CLIMATIC VARIABILITY IN THE ERA OF MIS‑11 (370–440 KA BP) ACCORDING TO ISOTOPE COMPOSITION (ΔD, Δ18O, Δ17O) OF ICE FROM THE VOSTOK STATION CORES

Abstract

The results of detailed isotopic studies of ice core samples from the Vostok station (East Antarctica) related to the MIS-11 era (the 11th sea isotope stage, i.e. 370–440 thousand years ago) are presented. Reconstruction of paleoclimatic conditions in this period of time was performed using the method of interpretation of the results of isotopic studies of ice, developed by the authors of the article, which is based on the joint analysis of three independent parameters: δD, d-excess, 17 O-excess. The isotopic composition (δD) and the deuterium excess depend on the following three meteorological parameters – the condensation temperature near the Vostok station, relative humidity, and the sea surface temperature at the source of moisture, whereas 17 O-excess depends only on the first two parameters. Accordingly, the proposed method of interpretation allows reconstructing the paleoclimatic conditions (the condensation temperature and surface air temperature at the Vostok station; sea surface temperature and relative humidity above the ocean) in two different regions in past epochs. For the first time, data on minor fluctuations in the relative humidity of the air in themoisture source throughout the MIS-11 era were obtained. The data resulted from the interpretation demonstrated that the relative humidity fluctuated within the measurement error of ±5%. Reconstructed climatic conditions in the era of MIS-11 were compared with published data for stations Vostok and Concordia, aswell as with the marine core data from 94-607 DSDP and ODP 177-1090. The results obtained on the basis of isotopic analysis of ice cores from stations Vostok and Concordia indicated that in the optimum MIS-11the air temperature was4 °C higher, and in the Termination V –8 °C lower than the present-day values. Thesimilarity of data between the marine columns DSDP 94-607 (North Atlantic), ODP 177-1090 (South Ocean)and our results points to the global nature of changes in the sea surface temperature during the MIS-11 era. The coordination of the above results proves the high quality of the methods developed by the authors for measuring and interpreting the isotope composition of ice.