Applicability of chemical weathering indices of eolian sands from the deserts in northern China

Abstract

Chemical weathering is an important process that controls the evolution of the Earth’s surface. By accurately and reliably estimating the intensity of chemical weathering, we can improve our understanding of the processes occurring at the Earth’s surface as well as environmental changes. However, chemical weathering indices, which are influenced by source rocks and grain size, may not always accurately reflect the intensity of chemical weathering. Therefore, the use of chemical weathering indices to reliably reflect the changes in the intensity of chemical weathering in deserts remains uncertain. In this study, several chemical weathering indices, including the chemical index of alteration, Parker’s weathering index, chemical index of weathering, plagioclase index of alteration, chemical proxy of alteration, Rb/Sr, and αAlE indices, were calculated for 521 eolian sand samples collected from across twelve deserts in northern China. The results show that, for all the chemical weathering indices, eolian sands from the different deserts differed significantly. Rather than the climatic conditions in the studied deserts. factors such as source rocks and grain size had a larger impact on these indices. These indices cannot generally be used to reflect the intensity of chemical weathering. However, results showed that when the mean annual precipitation varies greatly between deserts, the changes in the WIP values of the fine fraction samples (<125 μm) could be used to reflect the intensity of chemical weathering. This study enables accurate and reliable estimations of the intensity of chemical weathering and its variations in arid and semi-arid areas.