Dissolved Fluoride Concentrations in Methane-Charged Sediment Sequences

Subseafloor microbial communities associated with rapid turbidite deposition in the Gulf of Mexico continental slope (IODP Expedition 308)

“…With expected methanogenesis rates in subseafloor estimated by Colwell et al (2008) at o 1.5 pmol methane per 1000 methanogenic cells year À1 , small numbers of methanogens are unlikely to produce the observed in situ concentration of methane after sediment deposition. Furthermore, recent studies estimating methanogenesis rates and the abundance of methanogens using radio-active tracers, mcrA populations or modeling studies using interstitial water chemistry have shown that high methanogenesis rates or abundances of mcrA occur in specific layers (Claypool et al, 2005;Parkes et al, 2005;Webster et al, 2006;Sivan et al, 2007;Colwell et al, 2008;Fry et al, 2008). The biogenic methane was more likely introduced by migration in poor fluids as the dip seismic section shows several potential gas migration pathways below the BT Basin (Fig.…”

Bacterial methane in the Atzbach-Schwanenstadt gas field (upper Austrian Molasse Basin), Part II: Retracing gas generation and filling history by mass balancing of organic carbon conversion applying hydrogeochemical modelling

“…The scientific findings achieved by ODP Leg 204 also argued for proxies for former gas hydrate content in sediments. Here, d 18 O of authigenic carbonate as well as fluoride concentrations of pore water were introduced to serve as proxies for the documentation of a gas hydrate history as both are affected by hydrate formation Dickens et al, 2006).…”