Outburst floods of the ice-dammed lakes in the SW of Tuva, southern Siberia
Agatova, Anna; Nepop, Roman; Bronnikova, Maria
published: Nov 1, 2015
ArtNo. ESP023105903008, Price: 29.00 €
We conducted a preliminary study of high mountain depressions of the SW Tuva (Mountains of Southern Siberia). For the first time the hydrological system transformation and landscape evolution in the region was considered in detail in relation to the cataclysmic outburst floods of ice-dammed lakes. The paper presents the geological and geomorphological evidence of ice-dam lake development and drainage within the Dzhulukul, Khindiktik-Kol', Akhol' basins. Multidisciplinary investigations including geomorphological and geoarchaeological approaches, lithostratigraphic and pedogenetic analysis accompanied by radiocarbon dating were applied to reconstruct the landscape evolution. The new data suggests the existence of significantly larger lakes which relate to the degradation of extensive Pleistocene ice-sheet glaciations. Floods from these lakes, including those from the palaeo Dzhulukul, where modern runoff goes northward into the Arctic Ocean basin, flowed southward into the Mongolian Inland Drainage Basin. Together with the more humid climate, the significant water supply from the lakes within the Dzhulukul depression (Dzhulukul, Khindiktik-Kol', Akhol') is another factor that controlled much higher former lake levels in the northern part of the Great Lakes Basin, which was not previously considered. The most obvious evidence of palaeolake development is preserved in the Akhol' Basin. Associated landforms and available absolute dates indicate four main stages of lake development. The first stage started no later than 14000 cal. years BP and was characterized by the maximal water level at about 2380 m a. s. l. (180 above present). Partial lake drainage down to 2270 m a. s. l. marks the second stage which ended before 8000 years BP. There are no sufficient data to clearly separate the next two stages of lake evolution. The level 2220 m a. s. l. was quite prolonged before final draining to approximately the modern state. During this time there were only climatically driven oscillations of the lake level and in these final stages the soils developed about 3000 – 3500 cal. years BP and the Akhol' Basin was settled by nomads as- sociated with the Saglyn Culture of the Scythian epoch (6th – 2nd centuries BC).