Allen, C, Gomis-Cartesio, L, Hodgson, DM orcid.org/0000-0003-3711-635X et al. (2 more authors)
(2022)
Channel incision into a submarine landslide on a Carboniferous basin margin, San Juan, Argentina: Evidence for the role of knickpoints.
The Depositional Record, 8 (2).
pp. 628-655.
ISSN 2055-4877
Abstract
Emplacement of submarine landslides, or mass-transport deposits, can radically reshape the physiography of continental margins, and strongly influence subsequent sedimentary processes and dispersal patterns. Typically, progressive healing of the complicated relief generated by the submarine landslide occurs prior to progradation of sedimentary systems. However, subsurface and seabed examples show that submarine channels can incise directly into submarine landslides. Here, the evolution of a unique exhumed example of two adjacent, and partially contemporaneous, submarine channel-fills is documented. The channels show deep incision (>75 m), and steep lateral margins (up to 70°), cut into a >200 m thick submarine landslide. The stepped basal erosion surface, and multiple terrace surfaces, are mantled by clasts (gravels to cobbles) reflecting periods of bedload-derived sedimentation, punctuated by phases of downcutting and sediment bypass. The formation of multiple terrace surfaces in a low aspect ratio confinement is consistent with the episodic migration of knickpoints during entrenchment on the dip slope of the underlying submarine landslide. Overlying sandstone-rich channel-fills mark a change to aggradation. Laterally stacked channel bodies coincide with steps in the original large-scale erosion surface, recording widening of the conduit; this is followed by tabular, highly aggradational fill. The upper fill, above a younger erosional surface, shows an abrupt change to partially confined tabular sandstones with normally graded caps, interpreted as lobe fringe deposits, which formed due to down-dip confinement, followed by prograding lobe deposits. Overlying this, an up-dip avulsion induced lobe switching and back-stepping, and subsequent failure of a sandstone body up-dip led to emplacement of a sandstone-rich submarine landslide within the conduit. Collectively, this outcrop represents episodic knickpoint-generated incision, and later infill, of a slope adjusting to equilibrium. The depositional signature of knickpoints is very different from existing models, but is probably reflective of other highly erosional settings undergoing large-scale slope adjustment.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2022 The Authors. The Depositional Record published by John Wiley & Sons Ltd on behalf of International Association of Sedimentologists. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
Keywords: | knickpoints; lobes; mass-transport deposit; submarine channel; submarine landslides; terrace deposits |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Institute for Applied Geosciences (IAG) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 19 Jan 2022 15:53 |
Last Modified: | 17 Mar 2023 12:13 |
Status: | Published |
Publisher: | Wiley |
Identification Number: | 10.1002/dep2.178 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:182607 |