Carbon isotope systematics of individual hydrocarbons in hydrothermal petroleum from Middle Valley, Northeastern Pacific Ocean

Individual aliphatic hydrocarbons in samples of bulk hydrothermal petroleum from Middle Valley (ODP Site 858) were submitted to compound specific isotope analysis to trace their origins. The C isotope compositions of the n-alkanes and isoprenoid hydrocarbons [means n-alkanes: −30.1±1.01 (858A), −28.3±1.7 (858C) and −24.8±1.4 (858D)‰; isoprenoids: −26.0±2.7 (858C) and −27.9±0.4 (858D)‰, respectively] reflect mixed marine and terrestrial organic matter sources. Biphytane from thermophiles has a δ13C value of −21.0‰.