Textural differentiation in chronosequences from eastern australia, II. evidence from particle-size distributions

摘要: Abstract Data from particle-size analyses were used to determine the relative importance of four mechanisms proposed explain development strong textural contrast in end members chronosequences. The sedimentary layering, in-situ chemical weathering, clay illuviation and physical breakdown. Depth functions fine clay: total ratios detailed distributions at o intervals 0.6 μm 2000 indicated that there had been a marked increase B horizons older soils each sequence, result consistent with, but not proving, hypothesis. Cumulative distribution indices showed most profiles texturally uniform parent materials. Changes ratio silt : with depth slight for all one profile, indicating no significant contribution fraction by weathering fraction. From changes gravel time, it was concluded breakdown occurred responsible horizon. rate disintegration particularly high early pedogenesis, preceding texture-contrast. Breakdown contributed fines whole solum generally any more intense horizon than another. Grain counts rock fragments medium sand range lent support this conclusion. quartz 0.2 only slight.