History of late Pleistocene glaciations in the central Sayan-Tuva Upland (southern Siberia)

Abstract

This work describes the history of late Pleistocene glaciations in the central Sayan-Tuva Upland (southern Siberia). Geological and geomorphological analysis as well as 10Be surface-exposure dating revealed the glacier fluctuations in this continental area. The available published data show that the glaciers were formed in the MIS 6 and probably survived in the MIS 5. Data are also available concerning glacial advances in different periods of MIS 4, MIS 3 and MIS 2. ELAs were 2030–2230 m. Two distinct 10Be exposure ages groups are highlighted reflecting the time of formation of glacial deposits in the MIS 2 associated to the Big Sayan Ridge outlet glaciers. The Sentsa – Sailag group (terminal moraine) has a mean exposure age of 16.44 ± 0.38 ka. The Jombolok (terminal moraine) – Jombolok (outwash plain) group has a mean exposure age of 22.80 ± 0.56 ka. The last glaciation that occurred at MIS 2 is characterized by the absence of ice cap on the Azas volcanic Plateau and of ice field in the Todza Basin. The thickness of the valley glacier was 300–400 m. At MIS 2, the terminal moraines were ∼1300–1400 m a.s.l. in the Tissa, Sentsa, Jombolok and Sailag river valleys.