Data/hora: 04/06/2024 05:38:18

Provedor de dados: | 5
País: | France
Título: | A joint electromagnetic and seismic study of an active pockmark within the hydrate stability field at the Vestnesa Ridge, West Svalbard margin
Autores: | Goswami, Bedanta K.; Weitemeyer, Karen A.; Minshull, Timothy A.; Sinha, Martin C.; Westbrook, Graham; Chabert, Anne; Henstock, Timothy J.; Ker, Stephan.
Data: | 2015-10
Ano: | 2015
Palavras-chave: | Gas hydrate; Svalbard; CSEM; Saturation; Pockmark; Vestnesa.
Resumo: | 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.
Tipo: | Text
Idioma: | Inglês

Identificador:

http://archimer.ifremer.fr/doc/00283/39458/37928.pdf

DOI:10.1002/2015JB012344

http://archimer.ifremer.fr/doc/00283/39458/

Editor: | Amer Geophysical Union
Formato: | application/pdf
Fonte: | Journal Of Geophysical Research-solid Earth (0148-0227) (Amer Geophysical Union), 2015-10 , Vol. 120 , N. 10 , P. 6797-6822

Fonte:

2015. American Geophysical Union. All Rights Reserved.

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