Short Paper Glacial Lake Vitim, a 3000-km 3 outburst flood from Siberia to the Arctic Ocean Martin Margold ⁎, Krister N. Jansson, Arjen P. Stroeven, John D. Jansen abstract article info Article history: Received 22 February 2011 Available online 4 August 2011 Keywords: Glacial lake outburst flood (GLOF) Freshwater influx Transbaikalia Ice-dammed lake A prominent lake formed when glaciers descending from the Kodar Range blocked the River Vitim in central Transbaikalia, Siberia. Glacial Lake Vitim, evidenced by palaeoshorelines and deltas, covered 23,500 km 2 and held a volume of ~3000 km 3 . We infer that a large canyon in the area of the postulated ice dam served as a spillway during an outburst flood that drained through the rivers Vitim and Lena into the Arctic Ocean. The inferred outburst flood, of a magnitude comparable to the largest known floods on Earth, possibly explains a freshwater spike at ~ 13 cal ka BP inferred from Arctic Ocean sediments. © 2011 University of Washington. Published by Elsevier Inc. All rights reserved. Introduction Pleistocene glacial lakes formed where glacier or ice-sheet margins obstructed natural drainage routes (Upham, 1896; Mangerud et al., 2001, 2004). The failure of such dams triggered catastrophic outburst floods, and those from glacial lakes Missoula (northwestern USA) and Chuja–Kuray (southern Siberia) count amongst the greatest known floods on Earth (Waitt, 1985; Baker et al., 1993; Herget, 2005; Table 1). Furthermore, large meltwater fluxes, like those stemming from the sudden drainage of North American glacial lakes during late glacial times, are thought to have triggered shifts in ocean circulation that propagated major climate changes on a global scale (Barber et al., 1999; Teller et al., 2002; Tarasov and Peltier, 2005; Broecker, 2006). In this pilot study, based on a GIS analysis of remotely sensed data, we argue for the occurrence of a large glacial lake outburst flood in a remote and little-researched region of Siberia. The outlines of glacial lakes and drainage diversions created by outburst floods are relatively well known from North America, western Eurasia, and the Himalayas (e.g., Waitt, 1985; Leverington et al., 2000, 2002; Mangerud et al., 2001; Montgomery et al., 2004; Herget, 2005; Jakobsson et al., 2007; Komatsu et al., 2009; Wiedmer et al., 2010). Far less is known of the mountains of central and eastern Siberia. The Transbaikalia region, east of Lake Baikal, supports only a few small contemporary glaciers, and the existing knowledge of the character and extent of former glaciation is limited and contradictory (Shahgedanova et al., 2002; Enikeev, 2009). Yet, evidence of former alpine glaciers descending into large extensional intermontane basins with narrow outlets fuels potential for major ice dams in the Pleistocene. In the River Vitim catchment (Fig. 1), well-preserved deltas and palaeoshorelines occur at concordant elevations around the Muya– Kuanda depression and upstream. The existence of a glacial lake in the Vitim area was suggested by Grosswald and Rudoy (1996) and described by Krivonogov and Takahara (2003), Enikeev (2009, in Russian), and Margold and Jansson (2011); however, the configura- tion of the damming glaciers and the outburst chronology is yet to be documented. Here, building on a recently conducted remote-sensing mapping survey (Margold and Jansson, 2011), we provide the dimensions of Glacial Lake Vitim, inferences on the ice-dam configurations, and geomorphological evidence for the passage of a catastrophic outburst flood that possibly compared with the largest known floods on Earth. We postulate that the magnitude of this flood was sufficiently large to have caused far-reaching climatic and environmental impacts connected with large freshwater influx to the Arctic Ocean. Sediment core PS2458 from the Laptev Sea analysed by Spielhagen et al. (2005) reveals an ‘outstanding’ δ 18 O spike at ~13 cal ka from freshwater runoff. The source of the freshwater influx remains unknown, but we argue that Glacial Lake Vitim is a strong candidate. Glacial Lake Vitim North of the Muya–Kuanda depression, the River Vitim cuts a narrow valley through the Northern Muysk Range (Fig. 1). It has been suggested that a valley glacier emanating from the Kodar Mountains blocked the River Vitim beyond present-day Lake Oron (Fig. 2), creating a glacial lake (Krivonogov and Takahara, 2003; Margold and Jansson, 2011). This case, in which a valley glacier from the Lake Oron tributary formed a dam, represents the most restricted ice configu- ration leading to the formation of Glacial Lake Vitim. Another significantly more extensive configuration of damming glaciers is inferred for the area downstream of the Lake Oron tributary where interconnecting valleys indicate the development of a network of confluent valley glaciers that blocked the Vitim valley. The blocking ice probably filled the Vitim valley for some distance, as shown by the U-shaped valley profile that extends downstream from this Quaternary Research 76 (2011) 393–396 ⁎ Corresponding author at: Department of Physical Geography and Quaternary Geology, Stockholm University, 106 91 Stockholm, Sweden. Fax: + 46 8164818. E-mail address: martin.margold@natgeo.su.se (M. Margold). 0033-5894/$ – see front matter © 2011 University of Washington. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.yqres.2011.06.009 Contents lists available at ScienceDirect Quaternary Research journal homepage: www.elsevier.com/locate/yqres