Brine Vents on the Gulf of Mexico Slope: Hydrocarbons, Carbonate-Barite-Uranium Mineralization, Red Beds, and Life in an Extreme Environment

Enormous volumes of middle Jurassic Louann salt dissolve during migration of fluids from depth. At the seafloor, the result is vents, pools, and down-slope flows of brine. At these locations, biogenic methane or C1-C5 thermogenic gases are present in high concentrations. New Δ14C measurements indicate a deep fossil source of this biogenic methane. However, gas hydrate is not found at brine sites because high salinity retards the crystallization process. Microbial hydrocarbon oxidation and sulfate reduction occur in brine and associated sediment that drives massive precipitation of authigenic carbonate rock depleted in 13C. The...