The Rainbow Hydrothermal Field (36°N, Mid-Atlantic Ridge) is one of three presently known fields related to serpentinization of ultramafic rocks accompanied by formation of hydrogen- and methane rich solutions. Gas chromatographic and molecular gas chromatographic - mass spectrometric investigations of sulfide ores and sediments from this field confirmed predominantly biological nature of bitumoids related to high-temperature transformation of biomass of the hydrothermal biological community. At the same time ores of the Rainbow field contain significant amounts of compounds that are not directly related to biogenic synthesis. This fact suggests possibility of abiogenic synthesis of methane and even complex hydrocarbons during serpentinization of ultramafic rocks.
Supplement to: Lein, Alla Yu; Peresypkin, Valery I; Simoneit, Bernd R T (2003): Origin of Hydrocarbons in Hydrothermal Sulfide Ores in the Mid-Atlantic Ridge. Lithology and Mineral Resources, 38(5), 383-393