A new modelling approach to sediment bypass prediction applied to the East Coast Basin, New Zealand

Crisóstomo-Figueroa, Adriana; McArthur, Adam D.; Dorrell, Robert M.; Amy, Lawrence; McCaffrey, William D.

Abstract

Predicting when turbidity currents are erosional or depositional (i.e., leaving no depositional record versus leaving a deposit) remains challenging. Here we combine observations from submarine channel morphology with a new sediment transport model to derive thresholds for net erosional, equilibrium, or net depositional flow to predict how far turbidity currents can transport different grain size classes down the channel. The approach was applied to the modern Madden and Omakere Channels, which traverse the Hikurangi subduction margin of the North Island of New Zealand. A bathymetric data set was used to establish the downstream change of channel geometry. Taking account of centripetal and Coriolis forces, the flow superelevation method was used to estimate variations in flow velocity and concentration along the channels. These parameters were used as model inputs to estimate the potential distribution of sand in the system assuming the separate cases of well-sorted and poorly-sorted sediment in suspension. The predicted sand distribution maps deposited by poorly-sorted flows in the channels show good agreement with root mean square amplitude mapping of the seafloor. These results confirm that thicker flows, and those carrying well-sorted suspensions, can bypass sediment over lower slopes than thinner flows and those carrying more poorly-sorted suspensions. The net erosion and net deposition thresholds derived from this study may help to guide and constrain predictions of potential sediment bypass zones in seafloor and subsurface systems and hence better constrain the predicted loci of deposition.

Citation

Crisóstomo-Figueroa, A., McArthur, A. D., Dorrell, R. M., Amy, L., & McCaffrey, W. D. (2021). A new modelling approach to sediment bypass prediction applied to the East Coast Basin, New Zealand. Geological Society of America Bulletin, 133(7-8), 1734-1748. https://doi.org/10.1130/B35687.1

• Journal Article Type: Article
• Acceptance Date: Sep 23, 2020
• Online Publication Date: Dec 16, 2020
• Publication Date: Jul 1, 2021
• Deposit Date: Nov 6, 2020
• Publicly Available Date: Dec 17, 2021
• Journal: Bulletin of the Geological Society of America
• Print ISSN: 0016-7606
• Electronic ISSN: 1943-2674
• Publisher: Geological Society of America
• Peer Reviewed: Peer Reviewed
• Volume: 133
• Issue: 7-8
• Pages: 1734-1748
• DOI: https://doi.org/10.1130/B35687.1
• Keywords: Australasia; Bathymetry; Channels; Clastic sediments; Currents; Deposition; East Coast Basin; Equilibrium; Erosion; Geometry; Grain size; Hikurangi Margin; Marine environment; New Zealand; North Island; Ocean floors; Prediction; Sand; Sediment transport
• Public URL: https://hull-repository.worktribe.com/output/3654929
• Publisher URL: https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/doi/10.1130/B35687.1/593338/A-new-modelling-approach-to-sediment-bypass?redirectedFrom=fulltext