Characterization of a stratigraphically constrained gas hydrate system along the western continental margin of Svalbard from ocean bottom seismometer data
The ongoing warming of bottom water in the Arctic region is anticipated to destabilize some of the gas hydrate present in shallow seafloor sediment, potentially causing the release of methane from dissociating hydrate into the ocean and the atmosphere. Ocean-bottom seismometer (OBS) experiments were...
Published in: | Journal of Geophysical Research |
---|---|
Main Authors: | , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2011
|
Subjects: | |
Online Access: | http://nora.nerc.ac.uk/id/eprint/307905/ https://nora.nerc.ac.uk/id/eprint/307905/1/chabert_et_al_compressed.pdf https://nora.nerc.ac.uk/id/eprint/307905/3/chabert_et_al_2011_PubVersion.pdf |
id |
ftnerc:oai:nora.nerc.ac.uk:307905 |
---|---|
record_format |
openpolar |
spelling |
ftnerc:oai:nora.nerc.ac.uk:307905 2023-05-15T15:17:45+02:00 Characterization of a stratigraphically constrained gas hydrate system along the western continental margin of Svalbard from ocean bottom seismometer data Chabert, Anne Minshull, Tim A. Westbrook, Graham K. Berndt, Christian Thatcher, Kate E. Sarkar, Sudipta 2011 application/pdf http://nora.nerc.ac.uk/id/eprint/307905/ https://nora.nerc.ac.uk/id/eprint/307905/1/chabert_et_al_compressed.pdf https://nora.nerc.ac.uk/id/eprint/307905/3/chabert_et_al_2011_PubVersion.pdf en eng https://nora.nerc.ac.uk/id/eprint/307905/1/chabert_et_al_compressed.pdf https://nora.nerc.ac.uk/id/eprint/307905/3/chabert_et_al_2011_PubVersion.pdf Chabert, Anne; Minshull, Tim A.; Westbrook, Graham K.; Berndt, Christian; Thatcher, Kate E.; Sarkar, Sudipta. 2011 Characterization of a stratigraphically constrained gas hydrate system along the western continental margin of Svalbard from ocean bottom seismometer data. Journal of Geophysical Research, 116 (B12). B12102. https://doi.org/10.1029/2011JB008211 <https://doi.org/10.1029/2011JB008211> Publication - Article PeerReviewed 2011 ftnerc https://doi.org/10.1029/2011JB008211 2023-02-04T19:35:57Z The ongoing warming of bottom water in the Arctic region is anticipated to destabilize some of the gas hydrate present in shallow seafloor sediment, potentially causing the release of methane from dissociating hydrate into the ocean and the atmosphere. Ocean-bottom seismometer (OBS) experiments were conducted along the continental margin of western Svalbard to quantify the amount of methane present as hydrate or gas beneath the seabed. P- and S-wave velocities were modeled for five sites along the continental margin, using ray-trace forward modeling. Two southern sites were located in the vicinity of a 30 km long zone where methane gas bubbles escaping from the seafloor were observed during the cruise. The three remaining sites were located along an E-W orientated line in the north of the margin. At the deepest northern site, Vp anomalies indicate the presence of hydrate in the sediment immediately overlying a zone containing free gas up to 100-m thick. The acoustic impedance contrast between the two zones forms a bottom-simulating reflector (BSR) at approximately 195 m below the seabed. The two other sites within the gas hydrate stability zone (GHSZ) do not show the clear presence of a BSR or of gas hydrate. However, anomalously low Vp, indicating the presence of free gas, was modeled for both sites. The hydrate content was estimated from Vp and Vs, using effective-medium theory. At the deepest northern site, modeling suggests a pore-space hydrate concentration of 7–12%, if hydrate forms as part of a connected framework, and about 22% if it is pore-filling. At the two other northern sites, located between the deepest site and the landward limit of the GHSZ, we suggest that hydrate is present in the sediment as inclusions. Hydrate may be present in small quantities at these two sites (4–5%) of the pore space. The variation in lithology for the three sites indicated by high-resolution seismic profiles may control the distribution, concentration and formation of hydrate and free gas. Article in Journal/Newspaper Arctic Svalbard Natural Environment Research Council: NERC Open Research Archive Arctic Svalbard Journal of Geophysical Research 116 B12 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
English |
description |
