FY 1990

Hydrothermal plume prospecting: hydrographic and geochemical techniques

Baker, E.T.

In Gorda Ridge: A Seafloor Spreading Center in the United States Exclusive Economic Zone, G.R. McMurray (ed.), Springer-Verlag, New York, 155–167 (1990)

Hydrothermal plumes, formed by the mixing of hot vent fluids and ambient seawater, can be used to locate, characterize, and quantify sources of seafloor hydrothermal emissions. Vent fluids typically undergo a 10⁴-fold dilution as they rise several hundred meters above the sea floor and form neutrally buoyant plumes with heat and chemical anomalies that stretch tens to thousands of kilometers downcurrent of their source. Real-time mapping of these plumes by towing sensitive hydrographic and optical sensors from a surface ship can efficiently locate the plume source, guide discrete chemical sampling of the diluted hydrothermal fluids, and estimate the heat and mass flux of individual vent fields. This paper uses case histories of investigations along the Juan de Fuca and Gorda Ridges to describe strategies for mapping and characterizing hydrothermal plumes at spatial scales ranging from hundreds of meters to hundreds of kilometers.