Outburst floods of the Maly Yenisei. Part II – new age constraints from Darhad basin

ABSTRACT

Some of the largest cataclysmic floods of the Quaternary followed multiple breaches of glaciers damming the headwaters of the Maly Yenisei river in southern Siberia. The shorelines of the impounded lake in Darhad basin suggest at least four depths of 290, 175, 145, and 65 m. Fossil evidence, together with previous ¹⁴C and luminescence dating, indicates the existence of a deep lake during MIS 3; the eroded character of the highest shoreline suggests that the deepest lake was older. ¹⁰Be dating of moraines in the surrounding mountains has documented major glacial advances during MIS 2, although no published direct dating has confirmed a highstand of the lake then. To address this problem, we extracted lake sediments from a 92.6 m deep borehole, sampled beach sands from the nearby basin edge, and dated them both using luminescence methods. We also dated, with ¹⁰Be, the eroded remnants of the end moraine deposited by the last glacier that dammed Darhad basin, as well as other moraines in the mountains surrounding the basin. These numerical ages confirm that a deep lake existed in Darhad basin at ~20 ka and that a large glacier crossed the Maly Yenisei and dammed Darhad basin at ~21 ka. The deep lake persisted episodically until ~14 ka. The ¹⁰Be dating in the surrounding mountains shows that the MIS 2 glaciers subsequently retreated but stalled or re-advanced at ~12, 10, and 1.5 ka. ¹⁰Be dating from the central massif of Mongolia is consistent with this chronology and confirms that MIS 3 equilibrium-line altitudes were slightly (~75 m) lower or approximately the same as those of the MIS 2. The temporal and spatial patterns of glacial advances in southern Siberia and central Mongolia coincided with those of glacial advances in similar climate conditions of the Altai mountains.

KEYWORDS:

• Outburst floods
• megafloods
• cataclysmic floods
• glacial dams
• Maly Yenisei
• Bolshoy Yenisei
• palaeolake Darhad
• Darhad basin
• Sayan

Acknowledgements

We are grateful to the following persons for discussions and assistance with this research: Anastasia Arzhannikova (Siberian Branch, Russian Academy of Sciences), Sergei Arzhannikov (Siberian Branch, Russian Academy of Sciences), A. Bayasgalan (Mongolian University of Science and Technology), Beejinkhuu and his drilling crew (Ulaanbaatar), Raymond (Bud) Burke (Humboldt State University), James Feathers (University of Washington), Andrei Fedotov (Siberian Branch, Russian Academy of Sciences), David Fink (Australian Nuclear Science and Technology Organisation), Carrie Garrison-Laney (University of Washington), Goro Komatsu (Università d’Annunzio, Pescara, Italy), Sergey Krivonogov (Siberian Branch, Russian Academy of Sciences), Ari Matmon (The Hebrew University of Jerusalem), B. Charlotte Schreiber (University of Washington), Vladimir Sheinkman (Siberian Branch, Russian Academy of Sciences), Brian Sherrod (U.S. Geological Survey), and John Stone (University of Washington). We are especially grateful to D. Sukhbaatar and the Damdin Da Fund for the Development of Intellectual Potential (Ulaanbaatar) for continuing logistical support. We thank Victor Baker and Sergei Arzhannikov for insightful and helpful formal reviews.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental Material

Supplemental data for this article can be accessed here.

Notes

1. Lisiecki and Raymo (2005) defined MIS 2 as 29–14 ka, and MIS 3 as 57–29 ka. We used the term ‘MIS’ in its stratigraphic sense in this article.

Additional information

Funding

Funding for drilling was provided by the Royalty Research Fund of the University of Washington and for CRE analysis by a grant from the Quaternary Research Center (UW). Aspects of the research were also supported by the Terra/ASTER program operated by the Jet Propulsion Laboratory of NASA.