It has recently been recognized that abundant gas hydrates occur in localized zones of upwelling
fluids, with concentrations much higher than in regional distributions associated with bottomsimulating
reflectors (BSRs). We report a study of multi-channel seismic reflection data across
such structures in the Ulleung Basin, East Sea backarc offshore Korea, an area with few BSRs.
The structures are commonly up to several km across and a few hundred meters in depth extent,
and are characterized by reduced reflectivity and bowed-up sediment reflectors on time-migrated
sections. The seismic pull-up mainly results from higher velocities, although physical
deformation due to folding and faulting is not ruled out. Some of the features extend upward
close to the seafloor and others only partway through the gas hydrate stability zone. The base of
gas hydrate stability zone (BGHSZ), calculated assuming a regional average constant heat flow
of 110 mW/m2, is confirmed by the presence of gas inferred from reduced instantaneous
frequencies and high instantaneous amplitudes, and from a decrease in seismic velocities. The vents are fed by upward migrating free gas or gas-rich fluids through near-vertical conduits
probably due to regional, upward fluid flow caused by tectonic compression of the basin.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/1162 |
| Date | 07 1900 |
| Creators | Stoian, Iulia, Park, Keun-Pil, Yoo, Dong-Geun, Haacke, R. Ross, Hyndman, Roy D., Riedel, Michael, Spence, George D. |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Rights | Stoian, Iulia |
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