Late Pleistocene – Holocene Exodynamics and Sedimentation Environments of the Tunka Rift Valley (Southwestern Baikal Region) Based on the Analysis of Lithological and Petromagnetic Features of the Upper Paleolithic Deposits

Sediments in the Tunka rift valley are deposited in high-energy geomorphic and lithodynamic processes. A number of Paleolithic sites are located here, but the number of archaeological finds in different parts of the rift varies greatly. The aim of this study was to reconstruct the features of exogeodynamics and the sedimentation environments in the Tunka valley to explain the reasons for the different degree of preservation and spatial distribution of archaeological material from the Upper Paleolithic sites and to assess the potential of sites for the discovery of cultural horizons in situ. Based on the petromagnetic and granulometric analyses of the samples (923), a study has been made on 6 sections, similar in age and different in geological structure, thickness, and geomorphological position. All sections are 14 C and TL dated. The integration of granulometric and petromagnetic data helps to reconstruct different sedimentation conditions in the explored sites of the Tunka depression and to estimate their suitability for prehistoric human habitation. The Belyi Yar I and Belyi Yar II section are characterized by high sedimentation rates and a large influx of loose sedimentary material due to catastrophic floods and other processes. High sedimentation rates were also reconstructed for the Shimki section (where archeological discoveries have not yet been made), but the presence of paleosoil horizons indicates milder environmental conditions. The Tuyana site, located highest relative to the bottom, contains numerous archaeological finds. This is due to low sedimentary input, well-developed buried soils, and a lack of signs indicating catastrophic floods. The Zaktui site, located hypsometrically lower than the Tuyana site, is less suitable for preservation of culture-containing horizons. An intermediate position is occupied by the Slavin Yar section.