LAYER CHARGE OF EXPANDABLE 2-1 PHYLLOSILICATES IN SELECTED PARENT MATERIALS OF SOME CANADIAN SOILS

We investigated the nature of the layer charge of the different expand able 2:1 phyllosilicates present in glacial till, marine sediment, bea ch sand, loess, weathered sandstone and acid shale parent materials of selected soils from the arctic, alpine and interior plateau regions o f Canada. Detailed characterization of 2:1 clay minerals, using the la yer charge, was done by intercalation of the clay fractions with diffe rent chains (n(c) = 6 to 18) of n-alkylammonium cations (AC). Results indicated that AC were able to detect a mixture of smectite and vermic ulite that was not detected by previous studies, using the glycerol (G LY) and ethylene glycol (EG) solvation techniques. The mean unit cell layer charge [in mol(+)/Si,Al)4O10)] varies from 0.30 to 0.39 for the smectite and from 0.71 to 0.74 for vermiculite. Vermiculite from the b each sand is trioctahedral in which most of the charge is located in t he tetrahedral sheet, while vermiculite in the weathered sandstone is dioctahedral in which part of the charge originates from the octahedra l layers. The presence of smectite, associated with the weathering of chlorite and an expanding component associated with the degradation of biotite, was also observed.