Anaerobic oxidation of methane in a cold-water coral carbonate mound from the Gulf of Cadiz
Maignien, L.; Depreiter, D.; Foubert, A.; Reveillaud, J.; De Mol, L.; Boeckx, P.; Blamart, D.; Henriet, J.-P.; Boon, N. (2011). Anaerobic oxidation of methane in a cold-water coral carbonate mound from the Gulf of Cadiz. Int. J. Earth Sci. 100(6): 1413-1422. dx.doi.org/10.1007/s00531-010-0528-z
In: International Journal of Earth Sciences. Springer: Berlin; Heidelberg. ISSN 1437-3254; e-ISSN 1437-3262
The Gulf of Cadiz is an area of mud volcanism and gas venting through the seafloor. In addition, several cold-water coral carbonate mounds have been discovered at the Pen Duick escarpment amidst the El Arraiche mud volcano field on the Moroccan margin. One of these mounds -named Alpha mound- has been studied to examine the impact of the presence of methane on pore-water geochemistry, potential sulphate reduction (SR) rate and dissolved inorganic carbon (DIC) budget of the mound in comparison with off-mound and off-escarpment locations. Pore-water profiles of sulphate, sulphide, methane, and DIC from the on-mound location showed the presence of a sulphate to methane transition zone at 350 cm below the sea floor. This was well correlated with an increase in SR activity. 13C-depleted DIC at the transition zone (-21.9‰ vs. Vienna Pee Dee Belemnite) indicated that microbial methane oxidation significantly contribute to the DIC budget of the mound. The Alpha mound thus represents a new carbonate mound type where the presence and anaerobic oxidation of methane has an important imprint on both geochemistry and DIC isotopic signature and budget of this carbonate mound.
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