Verification of paleo reconstructions of climatic conditions of the Late Pleistocene summer seasons based on palynological analysis of Yedoma deposits and ice wedges

Abstract

The object of this research is the reconstruction of the climatic conditions of the Late Pleistocene summer seasons based on the pollen spectra of syngenetic ice wedges and inclosing Yedoma deposits. For quantitative assessment of summer temperatures and phenological relationships, the author applies the total annual thaw index, since namely the sum of positive temperatures is the only indicator that determines the beginning of pollen emission in majority of plant species. The relationship between the composition of pollen spectra and the total annual thaw index is deterministic, although it cannot be formulated strictly mathematically. Yedoma is a unique object for research by many parameters, which allows acquiring paleogeographic information on two components, such as ice wedges and deposits, because the accumulation of pollen and spores occurs differently therein. The structure of vegetation cover during the accumulation of Yedoma deposits during the Late Pleistocene differed significantly from the Holocene and modern periods, which is recorded in the pollen spectra of syngenetic deposits and ice wedges. It is established that in certain periods, the diversity of species of Late Pleistocene vegetation was higher compared to modern vegetation of tundra and forest tundra due to the large number of ecological niches and peculiarity of temperature regime of the summer season.