Heavy metal and sulfur transport during subcritical and supercritical hydrothermal alteration of basalt: Influence of fluid pressure and basalt composition and crystallinity

Crystalline basalt, diabase and basalt glass have been reacted with a Na-Ca-K-Cl fluid of seawater ionic strength at 350-425°C, 375-400 bars pressure and fluid/rock mass ratios of 0.5-1.0, to assess the role of temperature, basalt/diabase chemistry and texture on heavy metal and sulfur mobility during hydrothermal alteration. Alteration of basalt/diabase is characterized by cation fixation and hydrolysis reactions which show