PEDOGENIC IMOGOLITE IN SANDY BRUNISOLS OF EASTERN ONTARIO

Imogolite that appears to have formed by weathering in the present soil (pedogenic imogolite) occurred in two well-drained Dystric Brunisols on fine sand materials in eastern Ontario. Imogolite was detected by electron microscopy and was most abundant in the fine clay fraction of the lower B horizons. Several characteristics of these two pedons considered to be favorable for the occurrence of imogolite are: low organic matter content in the sola; high ratio of (Alo-Alp)/Alp in the B horizons; the strong but not extremely acid soil reaction in the B horizons and the porous nature of the soils. The finding is consistent with the hypothesis that the downward movement and precipitation of inorganic amorphous forms of Al and Si is a major process in podzolization. It also demonstrates that the occurrence of imogolite is not restricted to Spodosols or Podzolic soils. Key words: Pedogenic imogolite, proto-imogolite allophane, Dystric Brunisols, Spodosols