Data/hora: 09/06/2024 15:35:29

Provedor de dados: | 5
País: | France
Título: | Seafloor facies related to upward methane flux within a Giant Pockmark of the Lower Congo Basin
Autores: | Gay, Aurelien; Lopez, M; Ondreas, Helene; Charlou, Jean-luc; Sermondadaz, G; Cochonat, Pierre.
Data: | 2006-02
Ano: | 2006
Palavras-chave: | BIOZAIRE; ZAIANGO; Palaeochannel; Hydrates; Chemosynthesis; Seafloor facies; Fluid migration; Pockmark.
Resumo: | The origin of the cold fluid venting from a Giant Pockmark within the Lower Congo Basin has been elucidated based upon results of precise mapping, submersible dives, gravity coring and isotopic analyses realized under a TOTAL-IFREMER cooperative project (ZAIANGO and BIOZAIRE projects). During four dives of the IFREMER ROV-Victor 6000, the bottom was filmed, hard and soft samples were lifted from the sediment, and water samples were collected with a CTD-rosette system. The detailed dip map shows that the 800 in wide Giant Pockmark is a composite feature due to the coalescence of multiple 100 in wide depressions that displays a broad range of biological, mineralogical and chemical features on the seafloor, leading to a seafloor anomaly recorded on the multibeam imagery. Methane-rich fluids migrating through the sedimentary column from a buried palaeochannel clearly react with the sulphate-rich circulating sea water to produce hydrogen sulphide and bicarbonate ions. This situation leads to a concentrical arrangement of the sedimentary facies, with methane-related features in the centre and sulphide-related features at the periphery. This organization is correlated with high levels of methane (up to 20 mu mol/l) measured in the centre of the Giant Pockmark, responsible for the crystallization of gas hydrates at the bottom. In this model, the concentrical organization of mineralogical and biological features reflects a geochemical partitioning related to the peripheral progressive mixing of the methane flux.
Tipo: | Text
Idioma: | Inglês

Identificador:

http://archimer.ifremer.fr/doc/2006/publication-1114.pdf

DOI:10.1016/j.margeo.2005.09.011

Editor: | Elsevier
Relação: | http://archimer.ifremer.fr/doc/00000/1114/
Formato: | application/pdf
Fonte: | Marine Geology (0025-3227) (Elsevier), 2006-02 , Vol. 226 , N. 1-2 , P. 81-95
Fonte: | 2005 Elsevier B.V. All rights reserved