Formation rates of smectites derived from two Holocene chronosequences in the Swiss Alps

摘要: The formation rate of smectitic components in alpine soils is derived from two chronosequences the Swiss Alps covering a time span 11 500 years. developed on granitic parent material. lithologies between (investigation areas), however, showed some distinct differences with respect to main mineralogy and, lower extent, chemistry. chronofunctions phase (g/kgclay/year) were fitted data using an exponential model. Extensive mineral weathering resulted significant losses chlorite and mica corresponding smectite regularly irregularly interstratified mica–smectite. This especially pronounced early stages soil formation. Our investigations reveal that greatest changes clay or gneiss host material occur within first 1000–3000 years development. At both investigation sites, annual rates are similar order magnitude 0.1 g/kg/year even higher at start values <0.01 after about 7000 pedogenetic smectites E Bs horizons included several populations various interlayer charges. heterogeneity seems be related nature their precursors.