Quaternary paleolake formation and cataclysmic flooding along the upper Yenisei River Goro Komatsu a, ⁎, Sergei G. Arzhannikov b , Alan R. Gillespie c , Raymond M. Burke d , Hideaki Miyamoto e , Victor R. Baker f a International Research School of Planetary Sciences, Universita' d'Annunzio, Viale Pindaro 42, 65127 Pescara, Italy b The Institute of the Earth's Crust, Russian Academy of Sciences, Siberian Branch, Lermontova 128, 664033 Irkutsk, Russia c Quaternary Research Center 35-1310, University of Washington, Seattle, Washington 98195-1310, USA d Department of Geology, Humboldt State University, Arcata, California 95521, USA e Department of Museum Collection Utilization Studies, The University Museum, University of Tokyo, Tokyo 113-0033, Japan f Department of Hydrology and Water Resources, University of Arizona, Tucson, Arizona 85721, USA abstract article info Article history: Received 2 May 2008 Received in revised form 9 August 2008 Accepted 20 August 2008 Available online 3 September 2008 Keywords: Quaternary Siberia Mongolia Floods Paleolakes Glacial history A suite of geomorphological and sedimentological features in the catchment of the upper Yenisei River in the Sayan mountains of southern Siberia testifies to the occurrence of cataclysmic floods that flowed down the river. Evidence of large-scale high-energy flood events includes: 1) gravel dunes, up to a few meters high and spaced 50 to 80 m apart, in the Kyzyl Basin 2) landforms such as hanging valleys and paleochannels and 3) flood sediments in a tributary valley. The origins of the Yenisei floods were likely diverse due to complex hydrological processes operating in the Sayan mountains. The possibilities include failures of multiple, variably impounded (ice, sedimentary, tectonic scarp, and lava flow dams) paleolakes in the two large intermontane basins of Darkhadyn Khotgor and Todza, and other minor basins, in the upper Yenisei River catchment. Dating techniques applied to the paleolakes in the Darkhadyn Khotgor and Todza basins revealed their formation during various periods in the middle–late Pleistocene and Holocene. Flooding from the Darkhadyn Khotgor appears to explain many of the inferred flood features, although contributions by flooding from other paleolake basins cannot be ruled out. Computer simulation of the flooding caused by a Darkhadyn Khotgor paleolake ice-dam failure indicates a probable peak discharge of ∼ 3.5 × 10 6 m 3 s - 1 , approximately one-fifth that of the floods that formed the Channeled Scabland in the U.S.A. Many of the outburst events probably occurred in the late Quaternary, but earlier floods could also have occurred. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Cataclysmic floods drastically alter landscapes on geologically instantaneous time scales of hours to weeks. The best-known example may be the floods that created the Channeled Scabland (e.g., Bretz, 1928; Baker, 1973) in eastern Washington State, U.S.A.. It has been proposed that the Channeled Scabland, characterized by a variety of gigantic erosional and depositional landforms over a loess–basalt complex, was formed by repeated outbursts of glacier-dammed Lake Missoula at the end of the Pleistocene (e.g., Baker and Bunker, 1985), although more recently a sub-ice reservoir has been suggested as an additional source (Shaw et al., 1999). Such events are not limited to North America and evidence for late-Pleistocene cataclysmic floods in Northern Eurasia has been discovered or proposed, including floods following the failures of ice-dammed lakes in the Altai mountains (Table 1)(Baker et al., 1993; Rudoy and Baker, 1993; Carling et al., 2002; Reuther et al., 2006). Cataclysmic floods may have occurred also down some of the spillways connecting ice-dammed Lake Mansi and the paleo-Aral, Caspian and Black seas (Komatsu and Baker, 2007), and Geomorphology 104 (2009) 143–164 ⁎ Corresponding author. Tel.: +39 085 4537507; fax: +39 085 4537545. E-mail addresses: goro@irsps.unich.it, goro@sci.unich.it (G. Komatsu). Table 1 Explanation of some geographic terms used in this paper Geographical terms Explanation aimag “province” in Mongolia Altai “mountains of gold” in the Mongolian language gol “river” in the Mongolian language khem “river” in the modern Tuvan language, but means also “Yenisei” khotgor “basin” in the Mongolian language kol Turkic word meaning “river” or “valley” nuur “lake“ in the Mongolian language Sayan mountain range on the Russia–Mongolia border urotchishche “an area with atypical relief and/or soils” in the Russian language 0169-555X/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.geomorph.2008.08.009 Contents lists available at ScienceDirect Geomorphology journal homepage: www.elsevier.com/locate/geomorph