New data on the composition of polycyclic aromatic hydrocarbons in sulfides and bottom sediments of the Guaymas Basin (Gulf of California)

The composition of polycyclic aromatic hydrocarbons (PAH) from bottom-sediment and sulfide-ore samples in the Northern and Southern Troughs of the Guaymas Basin (Gulf of California) has been studied. The highest concentrations of carbon, bituminous substances, and PAH have been discovered in sulfide crusts at the sites with active hydrothermal plumes. These crusts are petroliferous with a characteristic odor. Substituted homologs of naphthalene, phenatrene, benzfluorene, chrysene, 3,4-benzpyrene, pyrene, perylene as well as unsubstituted PAH-pyrene, tetraphene, 3,4-benzpyrene, perylene, 1,12-benzpyrene, anthanthrene, and coronene have been identified in sulfide-ore samples. It is these samples that display the highest diversity of PAH. A similar range of the PAH was identified both in oil components from the Guaymas Basin and in oils from the Uzon Caldera (Kamchatka); the latter oils are believed to have originated from hydrotherms. At the sites with weak or no hydrothermal activity, the PAH content is lower by a factor of 100-1000 and less diverse. The genesis of the oil shows and the PAH concentrations in the Guaymas Basin are discussed in the context of their possible supply by hydrothermal solutions from deep zones of the earth's crust.