Processes of sedimentation in Gollum Channel, Porcupine Seabight: submersible observations and sediment analyses

AbstractManned submersible dives were conducted in the submarine canyon channel system of Porcupine Seabight, NE Atlantic Ocean. Visual observations were made, and sediment samples collected and analysed to elucidate the nature of the sedimentary regime. In the upper part of the canyon (480-940 m water depth) sediments consisted of a mixture of terrigenous quartz rich silts and sands, skeletal carbonate of benthonic and planktonic origin and minor clay minerals and authigenic dolomite. There were localised Lophelia pertusa coral thickets on both the flanks and floor of the canyon. Sedimentary structures and physical measurements revealed there to be active transport of sediments in the canyon down to a depth of at least 940 m, effected by (?tidal) reversing currents and bioturbation. In these parts of the canyon, deposits around glacial dropstones and coral thickets indicate that there has been a maximum of 0-1 m of net sediment accumulation since the last glacial period. At 3000 m water depth, in the channel system, the sediments were fine calcareous ooze with a drape (up to 0-3 m thick) of flocculant phytoplankton detritus. At these depths, there was no evidence for present-day sediment resuspension by currents.

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Suspended particulate matter in a submarine canyon (Whittard Canyon, Bay of Biscay, NE Atlantic Ocean): Assessment of commonly used instruments to record turbidity

Marine Geology ◽

10.1016/j.margeo.2021.106439 ◽

2021 ◽

Vol 434 ◽

pp. 106439

Author(s):

Sabine Haalboom ◽

Henko de Stigter ◽

Gerard Duineveld ◽

Hans van Haren ◽

Gert-Jan Reichart ◽

...

Keyword(s):

Particulate Matter ◽

Atlantic Ocean ◽

Suspended Particulate Matter ◽

Submarine Canyon ◽

Bay Of Biscay ◽

Ne Atlantic ◽

Suspended Particulate ◽

Ne Atlantic Ocean

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Effects of a major typhoon on sediment accumulation in Fangliao Submarine Canyon, SW Taiwan

Marine Geology ◽

10.1016/j.margeo.2012.07.008 ◽

2012 ◽

Vol 326-328 ◽

pp. 116-130 ◽

Cited By ~ 22

Author(s):

Richard P. Hale ◽

Charles A. Nittrouer ◽

James T. Liu ◽

Richard G. Keil ◽

Andrea S. Ogston

Keyword(s):

Sediment Accumulation ◽

Submarine Canyon

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Tectonic controls on nearshore sediment accumulation and submarine canyon morphology offshore La Jolla, Southern California

Marine Geology ◽

10.1016/j.margeo.2009.10.026 ◽

2010 ◽

Vol 268 (1-4) ◽

pp. 115-128 ◽

Cited By ~ 28

Author(s):

Nicolas Le Dantec ◽

Leah J. Hogarth ◽

Neal W. Driscoll ◽

Jeffrey M. Babcock ◽

Walter A. Barnhardt ◽

...

Keyword(s):

Southern California ◽

Sediment Accumulation ◽

Submarine Canyon ◽

La Jolla

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RECENT SEDIMENTARY PROCESSES IN THE WESTERN GULF OF CORINTH, GREECE: SEISMIC AND ASEISMIC TURBITIDES

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.11739 ◽

2017 ◽

Vol 50 (1) ◽

pp. 383

Author(s):

S. Sergiou ◽

A. Beckers ◽

M. Geraga ◽

G. Papatheodorou ◽

I. Iliopoulos ◽

...

