Glacial Geomorphology of Mt. Munkh Saridag in the Khuvsgul Mountain Range, Northern Mongolia

This study reconstructs palaeoglacial extent in the Khuvsgul Mountain Range in northern Mongolia based on the mapping of glacial landforms of Mt. Munkh Saridag. For the accurate reconstruction of palaeoglaciations in the Khuvsgul Mountain Range, glacial landforms including glacial valleys, glacial cirques, end moraines, medial moraines, marginal moraines and glacial lineations were mapped at a scale of 1:100.000 for Mt. Munkh Saridag. Mapping was conducted using Google Earth, 30 m resolution ASTER DEM data and 30 m resolution Landsat 5TM satellite imagery. This mapping revealed abundant glacial erosional and depositional landforms in the Khuvsgul Mountain Range, in particular, large end moraine complexes mark palaeoglacial advances in the mountain valleys of Mt. Munkh Saridag. Results indicate that Mt. Munkh Saridag, the center of Khuvsgul Mountain Range, had lost 42.6% of its total glacier area between 1970 (900 m²) and 2007 (384 m²) when the equilibrium-line altitudes (ELAs) of the glaciers were retreated by 47 m and 80 m on north and south aspects, respectively. The outer limits of these glacial landforms show development of small ice caps on peaks and ice fields in valleys of Mt. Munkh Saridag where their maximum glaciation was reconstructed to have covered 186 km². The spatial analyses show the dynamic change of the modern glaciers in Mt. Munkh Saridag, and how this depends on topographical elements of elevation and aspects, durations of solar radiation and vulnerability to the solar insolation. This study demonstrates that spatial analysis of the glacial landforms is crucial for reviewing the extent of palaeoglaciers that could be detailed with dates in further work.Cette étude reconstitue l'extension glaciaire récente dans la chaîne de Khuvsgul (Nord de la Mongolie), en se basant sur la cartographie des modelés glaciaires du Mont Munkh Saridag. Pour la reconstitution précise de l’englacement, les formes glaciaires - vallées, cirques, moraines terminales, médianes et marginales, linéaments glaciaires - ont été cartographiées à l'échelle de 1:100 000 en utilisant Google Earth, et des images à 30 m de résolution ASTER DEM et Landsat 5TM. Cette cartographie a révélé de nombreuses formes d'érosion et d'accumulation glaciaires, en particulier de grands complexes de moraines terminales qui marquent des avancées glaciaires dans les vallées du Mont Munkh Saridag. Celles-ci, au centre de la chaîne de Khuvsgul, ont perdu 42,6 % de leur surface englacée entre 1970 (900 m²) et 2007 (384 m²) alors que l'altitude de la ligne d'équilibre des glaciers s’est élevée de 47 m et 80 m sur les versants respectivement Nord et Sud. La localisation de ces formes glaciaires montre le développement de petites calottes de glace sur les sommets et des glaciers dans les vallées du Mont Munkh Saridag où leur extension maximale a atteint 186 km². Les analyses spatiales montrent l'évolution de la dynamique des glaciers modernes, et de quelle manière elle dépend de la topographie, de l'exposition, de la durée du rayonnement solaire et de la vulnérabilité à l'insolation. Cette étude démontre que l'analyse spatiale des modelés glaciaires est cruciale pour déterminer l'étendue ancienne des glaciers, analyse qui pourrait être confortée dans de futurs travaux par des éléments de datation

Middle to late Holocene sedimentation dynamics and paleoclimatic conditions in the Lake Ulaan basin, southern Mongolia

This study presents a reconstruction of the middle to late Holocene sedimentation dynamics and paleoclimatic implications in Lake Ulaan, southern Mongolia for the first time. The dynamics is inferred from weathering intensity, Accelerator Mass Spectrophotometry (AMS) radiocarbon dating and estimated sedimentation rates. Result shows that a higher sedimentation rate of 4.6 cm.kyr‑¹ between 2.7 and 6.0 cal kyr BP and a lower sedimentation rate of 1.6-1.8 cm.kyr‑1 after 2.7-3.2 cal kyr BP are associated with a climatic shift from humid in the middle Holocene to arid in the late Holocene within the Lake Ulaan basin. This result from the Lake Ulaan basin in southern Mongolia correlates with the middle and late Holocene climatic records reconstructed from other lakes in Mongolia and Central Asia. Further investigation of lacustrine sedimentary sequences and more age data from Lake Ulaan are still needed to constrain better the Holocene sedimentation history in southern Mongolia and Central Asia.Cette étude propose une reconstruction de la dynamique de la sédimentation à l'Holocène moyen et final et de ses implications paléoclimatiques dans le lac Ulaan, au sud de la Mongolie. Cette dynamique est reliée à l'intensité des intempéries, à l'estimation de taux de sédimentation et est calée temporellement par datation au radiocarbone (AMS). Les résultats montrent qu'un fort taux de sédimentation équivalant à 4,6 cm/1000 ans, entre 2,7 et 6,0 années cal BP, et un taux de sédimentation très bas d’environ 1,6-1,8 cm/1000 ans après 2,7‑3,2 années cal BP, sont associés à un changement climatique évoluant d'une ambiance humide au milieu de l'Holocène à une ambiance aride à la fin de l'Holocène dans le bassin du lac Ulaan. Ce résultat est corrélé avec les relevés climatiques de l'Holocène moyen et final reconstitués à partir d'autres lacs en Mongolie et en Asie centrale. Une étude plus approfondie des séquences sédimentaires lacustres et des données temporelles sont encore nécessaires pour mieux contraindre l'histoire de la sédimentation holocène dans le sud de la Mongolie et en Asie centrale

