TAG hydrothermal system

Abstract

The overall scientific objectives of Leg 158 are to investigate the fluid flow; geochemical fluxes and associated alteration and mineralization; microbiological processes; and the subsurface nature of an active hydrothermal system on a slow-spreading, sediment-free ridge. The active mound within the Trans-Atlantic Geotraverse (TAG) hydrothermal field at 26°N latitude on the Mid-Atlantic Ridge (MAR) is a large, mature deposit of varying mineralogy with emanating fluids displaying a wide range of temperatures and two distinct, but related, chemistries. Studies of this feature will give insight into fluid flow, structure, and "zone-refining' in active hydrothermal systems, and clarify how large, massive sulfide deposits, similar in size to those mined on land today, are formed on the modern seafloor. -from Authors