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Helium, neon and argon isotope compositions of fluid inclusions have been measured in massive sulfide samples from theJade hydrothermal field in the central Okinawa Trough. Fluid-inclusion 3He/4He ratios are between 6.2 and 10.1 times theair value (Ra), and with a mean of 7.8Ra, which are consistent with the mid-ocean ridge basalt values [3He/4He≈(6Ra~11Ra)]. Values for 20Ne/22Ne are from 10.7 to 11.3, which are significantly higher than the atmospheric ratio (9.8).And the fluid-inclusion 40Ar/36Ar ratios range from 287 to 334, which are close to the atmosperic values (295.5). Theseresults indicate that the noble gases of trapped hydrothermal fluids in massive sulfides are a mixture of mantle- andseawater-derived components, and the helium of fluid inclusions is mainly from mantle, the nelium and argon isotopecompositions are mainly from seawater.
Helium, neon and argon isotope compositions of fluid inclusions have been measured in massive sulfide samples from the Jade hydrothermal field in the central Okinawa Trough. Fluid-inclusion 3He / 4He ratios are between 6.2 and 10.1 times theair value (Ra), and with amean of 7.8Ra, which are consistent with the mid-ocean ridge basalt values [3He / 4He≈ (6Ra ~ 11Ra)]. Values for 20Ne / 22Ne are from 10.7 to 11.3, which are significantly higher than the atmospheric ratio (9.8). And these fluid-inclusion 40Ar / 36Ar ratios range from 287 to 334, which are close to the atmosperic values (295.5). These results indicate that the noble gases of trapped hydrothermal fluids in massive sulfides are a mixture of mantle- and soater-derived components, and the helium of fluid inclusions is mainly from mantle, the nelium and argon isotopecompositions are mainly from seawater.