Geochemical Significance of Bicyclic Sesquiterpanes in Hydrothermal Oil of the Uzon Volcano Caldera (Kamchatka)

The composition and relative content of C14-C16 bicyclic sesquiterpanes in oil seeps from thermal springs of the Uzon Caldera have been studied by GC-MS technique. It is shown that C16 homodrimanes prevail in oil composition, C15 drimane content is insignificant, and C14 nordrimanes are present in trace amounts. Homodrimane with biological configuration 8α(H) was detected. Bicyclic sesquiterpanes of Uzon oil are probably its derivatives. It has been revealed that the relative content of C15 drimanes increases with the oil maturity. A sesquiterpane maturity index, which has not been used previously in organic geochemistry, is proposed.