Les structures en araignée : enregistrement d'échappements de fluide provenant des hydrates de méthane sur la pente continentale du Congo
Fluid seepage features on the upper continental slope offshore Congo are investigated using multi-disciplinary datasets acquired during several campaigns at sea carried out over the last 15 years. This datasets includes multibeam bathymetry, seismic data, seafloor videos, seafloor samples and chemic...
Published in: | Bulletin de la Société géologique de France |
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Online Access: | https://archimer.ifremer.fr/doc/00409/52076/52779.pdf https://doi.org/10.1051/bsgf/2017189 https://archimer.ifremer.fr/doc/00409/52076/ |
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ftarchimer:oai:archimer.ifremer.fr:52076 2023-06-11T04:14:02+02:00 Les structures en araignée : enregistrement d'échappements de fluide provenant des hydrates de méthane sur la pente continentale du Congo Spider structures: records of fluid venting from methane hydrates on the Congo continental slope Casenave, Viviane Gay, Aurelien Imbert, Patrice 2017 application/pdf https://archimer.ifremer.fr/doc/00409/52076/52779.pdf https://doi.org/10.1051/bsgf/2017189 https://archimer.ifremer.fr/doc/00409/52076/ fre eng fre eng Edp Sciences S A https://archimer.ifremer.fr/doc/00409/52076/52779.pdf doi:10.1051/bsgf/2017189 https://archimer.ifremer.fr/doc/00409/52076/ SGF, Published by EDP Sciences 2017 info:eu-repo/semantics/openAccess restricted use Bulletin De La Societe Geologique De France (0037-9409) (Edp Sciences S A), 2017 , Vol. 188 , N. 4 , P. 27 methane seep methane hydrates bottom-simulating reflector (BSR) dynamic seepage methane-derived authigenic carbonates (MDAC) text Article info:eu-repo/semantics/article 2017 ftarchimer https://doi.org/10.1051/bsgf/2017189 2023-05-30T22:50:57Z Fluid seepage features on the upper continental slope offshore Congo are investigated using multi-disciplinary datasets acquired during several campaigns at sea carried out over the last 15 years. This datasets includes multibeam bathymetry, seismic data, seafloor videos, seafloor samples and chemical analyses of both carbonate samples and of the water column. Combined use of these datasets allows the identification of two distinctive associations of pockmark-like seabed venting structures, located in water depths of 600–700 m and directly above a buried structural high containing known hydrocarbon reservoirs. These two features are called spiders due to the association of large sub-circular depressions (the body) with smaller elongate depressions (the legs). Seismic reflection data show that these two structures correspond to amplitude anomalies located ca. 60–100 ms below seabed. The burial of these anomalies is consistent with the base of the methane hydrate stability domain, which leads to interpret them as patches of hydrate-related bottom-simulating reflection (BSR). The morphology and seismic character of the two structures clearly contrasts with those of the regional background (Morphotype A). The spider structures are composed of two seafloor morphotypes: Morphotype B and Morphotype C. Morphotype B makes flat-bottomed depressions associated with the presence of large bacterial mats without evidence of carbonates. Morphotype C is made of elongated depressions associated with the presence of carbonate pavements and a prolific chemosynthetic benthic life. On that basis of these observations combined with geochemical analyses, the spider structures are interpreted to be linked with methane leakage. Methane leakage within the spider structures varies from one morphotype to another, with a higher activity within the seafloor of Morphotype C; and a lower activity in the seafloor of Morphotype B, which is interpreted to correspond to a domain of relict fluid leakage. This change of the seepage activity is due ... Article in Journal/Newspaper Methane hydrate Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) Bulletin de la Société géologique de France 188 4 27 |
institution |
Open Polar |
collection |
Archimer (Archive Institutionnelle de l'Ifremer - Institut français de recherche pour l'exploitation de la mer) |
op_collection_id |
ftarchimer |
language |
French English |
topic |
methane seep methane hydrates bottom-simulating reflector (BSR) dynamic seepage methane-derived authigenic carbonates (MDAC) |
spellingShingle |
