Sulfur isotopic composition of seafloor hydrothermal sediment from the Jade hydrothermal field in the central Okinawa Trough and its geological significance

Eighteen samples of hydrothermal sediments from the Jade hydrothermal field in the Central Okinawa Trough have been analyzed. Sulfur isotopic values for 10 sulfur samples vary from 5.2 x 10 super(-3) to 7.2 x 10 super(-3), delta super(34)S values for 7 sulfate samples vary from 16.3 x 10 super(-3) to 22.3x 10 super(-3), and 1 native sulphur sample had a delta super(34)S value of 8.2 x 10 super(-3). The major sources of sulfur for hydrothermal sediment are intermediate to acid volcanic rocks and sea water sulfate, and it is possible that the partial sulfur of hydrothermal sediment is from the pelagic sediment by the interaction between hydrothermal fluid and sediment. The reasons of causing the distinct differences in sulfur isotopic values for sulfide samples from hydrothermal sediment (compared with other hydrothermal fields), are the difference in the sources of sulfur, the magmatic activity and the tectonic evolution in different hydrothermal fields. The sulfur evolution is a long the complex process in the seafloor hydrothermal system, involving the ascending of heating sea water, the interaction between fluid and volcanic rocks, the mixing of sea water sulfate and sulfur from intermediate to acid volcanic rocks, and the fluid/pelagic-sediment interaction. And the interaction between sea water and intermediate to acid volcanic rocks is and important mechanism for sulfur evolution n the Jade hydrothermal field.