Sr-Nd Isotopic Compositions of Aeolian Sand in the Northern Ulan Buh Desert: Implications for Provenance and Transport Processes

Abstract

Tracing the provenance of aeolian sand in deserts is essential for understanding the mechanisms behind desert formation and sediment transportation processes. There are multiple sand belts that interconnect major deserts within the Alxa Plateau of northern China, observed from satellite images and field research. However, the aeolian sand transport from the Badain Jaran Desert (BJD) to the Yamalik Desert (YD) and Ulan Buh Desert (UBD) through these expanding sand belts is still being underestimated. In this study, we analyzed the content of trace metals and Sr-Nd isotopic compositions in the < 125 μm fraction of dune sands in the northern UBD, the eastern YD, and bedrocks from the Langshan Mountains (LM). Based on bivariate plots of Zr vs. Hf, Zr/Hf vs. Hf, Cr/V vs. Y/Ni, and Th/Co vs. Th/Sc, the aeolian sands in the northern UBD and YD have similar sources but are different from the southern UBD. Comparison of Sr-Nd isotopes with potential source areas suggests that fine-grained aeolian sands in the YD and northern UBD are mainly sourced from the BJD and the southern Mongolian Gobi. Moreover, the low εNd(0) signatures observed in the UBD suggest that approximately 25% of the contribution is derived from the LM, which displays highly negative εNd(0) values. On a larger geographical scale, the northern UBD serves as a transfer intersection for long-distance transportation of sand and dust ultimately sourced from the Central Asian Orogen and northern Tibetan Plateau.

Keywords: Sr-Nd isotopes, Sand provenance, Ulan Buh Desert, Yamalik Desert, Sand transport