Seasonal geochemical signals in varves of the Lake Donguz-Orun bottom sediments from scanning X-ray fluorescence with the use of microcapillary X-ray optics

The distribution of minor elements in a sample of bottom sediments from Lake Donguz-Orun, Northern Caucasus, is studied via scanning X-ray fluorescence microanalysis using beams of synchrotron radiation from the VEPP-3 storage ring. A beam of exciting radiation 15 μm in diameter is obtained with microcapillary X-ray optics to conduct detailed studies of the inner structure of individual varves. It is shown that the Rb/Sr ratio is related to particle size and could be a spring flood marker. Estimates of the current rate of sedimentation in the lake, based on counting visually discernible layers and from geochemical indicators, coincides with the isotopic data. Quantitative links between sediment composition and meteorological data (temperature and atmospheric precipitation) were found.