Pockmarks on the South Aquitaine Margin continental slope: The seabed expression of past fluid circulation and former bottom currents
|Author(s)||Michel Guillaume1, Dupre Stephanie1, Baltzer Agnes2, Ehrhold Axel1, Imbert Patrice3, Pitel Mathilde1, Loubrieu Benoit1, Scalabrin Carla1, Lazure Pascal4, 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|
|WOS© Times Cited||11|
|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.