scholarly journals How Do Deep-Sea Gravity Currents Transport Sediment So Far?

Eos ◽  
2018 ◽  
Vol 99 ◽  
Author(s):  
Terri Cook
Keyword(s):  
Deep Sea ◽  
Field Measurements ◽  
Gravity Currents ◽  
Turbidity Currents ◽  
Spiral Flow ◽  
Submarine Channel

The first field measurements of turbidity currents flowing around submarine channel bends indicate spiral flow plays a key role in keeping sediment suspended for hundreds of kilometers.

Linking submarine channel-levee facies and architecture to flow structure of turbidity currents: insights from flume tank experiments

Sedimentology ◽  
2017 ◽  
Vol 65 (3) ◽  
pp. 931-951 ◽  
Author(s):  
Jan de Leeuw ◽  
Joris T. Eggenhuisen ◽  
Matthieu J. B. Cartigny
Keyword(s):  
Flow Structure ◽  
Turbidity Currents ◽  
Submarine Channel

Disposal in the deep sea: analogue of nature or faux ami?

2003 ◽  
Vol 30 (1) ◽  
pp. 26-39 ◽  
Author(s):  
Paul A. Tyler
Keyword(s):  
Carbon Dioxide ◽  
Radioactive Waste ◽  
Deep Sea ◽  
Hydrothermal Vents ◽  
Natural Radionuclides ◽  
Deep Ocean ◽  
Turbidity Currents ◽  
Chemical Contamination ◽  
Seabed Sediment ◽  
Dredge Spoil

The deep sea is the world's largest ecosystem by volume and is assumed to have a high assimilative capacity. Natural events, such as the sinking of surface plant and animal material to the seabed, sediment slides, benthic storms and hydrothermal vents can contribute vast amounts of material, both organic and inorganic, to the deep ocean. In the past the deep sea has been used as a repository for sewage, dredge spoil and radioactive waste. In addition, there has been interest in the disposal of large man-made objects and, more recently, the disposal of industrially-produced carbon dioxide. Some of the materials disposed of in the deep sea may have natural analogues. This review examines natural processes in the deep sea including the vertical flux of organic material, turbidity currents and benthic storms, natural gas emissions, hydrothermal vents, natural radionuclides and rocky substrata, and compares them with anthropogenic input including sewage disposal, dredge spoil, carbon dioxide disposal, chemical contamination and the disposal of radioactive waste, wrecks and rigs. The comparison shows what are true analogues and what are false friends. Knowledge of the deep sea is fragmentary and much more needs to be known about this large, biologically-diverse system before any further consideration is given to its use in the disposal of waste.

Flow parameters of turbidity currents in a low-sinuosity giant deep-sea channel

Sedimentology ◽  
2008 ◽  
Vol 44 (6) ◽  
pp. 1093-1102 ◽  
Author(s):  
INGO KLAUCKE ◽  
R. HESSE ◽  
W. B. F. RYAN
Keyword(s):  
Deep Sea ◽  
Turbidity Currents ◽  
Flow Parameters

scholarly journals Lessons learned from the monitoring of turbidity currents and guidance for future platform designs

2020 ◽  
Vol 500 (1) ◽  
pp. 605-634 ◽  
Author(s):  
Michael Clare ◽  
D. Gwyn Lintern ◽  
Kurt Rosenberger ◽  
John E. Hughes Clarke ◽  
Charles Paull ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Engineering Design ◽  
Surface Area ◽  
Deep Sea ◽  
Critical Infrastructure ◽  
Lessons Learned ◽  
Turbidity Currents ◽  
Improve Design ◽  
Current Behaviour ◽  
Water Depths

AbstractTurbidity currents transport globally significant volumes of sediment and organic carbon into the deep-sea and pose a hazard to critical infrastructure. Despite advances in technology, their powerful nature often damages expensive instruments placed in their path. These challenges mean that turbidity currents have only been measured in a few locations worldwide, in relatively shallow water depths (<<2 km). Here, we share lessons from recent field deployments about how to design the platforms on which instruments are deployed. First, we show how monitoring platforms have been affected by turbidity currents including instability, displacement, tumbling and damage. Second, we relate these issues to specifics of the platform design, such as exposure of large surface area instruments within a flow and inadequate anchoring or seafloor support. Third, we provide recommended modifications to improve design by simplifying mooring configurations, minimizing surface area and enhancing seafloor stability. Finally, we highlight novel multi-point moorings that avoid interaction between the instruments and the flow, and flow-resilient seafloor platforms with innovative engineering design features, such as feet and ballast that can be ejected. Our experience will provide guidance for future deployments, so that more detailed insights can be provided into turbidity current behaviour, in a wider range of settings.

