Elimination and evaluation of grain size's effect in analysis of chemical weathering of loess-paleosol sequences

摘要

The elimination of grain size's effect is vital to analyze the chemical weathering history of eolian deposits. In this study, the relationship between chemical weathering and grain-size distribution of eolian deposits are analyzed and a new approach was developed to eliminate the effect of grain size in evaluation of chemical weathering. It was concluded (1) the effect of grain size to major elemental abundances (MEA) can be eliminated by deducting the grain size-led offset from measured major elemental abundances, (2) The effect of grain size to MEA intensified from south to north in Chinese loess plateau as chemical weathering weakened. The effect of grain size to MEA did not change the whole evolution trend of MEA in time series. (3) The similarity between median size and MMEA indicated the effect level of grain size to MEA. (4) The effect of chemical weathering to grain-size distribution is neglectable for loess-paleosol formation. (5) Usually, the effect of grain size to chemical weathering index is more remarkable in interglacial periods than in glacial period.