Effects of acidic and basic parent materials on formation of some soils in Quebec (Canada)

Abstract

Five profiles developed on basic or acidic parent materials were sampled in southern Quebec, Canada. Physical, chemical and mineralogical properties were determined. Among the three profiles developed on basic parent materials, one formed in disaggregated metabasalt whereas the two others developed in preglacial saprolites derived from the metabasalt, as indicated by till cover in a nearby area. In the lower part of the latter profiles, the saprolites had a loamy texture and the mineralogical plus chemical data indicated very slight changes with respect to the metabasalt. In these profiles, CBD-extractable Fe content was > 1% in most horizons, and the pyrophosphate-extractable Fe was generally higher in the Ah than in the B horizons. In the profiles developed on acidic till, CBD-extractable Fe was > 1% only in the B horizons, which also contained the maximum of pyrophosphate-extractable Fe. In the latter profiles, free Fe and Al sesquioxides were associated with the clay fractions whereas in the former profiles, one third of the Fe came from the sand and silt fractions. Chlorite was the dominant phyllosilicate in the basic material and it was transformed into interstratified minerals and smectite. Several hypotheses about smectite formation and distribution were discussed. In the profiles developed on acidic till, illite and chlorite were the major phyllosilicates and, through weathering, transformed into interstratified minerals, vermiculite and smectite. Major differences in the properties of the profiles developed on the two parent materials were not reflected by current soil classification.