At 25oC, silicate dissolution rates are pH dependent and vary widely from one mineral to another. At high T (300-700oC), however, the available data indicate that most minerals dissolve in aqueous and H2O-CO2 fluids with similar rate constants if their rates are normalized to a constant number of oxygen gramme atoms. These observations suggest the presence of a compensation relationship between pre-exponential and activation energy terms in the Arrhenius equation. A semiempirical correlation is noted between 25oC dissolution rate constants and the entropy per unit volume (So/Vo) of the dissolving mineral. At T >300oC, the relationship is summarized by the equation log k = -2900/T - 6.85 g atom oxygen cm-2 s-1. Uses of this equation show that isograd reactions go to completion with minimal T overstep (0.13oC for a 10oC/m.y. event) provided a fluid transporting medium is present.-R.A.H.
|Number of pages||18|
|Publication status||Published - 1986|