Kinetics of Dissolution and Crystal Growth of Silicates and Aluminosilicates in Aqueous Solutions at Low Temperatures

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We will continue studies of the experimental determination of the dissolution and precipitation kinetics of silicates and aluminosilicates as functions of pH, temperature, ionic strength, and the Gibbs Free energy of reaction (delta G); to examine the surfaces of the reacted minerals using surface analytical techniques (XPS, AES, SEM, AFM in particular), which when combined with rates determined from solution chemistry using flow-through reactors will provide information on surface reaction mechanisms; and to apply the rate data obtained to model low temperature field cases in particular the Pijiguaos, bauxite deposit Venezuela Our experimental work continues to lead the way in describing both dissolution and precipitation rates of major rock-forming silicates and aluminosilicates as a function delta G, as well as being the first to measure precipitation rates in phases more complex than quartz. The non-trivial full rate laws that have been developed in our prior work can now be incorporated into an accurate two- dimensional hydrodynamic model of fluid flow in porous media. With the continuing work proposed here, the coupling of experiment, theory and models should result in the first completely quantitative physical and chemical model of diagenesis in a dynamic sedimentary basin and to chemical evolution in a major bauxite deposit.