A submarine hydrothermal manganese deposit from the south-west Pacific island arc

Hydrothermal deposits of a wide variety of types are being found with increasing frequency on or near actively spreading mid-ocean ridges1–4. However, they also have a potential to occur in other submarine volcanic settings, including island arcs5. To follow up indications of mineralization associated with submarine hydrothermal activity in the south-west Pacific island arc6, a joint New Zealand Oceanographic Institute/Imperial College research cruise was mounted in May 1981 aboard the RV Tangaroa. During this cruise, over 130 sampling stations were occupied, at one of which were dredged manganese deposits with strong hydrothermal affinities. This is the first report of such deposits from an island arc setting.