Pockmarks on the South Aquitaine Margin continental slope: The seabed expression of past fluid circulation and former bottom currents

Type Article
Date 2017-12
Language English
Author(s) Michel Guillaume1, Dupre StephanieORCID1, Baltzer Agnes2, Ehrhold AxelORCID1, Imbert Patrice3, Pitel MathildeORCID1, Loubrieu Benoit1, Scalabrin CarlaORCID1, Lazure PascalORCID4, Marie Louis4, Geldof Jean-Baptiste5, Deville Eric6
Affiliation(s) 1 : IFREMER, Unite Geosci Marines, F-29280 Plouzane, France.
2 : Univ Nantes, CNRS, UMR 6554, F-44312 Nantes 3, France.
3 : Ctr Sci & Tech Jean Feger, TOTAL, Ave Larribau, F-64018 Pau, France.
4 : IFREMER, Lab Oceanog Phys & Spatiale, F-29280 Plouzane, France.
5 : TOTAL, 10 Pl Vosges, F-92072 Paris, France.
6 : IFP Energies Nouvelles, 1&4 Ave Bois Pre Preau, F-92852 Rueil Malmaison, France.
Source Comptes Rendus Geoscience (1631-0713) (Elsevier France-editions Scientifiques Medicales Elsevier), 2017-12 , Vol. 349 , N. 8 , P. 391-401
DOI 10.1016/j.crte.2017.10.003
WOS© Times Cited 17
Keyword(s) Pockmark, Fluid, Seabed morphology, Aquitaine slope, GIS, Currents

Inactive and mostly elongated pockmarks of 100–200 m in dimension were recently discovered on the South Aquitaine Margin continental slope. They are distributed at water depths greater than 350 m in both interfluve and sediment-wave areas, and are strongly controlled by the sedimentary morphology and architecture. Water column and seafloor backscatter and sub-bottom profiler data do not exhibit present-day or past gas evidence, e.g., massive and continuous gas releases at the seabed and fossil methane-derived authigenic carbonates. It is thus proposed that the pockmarks originated from a shallow source and result from relatively recent and short-duration gas or water expulsion events. Former near-bottom currents may have contributed to the elongation of these WNW–ESE-oriented pockmarks, whereas present-day weaker near-bottom currents may induce upwelling, contributing to the maintenance of the elongated shapes of the pockmarks.

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Michel Guillaume, Dupre Stephanie, Baltzer Agnes, Ehrhold Axel, Imbert Patrice, Pitel Mathilde, Loubrieu Benoit, Scalabrin Carla, Lazure Pascal, Marie Louis, Geldof Jean-Baptiste, Deville Eric (2017). Pockmarks on the South Aquitaine Margin continental slope: The seabed expression of past fluid circulation and former bottom currents. Comptes Rendus Geoscience, 349(8), 391-401. Publisher's official version : https://doi.org/10.1016/j.crte.2017.10.003 , Open Access version : https://archimer.ifremer.fr/doc/00413/52491/