ИСТИНА

The dynamics of the Selenga Delta in the last 50 years is very poorly studied in accordance with climatic changes in the Baikal Region. Up to date a reliable integral assessment of the accumulation dynamics in deltas, the condition to sedimentation in deltaic and floodplain traps, and each contribution to the total accumulation in the Selenga delta have not been achieved yet. Determining the sources of sediment supply is a problem solution of which could help to ascertain not only the genesis, but also the formation mechanism of deltaic landscape units. Also, it could contribute to pinpoint the sources of pollution. We used geochemical fingerprinting (fingerPro package), which is, in fact, a modern implementation of the method of sedimentary provenances analysis (Vermeesch & Garzanti, 2015). Based on the field data collected in the Selenga delta we considered the principle of the mixing model. This topic gives representation about the transport and accumulation of sediment within the delta, and consequently of pollutants actively coming from the catchment. Fine-grained suspended material accumulates at the studied geomorphological positions (20-year floodplain, pool and oxbow lakes): from 70-50% on the floodplain, near 50% and up to 15-10% in pools. The finely dispersed component of suspended sediment corresponds to floodplain deposit as the dominant source of accumulation. The most similar in composition are the facies of oxbow lakes and pools.