Geochemical prospecting for hydrocarbons in the outer continental shelf, Southern Bering Sea, Alaska

This geochemical survey is based on 20 stations located on the outer continental shelf of the southern Bering Sea in an area of 30,000 km2 that includes St. George basin. Hydrocarbon gases from sediment samples recovered by gravity coring at each of the stations were analyzed by gas chromatography. Data are summarized for a subbottom depth of 0.5 m, because core penetration, although variable, reached at least this depth at all of these stations. Two parameters were used to distinguish the possible presence of thermogenic hydrocarbons: (1) ratios less than 50 of methane to ethane plus propane; and (2) ratios greater than 1 of ethane to ethene. No major hydrocarbon anomalies were discovered; however, at two stations at the northern end of St. George basin, our data indicate that thermogenic hydrocarbons may be present at depth. Major faulting in the vicinity of these stations could provide the pathways for the gas. ?? 1981.