Late Holocene Peatland Evolution in Terelj and Tuul Rivers Drainage Basins in the Khentii Mountain Range of Northeastern Mongolia

This study reviews the late Holocene peatlands in Terelj River and Tuul River drainage basins in the Khentii (Khentii has been misspelled as Khentey (or Hentey) and Khentei (or Hentei) in many publications. The Khentii is the right English translation from Mongolian Xэнmuй) Mountain Range of northeastern Mongolia. The peatlands were examined through their physical and chemical properties, diatom assemblages, and radiocarbon dating. In the Terelj River basin, the high contents of organic matter and biogenic silica and the dominant benthic diatom assemblages such as Eunotia praerupta, Pinnularia borealis, and Navicula mutica in the peat deposits indicate the warm and humid climates in the late Holocene. The high accretion rate of 0.97 mm/yr in the peatland records the intensive erosion in the surrounding landscape and deposition in the peatland due to increased precipitation and runoff in the humid climate since 0.5 cal. ka BP. In the Tuul River basin, the high content of mineral fractions and diatom assemblages dominated by benthic species Cymbella proxima, Encyonema silesiacum, and planktonic species Cyclotella ocellata in the peat deposits show a transition from humid to arid climates at 0.9 cal. ka BP. The accretion rate of 0.56 mm/yr in the peatland on the paleo-floodplain indicates strengthened erosion in the peatland over the past ~1000 years. This study in the southern Khentii Mountain Range provides new descriptive insights to extend the underestimated Mongolia’s peat studies, and it would be a useful proof-of-concept study for future detailed paleo-environmental analyses

Holocene Landform Evolution of Lake Khuvsgul basin, Mongolia

This study presents landform evolution within the lake Khuvsgul basin (also known as Hovsgol and Khubsugul) in northern Mongolia during the Holocene: beach bars, spits, lake terraces and fluvial processes (sediment and organic components) in the River Borsog which flows into the lake. Lake Borsog, an eastern former bay of Lake Khuvsgul, separated from Lake Khuvsgul during its post-glacial transgression and possesses high-resolution record of the Holocene landscape evolution. Sedimentary sequence of a 13 m long core BB03 from Lake Borsog shows three short-term events of higher-sedimentation rate at 7.4-7.1 ka cal. BP, 4.8-4.5 ka cal. BP and 1.0-0.9 ka cal. BP, which are possibly related to drops in lake level, reductions of lake area, progradation of the delta of the Borsog River and erosion of the exposed lake shores. The drops in the lake level match the previously documented drops of the level of Lake Khuvsgul at ca. 7.2-7.0, 4.5-4.1 and 2.1-0.5 ka cal. BP, suggesting continued mutually-related and climatically-controlled evolutions of both lakes after their separation.Cette étude présente l'évolution de l'environnement du lac Khuvsgul (également connu sous les noms de Hovsgol et Khubsugul) dans le nord de la Mongolie durant l'Holocène : barres de plage et flèches littorales, terrasses lacustres et processus fluviatiles (composantes sédimentaires et organiques) de la rivière Borsog qui se jette dans le lac. Le lac Borsog, ancienne baie orientale du lac Khuvsgul, en fut séparée lors de sa trangression post-glaciaire. Il offre un enregistrement à haute résolution de l'évolution holocène du paysage. Une séquence sédimentaire de 13 m de profondeur issue du sondage BB03 dans le lac Borsog montre trois phases de forte sédimentation et de courte durée à 7,4-7,1 ka cal. BP, 4,8-4,5 cal. BP et 1,0-0,9 cal. BP, qu'il est possible de relier à des abaissements du niveau du lac, des réductions de sa surface, à la progradation du delta de la rivière Borsog et à l'érosion des rivages exposés du lac. Les abaissements de niveau du lac font écho à ceux déjà enregistrés sur le lac Khuvsgul à 7,2-7,0, 4,5-4,1 et 2,1-0,2 ka cal. BP., suggérant une interrelation et un contrôle climatique continu de l'évolution des deux lacs après leur séparation

