Spider structures: records of fluid venting from methane hydrates on the Congo continental slope
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...
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ftdoajarticles:oai:doaj.org/article:41d5063905354f7bb8b00aa40d8fe793 2023-05-15T17:12:10+02:00 Spider structures: records of fluid venting from methane hydrates on the Congo continental slope Casenave Viviane Gay Aurélien Imbert Patrice 2017-01-01T00:00:00Z https://doi.org/10.1051/bsgf/2017189 https://doaj.org/article/41d5063905354f7bb8b00aa40d8fe793 EN FR eng fre EDP Sciences https://www.bsgf.fr/articles/bsgf/full_html/2017/03/bsgf150025/bsgf150025.html https://doaj.org/toc/0037-9409 https://doaj.org/toc/1777-5817 0037-9409 1777-5817 doi:10.1051/bsgf/2017189 https://doaj.org/article/41d5063905354f7bb8b00aa40d8fe793 BSGF - Earth Sciences Bulletin, Vol 188, Iss 4, p 27 (2017) methane seep methane hydrates bottom-simulating reflector (bsr) dynamic seepage methane-derived authigenic carbonates (mdac) Geology QE1-996.5 article 2017 ftdoajarticles https://doi.org/10.1051/bsgf/2017189 2022-12-31T06:17:40Z 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 Directory of Open Access Journals: DOAJ Articles Bulletin de la Société géologique de France 188 4 27 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English French |
topic |
methane seep methane hydrates bottom-simulating reflector (bsr) dynamic seepage methane-derived authigenic carbonates (mdac) Geology QE1-996.5 |
spellingShingle |
methane seep methane hydrates bottom-simulating reflector (bsr) dynamic seepage methane-derived authigenic carbonates (mdac) Geology QE1-996.5 Casenave Viviane Gay Aurélien Imbert Patrice Spider structures: records of fluid venting from methane hydrates on the Congo continental slope |
topic_facet |
methane seep methane hydrates bottom-simulating reflector (bsr) dynamic seepage methane-derived authigenic carbonates (mdac) Geology QE1-996.5 |
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 Aurélien Imbert Patrice |
author_facet |
Casenave Viviane Gay Aurélien Imbert Patrice |
author_sort |
Casenave Viviane |
title |
Spider structures: records of fluid venting from methane hydrates on the Congo continental slope |
title_short |
Spider structures: records of fluid venting from methane hydrates on the Congo continental slope |
title_full |
Spider structures: records of fluid venting from methane hydrates on the Congo continental slope |
title_fullStr |
Spider structures: records of fluid venting from methane hydrates on the Congo continental slope |
title_full_unstemmed |
Spider structures: records of fluid venting from methane hydrates on the Congo continental slope |
title_sort |
spider structures: records of fluid venting from methane hydrates on the congo continental slope |
publisher |
EDP Sciences |
publishDate |
2017 |
url |
https://doi.org/10.1051/bsgf/2017189 https://doaj.org/article/41d5063905354f7bb8b00aa40d8fe793 |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_source |
BSGF - Earth Sciences Bulletin, Vol 188, Iss 4, p 27 (2017) |
op_relation |
https://www.bsgf.fr/articles/bsgf/full_html/2017/03/bsgf150025/bsgf150025.html https://doaj.org/toc/0037-9409 https://doaj.org/toc/1777-5817 0037-9409 1777-5817 doi:10.1051/bsgf/2017189 https://doaj.org/article/41d5063905354f7bb8b00aa40d8fe793 |
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 |
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1766068962077966336 |