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Observations and Models of Heat and Salt Generation at a Deepwater Gulf of Mexico Vent

UTIG Seminars

Observations and Models of Heat and Salt Generation at a Deepwater Gulf of Mexico Vent

Andrew Smith
MS student, UTIG

When: Friday, Dec. 2, 2011, 10:30 a.m. to 11:30 a.m.
Join us for coffee beginning at 10:00 a.m.
Where: Seminar Conference Room, 10100 Burnet Road, Bldg 196-ROC, Austin, Texas 78758
Host: Charles Jackson, UTIG

Live broadcast

Deepwater vents in the Northern Gulf of Mexico are actively releasing water and hydrocarbons. They are ubiquitous across the continental slope, and we focus on one in the Ursa Basin at lease blocks MC852/853. The vent is elevated ~75 meters relative to the surrounding seafloor, and its core is ~1.6 km in diameter. It is bounded by a strong negative polarity seismic reflection. We interpret that this reflection records a negative impedance contrast marking the boundary between hydrate above and gas below: it is the Bottom Simulating Reflector (BSR). This BSR rises sharply at the boundaries of the vent and is horizontal within a few meters of the seafloor beneath the vent edifice. High temperature gradients and elevated salinities are present within the vent (Ruppel et al., 2005; Paull et al., 2005). We model the coexistence of elevated temperature gradients, saline fluids, and an uplifted BSR by assuming that warm, salty fluids are sourced from depth and expelled vertically through the vent conduit. We show that both the observed temperature gradients and salinities cannot be reconciled with a single-phase flow model. They can, however, be reconciled if gas and water are flowing upwards together, and if the flux of gas is large relative to the flux of water. A better understanding of the hydrogeological processes at vents is important for estimating the fluxes of water and gas from vents and for understanding the conditions under which deep-sea biological communities exist at vent locations.