Quantification of the aeolian sand source in the Ulan Buh Desert using the sediment source fingerprinting (SSF) method within MixSIAR modelling framework

Identifying and quantifying source contributions of aeolian sands in desert where extensive dunes and paleolakes coexist is crucial to elucidate the formation mechanism of aeolian and lacustrine landforms in the earth system. In this study, we identified the aeolian sediment sources in the Ulan Buh Desert (UBD) using geomorphological and sedimentological methods, and further quantified the source contributions via the sediment source fingerprinting (SSF) method within MixSIAR modelling framework. Our results revealed that the mean contribution from each source to the UBD sediments were assessed to be 32.2 % for detrital deposits weathered and eroded from the Helan Mountains (HLM), Bayan Urals Mountains (BUM), and Langshan Mountains (LM), 26.2 % for aeolian and Gobi deposits from the adjacent Yamalik Desert (YMD) and Bayin Wendur Desert (BWD), 26.1 % for aeolian and Gobi sediments from the upwind Badain Jaran Desert (BJD), and 15.5 % for the paleolacustrine sediments in the UBD. The bulk fraction sands in the UBD are mainly contributed by detrital deposits from its surrounding mountains, whereas the fine sands are supplied by the upwind deserts of the UBD. As shown by the dunes migration rate (averaged 9.1 m/yr) and direction (averaged 118.3 degrees) in the YMD, sands from upwind desert can be easily transported to the adjacent downwind desert, i.e., the UBD. Therefore, much attention should be paid to their role in sediment source contribution rather than ignore them for their limited area. Similarly, although the sediment source contribution from paleo-lacustrine deposits within the desert is relatively small, they served as a direct source for the UBD. The GOF evaluation demonstrated that the MixSIAR Bayesian model is an effective approach to aid aeolian sediment fingerprinting. In addition, we found that the aeolian sediments in the UBD is the combined results of wind and fluvial systems.