methane seep methane hydrates bottom-simulating reflector (BSR) dynamic seepage methane-derived authigenic carbonates (MDAC) Casenave, Viviane Gay, Aurelien Imbert, Patrice Les structures en araignée : enregistrement d'échappements de fluide provenant des hydrates de méthane sur la pente continentale du Congo |
topic_facet |
methane seep methane hydrates bottom-simulating reflector (BSR) dynamic seepage methane-derived authigenic carbonates (MDAC) |
description |
Fluid seepage features on the upper continental slope offshore Congo are investigated using multi-disciplinary datasets acquired during several campaigns at sea carried out over the last 15 years. This datasets includes multibeam bathymetry, seismic data, seafloor videos, seafloor samples and chemical analyses of both carbonate samples and of the water column. Combined use of these datasets allows the identification of two distinctive associations of pockmark-like seabed venting structures, located in water depths of 600–700 m and directly above a buried structural high containing known hydrocarbon reservoirs. These two features are called spiders due to the association of large sub-circular depressions (the body) with smaller elongate depressions (the legs). Seismic reflection data show that these two structures correspond to amplitude anomalies located ca. 60–100 ms below seabed. The burial of these anomalies is consistent with the base of the methane hydrate stability domain, which leads to interpret them as patches of hydrate-related bottom-simulating reflection (BSR). The morphology and seismic character of the two structures clearly contrasts with those of the regional background (Morphotype A). The spider structures are composed of two seafloor morphotypes: Morphotype B and Morphotype C. Morphotype B makes flat-bottomed depressions associated with the presence of large bacterial mats without evidence of carbonates. Morphotype C is made of elongated depressions associated with the presence of carbonate pavements and a prolific chemosynthetic benthic life. On that basis of these observations combined with geochemical analyses, the spider structures are interpreted to be linked with methane leakage. Methane leakage within the spider structures varies from one morphotype to another, with a higher activity within the seafloor of Morphotype C; and a lower activity in the seafloor of Morphotype B, which is interpreted to correspond to a domain of relict fluid leakage. This change of the seepage activity is due ... |
format |
Article in Journal/Newspaper |
author |
Casenave, Viviane Gay, Aurelien Imbert, Patrice |
author_facet |
Casenave, Viviane Gay, Aurelien Imbert, Patrice |
author_sort |
Casenave, Viviane |
title |
Les structures en araignée : enregistrement d'échappements de fluide provenant des hydrates de méthane sur la pente continentale du Congo |
title_short |
Les structures en araignée : enregistrement d'échappements de fluide provenant des hydrates de méthane sur la pente continentale du Congo |
title_full |
Les structures en araignée : enregistrement d'échappements de fluide provenant des hydrates de méthane sur la pente continentale du Congo |
title_fullStr |
Les structures en araignée : enregistrement d'échappements de fluide provenant des hydrates de méthane sur la pente continentale du Congo |
title_full_unstemmed |
Les structures en araignée : enregistrement d'échappements de fluide provenant des hydrates de méthane sur la pente continentale du Congo |
title_sort |
les structures en araignée : enregistrement d'échappements de fluide provenant des hydrates de méthane sur la pente continentale du congo |
publisher |
Edp Sciences S A |
publishDate |
2017 |
url |
https://archimer.ifremer.fr/doc/00409/52076/52779.pdf https://doi.org/10.1051/bsgf/2017189 https://archimer.ifremer.fr/doc/00409/52076/ |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_source |
Bulletin De La Societe Geologique De France (0037-9409) (Edp Sciences S A), 2017 , Vol. 188 , N. 4 , P. 27 |
op_relation |
https://archimer.ifremer.fr/doc/00409/52076/52779.pdf doi:10.1051/bsgf/2017189 https://archimer.ifremer.fr/doc/00409/52076/ |
op_rights |
SGF, Published by EDP Sciences 2017 info:eu-repo/semantics/openAccess restricted use |
op_doi |
https://doi.org/10.1051/bsgf/2017189 |
container_title |
Bulletin de la Société géologique de France |
container_volume |
188 |
container_issue |
4 |
container_start_page |
27 |
_version_ |
1768391530002776064 |