Seismic reflection data from a multi-channel streamer deployed offshore Korea reveal evidence of hydrateforming
gases being vented into the ocean. Numerous, localised vent structures are apparent from reduced
seismic reflection amplitude, high seismic velocities, and reflector pull-up. These structures penetrate
upward from the base of the gas hydrate stability zone (GHSZ) and are typically several hundred metres
wide, and only a few hundred metres high. Underlying zones of reduced reflection amplitude and low
velocities indicate the presence of gas many kilometers below the seabed, which migrates upward through
near-vertical conduits to feed the vent structures. Where the local geology and underlying plumbing
indicates a high flux of gases migrating through the system, the associated vent structures show the greatest
change of reflector pull-up (the greatest concentration of hydrate) to be near the seabed; where the local
geology and underlying plumbing indicates a moderate flux of gases, the greatest change of reflector pullup
(the greatest concentration of hydrate) is near the base of the GHSZ. The distribution of gas hydrate in
the high-flux gas vent is consistent with the recent salinity-driven model developed for a rapid and
continuous flow of migrating gas, while the hydrate distribution in the lower-flux vent is consistent with a liquid-dominated system. The high-flux vent shows evidence of recent activity at the seabed, and it is likely
that a substantial amount of gas is passing, or has passed, through this vent structure directly into the
overlying ocean.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/1049 |
| Date | 07 1900 |
| Creators | Haacke, R. Ross, Park, Keun-Pil, Stoian, Iulia, Hyndman, Roy D., Schmidt, Ulrike |
| 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 | Haacke, Ross |
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