The environment of the upper Kama region during the late glacial and early Holocene as revealed by the study of bottom sediments from lake Novozhilovo

For the first time, a high-resolution record of natural events covering the Late Glacial and Early Holocene (14 150–9 730 cal BP) was obtained for the southern part of the Kama-Vychegda watershed based on drilling sediments in lake Novozhilovo (Kama-Keltma lowland, Upper Kama basin). The article presents the results of the study on the reconstruction of sedimentation conditions, based on paleobotanical, sedimentological and radiocarbon dating analyses. The beginning of the lake's formation was apparently preceded by a period of predominantly alluvial morpholithogenesis, which is thought to correspond to the LGM. There were four stages in the evolution of the lake basin, with the first three characterized by lacustrine-alluvial sedimentation that was predominantly mineralogenic in nature, and the fourth stage marked by typical lacustrine organic-rich sedimentation. The first stage covered the Bølling-Allerød interstadial period from 14 150 to 13 500 cal BP, and it was characterized by the accumulation of sand under conditions of high water flow. At the boundary between the Allerød and Younger Dryas periods, bioproductivity increased significantly. During the second stage, which lasted from 13 500 to 12 420 cal BP, water exchange slowed down and organic-mineral lake sediment formed. The third stage, known as the transitional sedimentation period, refers to the Younger Dryas and Early Holocene periods (12 420–10 700 cal BP). During this time, alluvial inputs predominated, with a decrease in organic matter content. Finally, the fourth stage, the eutrophic lake stage (10 700–9 730 cal BP), was characterized by a high organic matter content in sediment, and an increase in the size of silty particles.