Thickness of the gas hydrate stability zone, Gulf of Mexico continental slope

The maximum thickness of the gas hydrate stability zone (GHSZ) at key gas hydrate study sites was estimated, and a generalized GHSZ profile across part of the central Gulf of Mexico slope was constructed. Maximum thickness of the GHSZ increases with water depth at the shallowest site (∼540 m water depth) from about 450 m to about 1150 m at the deepest site (∼1930 m water depth). The occurrence of gas hydrate in the subsurface is largely controlled by structural focussing of hydrocarbons, with gas hydrate most abundant at the rims of salt withdrawal basins and less abundant within intrasalt basins. The postulated geometry of large subsurface gas hydrate accumulations shows strong structural control. Bottom simulating reflectors (BSRs) are absent or infrequently observed in the Gulf of Mexico because of structural focusing of the free hydrocarbon gases that form gas hydrate. New insight to the geometry of the GHSZ in the Gulf of Mexico continental slope will contribute to improved application of geophysics to map the distribution of gas hydrates. Improved understanding of three-dimensional geometry of gas hydrate accumulations will contribute to better assessment of gas hydrate volumes as a future energy resource, as a geohazard, and will constrain theories relating the role of gas hydrate in past climate change.

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