Matthew Abrams

Natural methane gas hydrate in Canada's offshore continental margin represents a potential massive storehouse of naturally occurring crystalline methane formed under specific pressure-temperatures regimes. Natural gas hydrate is a crystalline substance composed of water and natural gas (commonly CH4) that forms in Arctic permafrost and offshore continental slope environments. Recognition of gas hydrate is continuing to evolve as a potential energy resource, a possible greenhouse gas contributor, and as a geohazard. The objective of this thesis is to estimate the volume of methane gas hydrate at Sackville Spur; a tapering sediment ridge under influence of the Labrador Current, a shallow-water ocean current that transports cold water from Baffin Bay in the North Atlantic southwards, roughly paralleling the continental shelf break offshore Newfoundland and Labrador. The presence of gas hydrate at Sackville Spur is inferred by the existence of a high-amplitude, phase-reversed BSR roughly 156km² in size. Two wide-angle reflection profiles at Sackville Spur were depth-converted using an averaged OBS velocity model to determine the depth of the BSR; found to range from 1280 - 1400 m below sea level. Sediment mineralogy approximations, derived from piston core data, suggest a mixture of 39% clay, 27% quartz, and 34% calcite. Effective medium modeling by fitting velocity gradients influenced by hydrate existence yields 9% hydrate concentrations at Sackville Spur, and estimated total hydrate volumes of 1.12x109 m³ .

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Pages: 59
Supervisor: Keith Louden