Supercritical Fluid Geochemistry in Geothermal Systems

Table 4

Mineral-fluid reactions that describe how aqueous neutral species and ion activity ratios are presumably controlled at subcritical and supercritical conditions.

Buffer reactions	Controlled neutral species and ion activity ratios
Subcritical buffer reactions
	H4SiO4
	H2S
	H2
	CO2
	Ca^2+/(H^+)^2
	Ca^2+/(Na^+)^2
	Na^+/K^+
	Fe^2+/(H^+)^2
^-	Al(OH)4^-/OH^-
	Mg^2+/Ca^2+
Supercritical reactions
	SiO2(g)
	Na (NaCl)
	K (KCl)
	Ca (CaCl2)
	Mg (MgCl2)
	Cl (sum of MClx(g) species)