Helium, neon and argon isotope compositions of fluid inclusions in massive sulfides from the Jade hydrothermal field, the Okinawa Trough

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.Huid-inclusion ³He/⁴He ratios are between 6.2 and 10.1 times the air 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).These results indicate that the noble gases of trapped hydrothermal fluids in massive sulfides are a mixture of mantle-and seawater-derived components,and the helium of fluid inclusions is mainly from mantle,the nelium and argon isotope compositions are mainly from seawater.