Geochemical Features of Annual Layers of Bottom Sediments of Freshwater Lakes, Studied via Synchrotron Radiation–Induced XRF Microanalysis

Resumo

The possibility of distinguishing layer boundaries through lithological and geochemical indicators (Rb/Sr ratio) is shown by a case study of bottom sediments from Lake Kucherlinskoe (Altai). Based on the data from scanning synchrotron radiation–induced XRF microanalysis and isotope studies, a record of the Tunguska event of 1908 is found in the bottom sediments of Lake Zapovednoye, forty kilometers from the explosion’s epicenter. An anomalous layer in the sediments is associated with an increase in the terrigenous drift in the catchment area due to massive forest outfall and subsequent fires. The possibility of a targeted search for microparticles of extraterrestrial origin in lake sediments is demonstrated.