Estimation of the depth of origin of fluids using noble gases in the surface sediments of submarine mud volcanoes off Tanegashima Island.

The helium isotope ratio (He/He), concentration ratio of neon-20 to helium-4 (Ne/He), argon (Ar), krypton (Kr), and xenon (Xe) concentrations were measured in the porewater of surface sediments of several submarine mud volcanoes. From the He/He values (0.18-0.