HR: 0830h
AN: OS51B-0851    [PDF]
TI: Preliminary Results of 3D Seismic Analysis of Methane Hydrate on the Blake Ridge
AU: * Hornbach, M J
EM: mhornbac@uwyo.edu
AF: University of Wyoming, Department of Geology and Geophysics, Laramie, Wy 82071 United States
AU: Holbrook, W S
EM: steveh@uwyo.edu
AF: University of Wyoming, Department of Geology and Geophysics, Laramie, Wy 82071 United States
AU: Gorman, A R
EM: andrew.gorman@stonebow.otago.ac.nz
AF: University of Otago, Department of Geology P.O. Box 56, Dunedin, 9015 New Zealand
AU: Van Avendonk, H
EM: harm@ig.utexas.edu
AF: University of Texas Institute for Geophysics, 4412 Spicewood springs Rd. Bld 600, Austin, Tx 78759 United States
AU: Lizarralde, D
EM: danl@eas.gatech.edu
AF: Georgia Tech, School of Earth and Atmospheric Sciences, Atlanta, GA 30332 United States
AU: Pecher, I
EM: i.pecher@gns.cri.nz
AF: Institute of Geological and Nuclear Sciences, 69 Gracefield Rd., Lower Hutt, 30368 New Zealand
AB: Methane hydrates may play a significant role in past and perhaps future global warming events; nonetheless, mechanisms for hydrate dissociation and subsequent gas escape remain controversial . During the fall of 2000, we conducted a 3D seismic survey over a 290 km square area of the Blake Ridge to investigate the dynamics of methane hydrate and free-gas at passive ocean margins. A primary goal of this study is to identify possible migration pathways of methane gas and their relationship with the free-gas reservoir below the BSR. Initial results from amplitude analysis of the stacked 3D volume reveal significant amplitude variability at the BSR, suggesting highly uneven free-gas concentrations beneath the Blake Ridge. In particular, the lowest amplitudes exist beneath erosional features at the seafloor where normal faults extend continuously from below the BSR to the surface. The results suggest faults that outcrop at the seafloor act as primary conduits for gas-migration into the water-column. In addition, 3D mapping of regions where concentrated hydrate exists shows faults bounding most hydrate reservoirs, implying that faults act both as pathways and barriers for free-gas migration and hydrate formation.
DE: 0935 Seismic methods (3025)
DE: 1724 Ocean sciences
DE: 1734 Seismology
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting