Original article Neotectonic formation and localization conditions of groundwater reserves in over-deepened sections of the Kitoy River valley

The purpose of the study is to identify the main neotectonic formation features of over-deepened valleys where fresh groundwater is localized. The object and the subject of the study is the Kitoy deposit of drinking groundwater located in the U-shape valley of the Kitoy river, which is composed of constratal alluvium, as well as hydrogeological and hydrogeochemical conditions of the deposit. The study of the over-deepened alluvial dislocation is carried out based on the analysis of the works performed at the Kitoy fresh groundwater deposit for the period from 1956 to 2020. The deposit is located at the southern margin of the Siberian platform within the Irkutsk-Cheremkhovo plain. The article studies the origin of the dislocation formed by the intersection of waves of pitching and subsidence of the Baikal and Sayan directions accompanied by the groundwater localization. The described over-deepened valley is 9-39 m thick. It is represented by boulder-gravelpebble material with sandy aggregate. The average filtration coefficient for the deposit is 122 m/day, the average water permeability coefficient is 3400 m 2 /day, whereas beyond its limits the indicators decrease. The qualitative composition of groundwater meets the standards, but some areas feature increased mineralization, high content of iron and manganese due to the inflow of groundwater from the underlying Jurassic aquifers. The authors made a generalization on the variations of the effective thickness of the aquifer and analyzed the favorable conditions for the formation of fresh groundwater within the depression structure for the purpose of water supply for drinking and household uses.