In the Campeche Knolls, in the southern Gulf of Mexico, lava-like flows of solidified asphalt cover more than 1 square kilometer of the rim of a dissected salt dome at a depth of 3000 meters below sea level. Chemosynthetic tubeworms and bivalves colonize the sea floor near the asphalt, which chilled and contracted after discharge. The site also includes oil seeps, gas hydrate deposits, locally anoxic sediments, and slabs of authigenic carbonate. Asphalt volcanism creates a habitat for chemosynthetic life that may be widespread at great depth in the Gulf of Mexico.

Gas hydrate concentrations (Conc.) are reported as parts per million by volume (ppmv) of hydrate gas. Sediment gas concentrations are reported as ppmv of interstitial water. Stable carbon isotopes (d13C) are reported as parts per thousand relative to Pee Dee Belemnite standard.

Supplement to: MacDonald, Ian R; Bohrmann, Gerhard; Escobar, E; Abegg, Friedrich; Blanchon, Paul; Blinova, Valentina N; Brueckmann, Warner; Drews, Manuela; Eisenhauer, Anton; Han, X; Heeschen, Katja U; Meier, Felix; Mortera-Gutierrez, Carlos; Naehr, T; Orcutt, B; Bernard, B; Brroks, J; de Farágo, M (2004): Asphalt volcanism and chemosynthetic life, Campache Knolls, Gulf of Mexico. Science, 304(5673), 999-1002