Clay mineralogy and chemical properties of argillic horizons in central Yukon paleosols

Abstract

Daviel, E., Sanborn, P., Tarnocai, C. and Smith, C. A. S. 2011. Clay mineralogy and chemical properties of argillic horizons in central Yukon paleosols. Can. J. Soil Sci. 91: 83-93. Wounded Moose paleosols occur on Middle Pleistocene and older glacial deposits in central Yukon, and exhibit thick sola with distinctive reddish brown argillic (Bt) horizons. Extensive field investigations in the mid-1980s documented the distribution, morphology, and standard physical and chemical properties of these paleosols, but paleoenvironmental interpretations of their clay mineralogy relied on analyses of only two pedons. New analyses of archived B horizon samples from 15 paleosol pedons demonstrate that these exhibit the highest degree of mineral weathering documented in Yukon soils and surficial materials, as expressed by Chemical Index of Alteration values that can exceed 80. This strong weathering is accompanied by ∼90% conversion of pedogenic iron oxides to crystalline forms. Clay mineral assemblages in this larger...