Ra. Mills et al., LOW-TEMPERATURE FLUID-FLOW THROUGH SULFIDIC SEDIMENTS FROM TAG - MODIFICATION OF FLUID CHEMISTRY AND ALTERATION OF MINERAL-DEPOSITS, Geophysical research letters, 23(23), 1996, pp. 3495-3498
Low-temperature fluid flow has been identified as an important compone
nt of the heat, mass and chemical flux at sites of active venting. One
way to study the movement of water through hydrothermal deposits is t
o analyse the pore-fluids extracted from sulfidic sediments. The compo
sition of diffuse flow fluids in one sediment core from the south of t
he active TAG mound reflects the dilution of high-temperature, black s
moker fluids, with modification inside the mound during ongoing circul
ation. Fluid modification includes conductive cooling, removal of Si f
rom solution and entrainment and removal of U from seawater which can
represent significant sinks of these elements. Precipitation of clay m
inerals and Fe-oxides is currently occurring within this sediment core
generating ochreous type material subsurface. Extensive low-temperatu
re alteration of basaltic material at the core-top is apparent in conj
unction with supergene enrichment of Cu and Mn.