hide
Free keywords:
-
Abstract:
catenas the redistribution of mass occurs predominantly as plasma, the dissolved and suspended constituents
in soil water. We applied mass balance methods to track how redistribution via plasma contributed to
physical and geochemical differentiation of nine slowly eroding (~5 mm ky−1) granitic catenas. The catenas
were arrayed in a 3 × 3 climate by relief matrix and located in Kruger National Park, South Africa. Most of
the catenas contained at least one illuviated soil profile that had undergone more volumetric expansion and
less mass loss, and these soils were located in the lower halves of the slopes. By comparison, the majority of
slope positions were eluviated. Soils from the wetter climates (550 and 730 mm precipitation yr−1) generally
had undergone greater collapse and lost more mass, while soils in the drier climate (470 mm yr−1) had undergone
expansion and lost less mass. Effects of differences in catena relief were less clear. Within each climate
zone, soil horizon mass loss and strain were correlated, as were losses of most major elements, illustrating
the predominant influence of primary mineral weathering. Nevertheless, mass loss and volumetric collapse
did not become extreme because of the skeleton of resistant primary mineral grains inherited from the granite.
Colloidal clay redistribution, as traced by the ratio of Ti to Zr in soil, suggested clay losses via suspension from
catena eluvial zones. Thus illuviation of colloidal clays into downslope soils may be crucial to catena development
by restricting subsurface flow there. Our analysis provides quantitative support for the conceptual understanding
of catenas in cratonic landscapes and provides an endmember reference point in understanding the development of slowly eroding soil landscapes
