Weathering tropical humid environments

Viers J., Dupre B., Deberdt S., Braun J. J., Angeletti B., Ndam Ngoupayou J., and Michard A. (2000) Major and traces elements abundances, and strontium isotopes in the Nyong basin rivers (Cameroon) constraints on chemical weathering processes and elements transport mechanisms in humid tropical environments. Chem. Geol. 169, 211-241. 

These estimates show that chemical weathering denudation rates should be on the order of a few millimeters per century. They might be as high as a few centimeters per century in humid tropical settings or as low as a few hundred microns per century in arid cold environments. Because these estimates constrain model predictions to fall within this range of values, they can be used as a validation test of a chemical weathering denudation model. 

All clay minerals are products of the interaction of rocks with aqueous solutions of the weathering environment (Velde and Meunier, 2008). These interactions are essentially a series of leaching and precipitation processes whereby the pH of the solutions is of great importance. In addition to the type of rock and its mineral constituents (Figure 2.1), one of the most important variables is the dimate. There is a basic distinction to be made between leaching reactions that occur in temperate or tropical climates, and precipitation reactions that occur in humid or arid environments. Thus, the compositional and structural variabiUty of clay minerals can be understood on the basis of the different modes of environmental interaction schemes (see Table 2.1). 

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