Seismoacoustic research of lakes bottom sediments of the eastern part of the Republic of Bashkortostan (Russia).

Seismoacoustic survey is a necessary and important method for studying a water area, both from the point of view of studying the structure of bottom sediments bedding, and choosing the optimal point for selecting core columns. In the process of sedimentation, the bottom sediments of modern lakes react very sensitively to climate changes due to changes in the nature and rate of incoming terrigenous material, changes in the lake level and its area, and changes in its bio productivity. Large lakes are investigated using large ships and installations; however, the study of small water areas is rare for a number of reasons. Nevertheless, new detailed results of the regional climate changes can be obtained in such lakes. In 2019, it was conducted detailed seismic investigations of 6 lakes in the eastern part of the Republic of Bashkortostan (Russia) using the “Boomer” seismic complex. For field work we used an inflatable boat and an environmentally friendly electric motor. All lakes are relatively close to each other. However, different structure of bottom sediments bedding on seismic sections was obtained in all lakes. For example, in Lake Sabakty, a layered thickness of bottom sediments of up to 6 m was observed. In some places there are gas-saturated sediments. A slight uplift is observed in these areas, probably related to the “swelling” of bottom sediments as the gas concentration in the sediments increases. In Lake Bannoye, on seismic section observed a bedding structure on a slope of greater thickness (more than 8m) than in the deepest plane part (thickness 2m). 8 cores were selected in these 2 lakes for laboratory investigations. In the remaining 4 lakes, bottom sediments with lower thickness, with the presence of gas-saturation, or sediments were not detected. This work was funded by the Russian Science Foundation under grant № 18-17-00251.