Interregional Correlations of Late Pleistocene Events MIS 5 and MIS 3 in Northern Eurasia: New Data from the Chukotka Peninsula

This paper presents new data on the stratigraphy, palaeogeography, and chronology of Upper Pleistocene marine deposits from the eastern Chukotka Peninsula. Particular emphasis is placed on the reconstruction of transgressive events attributed to Marine Isotope Stages (MIS) 5 and 3. The palaeogeographical interpretation is based on published data on molluscan assemblages, foraminifera, diatoms, and pollen spectra, which indicate periods of climatic amelioration and relative sea-level rise. New chronological constraints are obtained using two independent absolute dating methods: electron spin resonance (ESR) applied to marine mollusc shells, and infrared optically stimulated luminescence (IR-OSL) applied to sandy deposits, including both those containing and those devoid of shell material. ESR and IR-OSL dating link the 105–78 ka interval—corresponding to the latter half of MIS 5—with part of the Valkatlen–Konergin transgressive-regressive cycle. IR-OSL ages from overlying sands and gravelly deposits (41.7–39.3 ka) are attributed to the Amguema transgression and correlate with the Malokhet climatic optimum recognised in Western Siberia during MIS 3. This interval represents a regional phase of climatic amelioration accompanied by a rise in sea level. The combined application of ESR and IR-OSL dating provides a robust chronostratigraphic framework for major Upper Pleistocene palaeogeographical events in eastern Chukotka. Comparison of the established age intervals with marine successions from the western sector of the Eurasian Arctic and Alaska reveals the pan-Arctic synchronicity of transgressive–regressive cycles during MIS 5 and MIS 3. The results refine the stratigraphic position of Upper Pleistocene marine deposits in Chukotka and improve interregional correlations of Late Quaternary palaeogeographical events.