Salt, Seeps and Symbiosis in the Gulf of Mexico

Seafloor oil seepage on the continental slope of the Gulf of Mexico drives a number of distinct biological, chemical and geological processes. Macroseepage of oil and gas controls the extent and distribution of chemosynthetic “oil seep” communities, the seafloor configuration, sediment character and sediment geochemistry [Kennicutt et al., 1985; Brooks et al., 1986, 1987; MacDonald et al., 1989, 1990; Roberts et al., 1987]. Besides providing substrates for chemosynthetic communities, these macroseeps charge the sediments with gas and oil resulting in acoustic wipe‐out zones [MacDonald et al., 1989], the formation of gas hydrates [Brooks et al., 1986]. massive carbonate formation [Roberts et al., 1987] and in extreme cases, create mud volcanos with blow‐out craters [Prior et al., 1989]. Besides gas and oil, brine is also seeping upward into and out of Gulf of Mexico continental slope sediments. In many areas the gas and salt migrate together, forming seabottom salt pools charged with methane and hydrogen sulfide, which support chemosynthetic organisms [MacDonald et al., 1990].