Data/hora: 26/07/2024 22:42:23

Provedor de dados: 	Institutional Archive of Ifreme (ArchiMer)	
País: 	France	
Título: 	Resistivity image beneath an area of active methane seeps in the west Svalbard continental slope	
Autores: 	Goswami, Bedanta K.; Weitemeyer, Karen A.; Minshull, Timothy A.; Sinha, Martin C.; Westbrook, Graham; Marin-moreno, Hector.	
Data: 	2016-11	
Ano: 	2016	
Palavras-chave: 	Electrical properties; Marine electromagnetics; Gas and hydrate systems; Arctic region.	
Resumo: 	The Arctic continental margin contains large amounts of methane in the form of methane hydrates. The west Svalbard continental slope is an area where active methane seeps have been reported near the landward limit of the hydrate stability zone. The presence of bottom simulating reflectors (BSR) on seismic reflection data in water depths greater than 600 m suggests the presence of free gas beneath gas hydrates in the area. Resistivity obtained from marine controlled source electromagnetic (CSEM) data provides a useful complement to seismic methods for detecting shallow hydrate and gas as they are more resistive than surrounding water saturated sediments. We acquired two CSEM lines in the west Svalbard continental slope, extending from the edge of the continental shelf (250 m water depth) to water depths of around 800 m. High resistivities (5-12 Ωm) observed above the BSR support the presence of gas hydrate in water depths greater than 600 m. High resistivities (3-4 Ωm) at 390-600 m water depth also suggest possible hydrate occurrence within the gas hydrate stability zone (GHSZ) of the continental slope. In addition, high resistivities (4-8 Ωm) landward of the GHSZ are coincident with high-amplitude reflectors and low velocities reported in seismic data that indicate the likely presence of free gas. Pore space saturation estimates using a connectivity equation suggest 20-50% hydrate within the lower slope sediments and less than 12% within the upper slope sediments. A free gas zone beneath the GHSZ (10-20% gas saturation) is connected to the high free gas saturated (10-45%) area at the edge of the continental shelf, where most of the seeps are observed. This evidence supports the presence of lateral free gas migration beneath the GHSZ towards the continental shelf.	
Tipo: 	Text	
Idioma: 	Inglês	
Identificador: 	https://archimer.ifremer.fr/doc/00350/46081/45740.pdf

https://archimer.ifremer.fr/doc/00350/46081/46913.pdf

https://archimer.ifremer.fr/doc/00350/46081/46914.pdf

https://archimer.ifremer.fr/doc/00350/46081/46915.pdf

https://archimer.ifremer.fr/doc/00350/46081/46916.pdf

DOI:10.1093/gji/ggw330

https://archimer.ifremer.fr/doc/00350/46081/	
Editor: 	Oxford Univ Press	
Formato: 	application/pdf	
Fonte: 	Geophysical Journal International (0956-540X) (Oxford Univ Press), 2016-11 , Vol. 207 , N. 2 , P. 1286-1302	
Fonte: 	The Author 2016. Published by Oxford University Press on behalf of The Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

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