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Sediment volume and grain-size partitioning between submarine channel-levee systems and lobes; an experimental study

Jan de Leeuw, Joris T. Eggenhuisen, Yvonne T. Spychala, Maarten S. Heijnen, Florian Pohl and Matthieu J. B. Cartigny
Sediment volume and grain-size partitioning between submarine channel-levee systems and lobes; an experimental study
Journal of Sedimentary Research (July 2018) 88 (7): 777-794

Abstract

The width and depth of submarine channels change progressively as the channels evolve. This is inferred to act as an important control on the rate of sediment loss due overbank and in-channel deposition. Understanding the downstream extraction of sediment from turbidity currents is important for the prediction of grain-size trends and volume distribution in the stratigraphy. However, the partitioning of sediment by individual turbidity currents as a function of channel dimensions has not been investigated previously. We present a series of physical experiments studying the link between channel dimensions and the resulting partitioning of sediment volume and grain size between sub-environments. The experimental set-up consists of a slope (11 degrees ) with a straight pre-formed channel and a horizontal basin floor. An identical flow was released repeatedly into channels with different dimensions, resulting in various styles of overspill, erosion, and deposition under varying degrees of channel confinement. The fraction of sediment that was bypassed through the channel to the basin floor varied between 67% and 89%, depending on the amount of levee and in-channel deposition. The volume of levee deposition correlates well with channel depth. A large channel depth relative to flow thickness limits the amount of overspill. The amount of in-channel deposition correlates well with channel width/depth (W/D) ratio, where low-W/D-ratio channels have less deposition. We compare the experiments to natural system to show that the same patterns of volume and grain-size partitioning are present at different scales. The experiments provide snapshots of different phases of evolution of natural submarine channels. Natural submarine channels in an early evolution phase are inferred to be shallow and the experiments demonstrate that this results in significant sediment loss to levee deposition along the channel. The process of levee deposition preferentially extracts the fine-grained sediment fraction, which overspills from the channel. Therefore, we predict that the initial sediment pulse that reaches the basin floor is coarse grained and volumetrically small. As the channel matures and deepens, it will bypass more sediment with a mix of grain sizes to the basin floor.


ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 88
Serial Issue: 7
Title: Sediment volume and grain-size partitioning between submarine channel-levee systems and lobes; an experimental study
Affiliation: Utrecht University, Faculty of Geosciences, Utrecht, Netherlands
Pages: 777-794
Published: 20180724
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 45
Accession Number: 2019-003162
Categories: Sedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, block diags.
Secondary Affiliation: California Institute of Technology, USA, United StatesUniversity of Southampton, GBR, United KingdomDurham University, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 201902
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