Geological and morphological setting of 2778 methane seeps in the Dnepr paleo-delta, northwestern Black Sea
The Dnepr paleo-delta area in the NW Black Sea is characterized by an abundant presence of methane seeps. During the expeditions of May–June 2003 and 2004 within the EU-funded CRIMEA project, detailed multibeam, seismic and hydro-acoustic water-column investigations were carried out to study the rel...
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ftunivgent:oai:archive.ugent.be:329354 2023-10-01T03:57:25+02:00 Geological and morphological setting of 2778 methane seeps in the Dnepr paleo-delta, northwestern Black Sea Naudts, Lieven Greinert, Jens Artemov, Y Staelens, Peter Poort, Jeffrey Van Rensbergen, Pieter De Batist, Marc 2006 https://biblio.ugent.be/publication/329354 http://hdl.handle.net/1854/LU-329354 eng eng Elsevier Science https://biblio.ugent.be/publication/329354 http://hdl.handle.net/1854/LU-329354 MARINE GEOLOGY ISSN: 0025-3227 Earth and Environmental Sciences methane seeps seismic gas front gas hydrates pockmarks canyons sedimentary ridges methane derived carbonated cementation Dnepr paleo-delta Black Sea journalArticle info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2006 ftunivgent 2023-09-06T22:35:43Z The Dnepr paleo-delta area in the NW Black Sea is characterized by an abundant presence of methane seeps. During the expeditions of May–June 2003 and 2004 within the EU-funded CRIMEA project, detailed multibeam, seismic and hydro-acoustic water-column investigations were carried out to study the relation between the spatial distribution of methane seeps, sea-floor morphology and sub-surface structures. 2778 new methane seeps were detected on echosounding records in an area of 1540 km2. All seeps are located in the transition zone between the continental shelf and slope, in water depths of 66 to 825 m. The integration of the different geophysical datasets clearly indicates that methane seeps are not randomly distributed in this area, but are concentrated in specific locations. The depth limit for the majority of the detected seeps is 725 m water depth, which corresponds more or less with the stability limit for pure methane hydrate at the ambient bottom temperature (8.9 8C) in this part of the Black Sea. This suggests that, where gas hydrates are stable, they play the role of buffer for the upward migration of methane gas and thus prevent seepage of methane bubbles into the water column. Higher up on the margin, gas seeps are widespread, but accurate mapping illustrates that seeps occur preferentially in association with particular morphological and sub-surface features. On the shelf, the highest concentration of seeps is found in elongated depressions (pockmarks) above the margins of filled channels. On the continental slope where no pockmarks have been observed, seepage occurs along crests of sedimentary ridges. There, seepage is focussed by a parallel-stratified sediment cover that thins out towards the ridge crests. On the slope, seepage also appears in the vicinity of canyons (bottom, flanks and margins) or near the scarps of submarine landslides where mass-wasting breaches the fine-grained sediment cover that acts as a stratigraphic seal. The seismic data show the presence of a distinct bgas front,Q which ... Article in Journal/Newspaper Methane hydrate Ghent University Academic Bibliography |
institution |
Open Polar |
collection |
Ghent University Academic Bibliography |
op_collection_id |
ftunivgent |
language |
English |
topic |
Earth and Environmental Sciences methane seeps seismic gas front gas hydrates pockmarks canyons sedimentary ridges methane derived carbonated cementation Dnepr paleo-delta Black Sea |
spellingShingle |
Earth and Environmental Sciences methane seeps seismic gas front gas hydrates pockmarks canyons sedimentary ridges methane derived carbonated cementation Dnepr paleo-delta Black Sea Naudts, Lieven Greinert, Jens Artemov, Y Staelens, Peter Poort, Jeffrey Van Rensbergen, Pieter De Batist, Marc Geological and morphological setting of 2778 methane seeps in the Dnepr paleo-delta, northwestern Black Sea |
topic_facet |
Earth and Environmental Sciences methane seeps seismic gas front gas hydrates pockmarks canyons sedimentary ridges methane derived carbonated cementation Dnepr paleo-delta Black Sea |
description |
The Dnepr paleo-delta area in the NW Black Sea is characterized by an abundant presence of methane seeps. During the expeditions of May–June 2003 and 2004 within the EU-funded CRIMEA project, detailed multibeam, seismic and hydro-acoustic water-column investigations were carried out to study the relation between the spatial distribution of methane seeps, sea-floor morphology and sub-surface structures. 2778 new methane seeps were detected on echosounding records in an area of 1540 km2. All seeps are located in the transition zone between the continental shelf and slope, in water depths of 66 to 825 m. The integration of the different geophysical datasets clearly indicates that methane seeps are not randomly distributed in this area, but are concentrated in specific locations. The depth limit for the majority of the detected seeps is 725 m water depth, which corresponds more or less with the stability limit for pure methane hydrate at the ambient bottom temperature (8.9 8C) in this part of the Black Sea. This suggests that, where gas hydrates are stable, they play the role of buffer for the upward migration of methane gas and thus prevent seepage of methane bubbles into the water column. Higher up on the margin, gas seeps are widespread, but accurate mapping illustrates that seeps occur preferentially in association with particular morphological and sub-surface features. On the shelf, the highest concentration of seeps is found in elongated depressions (pockmarks) above the margins of filled channels. On the continental slope where no pockmarks have been observed, seepage occurs along crests of sedimentary ridges. There, seepage is focussed by a parallel-stratified sediment cover that thins out towards the ridge crests. On the slope, seepage also appears in the vicinity of canyons (bottom, flanks and margins) or near the scarps of submarine landslides where mass-wasting breaches the fine-grained sediment cover that acts as a stratigraphic seal. The seismic data show the presence of a distinct bgas front,Q which ... |
format |
Article in Journal/Newspaper |
author |
Naudts, Lieven Greinert, Jens Artemov, Y Staelens, Peter Poort, Jeffrey Van Rensbergen, Pieter De Batist, Marc |
author_facet |
Naudts, Lieven Greinert, Jens Artemov, Y Staelens, Peter Poort, Jeffrey Van Rensbergen, Pieter De Batist, Marc |
author_sort |
Naudts, Lieven |
title |
Geological and morphological setting of 2778 methane seeps in the Dnepr paleo-delta, northwestern Black Sea |
title_short |
Geological and morphological setting of 2778 methane seeps in the Dnepr paleo-delta, northwestern Black Sea |
title_full |
Geological and morphological setting of 2778 methane seeps in the Dnepr paleo-delta, northwestern Black Sea |
title_fullStr |
Geological and morphological setting of 2778 methane seeps in the Dnepr paleo-delta, northwestern Black Sea |
title_full_unstemmed |
Geological and morphological setting of 2778 methane seeps in the Dnepr paleo-delta, northwestern Black Sea |
title_sort |
geological and morphological setting of 2778 methane seeps in the dnepr paleo-delta, northwestern black sea |
publisher |
Elsevier Science |
publishDate |
2006 |
url |
https://biblio.ugent.be/publication/329354 http://hdl.handle.net/1854/LU-329354 |
genre |
Methane hydrate |
genre_facet |
Methane hydrate |
op_source |
MARINE GEOLOGY ISSN: 0025-3227 |
op_relation |
https://biblio.ugent.be/publication/329354 http://hdl.handle.net/1854/LU-329354 |
_version_ |
1778528687228977152 |