Michael Klinge

The extent of Late Pleistocene glaciations in the Altai and Khangai Mountains

Summary The current state of research concerning the extent of Late Pleistocene glaciations in Mongolia and the Russian Altai is summarised. Pleistocene moraines resulting from valley glaciers, plateau glaciers, cirque glaciers and ice streams can be found. The most extensive Late Pleistocene glaciation occurred in the western part of the Altai. However, the extent of Late Pleistocene ice in the Russian Altai is still under debate. In the eastern Altai and especially in the northern part of the Mongolian Altai, Pleistocene glaciers were restricted to several isolated mountain systems. To show the variations in the ice extent, the modern and Late Pleistocene equilibrium-line altitudes (ELAs) and the glaciated area are presented in two cross-sections through the Altai and Western Mongolia. The ELAs are relatively low in the more humid outermost ranges of the arid and semi-arid regions of Central Asia and rise towards the central part of Mongolia. The limited extent of present and Pleistocene glaciers in the eastern part of the Russian Altai and in the Mongolian Altai is the result of decreasing precipitation from west to east. This results in a rise of both the present-day and Pleistocene ELAs towards the east. However, it was more pronounced during the Pleistocene than today. There is an essential lack of absolute dating of glacial sediments in this particular region. Nevertheless, on the basis of present knowledge, most Late Pleistocene glacier advances in Mongolia and in the Russian Altai took place during Marine Isotope Stages (MIS) 2 and 4.

Chapter 69 – The Extent and Timing of Late Pleistocene Glaciations in the Altai and Neighbouring Mountain Systems

Abstract Late Pleistocene glaciations for Mongolia and the Russian Altai are summarized. Whereas an ice sheet occurs in the western Russian Altai, the Pleistocene glaciers have been restricted to several isolated mountain systems in the eastern part of the Altai. Most Late Pleistocene glacier advances took place in the MIS 2 and 4.

Distribution and timing of Holocene and late Pleistocene glacier fluctuations in western Mongolia

Abstract. Despite being a key location for paleoglaciological research in north-central Asia, with the largest number of modern and Pleistocene glaciers, and in the transition zone between the humid Russian Altai and dry Gobi Altai, little is known about the precise extent and timing of Holocene and late Pleistocene glaciations in western Mongolia. Here we present detailed information on the distribution of modern and late Holocene glaciers, and new results addressing the geomorphological differentiation and numerical dating (by optically stimulated luminescence, OSL) of Pleistocene glacial sequences in these areas. For the Mongolian Altai, geochronological results suggest large ice advances correlative to marine isotope stages (MIS) 4 and 2. This is in contrast to results from the Khangai mountains, central Mongolia, showing that significant ice advances additionally occurred during MIS3. During the Pleistocene, glacial equilibrium-line altitudes (ELAs) were ~500 to >1000m lower in the more humid portion of the Russian and western Mongolian Altai, compared to 300-600 m in the drier ranges of the eastern Mongolian Altai. Pleistocene ELAs in the Khangai mountains were depressed by 700-1000 m, suggesting more humid conditions at times of major glaciation than in the eastern Mongolian Altai. This paleo-ELA pattern reveals that the precipitation gradient from the drier to the more humid regions was more pronounced during glacial times than at present.

Higher climate warming sensitivity of Siberian larch in small than large forest islands in the fragmented Mongolian forest steppe

Abstract Forest fragmentation has been found to affect biodiversity and ecosystem functioning in multiple ways. We asked whether forest size and isolation in fragmented woodlands influences the climate warming sensitivity of tree growth in the southern boreal forest of the Mongolian Larix sibirica forest steppe, a naturally fragmented woodland embedded in grassland, which is highly affected by warming, drought, and increasing anthropogenic forest destruction in recent time. We examined the influence of stand size and stand isolation on the growth performance of larch in forests of four different size classes located in a woodland‐dominated forest‐steppe area and small forest patches in a grassland‐dominated area. We found increasing climate sensitivity and decreasing first‐order autocorrelation of annual stemwood increment with decreasing stand size. Stemwood increment increased with previous years June and August precipitation in the three smallest forest size classes, but not in the largest forests. In the grassland‐dominated area, the tree growth dependence on summer rainfall was highest. Missing ring frequency has strongly increased since the 1970s in small, but not in large forests. In the grassland‐dominated area, the increase was much greater than in the forest‐dominated landscape. Forest regeneration decreased with decreasing stand size and was scarce or absent in the smallest forests. Our results suggest that the larch trees in small and isolated forest patches are far more susceptible to climate warming than in large continuous forests pointing to a grim future for the forests in this strongly warming region of the boreal forest that is also under high land use pressure.

Geomorphology of the Tsetseg Nuur basin, Mongolian Altai – lake development, fluvial sedimentation and aeolian transport in a semi-arid environment

The landform ensemble of the Tsetseg Nuur Basin in Western Mongolia provides an archive for periods of different geomorphologic processes induced by changing climate conditions during the Holocene and late Pleistocene times. The geomorphologic map of Tsetseg Nuur basin in the Mongolian Altai illustrates the spatial relation and interaction between different types of sedimentation in semi-arid regions of Central Asia. The map is an instrument to visualize the geomorphologic settings, providing valuable information to distinguish periods of geomorphologic processes and to analyze the landscape evolution. This enables the creation of a relative morphostratigraphy of periods with different hydrological environments, mainly marked by the stages of lake level evolution in an interior drainage basin. The relative chronology calculated from the map receives an absolute chronostratigraphy through radiometric dating from selected sections investigated during field-work.