Hydrothermal plume detection in the deep ocean-A combination of technologies

Marine chemists, geologists and oceanographers have been studying the behaviour of hydrothermal plumes since the discovery of hot springs on the seafloor of the Pacific in 1977. Scientists are now trying to assess the amount of hydrothermal activity in the deep ocean, both past and present, to get some idea of the impact of hydrothermal fluid on the oceans as a whole, on the composition of seawater and marine sediments, and on the behaviour of marine ecosystems. Deep ocean hydrothermal vent sites tend to occur at plate tectonic boundaries. This article concentrates on recent research along the Mid-Atlantic Ridge (MAR), close to the area of the Azores Triple Junction, where the African, Eurasian and N. American oceanic plates diverge. The ridge in this area is broken up into several North-South trending segments, offset from each other by a series of East-West trending discontinuities. The ability to deploy a platform combining instruments for real-time geological study of the seafloor and geochemical studies of the water column above it, simultaneously, has resulted in the discovery of a much higher incidence of hydrothermal venting along the MAR than previously supposed. These improved techniques could now be applied to finding hydrothermal deposits in marginal basins where ore-grade deposits are known to accumulate.