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Quantifying the geomorphic response of modern submarine channels to actively growing folds and thrusts, deep-water Niger Delta

2017; Geological Society of America; Linguagem: Inglês

10.1130/b31544.1

1943-2674

Byami A. Jolly, Alexander C. Whittaker, Lidia Lonergan,

Geological and Geophysical Studies

Research Article| May 11, 2017 Quantifying the geomorphic response of modern submarine channels to actively growing folds and thrusts, deep-water Niger Delta Byami A. Jolly; Byami A. Jolly 1Department of Earth Science and Engineering, Royal School of Mines, Imperial College, London, SW7 2AZ, UK Search for other works by this author on: GSW Google Scholar Alexander C. Whittaker; Alexander C. Whittaker § 1Department of Earth Science and Engineering, Royal School of Mines, Imperial College, London, SW7 2AZ, UK §Corresponding author: a.whittaker@imperial .ac.uk Search for other works by this author on: GSW Google Scholar Lidia Lonergan Lidia Lonergan 1Department of Earth Science and Engineering, Royal School of Mines, Imperial College, London, SW7 2AZ, UK Search for other works by this author on: GSW Google Scholar Author and Article Information Byami A. Jolly 1Department of Earth Science and Engineering, Royal School of Mines, Imperial College, London, SW7 2AZ, UK Alexander C. Whittaker § 1Department of Earth Science and Engineering, Royal School of Mines, Imperial College, London, SW7 2AZ, UK Lidia Lonergan 1Department of Earth Science and Engineering, Royal School of Mines, Imperial College, London, SW7 2AZ, UK §Corresponding author: a.whittaker@imperial .ac.uk Publisher: Geological Society of America Received: 07 Apr 2016 Revision Received: 17 Dec 2016 Accepted: 09 Mar 2017 First Online: 23 Jun 2017 Online Issn: 1943-2674 Print Issn: 0016-7606 © 2017 Geological Society of America GSA Bulletin (2017) 129 (9-10): 1123–1139. https://doi.org/10.1130/B31544.1 Article history Received: 07 Apr 2016 Revision Received: 17 Dec 2016 Accepted: 09 Mar 2017 First Online: 23 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Byami A. Jolly, Alexander C. Whittaker, Lidia Lonergan; Quantifying the geomorphic response of modern submarine channels to actively growing folds and thrusts, deep-water Niger Delta. GSA Bulletin 2017;; 129 (9-10): 1123–1139. doi: https://doi.org/10.1130/B31544.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The interaction between submarine channels and active seabed deformation controls sediment delivery to the deep sea. Here, we combined seismic and geomorphic techniques to investigate quantitatively how the gravity-driven growth of thrust-related folds in the deep-water Niger Delta has influenced the morphology of four Pleistocene to Holocene submarine channels with present-day geomorphic expression. We extracted the bathymetric long profile of each of these modern seabed channel systems, and we evaluated the down-system evolution of channel widths, depths, and slopes as they have interacted with growing seabed structures. This information was used to derive estimates of bed shear stresses and velocities, to infer morphodynamic processes that have sculpted the channel systems through time, and to evaluate how these channels have responded to actively growing structures in the toe of the delta.The long profiles of these channels are relatively linear, with concavity from −0.08 to −0.34, and an average gradient of ∼1°. They are characterized by small knickpoints that are apparent near mapped structures and therefore implicitly reflect variations in substrate uplift rate. Channel incised depths increase significantly near the active structures, leading to entrenchment, but there is little change in the down-system distribution of channel width, in contrast to rivers crossing active faults, or buried submarine channel complexes. Reconstructed bed shear stresses near faults are estimated to lie in the range of 100–200 Pa, which would be associated with turbidite flow velocities of 2–4 m/s. A comparison of the magnitude and distribution of structural uplift since 1.7 Ma and the distribution of channel incision over this time shows that three of these channels have been able to keep pace with the time-integrated uplift since 1.7 Ma and have likely reached a local topographic steady state. Entrenchment of the submarine channels upstream of growing folds helps to drive this process, and we estimate that bed shear stresses of >100 Pa are sufficient to keep pace with structural strain rates of ∼4 × 10–3 m.y.–1. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.