A HYDROTHERMAL FIELD IN THE RIFT ZONE OF THE MANUS BASIN, BISMARCK SEA

Abstract

Several hydrothermal fields, active and inactive, in the spread-ing center of the Manus backarc basin were discovered, mapped, and sampled using Mir manned submersibles deployed from the R/V Akademik Mstislav Keldysh. In mineral and chemical composition and lateral zoning, these back-arc basin deposits are indistinguishable from those at hydro-thermal fields on median rifts in the open ocean. They are dominated by zinc sulfides; copperrich ores which might be expected in the highest-temperature parts of the field are perhaps being deposited within the underlying volcanic section.