Glaciation of the Davaatiin Area in the Hangay Mountains,

Central Mongolia

Brian Coggan

Whitman College, Walla Walla WA 99362

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The Davaatiin region contains a wide variety of glacial features including giant moraine complexes and ancient glacial lakes. Although the modern ELA for this region is approximately 4000 m above all but the highest peaks, the ELA at the Last Glacial Maximum was 2800 m. Extensive valley glaciers from five drainages merged into the Davaatiin glacier system, which ranged in elevation from 3494 m to 2200 m and covered an area of 355 km2. Geomorphic evidence for this glacier includes erosional landforms like cirques, hanging valleys, and U-shaped valleys, as well as depositional features like medial, lateral, and end moraines and meltwater channels. Kettles indicate that there were areas of ice stagnation during retreat. Surface boulder frequency counts on five end moraines support the idea of two major glaciations in the Hangay. The glacier flowed over a low plateau to block an unglaciated portion of the Chuluut Gol. The presence of possible ice-rafted boulders and fine-grained lacustrine sediment suggests that a large lake formed above the ice dam. Downvalley, elevated fluvial channels and more ice-rafted boulders imply that this lake may have drained catastrophically in one or more jökulhlaups. Glaciolacustrine sediment from a moraine-dammed lake in Botgon Gol yielded a calibrated radiocarbon date of 13155 ± 70 years BP. Dropstones in the sediment indicate that there must have been a glacier calving ice into the lake at this time. Further study into Central Asia’s past and present glacier systems is important in unraveling how they behave with a changing climate.