Modeling permafrost distribution over the river basins of Mongolia using remote sensing and analytical approaches

The spatial distribution of permafrost and associated mean annual ground temperature (MAGT) and active layer thickness (ALT) are crucial data for hydrological studies. In this paper, we present the current state of knowledge on the spatial distribution of the permafrost properties of 29 river basins in Mongolia. The MAGT and ALT values are estimated by applying TTOP and Kudryavtsev methods. The main input of both methods is the spatially distributed surface temperature. We used the 8-day land surface temperature (LST) data from the day- and night-time Aqua and Terra images of the moderate resolution imaging spectroradiometer (MODIS). The gaps of the MODIS LST data were filled by spatial interpolation. Next, an LST model was developed based on 34 observational borehole data using a panel regression analysis (Baltagi, Econometric analysis of panel data, 3 edn, Wiley, New York, 2005). The model was applied for the whole country and covered the period from August 2012 to August 2013. The results show that the permafrost covers 26.3% of the country. The average MAGT and ALT for the permafrost region is − 1.6 °C and 3.1 m, respectively. The MAGT above -2 °C (warm permafrost) covers approximately 67% of the total permafrost area. The permafrost area and distribution in cold and warm permafrost varies highly over the country, in particular in regions where the river network is highly developed. High surface temperatures associated with climate change would result in changes of permafrost conditions, and, thus, would impact the surface water availability in these regions. The data on permafrost conditions presented in this paper can be used for further research on changes in the hydrological conditions of Mongolia

Glacial geomorphology of the Altai and Western Sayan Mountains, Central Asia

In this article, we present a map of the glacial geomorphology of the Altai andWestern Sayan Mountains, covering an area of almost 600,000 km2. Although numerous studies provide evidence for restricted Pleistocene glaciations in this area, others have hypothesized the past existence of an extensive ice sheet. To provide a framework for accurate glacial reconstructions of the Altai and Western Sayan Mountains, we present a map at a scale of 1:1,000,000 based on a mapping from 30 m resolution ASTER DEM and 15 m/30 mresolution Landsat ETM+ satellite imagery. Four landform classes have been mapped: marginal moraines, glacial lineations, hummocky terrain, and glacial valleys. Our mapping reveals an abundance of glacial erosional and depositional landforms. The distribution of these glacial landforms indicates that the Altai and Western Sayan Mountains have experienced predominantly alpine-style glaciations, with some small ice caps centred on the higher mountain peaks. Large marginal moraine complexes mark glacial advances in intermontane basins. By tracing the outer limits of present-day glaciers, glacial valleys, and moraines, we estimate that the past glacier coverage have totalled to 65,000 km2 (10.9% of the mapped area), whereas present-day glacier coverage totals only 1300 km2 (0.2% of the mapped area). This demonstrates the usefulness of remote sensing techniques for mapping the glacial geomorphology in remote mountain areas and for quantifying the past glacier dimensions. The glacial geomorphological map presented here will be used for further detailed reconstructions of the paleoglaciology and paleoclimate of the region.Central Asia Paleoglaciology Project (CAPP

Timing and dynamics of glaciation in the Ikh Turgen Mountains, Altai region, High Asia

Spanning the northern sector of High Asia, the Altai region contains a rich landform record of glaciation. We report the extent, chronologies, and dynamics of two paleoglaciers on opposite flanks of the Ikh Turgen mountains (In Russian: Chikhacheva Range), straddling the border between Russia and Mongolia, using a combination of remote sensing-based glacial geomorphological mapping, 10Be surface exposure dating, and geomorphometric analysis. On the eastern side (Mongolia), the Turgen-Asgat paleoglacier, with its potential for developing a large accumulation area (∼257 km2), expanded 40 km down valley, and mean ages from a latero-frontal moraine indicate deglaciation during marine oxygen isotope stage (MIS) 3 (45.1 ± 1.8 ka, n = 4) and MIS 2 (22.8 ± 3.3 ka, n = 5). These minimum age constraints are consistent with other 10Be glacial chronologies and paleoclimate records from the region, which indicates glacier culmination during cold and wet conditions coinciding with MIS 3 (piedmont-style glaciation; inferred for a few sites across the region) and glacier culmination during cold and dry conditions coinciding with MIS 2 (mainly valley-style glaciation; inferred from several sites across the region). On the western side (Russia), the Boguty paleoglacier had a smaller accumulation area (∼222 km2), and advanced 30 km down valley across a low gradient forefield. Surface exposure ages from two moraine complexes on this side of the mountains exhibit wide scatter (∼14–53 ka, n = 8), making paleoclimate inferences and comparison to other proxies difficult. Ice surface profile reconstructions imply that the two paleoglaciers likely shared an ice divide