Rare earth element characteristics of Holocene sediments at the southern margin of the Gurbantunggut Desert and their implications for provenance

Abstract

The identification of Holocene sediment provenance at the southern edge of the Gurbantunggut Desert is of great significance for understanding the interaction processes of regional wind and water forces, the evolution of river-dune landform patterns and the atmospheric circulation change in the Junggar Basin. In this study, three aeolian-alluvial stratigraphic profiles in the desert-oasis transition zone at the southern edge of the Gurbantunggut Desert and different types of surface sediments in surrounding areas were taken as the research objects. Based on the chronological framework established by OSL dating, we analysed the REE characteristics, combined with grain size, quartz sand morphology and surface micro-texture features to explore the provenance change of Holocene sediments in the study area. The results indicated that there was no significant provenance change during the Holocene for alluvial deposits at the southern edge of the desert, which were mainly composed of detritus eroded and weathered by glaciers in the Tianshan Mountains. However, the aeolian sand may have undergone provenance change. From early to middle Holocene, detritus from the Western Junggar Mountains served as the sand provenance for dune development in the southwestern desert, with fine-grained components potentially being transported by westerlies, contributing to aeolian sand in the southeastern desert. During the middle to late Holocene, lacustrine sediments in the desert-oasis transition zone at the southern edge of the desert may have become an important source of aeolian sand. In the modern era, the Western Junggar Mountains continue to supply sand for dune development in the southwestern desert, while fine-grained components in the northern desert sand, transported southward by northwest wind, have, to some extent, influenced dune formation in the southeastern desert. However, Due to the limited transport capacity of the wind, we believed that only silt and finer components participated in and influenced the provenance change of the Holocene aeolian deposits at the southern edge of the desert. The results can provide a reference for studying the formation and evolution of the Gurbantunggut desert and preventing desertification in the future.