The Stratigraphy of the Blanket Peatland and the Development of Environments on Bolshoi Shantar Island in the Late Glacial–Holocene

A continuous record of paleogeographic events in the Shantar islands since the end of the Pleistocene has been obtained by a multy-proxy study of the stratigraphy of the blanket peatland. The biostratigraphical studies included botanical, diatom, and pollen analyses. The age-depth model has been developed using seven radiocarbon dates. Data on the development of the environment have been obtained for the first time in the coldest part of the Sea of Okhotsk. The paleoclimatic events were synchronous and metachronous with the regional data and the global changes. The Younger Dryas was much colder in the Shantar islands than in other areas around the Sea of Okhotsk. The climate became more marine after isolation of the islands in the early–middle Holocene. The cold sea and the drifting ice were among the major factors that resulted in the poorly defined early and middle Holocene optimums in this area and in the characteristics of the climatic rhythm. Models have been proposed to explain the alternation of relatively warm and cold periods with different humidity. The age of periods of heavy snowfall, as shown by changes in the role of dwarf pine in the island vegetation, has been estimated. The local swamp and zonal landscape phases have been highlighted. Spruce appeared in this area ~11 410–10 345 cal yr BP, when a landbridge existed; spruce trees became common in the middle Holocene, especially at the turn of the middle–late Holocene. The thermokarst processes were one of the controlling factors of swamp landscapes. The environment underwent major changes in the Little Ice Age; the most severe conditions occurred ~500–260 cal yr BP. In the most-recent 210 years, the most considerable changes in landscapes were related to fires of a human origin.