Geochemical role of the water/rock ratio during the experimental alteration of a synthetic basaltic glass at 50 °C. An XPS and STEM investigation
Thomassin, Jean-Hugues; Boutonnat, Frédérique; Touray, Jean-Claude; Baillif, Patrick
European Journal of Mineralogy Volume 1 Number 2 (1989), p. 261 - 274
published: May 3, 1989
manuscript accepted: Jan 4, 1989
manuscript received: Apr 14, 1988
ArtNo. ESP147050102003, Price: 29.00 €
Abstract The effect of water/rock ratio on the alteration of basaltic glass by seawater at 50 °C has been investigated experimentally in batch conditions for up to 24 months, using XPS and STEM techniques. At high ratios (180), alteration is dominated by magnesium from seawater, with formation of hydrotalcite, serpentine and smectite. At low ratios (18, 5), alteration is iron dominated. In all cases, the initial glass-solution interface is labelled by a Fe-Ti bearing layer, which persists throughout the experiments at low water/rock ratios. It is suggested that the alteration layers either side of this layer are formed by a) precipitation of minerals and adsorption of silica from the solution and b) in situ transformation within the hydrated glass. The growth rate of these layers is greater at lower water/rock ratios.