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What controls submarine channel development and the morphology of deltas entering deep-water fjords?

Gales, J. and Talling, P.J. and Cartigny, M.J.B. and Hughes Clarke, J. and Lintern, G. and Stacey, C. and Clare, M.A. (2019) 'What controls submarine channel development and the morphology of deltas entering deep-water fjords?', Earth surface processes and landforms., 44 (2). pp. 535-551.

Abstract

River deltas and associated turbidity current systems produce some of the largest and most rapid sediment accumulations on our planet. These systems bury globally significant volumes of organic carbon and determine the runout distance of potentially hazardous sediment flows and the shape of their deposits. Here we seek to understand the main factors that determine the morphology of turbidity current systems linked to deltas in fjords, and why some locations have well developed submarine channels whilst others do not. Deltas and associated turbidity current systems are analysed initially in five fjord systems from British Columbia in Canada, and then more widely. This provides the basis for a general classification of delta and turbidity current system types, where rivers enter relatively deep (>200 m) water. Fjord‐delta area is found to be strongly bimodal. Avalanching of coarse‐grained bedload delivered by steep mountainous rivers produces small Gilbert‐type fan‐deltas, whose steep gradient (11°‐25°) approaches the sediment's angle of repose. Bigger fjord‐head deltas are associated with much larger and finer‐grained rivers. These deltas have much lower gradients (1.5°‐10°) that decrease offshore in a near exponential fashion. The lengths of turbidity current channels are highly variable, even in settings fed by rivers with similar discharges. This may be due to resetting of channel systems by delta‐top channel avulsions or major offshore landslides, as well as the amount and rate of sediment supplied to the delta front by rivers.

Item Type:Article
Full text:(AM) Accepted Manuscript
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Status:Peer-reviewed
Publisher Web site:https://doi.org/10.1002/esp.4515
Publisher statement:This is the accepted version of the following article: Gales, J., Talling, P.J., Cartigny, M.J.B., Hughes Clarke, J., Lintern, G., Stacey, C. & Clare, M.A. (2019). What controls submarine channel development and the morphology of deltas entering deep-water fjords? Earth Surface Processes and Landforms 44(2): 535-551 which has been published in final form at https://doi.org/10.1002/esp.4515. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.
Date accepted:13 September 2018
Date deposited:16 October 2018
Date of first online publication:19 September 2018
Date first made open access:19 September 2019

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