CARBONATE PHASES IN CALCAREOUS SOILS OF THE WESTERN UNITED-STATES

The carbonate phases of 39 calcareous soil samples, representing 23 soil series from the western US, were studied by wet-chemical techniques, X-ray diffraction (XRD), and electron microscopy to determine the particle-size distribution, chemical composition, mineralogy, particle morphology, and Mg-substitution patterns of the carbonate phases. The multivariate relationship patterns of the carbonate phases. The multivariate relationship between carbonate mineralogy and saturated-paste extract composition was also investigated. Dolomite had a predominantly euhedral particle morphology, compared with calcite, which appeared as aggregates of smaller particles. The mineralogy and morphology of the specific carbonate phases probably reflect the environment of precipitation and seasonal differences in soil-solution composition. -from Authors