Chemical characterization and causes of differences in surface sediments of sand dunes in northern China under wind-water composite effects – A case study of the Kubuqi Desert

Abstract

Sediments comprise the base material for the development of wind-driven sand-based landscapes, and dune deposits contain fundamental information regarding the processes of dune formation and development. This study analyzed the surface sediments of seven different types of sand dunes in the Kubuqi Desert (China) from the perspectives of mineralogy, elemental geochemistry, and sedimentology. Results showed that the light mineral composition of Kubuqi Desert sediments is dominated by quartz, and feldspar, and that the overall maturity index is high. The chemical macronutrient composition is dominated by SiO₂ and Al₂O₃, and the trace elements are dominated by Cr and Zr. Analysis of elements based on the normalized average chemical composition of the upper continental crust revealed enrichment in Si and Cr. The characteristics of Kubuqi Desert sediments indicate moderate–low chemical weathering (the average Chemical Index of Alteration value is 55.97), representing relatively stable sediments formed under dry cold conditions that are in the early stage of chemical weathering. Parabolic dunes, together with central and eastern shrub-coppice dunes, were found to be the most weathered. Flood alluviation and wind transport jointly promote the weathering process of Kubuqi Desert sediments, resulting in ridge–honeycomb dunes and reticulate dune chains that do not have a unique source. Conversely, compound dunes and some crescent dunes and chains were found to have a common source of material. The findings of this study could provide a basic reference for analysis of desert material sources, inversion of dune formation and development processes, and reconstruction of ancient aeolian environments.