Figure 11. Interpretive plot of molecular ratios of hydrocarbons vs. carbon isotope compositions of methane in gas hydrate recovered from the Blake Ridge sediments on Leg 164 (diagram modified after Bernard, 1978). The other DSDP and ODP data are from Kvenvolden and Barnard (1983), Pflaum et al. (1986), Kvenvolden and Kastner (1990), and Hovland et al. (1995).