Distinguishing the sources of Asian dust based on electron spin resonance signal intensity and crystallinity of quartz

We report a newly developed provenance-tracing method by using a combination of electron spin resonance (ESR) signal intensity of the E₁′ center in quartz and crystallinity index (CI) of quartz, which reflect the formation age and crystallization conditions of quartz in their source rocks, respectively. ESR signal intensity and CI were determined for quartz in fine silt plus clay fraction (<16 μm) of 38 surface samples from nine Gobi and sandy deserts in north China and south Mongolia. Variations in ESR signal intensity and CI are minor within each desert, suggesting that fine-grained quartz in each desert is nearly homogeneous. Differences in ESR signal intensity and CI among the nine Gobi and sandy deserts are significant and, therefore, a combination of these two parameters can be used to effectively differentiate the nine Gobi and sandy deserts in East Asia. Spatial differences in these two parameters suggest that fine silt to clay-sized quartz in these deserts is heterogeneous and derived mainly from the nearby high-altitude mountains in East Asia.