Keyword(s):

Sediment Cores ◽

Sediment Accumulation ◽

Submarine Canyon ◽

Seismic Events ◽

Mass Movements ◽

Sedimentary Processes ◽

Gulf Of Corinth ◽

Active Tectonic ◽

Geochemical Analyses ◽

Seismic Origin

The Corinth rift is counted among the most active tectonic grabens in the world, with extension rates up to 15 mm/yr (Western part). These high extension rates are associated with very strong seismic events that are, occasionally, responsible for submarine mass movements. These movements, their consequential bottom currents, and the differential river-discharging sediment accumulation in the whole gulf, strongly affect the modern marine sedimentary processes. The definition and understanding of these processes is the main aim of this project. This is attempted through via sedimentological, mineral and geochemical analyses on sediment samples from two ~1.1 m long, sediment cores from a WE submarine canyon (10 km long, 3 km wide) that lies in the Western tip of the gulf. The general sedimentation motif reveals the presence of hemipelagic deposits which are occasionally interrupted by sandy turbidites. Occasionally, these turbidites seem to have seismic origin. The sedimentation rates range between 2.57 mm/yr in the western part and 0.67 mm/yr in the eastern part.

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Evaluating the historical sedimentation patterns in two different Mediterranean deep environments (Sardinia and Sicily Channels)

Mediterranean Marine Science ◽

10.12681/mms.19558 ◽

2019 ◽

Vol 20 (3) ◽

pp. 542 ◽

Cited By ~ 3

Author(s):

NOUR EL HOUDA HASSEN ◽

NAFAÂ REGUIGUI ◽

MOHAMED AMINE HELALI ◽

NEZHA MEJJAD ◽

ABDELMOURHIT LAISSAOUI ◽

...

Keyword(s):

Mediterranean Sea ◽

Water Depth ◽

Accumulation Rate ◽

Sediment Cores ◽

Sediment Accumulation ◽

Inverse Correlation ◽

Accumulation Rates ◽

Deep Sediment ◽

210Pb And 137Cs ◽

Excess 210Pb

The sediment accumulation rate in the Sardinia and Sicily channels in the central part of the Mediterranean Sea was studied by using short-lived radionuclides (210Pb and 137Cs) in two deep sediment cores. Different sedimentation regimes were identified indicating substantial differences in accumulation rates and historical patterns. The 210Pb-derived mean accumulation rate found in the Strait of Sardinia was 0.05 g.cm-2.y-1, lower than that in Sicily Channel (0.1 g.cm-2.y-1) suggesting an inverse correlation with water depth. Excess 210Pb inventories were 24 ± 1 and 6.0 ± 0.4 kBq.m-2, while the fluxes to the sediment were 745 ± 31 and 188 ± 11 Bq.m-2.y-1 in Sicily and Sardinia channels, respectively. 137Cs failed to use for the validation of the established chronologies, while its inventories found 450 Bq.m-2 and 355 Bq.m-2 in the Sicily and Sardinia channel, respectively.

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Uncrewed bathymetric survey in UK waters: Testing CARIS Mira AI and globally-distributed Nippon Foundation/ GEBCO training program Alumni to produce data products

10.5194/egusphere-egu21-15523 ◽

2021 ◽

Author(s):

Danai Lampridou ◽

Kemron Beache ◽

Aileen Bohan ◽

Mohamed Elsaied ◽

Travis Hamilton ◽

...

Keyword(s):

