HIGH-MOLECULAR-WEIGHT POLYCYCLIC AROMATIC-HYDROCARBONS IN HYDROTHERMAL PETROLEUMS FROM THE GULF OF CALIFORNIA AND NORTHEAST PACIFIC-OCEAN

Hydrothermal petroleums and heavy tars have been analyzed for polycycl ic aromatic hydrocarbons (PAH) with molecular weights greater than tha t of coronene (300 da). Samples from the hydrothermal systems in the G uaymas Basin (Gulf of California) and in the Escanaba Trough and Middl e Valley (Northeastern Pacific) were analyzed by gas chromatography-ma ss spectrometry and high pressure liquid chromatography with diode-arr ay absorbance detection. Mass spectra and fluorescence spectra were us ed to characterize the compounds. Several large PAHs with six and more rings were identified among the heavy PAH. Production routes via one- ring build-up and Scholl-condensation are proposed to explain the obse rved structures. The variations in PAH concentrations and distribution s between samples from different locales are a consequence of the hydr othermal conditions of generation, migration, and post-depositional al teration. Copyright (C) 1996 Elsevier Science Ltd