Magnesian calcites dissolution experiments

Figure 3.7. Solubilities of the magnesian calcites as a function of MgCC>3 content, expressed in terms of -log IAPMg.caicjte. The solid curve represents the general trend of dissolution experiment results.

Solubilities of annealed skeletal carbonates were estimated by Land (1967) by allowing the system to reach a steady state pH and by determining dissolved Ca2+ and Mg2+ concentrations. Dissolution of the magnesian calcites in Land s experiments appeared to be congruent in the sense that the steady state solution had a molar Ca2+/Mg2+ ratio similar to that of the solid. 

Figure 3.14. Stabilities of calcite, and synthetic (closed squares) and biogenic (closed circles) magnesian calcites as a function of composition. Stabilities are expressed as -log IAPMg-Calcite- The curve is a hand-drawn "best" fit to the synthetic data. Also plotted are the results of precipitation experiments by Mucci and Morse (1984, open squares) and biogenic dissolution experiments by Walter and Morse (1984a, open circles). (After Bischoff et al., 1987.)...

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