[MIS09-P04] Seasonal change of the Asian dust provenance within the Canadian ice core estimated from cathodoluminescence spectra of single quartz grains
Keywords:Asian dust, provenance, ice core
Ice cores from Mt. Logan (60N, 141E), Canada, are the ideal recorder of seasonal to decadal-scale changes in dust transport over a long distance (Zdanowicz et al., 2006). Hence here we examine the past seasonal change of dust provenance using an ice core from King col (4135m above sea level) at Mt. Logan by utilizing a new provenance-tracing method, cathodoluminescence (CL) spectral analysis of “single” quartz grains (Nagashima et al., 2017). 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, which are useful to identify the quartz from two major Asian deserts, the Taklimakan Desert and Mongolian Gobi. The CL analysis was performed on quartz grains within ice core samples corresponding to 1941, 1951, 1967, 1983, and 1986 A.D. (6–7 samples/year). We found most quartz grains from ice core samples show two CL emission bands in red and blue regions, which were deconvolved to at most five emission components, each of which represents a specific defect due to an impurity or imperfection. The statistical analysis using the ratios of emission components exhibits ratios of clusters of each sample, which are mostly between those of quartz from Taklimakan Desert and Mongolian Gobi, suggesting the mixing of quartz from the two deserts. Furthermore, the cluster compositions of ice core samples suggest seasonal and possible decadal-scale changes of the dust provenance transported over a long distance, of which detail will discuss in the presentation.