ROV study of a giant pockmark on the Gabon continental margin

Type Article
Date 2005-11
Language English
Author(s) Ondreas Helene1, Olu Karine2, Fouquet Yves1, Charlou Jean-Luc1, Gay Aurelien1, 3, Dennielou BernardORCID1, Donval Jean-Pierre1, Fifis Alexis2, Nadalig Thierry1, 4, Cochonat Pierre1, Cauquil E5, Bourillet Jean-FrancoisORCID1, Le Moigne Morgan6, Sibuet Myriam2
Affiliation(s) 1 : IFREMER, Dept Geosci, F-29280 Plouzane, France.
2 : IFREMER, Dept Environm Profond, F-29280 Plouzane, France.
3 : Univ Montpellier 2, Lab GTS, F-34095 Montpellier, France.
4 : Univ Strasbourg 1, Lab Microbiol & Genet, CNRS, FRE 2326,Inst Bot, F-67083 Strasbourg, France.
5 : TOTAL, F-92400 Courbevoie, France.
6 : IFREMER, F-44311 Nantes, France.
Source Geo-Marine Letters (0276-0460) (Springer), 2005-11 , Vol. 25 , N. 5 , P. 281-292
DOI 10.1007/s00367-005-0213-6
WOS© Times Cited 85
Keyword(s) Gabon, Microbathymetric map, ROV, Exploration, Pockmark, Equatorial African margin
Abstract A giant, 800-m wide pockmark, called Regab, was discovered along the Equatorial African margin at 3160-m water depth and was explored by remote operated vehicle (ROV) as part of the Zaiango (1998-2000) and Biozaire (2001-2003) projects carried out conjointly by TOTAL and a number of French research institutes. A microbathymetric map obtained using the ROV sensors shows that the pockmark actually consists of a cluster of smaller pockmarks aligned N70 along a 15-m deep depression. Methane was recorded all over the pockmark, the highest values along the axis of the depression where massive carbonate crusts and dense seep communities were also found. Several faunal species belong to the Vesicomyidae and Mytilidae bivalve families, as well as to Siboglinidae (Vestimentifera) tubeworms. Preliminary analyses confirm their association with symbiotic bacteria, thus documenting their dependence on fluid seeps. The pockmark appears to be related to an infilled channel, visible on the seismic data 300 in below the seafloor, which may act as a reservoir for biogenic fluids supplied to the trap from the surrounding sediments.
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Ondreas Helene, Olu Karine, Fouquet Yves, Charlou Jean-Luc, Gay Aurelien, Dennielou Bernard, Donval Jean-Pierre, Fifis Alexis, Nadalig Thierry, Cochonat Pierre, Cauquil E, Bourillet Jean-Francois, Le Moigne Morgan, Sibuet Myriam (2005). ROV study of a giant pockmark on the Gabon continental margin. Geo-Marine Letters, 25(5), 281-292. Publisher's official version : https://doi.org/10.1007/s00367-005-0213-6 , Open Access version : https://archimer.ifremer.fr/doc/00000/1239/