First data on the age and formation conditions of secondary carbonate accumulations in upper pleistocene and holocene soils of Upper Angara region

The first data on the age of secondary carbonate pendants in the soils of the Upper Angara region are given. Based on the study of the conditions of occurrence, morphology, material and isotopic composition, three groups of carbonate kutans were identified. The direct 14C AMS dating of the coating’s microlayers allowed to determineintervals of their formation. Pendants of the first group were formed in the middle Holocene (3.6-3.3 kyr BP). The formation of coatings of the second and third groups took place in the second half of MIS-3 (24.1-23.3 and ~34-35 kyr BP, respectively). The paleoecological conditions reconstructed for the identified stages of the formation of carbonate pendants satisfactorily correlate with the climate changes in the region and the northern hemisphere as a whole, reflecting the influence of temperature and moisture fluctuations on the dynamics of soil formation processes. Comparison of the age of carbonate accumulations with the age of modern and buried soils shows that pedogenic carbonatecoatings in the soils of the Upper Angara region are a relict feature of previous stages of pedogenesis (MIS-3) and the first stages of modern soil formation, which began, apparently, in the middle Holocene. The close ratios of the composition of stable carbon and oxygen isotopes in mid-Holocene and Late Kargin (MIS-3) coatings suggest that there is a similarity of pedogenesis conditions in these time intervals, primarily due to the relatively low temperature of pedogenesis and the duration of the seasonally frozen of soils.