Seismic velocities from the Yaquina forearc basin off Peru: evidence for free gas within the gas hydrate stability zone.

Netzeband, Gesa L., Huebscher, Christian P., Gajewski, Dirk, Grobys, Jan W. G. and Bialas, Jörg (2005) Seismic velocities from the Yaquina forearc basin off Peru: evidence for free gas within the gas hydrate stability zone. International Journal of Earth Sciences, 94 (3). pp. 420-432. DOI 10.1007/s00531-005-0483-2.

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Abstract

Multichannel seismic (MCS) data from the Yaquina forearc basin off Peru reveal a complex distribution of gas and gas hydrate related reflections. Lateral variations of the reflection pattern at the assumed base of the gas hydrate stability zone in terms of continuity, amplitude, and signal attenuation underneath are observed, as well as the possible occurrence of paleo-bottom simulating reflectors (BSRs). Phase reversed reflections above the bottom simulating reflector point to free gas within the gas hydrate stability zone (GHSZ). To constrain the interpretation of the observed reflection pattern we calculated the velocity distribution along the MCS line from high-resolution ocean bottom hydrophone recordings with two independent methods. Heat flux values estimated on the basis of the velocity-depth functions increase with decreasing amplitude of the BSR and peak near chemoherms. These results suggest a model of the Yaquina Basin where free gas is trapped under parts of the BSR, and within the GHSZ, particularly under the seafloor and under an erosional unconformity. The hypothesis of a paleo-BSR that reflects the uplift of the base of the hydrate stability zone caused by the deposition of a particular sediment sequence is supported by the estimated heat flux values.

Document Type: Article
Keywords: Yaquina forearc basin, gas hydrate, free gas, Paleo-BSR, interval velocities
Research affiliation: AWI
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1007/s00531-005-0483-2
ISSN: 1437-3254
Projects: GEOPECO
Date Deposited: 03 Dec 2008 16:51
Last Modified: 18 May 2017 08:20
URI: http://oceanrep.geomar.de/id/eprint/6309

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