Monosaccharide status of pre-Mazama Ahb horizons in Alberta, Canada

Abstract

Palaeosols, formed prior to deposition of Mazama tephra (6600 yr B.P.), are widespread in Alberta. Palaeo-Ahb horizons are readily identifiable, with colors ranging from very dark gray to gray and brown. Establishment of fundamental and stable properties of the original organic matter would facilitate the classification of these buried soils. Use of a suite of eight monosaccharides divided the 15 palaeosols examined in this study into one group of three, possibly formed under Brown Chernozemic soil-forming conditions or drier, and the remainder, possibly formed under Black Chernozemic soil-forming conditions. The former had C/N ratios approaching those of microorganisms and low xylose to mannose ratios. It is concluded that, because of the long time-window of surface stability between deglaciation and the Mazama tephra fall, pre-Mazama palaeosols can only be studied on a site-specific basis. Grouping these palaeosols, based on their pre-Mazama tephra deposition only, is not realistic. Synthesis of a unified hypothesis of palaeoenvironmental conditions is, therefore, not possible using only their monosaccharide status. Key words: Holocene soils, palaeosols, buried soils, monosaccharides, landscape