Zinc and lead isotope variation in hydrothermal deposits from the Okinawa Trough

Abstract

The study of submarine hydrothermal vent deposits from the Okinawa Trough (OT) is of important significance for understanding hydrothermal mineralization characteristics in incipient back-arc basins. Zinc and lead isotope compositions of hydrothermal deposits from the OT show large variation. Mixing of Pb derived from local volcanic rocks and sediments in different proportions is the major cause of Pb isotope variation. Compared with the hydrothermal deposits from the Middle Okinawa Trough, samples from the Southern Okinawa Trough contain a larger proportion of sediment-derived Pb. Incorporation of continental crust-derived Pb into the hydrothermal circulation also affected the Pb isotope compositions of hydrothermal sulfides from the OT. The Zn isotope compositions of the OT hydrothermal deposits reflect Zn is mainly sourced from the local volcanic rocks and kinetic fractionation is remarkable during sphalerite precipitation. Zinc isotopes may be of potential use in ore exploration and discovery of new active hydrothermal vents.