Clay Mineralogy of Soils Developed Partially from Volcanic Ash
1972
Pettapiece, W. W. | Pawluk, S.
Luvisols (Alfisols) in the Front Ranges of the Canadian Rocky Mountains of west-central Alberta have several distinctive features including surface horizons with a variable volcanic ash content and reddish Bt (B2t) horizons characterized by the presence of expanding clays. A study of the clay fractions indicates a marked increase in the content of smectitic clay in the sola and particularly in the Bt (argillic) horizons compared with the parent materials. Also, the expanding component is poorly organized and appears to result from the synthesis of amorphous material, probably from a volcanic ash source, accompanied by some degradation of primary chlorite and illite. The clay mineral profile does not fit the concepts generally held for lessivé soils (Luvisols, Alfisols, Sols Lessivé, pseudo-podzolic soils) and in some portions of the sola is similar to that noted in true podzols.
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