scholarly journals The Ogooue Fan (offshore Gabon): a modern example of deep-sea fan on a complex slope profile

Solid Earth ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 851-869 ◽  
Author(s):  
Salomé Mignard ◽  
Thierry Mulder ◽  
Philippe Martinez ◽  
Thierry Garlan
Keyword(s):  
Deep Sea ◽  
Sedimentary Facies ◽  
Turbidity Currents ◽  
Slope Gradient ◽  
Seismic Reflection Data ◽  
Fine Grained ◽  
Reflection Data ◽  
Deposition Processes ◽  
Sea Fan ◽  
The Impact

Abstract. The effects of changes in slope gradient on deposition processes and architecture have been investigated in different deep-sea systems both in modern and ancient environments. However, the impact of subtle gradient changes (< 0.3∘) on sedimentary processes along deep-sea fans still needs to be clarified. The Ogooue Fan, located in the northeastern part of the Gulf of Guinea, extends over more than 550 km westwards of the Gabonese shelf and passes through the Cameroon volcanic line. Here, we present the first study of acoustic data (multibeam echosounder and 3.5 kHz, very high-resolution seismic data) and piston cores covering the deep-sea part of this West African system. This study documents the architecture and sedimentary facies distribution along the fan. Detailed mapping of near-seafloor seismic-reflection data reveals the influence of subtle slope gradient changes (< 0.2∘) along the fan morphology. The overall system corresponds to a well-developed deep-sea fan, fed by the Ogooue River sedimentary load, with tributary canyons, distributary channel–levee complexes and lobe elements. However, variations in the slope gradient due to inherited salt-related structures and the presence of several seamounts, including volcanic islands, result in a topographically complex slope profile including several ramps and steps. In particular, turbidity currents derived from the Gabonese shelf deposit cross several interconnected intra-slope basins located on the low gradient segments of the margin (< 0.3∘). On a higher gradient segment of the slope (0.6∘), a large mid-system valley developed connecting an intermediate sedimentary basin to the more distal lobe area. Distribution and thickness of turbidite sands is highly variable along the system. However, turbidite sands are preferentially deposited on the floor of the channel and the most proximal depositional areas. Core description indicates that the upper parts of the turbidity flows, mainly composed of fine-grained sediments, are found in the most distal depocenters.

scholarly journals Environmental Conditions in a Carpathian Deep Sea Basin During the Period Preceding Oceanic Anoxic Event 2 - A Case Study from the Skole Nappe

2015 ◽  
Vol 65 (5) ◽  
pp. 433-450 ◽  
Author(s):  
Krzysztof Bąk ◽  
Marta Bąk ◽  
Zbigniew Górny ◽  
Anna Wolska
Keyword(s):  
Water Column ◽  
Deep Sea ◽  
Silica Content ◽  
Turbidity Currents ◽  
Ecological Groups ◽  
Deep Basin ◽  
Oceanic Anoxic Event ◽  
Plankton Production ◽  
Basin Floor

Abstract Hemipelagic green clayey shales and thin muddy turbidites accumulated in a deep sea environment below the CCD in the Skole Basin, a part of the Outer Carpathian realm, during the Middle Cenomanian. The hemipelagites contain numerous radiolarians, associated with deep-water agglutinated foraminifera. These sediments accumulated under mesotrophic conditions with limited oxygen concentration. Short-term periodic anoxia also occurred during that time. Muddy turbidity currents caused deposition of siliciclastic and biogenic material, including calcareous foramini-fers and numerous sponge spicules. The preservation and diversity of the spicules suggests that they originate from disarticulation of moderately diversified sponge assemblages, which lived predominantly in the neritic-bathyal zone. Analyses of radiolarian ecological groups and pellets reflect the water column properties during the sedimentation of green shales. At that time, surface and also intermediate waters were oxygenated enough and sufficiently rich in nutri-ents to enable plankton production. Numerous, uncompacted pellets with nearly pristine radiolarian skeletons inside show that pelletization was the main factor of radiolarian flux into the deep basin floor. Partly dissolved skeletons indicate that waters in the Skole Basin were undersaturated in relation to silica content. Oxygen content might have been depleted in the deeper part of the water column causing periodic anoxic conditions which prevent rapid bacterial degra-dation of the pellets during their fall to the sea floor.

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