A joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the Vestnesa Ridge, West Svalbard margin
We acquired coincident marine controlled-source electromagnetic (CSEM), high-resolution seismic reflection and ocean-bottom seismometer (OBS) data over an active pockmark in the crest of the southern part of the Vestnesa Ridge, to estimate fluid composition within an underlying fluid-migration chimn...
Published in: | Journal of Geophysical Research: Solid Earth |
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Online Access: | https://hal.science/hal-04200696 https://doi.org/10.1002/2015JB012344 |
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ftccsdartic:oai:HAL:hal-04200696v1 2023-10-09T21:56:11+02:00 A joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the Vestnesa Ridge, West Svalbard margin Goswami, Bedanta K. Weitemeyer, Karen A. Minshull, Timothy A. Sinha, Martin C. Westbrook, Graham Chabert, Anne Henstock, Timothy J. Ker, Stephan Géosciences Marines (GM) Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) 2015-10 https://hal.science/hal-04200696 https://doi.org/10.1002/2015JB012344 en eng HAL CCSD American Geophysical Union info:eu-repo/semantics/altIdentifier/doi/10.1002/2015JB012344 hal-04200696 https://hal.science/hal-04200696 doi:10.1002/2015JB012344 ISSN: 0148-0227 EISSN: 2156-2202 Journal of Geophysical Research https://hal.science/hal-04200696 Journal of Geophysical Research, 2015, 120 (10), pp.6797-6822. ⟨10.1002/2015JB012344⟩ [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2015 ftccsdartic https://doi.org/10.1002/2015JB012344 2023-09-23T22:56:37Z We acquired coincident marine controlled-source electromagnetic (CSEM), high-resolution seismic reflection and ocean-bottom seismometer (OBS) data over an active pockmark in the crest of the southern part of the Vestnesa Ridge, to estimate fluid composition within an underlying fluid-migration chimney. Synthetic model studies suggest resistivity obtained from CSEM data can resolve gas or hydrate saturation greater than 5% within the chimney. Acoustic chimneys imaged by seismic reflection data beneath the pockmark and on the ridge flanks, were found to be associated with high-resistivity anomalies (+2-4 m). High-velocity anomalies (+0.3 km/s), within the gas hydrate stability zone (GHSZ) and low-velocity anomalies (-0.2 km/s) underlying the GHSZ, were also observed. Joint analysis of the resistivity and velocity anomaly indicates pore saturation of up to 52% hydrate with 28% free gas, or up to 73% hydrate with 4% free gas, within the chimney beneath the pockmark assuming a non-uniform and uniform fluid distribution respectively. Similarly, we estimate up to 30% hydrate with 4% free gas or 30% hydrate with 2% free gas within the pore space of the GHSZ outside the central chimney assuming a non-uniform and uniform fluid distribution respectively. High levels of free-gas saturation in the top part of the chimney are consistent with episodic gas venting from the pockmark. Article in Journal/Newspaper Svalbard Svalbard margin Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Svalbard The Chimney ENVELOPE(-55.748,-55.748,52.617,52.617) Journal of Geophysical Research: Solid Earth 120 10 6797 6822 |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDU]Sciences of the Universe [physics] |
spellingShingle |
[SDU]Sciences of the Universe [physics] Goswami, Bedanta K. Weitemeyer, Karen A. Minshull, Timothy A. Sinha, Martin C. Westbrook, Graham Chabert, Anne Henstock, Timothy J. Ker, Stephan A joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the Vestnesa Ridge, West Svalbard margin |
topic_facet |
[SDU]Sciences of the Universe [physics] |
description |
We acquired coincident marine controlled-source electromagnetic (CSEM), high-resolution seismic reflection and ocean-bottom seismometer (OBS) data over an active pockmark in the crest of the southern part of the Vestnesa Ridge, to estimate fluid composition within an underlying fluid-migration chimney. Synthetic model studies suggest resistivity obtained from CSEM data can resolve gas or hydrate saturation greater than 5% within the chimney. Acoustic chimneys imaged by seismic reflection data beneath the pockmark and on the ridge flanks, were found to be associated with high-resistivity anomalies (+2-4 m). High-velocity anomalies (+0.3 km/s), within the gas hydrate stability zone (GHSZ) and low-velocity anomalies (-0.2 km/s) underlying the GHSZ, were also observed. Joint analysis of the resistivity and velocity anomaly indicates pore saturation of up to 52% hydrate with 28% free gas, or up to 73% hydrate with 4% free gas, within the chimney beneath the pockmark assuming a non-uniform and uniform fluid distribution respectively. Similarly, we estimate up to 30% hydrate with 4% free gas or 30% hydrate with 2% free gas within the pore space of the GHSZ outside the central chimney assuming a non-uniform and uniform fluid distribution respectively. High levels of free-gas saturation in the top part of the chimney are consistent with episodic gas venting from the pockmark. |
author2 |
Géosciences Marines (GM) Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER) |
format |
Article in Journal/Newspaper |
author |
Goswami, Bedanta K. Weitemeyer, Karen A. Minshull, Timothy A. Sinha, Martin C. Westbrook, Graham Chabert, Anne Henstock, Timothy J. Ker, Stephan |
author_facet |
Goswami, Bedanta K. Weitemeyer, Karen A. Minshull, Timothy A. Sinha, Martin C. Westbrook, Graham Chabert, Anne Henstock, Timothy J. Ker, Stephan |
author_sort |
Goswami, Bedanta K. |
title |
A joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the Vestnesa Ridge, West Svalbard margin |
title_short |
A joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the Vestnesa Ridge, West Svalbard margin |
title_full |
A joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the Vestnesa Ridge, West Svalbard margin |
title_fullStr |
A joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the Vestnesa Ridge, West Svalbard margin |
title_full_unstemmed |
A joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the Vestnesa Ridge, West Svalbard margin |
title_sort |
joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the vestnesa ridge, west svalbard margin |
publisher |
HAL CCSD |
publishDate |
2015 |
url |
https://hal.science/hal-04200696 https://doi.org/10.1002/2015JB012344 |
long_lat |
ENVELOPE(-55.748,-55.748,52.617,52.617) |
geographic |
Svalbard The Chimney |
geographic_facet |
Svalbard The Chimney |
genre |
Svalbard Svalbard margin |
genre_facet |
Svalbard Svalbard margin |
op_source |
ISSN: 0148-0227 EISSN: 2156-2202 Journal of Geophysical Research https://hal.science/hal-04200696 Journal of Geophysical Research, 2015, 120 (10), pp.6797-6822. ⟨10.1002/2015JB012344⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1002/2015JB012344 hal-04200696 https://hal.science/hal-04200696 doi:10.1002/2015JB012344 |
op_doi |
https://doi.org/10.1002/2015JB012344 |
container_title |
Journal of Geophysical Research: Solid Earth |
container_volume |
120 |
container_issue |
10 |
container_start_page |
6797 |
op_container_end_page |
6822 |
_version_ |
1779320727304929280 |