Continental Shelf ◽

Training Program ◽

Water Depth ◽

Submarine Canyon ◽

Satellite Communications ◽

Depth Range ◽

Seafloor Mapping ◽

The United Kingdom ◽

High Degree ◽

Globally Distributed

SEA-KIT USV Maxlimer successfully carried out a 22 day (24hrs per day), uncrewed survey operation offshore the United Kingdom in July-August 2020. The uncrewed vessel was controlled and manoeuvred from an operation room based in Essex, UK, while the data acquisition was performed by alumni of the Nippon Foundation/GEBCO Training Program, through the Map the Gaps NPO, spread across 10 countries. One of the main objectives of the trans-ocean survey was to test the remote survey capabilities through satellite communications, and also promote the contribution to seafloor mapping. CARIS Onboard, incorporating the new Sonar Noise Classifier tool via the CARIS Mira AI platform, was deployed to autonomously process the survey data in real-time, and provide products that could be streamed daily from SEA-KIT to ensure operations were successful and to help train the classifier as required. The data was post-processed with CARIS HIPS and SIPS using conventional and Ai techniques, and gridded at 10 m. The collected data size was 52.2 GB, surveyed area depth range from 57m to 1362 with 470m mean depth and around 900 km2 was totally covered.&#160; CARIS Mira AI with traditional QC approach reduced data processing time to 77% regarding the conventional path.The high-resolution bathymetric dataset provided the first detailed picture of the Brenot Spur, adjacent to Dangeart Canyon. Three major submarine canyon systems can be identified, cross-cutting the continental shelf nearly perpendicularly. The main axis of the first canyon, located at the far northern part of the surveyed area, is oriented NE-SW and becomes wider downstream. Both of the flanks are highly carved by gullies and tributaries, especially along the northern flank, where a complex system is developed depicting well-developed amphitheatric heads, indicating retrogressive erosion. Moreover, this network shows a high degree of incision and narrow interfluves. The second major canyon trends ENE-WSW and is a multi-fed system consisting of three sub-canyons that coalesce at 1095 m water depth. Although tributaries bisect the flanks of this system, they are not mature and have not yet breached the continental shelf, but are mostly confined on the slope. The final canyon is narrower than the previous ones and its&#160; thalweg is nearly N-S oriented. Additionally, the flanks of the later differ substantially when it comes to their morphology. The western flank is undulated by linear wall gullies and several landslides indicated by the crescent like rim of high slope values, while the eastern flank is smooth and featureless. Along the SW continental slope, evidence for several old landslide events can be identified. The major failure scars are located right at the edge of the shelf at 560 m water depth.

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First direct monitoring and time-lapse mapping starts to reveal how a large submarine fan works

10.5194/egusphere-egu2020-2407 ◽

2020 ◽

Author(s):

Peter Talling ◽

Ricardo de Silva Jacinto ◽

Megan Baker ◽

Ed Pope ◽

Maarten Heijnen ◽

...

Keyword(s):

Shallow Water ◽

Deep Ocean ◽

Submarine Canyon ◽

Time Lapse ◽

Turbidity Currents ◽

Submarine Fan ◽

Channel System ◽

Seabed Sediment ◽

Flow Monitoring ◽

Initial Results

Turbidity currents form many of the largest sediment accumulations, longest channels, and deepest canyons on our planet. These seabed sediment avalanches can be very (> 10 m/s) fast, runout for hundreds of kilometres, and break seabed cables that now form the backbone of the internet and global data transfer. It was once thought that detailed monitoring of turbidity currents in action was impractical, ensuring these flows were relatively poorly understood. However, a series of recent projects have used new approaches and technology to show how these flows can be measured in shallow water (< 2 km) settings, such as Monterey Canyon and Canadian fjords, where flows ran out for < ~50 km and had speeds of up to 8 m/s. Here we present initial results from an ambitious project to measure active flows that runout for >1,000 km to form a major submarine fan in the deep ocean. The project studies the Congo submarine canyon-channel system that extends for ~1,100 km from the mouth of the Congo River, offshore West Africa. Monitoring in 2010 at a single site in the upper Congo Canyon had previously shown that flows are active for ~30% of the time, and reach speeds of up to 3 m/s. In this new project, direct flow monitoring at 11 sites are being combined with detailed time-lapse mapping and coring of flow deposits, through a series of 4 or 5 major research cruises from 2019 to 2023. Here we present initial results from the first of these cruises (JC187) in August-to-October 2019, which placed 11 moorings with sensors at water depths of 1.6 to 5.5 km. The presentation will initially focus on the geomorphology of the channel system, and how it varies down-slope and through time. For example, it is apparent that a landslide partly blocked one location in the upper canyon in the last 20 years, causing meander bend cut-off and sediment ponding. The talk will then discuss models for how submarine channel bends evolve, and the implications for channel deposits. Recent work in sandy submarine channels suggests that they can be dominated by very fast-moving knickpoints (waterfall like features). However, the much muddier Congo channel displays well-developed meander bend bars for which cores are available. We therefore start to show how muddy deep-sea channels may differ in significant ways from their sandier cousins in shallow water.&#160;

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