Active hydrothermal system drilled at the Mid-Atlantic Ridge


  • ODP Leg 158 Shipboard Scientific Party


Between September and November 1994, drilling documented for the first time the sequence of events that led to the growth of a massive sulfide deposit on the seafloor and revealed the subsurface nature of a volcanic-hosted hydrothermal system on a mid-ocean ridge.

The drilling was conducted at the Trans-Atlantic Geotraverse (TAG) active hydrothermal mound at 26°08′N on the Mid-Atlantic Ridge (Figure 1) by Leg 158 of the Ocean Drilling Program. Drilling penetrated the mound and reached a depth of 125 m below the seafloor near the center of the mound, revealing the structure of the underlying zone of altered basalts through which the hydrothermal fluids flowed to the surface.