Aqueous fluid composition in CI chondritic materials: Chemical equilibrium assessments in closed systems

► Several compositional types of aqueous solutions could occur on asteroids and icy bodies. ► The NaCl type alkaline solution is most common and consistent with observations. ► Na2CO3, NaHCO3, and NaOH alkaline types may locally occur on some bodies. ► Acidic Mg-Fe-Cl type fluids may characterize initial stages of alteration. ► Aqueous alteration on Enceladus occurred at lower temperature than on Europa.