干旱区生态环境知识资源中心

Although dust from the Asian drylands significantly affects global climate, the provenance of dust transported over a long distance is often uncertain. In this study, we developed a new provenance-tracing method using cathodoluminescence (CL) spectral analysis of single quartz grains that is applicable to dust-fall samples, marine sediments, and ice cores far from Asian deserts. CL spectroscopy can detect crystal-chemical features in quartz such as impurities and intrinsic imperfections that depend on the conditions affecting quartz from its formation onward. Systematic CL analysis was performed on quartz grains from mountain loess and the riverbed near the Tarim Basin in northwestern China and surface sediments from the Gobi Desert in southern Mongolia to evaluate the differences in CL spectral features between quartz grains from the Taklimakan (northwestern China) and Gobi Deserts. Most quartz grains from both deserts showed two CL emission bands in red and blue regions, which were deconvolved to at most five emission components, each representing a specific defect due to an impurity or imperfection. Statistical analysis using the ratios of emission components obtained different compositions of clusters between the quartz grains from the two deserts, probably reflecting the lower abundance of volcanic rocks in the Taklimakan Desert compared to the Gobi Desert.