton ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Continental Slope ◽  
Deep Sea ◽  
Particle Transport ◽  
Bottom Topography ◽  
Regional Ocean Modeling System ◽  
Submarine Canyons ◽  
Northwestern Mediterranean Sea ◽  
The Impact ◽  
Northwestern Mediterranean

Abstract. Marine biophysical models can be used to explore the displacement of individuals in and between submarine canyons. Mostly, the studies focus on the shallow hydrodynamics in or around a single canyon. In the northwestern Mediterranean Sea, knowledge of the deep-sea circulation and its spatial variability in three contiguous submarine canyons is limited. We used a Lagrangian framework with three-dimensional velocity fields from two versions of the Regional Ocean Modeling System (ROMS) to study the deep-bottom connectivity between submarine canyons and to compare their influence on the particle transport. From a biological point of view, the particles represented eggs and larvae spawned by the deep-sea commercial shrimp Aristeus antennatus along the continental slope in summer. The passive particles mainly followed a southwest drift along the continental slope and drifted less than 200 km considering a pelagic larval duration (PLD) of 31 d. Two of the submarine canyons were connected by more than 27 % of particles if they were released at sea bottom depths above 600 m. The vertical advection of particles depended on the depth where particles were released and the circulation influenced by the morphology of each submarine canyon. Therefore, the impact of contiguous submarine canyons on particle transport should be studied on a case-by-case basis and not be generalized. Because the flows were strongly influenced by the bottom topography, the hydrodynamic model with finer bathymetric resolution data, a less smoothed bottom topography, and finer sigma-layer resolution near the bottom should give more accurate simulations of near-bottom passive drift. Those results propose that the physical model parameterization and discretization have to be considered for improving connectivity studies of deep-sea species.

Why do shelf-incising submarine canyons form? - Insights from global topographic analyses and regression trees

2020 ◽  
Author(s):  
Anne Bernhardt ◽  
Wolfgang Schwanghart
Keyword(s):  
Continental Slope ◽  
Regression Trees ◽  
Signal Propagation ◽  
Sediment Supply ◽  
Sediment Flux ◽  
Slope Gradient ◽  
Submarine Canyons ◽  
Data Set ◽  
Sediment Routing ◽  
River Mouths

<p>The efficiency of environmental signal propagation from terrestrial sources to marine sinks highly depends on the connectivity of the sediment-routing system. Submarine canyons that couple river outlets with marine depocenters are particularly crucial links in the routing network as they convey terrestrial sediment, associated pollutants and organic carbon to the deep ocean. However, why and where submarine canyons incise into shelves is still poorly understood. Several factors were proposed, including narrow shelves along active continental margins, onshore sediment flux, more proximal sediment supply during sea-level lowstands, mass wasting along high-gradient continental slopes, and the occurrence of durable bedrock in adjacent catchments. In this study, we test whether we can predict shelf incision of submarine canyons from onshore and offshore parameters.</p> <p>We used maps of global elevation and bathymetry and analyzed them together with a global compilation of 5900 submarine canyon heads. The analysis relies on bagged regression trees that predict the distance of each canyon head from the shelf edge as a function of numerous candidate predictor variables. These variables describe spatial relations of river mouths and canyons, shelf geometry, continental slope gradient, as well as numerous terrestrial catchment properties. Moreover, we added 120 m to the elevation of the present-day topography to simulate a coastal landscape during the Last Glacial Maximum (LGM) and recalculated the topographic terrestrial parameters and the shelf width.</p> <p>The trained model explains 66% (R<sup>2</sup>) of the variance within the data set with a root mean square error (RMSE) of 31 km and a mean absolute error (MAE, less sensitive to outliers) of 17 km. The highest predictor importance is consistently reported for the weighted distance from canyon heads to the adjacent river mouths during the LGM and the present-day catchment gradient. We find no significant influence of shelf width, continental slope gradient and sediment load, and the moderate fit of the model indicates that we are still missing one or more important controls on the spatial location of canyon heads. Our predictions may be refined by including a more detailed assessment of catchment lithologies, locations of submarine groundwater discharge, locations of tectonic faults, and longshore current directions. Notwithstanding, we conclude that our model identifies important controls on the spatial occurrence and shelf incision of submarine canyons and sorts out much debated but seemingly unimportant variables.  </p>

scholarly journals How do tectonics influence the initiation and evolution of submarine canyons A case study from the Otway Basin, SE Australia

2021 ◽  
Author(s):  
Nan Wu ◽  
Harya Nugraha ◽  
Michael Steventon ◽  
Fa Zhong
Keyword(s):  
Late Miocene ◽  
Submarine Canyon ◽  
Turbidity Currents ◽  
Submarine Canyons ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Depositional Processes ◽  
Seabed Topography ◽  
Gravity Driven ◽  
Unconformity Surface

The architecture of canyon-fills can provide a valuable record of the link between tectonics, sedimentation, and depositional processes in submarine settings. We integrate 3D and 2D seismic reflection data to investigate the dominant tectonics and sedimentary processes involved in the formation of two deeply buried (c. 500 m below seafloor), and large (c. 3-6 km wide, >35 km long) Late Miocene submarine canyons. We found the plate tectonic-scale events (i.e. continental breakup and shortening) have a first-order influence on the submarine canyon initiation and evolution. Initially, the Late Cretaceous (c. 65 Ma) separation of Australia and Antarctica resulted in extensional fault systems, which then formed stair-shaped paleo-seabed. This inherited seabed topography allowed gravity-driven processes (i.e. turbidity currents and mass-transport complexes) to occur. Subsequently, the Late Miocene (c. 5 Ma) collision of Australia and Eurasia, and the resulting uplift and exhumation, have resulted in a prominent unconformity surface that coincides with the base of the canyons. We suggest that the Late Miocene intensive tectonics and associated seismicity have resulted in instability in the upper slope that consequently gave rise to emplacement of MTCs, initiating the canyons formation. Therefore, we indicate that regional tectonics play a key role in the initiation and development of submarine canyons.

scholarly journals Comparison between Recent benthic foraminiferal faunas of the Porcupine Seabight and Western Approaches Continental Slope

1985 ◽  
Vol 4 (2) ◽  
pp. 165-183 ◽  
Author(s):  
Janice F. Weston
Keyword(s):  
Continental Slope ◽  
Bottom Water ◽  
Sediment Type ◽  
The South ◽  
Submarine Canyons ◽  
Porcupine Seabight ◽  
Water Characteristics ◽  
Continental Slopes ◽  
Well Depth

Abstract. Although only 1 degree of latitude apart, the South Western Approaches and Porcupine Seabight continental slopes support widely differing benthic foraminiferal faunas. The less energetic, less variable, muddier conditions of the prograding margin of the Porcupine Seabight yield foraminiferal faunas which show extremely good zonations with respect to depth and are dominated by species such as Trifarina angulosa, Gavelinopsis lobatulus and Uvigerina pygmaea. The more variable and more energetic conditions of the submarine canyons of the Western Approaches margin do not support well depth zones faunas, but assemblages which are generally dominated by more cosmopolitan and robust species, such as Cassidulina carinata, Brizalina dilatata and B.subaenariensis. Such differences may be related to factors such as a greater variability of sediment type and bottom water characteristics and a more energetic environment in the Western Approaches area.

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