EXPERIMENTAL STUDY OF BASALT GLASS NA-CARBONATES (±NACL) SOLUTIONS REACTION AT 300℃ AND 500 BARS:FORMATION OF ALTERED MINERALS AND SOLUTION CHEMISTRY

<正> In order to understand the mechanism of basalt-seawater interaction, including the role ofCO2-species, the change in solution chemistry and the formation of the secondary minerals in thereaction between JB-2 basalt glass-hydrothermal solution have been studied by both Dicksongold cell and sealed capsule techniques at 300℃ and 500 bars and solution/rock mass ratio ofabout 10. Solutions used are H2O, 0.5% Na2CO3, 0.5% NaHCO3, 0.14% NaHCO3, NaCl-NaHCO3with different Cl-/HCO3- ratio, and 0.1% NaCl solutions. The results clearly indicate thatthe two tyges of experiments have a basically identical alteration mineralogy. The basaltglass-Na-salt solution （including seawater） reaction at 300℃ and 500 bars essonfially is areaction between basalt glass and water. The presence of CO2-species causes the decrease ofNa-content in the reacted solution and the formation of the secondary carbonate.