The ongoing warming of bottom water in the Arctic region is anticipated to destabilize some of the gas hydrate present in shallow seafloor sediment, potentially causing the release of methane from dissociating hydrate into the ocean and the atmosphere. Ocean-bottom seismometer (OBS) experiments were conducted along the continental margin of western Svalbard to quantify the amount of methane present as hydrate or gas beneath the seabed. P- and S-wave velocities were modeled for five sites along the continental margin, using ray-trace forward modeling. Two southern sites were located in the vicinity of a 30 km long zone where methane gas bubbles escaping from the seafloor were observed during the cruise. The three remaining sites were located along an E-W orientated line in the north of the margin. At the deepest northern site, Vp anomalies indicate the presence of hydrate in the sediment immediately overlying a zone containing free gas up to 100-m thick. The acoustic impedance contrast between the two zones forms a bottom-simulating reflector (BSR) at approximately 195 m below the seabed. The two other sites within the gas hydrate stability zone (GHSZ) do not show the clear presence of a BSR or of gas hydrate. However, anomalously low Vp, indicating the presence of free gas, was modeled for both sites. The hydrate content was estimated from Vp and Vs, using effective-medium theory. At the deepest northern site, modeling suggests a pore-space hydrate concentration of 7–12%, if hydrate forms as part of a connected framework, and about 22% if it is pore-filling. At the two other northern sites, located between the deepest site and the landward limit of the GHSZ, we suggest that hydrate is present in the sediment as inclusions. Hydrate may be present in small quantities at these two sites (4–5%) of the pore space. The variation in lithology for the three sites indicated by high-resolution seismic profiles may control the distribution, concentration and formation of hydrate and free gas. |
format |
Article in Journal/Newspaper |
author |
Chabert, Anne Minshull, Tim A. Westbrook, Graham K. Berndt, Christian Thatcher, Kate E. Sarkar, Sudipta |
spellingShingle |
Chabert, Anne Minshull, Tim A. Westbrook, Graham K. Berndt, Christian Thatcher, Kate E. Sarkar, Sudipta Characterization of a stratigraphically constrained gas hydrate system along the western continental margin of Svalbard from ocean bottom seismometer data |
author_facet |
Chabert, Anne Minshull, Tim A. Westbrook, Graham K. Berndt, Christian Thatcher, Kate E. Sarkar, Sudipta |
author_sort |
Chabert, Anne |
title |
Characterization of a stratigraphically constrained gas hydrate system along the western continental margin of Svalbard from ocean bottom seismometer data |
title_short |
Characterization of a stratigraphically constrained gas hydrate system along the western continental margin of Svalbard from ocean bottom seismometer data |
title_full |
Characterization of a stratigraphically constrained gas hydrate system along the western continental margin of Svalbard from ocean bottom seismometer data |
title_fullStr |
Characterization of a stratigraphically constrained gas hydrate system along the western continental margin of Svalbard from ocean bottom seismometer data |
title_full_unstemmed |
Characterization of a stratigraphically constrained gas hydrate system along the western continental margin of Svalbard from ocean bottom seismometer data |
title_sort |
characterization of a stratigraphically constrained gas hydrate system along the western continental margin of svalbard from ocean bottom seismometer data |
publishDate |
2011 |
url |
http://nora.nerc.ac.uk/id/eprint/307905/ https://nora.nerc.ac.uk/id/eprint/307905/1/chabert_et_al_compressed.pdf https://nora.nerc.ac.uk/id/eprint/307905/3/chabert_et_al_2011_PubVersion.pdf |
geographic |
Arctic Svalbard |
geographic_facet |
Arctic Svalbard |
genre |
Arctic Svalbard |
genre_facet |
Arctic Svalbard |
op_relation |
https://nora.nerc.ac.uk/id/eprint/307905/1/chabert_et_al_compressed.pdf https://nora.nerc.ac.uk/id/eprint/307905/3/chabert_et_al_2011_PubVersion.pdf Chabert, Anne; Minshull, Tim A.; Westbrook, Graham K.; Berndt, Christian; Thatcher, Kate E.; Sarkar, Sudipta. 2011 Characterization of a stratigraphically constrained gas hydrate system along the western continental margin of Svalbard from ocean bottom seismometer data. Journal of Geophysical Research, 116 (B12). B12102. https://doi.org/10.1029/2011JB008211 <https://doi.org/10.1029/2011JB008211> |
op_doi |
https://doi.org/10.1029/2011JB008211 |
container_title |
Journal of Geophysical Research |
container_volume |
116 |
container_issue |
B12 |
_version_ |
1766347992683511808 |