Pedogenic processes can explain the trends in magnetic susceptibility and soil magneticmineralogy of the Ljubljana Basin chronosequence. The chronosequence formed in predominantlycarbonate sandy gravel outwash terrace...Pedogenic processes can explain the trends in magnetic susceptibility and soil magneticmineralogy of the Ljubljana Basin chronosequence. The chronosequence formed in predominantlycarbonate sandy gravel outwash terraces ranging from 5 to 1800 ka. Magnetic susceptibilityenhancement can be attributed to the formation of secondary superparamagnetic （SP） and singledomain （SD） ferrimagnetic minerals in eluvial horizons. Magnetic minerals that form in illuvialhorizons are predominantly antiferromagnetic. Downward migration of pedogenic iron compoundswith clay （formation of ferri-argillans） causes thickening of the enhanced zone with soil age.In contrast to other published soil chronosequence studies, magnetic susceptibility values donot increase with soil-age （duration of pedogenesis）. Nevertheless, frequency dependence ofmagnetic susceptibility （FD%） and indices such as maximum eluvial magnetic susceptibility （MS）divided by minimum illuvial MS (Max. E / Min. IX<sub>lf</sub> and maximum eluvial MS minus minimumilluvial MS (Max. E -Min. IX<sub>lf</sub>) increase with the logarithm of soil age suggesting that the magneticmineral transformations continue with time, but that their rate decreases. These indices are usefulfor comparisons, and may be useful for age correlations. Hypothesis that magnetic susceptibilityenhancement and precipitation have a positive correlation seems to be valid until the precipitationexceeds the critical value of 100-150 cm/year. The critical value in different settings may dependon the temperature regime and on the yearly distribution of precipitation.展开更多
文摘Pedogenic processes can explain the trends in magnetic susceptibility and soil magneticmineralogy of the Ljubljana Basin chronosequence. The chronosequence formed in predominantlycarbonate sandy gravel outwash terraces ranging from 5 to 1800 ka. Magnetic susceptibilityenhancement can be attributed to the formation of secondary superparamagnetic （SP） and singledomain （SD） ferrimagnetic minerals in eluvial horizons. Magnetic minerals that form in illuvialhorizons are predominantly antiferromagnetic. Downward migration of pedogenic iron compoundswith clay （formation of ferri-argillans） causes thickening of the enhanced zone with soil age.In contrast to other published soil chronosequence studies, magnetic susceptibility values donot increase with soil-age （duration of pedogenesis）. Nevertheless, frequency dependence ofmagnetic susceptibility （FD%） and indices such as maximum eluvial magnetic susceptibility （MS）divided by minimum illuvial MS (Max. E / Min. IX<sub>lf</sub> and maximum eluvial MS minus minimumilluvial MS (Max. E -Min. IX<sub>lf</sub>) increase with the logarithm of soil age suggesting that the magneticmineral transformations continue with time, but that their rate decreases. These indices are usefulfor comparisons, and may be useful for age correlations. Hypothesis that magnetic susceptibilityenhancement and precipitation have a positive correlation seems to be valid until the precipitationexceeds the critical value of 100-150 cm/year. The critical value in different settings may dependon the temperature regime and on the yearly distribution of precipitation.
