Figure 6. Relative abundance of certain noble gas isotopes in gas hydrate samples from the Blake Ridge (solid circles) compared to gases in the Messoyakha gas field (open triangles; Verkhovsky et al., 1988), gases in other gas fields (shaded boxes; Verkhovsky et al., 1988 and Hiyagon and Kennedy, 1992), and air-saturated seawater at 10°C (solid line; from Ozima and Podosek, 1983).