How to recognize crescentic bedforms formed by supercritical turbidity currents in the geologic record: Insights from active submarine channels
| Type | Article | ||||||||
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| Date | 2018-06 | ||||||||
| Language | English | ||||||||
| Author(s) | Hage Sophie 1, 2, Cartigny Matthieu J. B.3, 4, Clare Michael A.1, Sumner Esther J.2, Vendettuoli Daniela1, 2, Clarke John E. Hughes5, Hubbard Stephen M.6, Talling Peter J.2, Lintern D. Gwyn7, Stacey Cooper D.7, Englert Rebecca G.6, Vardy Mark E.1, Hunt James E.1, Yokokawa Miwa8, Parsons Daniel R.9, Hizzett Jamie L.1, 2, Azpiroz-Zabala Maria1, 2, Vellinga Age J.1, 2 |
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| Affiliation(s) | 1 : Univ Southampton, Natl Oceanog Ctr, Waterfront Campus, Southampton SO14 3ZH, Hants, England. 2 : Univ Southampton, Ocean & Earth Sci, Southampton SO14 3ZH, Hants, England. 3 : Univ Durham, Dept Earth Sci, Durham DH1 3LY, England. 4 : Univ Durham, Dept Geog, Durham DH1 3LY, England. 5 : Univ New Hampshire, Ctr Coastal & Ocean Mapping, Durham, NH 03824 USA. 6 : Univ Calgary, Dept Geosci, Calgary, AB T2N 1N4, Canada. 7 : Geol Survey Canada, Nat Resources Canada, Sidney, BC V8L 4B2, Canada. 8 : Osaka Inst Technol, Hirakata, Osaka 5730196, Japan. 9 : Univ Hull, Fac Sci, Dept Geog Environm & Earth Sci, Kingston Upon Hull HU6 7RX, N Humberside, England. |
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| Source | Geology (0091-7613) (Geological Soc Amer, Inc), 2018-06 , Vol. 46 , N. 6 , P. 563-566 | ||||||||
| DOI | 10.1130/G40095.1 | ||||||||
| WOS© Times Cited | 75 | ||||||||
| Abstract | Submarine channels have been important throughout geologic time for feeding globally significant volumes of sediment from land to the deep sea. Modern observations show that submarine channels can be sculpted by supercritical turbidity currents (seafloor sediment flows) that can generate upstream-migrating bedforms with a crescentic planform. In order to accurately interpret supercritical flows and depositional environments in the geologic record, it is important to be able to recognize the depositional signature of crescentic bedforms. Field geologists commonly link scour fills containing massive sands to crescentic bedforms, whereas models of turbidity currents produce deposits dominated by back-stepping beds. Here we reconcile this apparent contradiction by presenting the most detailed study yet that combines direct flow observations, time-lapse seabed mapping, and sediment cores, thus providing the link from flow process to depositional product. These data were collected within the proximal part of a submarine channel on the Squamish Delta, Canada. We demonstrate that bedform migration initially produces back-stepping beds of sand. However, these back-stepping beds are partially eroded by further bedform migration during subsequent flows, resulting in scour fills containing massive sand. As a result, our observations better match the depositional architecture of upstream-migrating bedforms produced by fluvial models, despite the fact that they formed beneath turbidity currents. | ||||||||
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