In-Situ Silt Generation in the Taklimakan Desert Evidenced by Uranium Isotopes

Understanding the mechanism of dust generation is critical for evaluating the global cycles of nutrient elements and for interpreting paleorecords derived from aeolian deposits. Here, we use a novel geochemical tracer, the U-234/U-238 activity ratio that reveals particle comminution age, and Sr-Nd isotopes to investigate how silt-sized particles are produced in the Taklimakan Desert, a major dust source region having effects on global ecosystems. Based on the results from 20- to 25-mu m size fractions, we find that approximately 40% of the Taklimakan Desert silts and approximately 30% of the silts in the aeolian dust flux from the area are produced by in-situ desert processes (e.g., abrasion). The silt-sized materials in the Taklimakan Desert are mainly sourced from the eastern Kunlun Shan and are unlikely to be a major source of the Chinese Loess Plateau. Our findings demonstrate the importance of in-situ desert processes in producing silt-sized particles, providing new insights into the global dust cycle.