X and Carbonate Mineral Stability

Carbonate minerals subjected to high P and T conditions will decarbonate that is, the metal carbonate will decompose into a metal oxide and CO2  

The subsurface situation, however, with respect to dolomitization is more complex, as shown by the work of Land and Prezbindowski (1981). It appears that in the Cenozoic Gulf Coast basin of the United States, subsurface, Ca-rich saline formation waters may be undersaturated with respect to dolomite, and as the brine moves updip, and is progressively diluted by shallow subsurface waters, the brine may cause dedolomitization of carbonates encountered in the subsurface. 

Aside from mineral stabilities, the behavior of the CO2-H2O system with increasing P and T is also important to an understanding of the deep burial diagenesis of carbonate rocks. One reaction of interest, which represents the summation of K0 and Ki (see Chapter 1) for the carbonic acid system, is 

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