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Type: Journal article
Title: Flow processes and sedimentation in submarine channel bends
Author: Peakall, J.
Amos, K.
Keevil, G.
Bradbury, P.
Gupta, S.
Citation: Marine and Petroleum Geology, 2007; 24(6-9):470-486
Publisher: Elsevier Sci Ltd
Issue Date: 2007
ISSN: 0264-8172
Statement of
Jeff Peakall, Kathryn J. Amos, Gareth M. Keevil, P. William Bradbury and Sanjeev Gupta
Abstract: Turbidity currents in sinuous submarine channels are an important mechanism for transporting terrestrial sediments to deep water, and their deposits are of increasing importance as hydrocarbon exploration targets. Despite this, the architecture and dynamics of submarine channel systems are not well understood. Analogies are often drawn with fluvial systems due to similarities between their planform shapes even though differences in channel evolution and hydrodynamics have been noted. A key question is the nature of deposition within submarine channel bends; in particular at inner bends where point bars form in alluvial meandering rivers. Recent experimental and numerical work has demonstrated that the fluid dynamics of submarine channel bend flow are markedly different from rivers. Notably, a reversal in the orientation of secondary (helical) flow at bend apices occurs in submarine channels. The potential influence of these differences in fluid dynamics on deposition within submarine channel bends is investigated herein. We report the results of a series of physical experiments in which solute-driven gravity currents were run through pre-formed sinuous channels containing mobile beds. These experiments reveal sedimentation patterns characterised by accumulation zones downstream of bend apices and erosion zones at outer bends. These patterns are broadly analogous to the point bars and outer-bank pools observed in meandering rivers, demonstrating that the longitudinal flow component dominates over the cross-stream component, as also occurs in rivers. However, the data suggest that the reversal in direction of the cross-stream flow component compared with subaerial flows is important in determining the position and morphology of ‘point bars’ relative to bend apices. From analogy with fluvial compound channels, and fluvial theory, this reversal in secondary flow cell orientation is also expected to influence the spatial variations of grain size in submarine channel ‘point-bar’ deposits.
Keywords: Gravity current; Point bar; Submarine channel
Description: Copyright © 2007 Published by Elsevier Ltd.
RMID: 0020081595
DOI: 10.1016/j.marpetgeo.2007.01.008
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Appears in Collections:Australian School of Petroleum publications

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