MINERAL TRANSFORMATIONS IN SOME SANDY SOILS FROM ALBERTA, CANADA

Three sandy Luvisols from Alberta were studied through mineral investigations and geochemical prediction based on the ionic composition of the in situ soil solution to evaluate the stability and formation of minerals. The transformation of phyllosilicates in this study appears to be dominated by the vermiculitization of mica and to a lesser extent of chlorite. Hydroxy interlayered phyllosilicate is also observed throughout the sola. There are good agreements between geochemical predictions and mineral determination for calcite, dolomite, goethite, hematite and lepidocrocite. These observation suggest that a geochemical model using data from the composition of in situ soil solution can be used to evaluate the stability and formation of the low quantities of the common carbonates, oxides and oxyhydroxides. The unique micro- or paleo-environments are believed to be responsible for the disagreement between the model and the mineral observation for gypsum while the ''anti-gibbsite'' effect of organic components may be responsible for the non-formation of gibbsite.