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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.
T his study aims to reconstruct paleoclimate change in eastern Mongolia inferred from sedimentological and geochronological records from Lake Yakhi in the drainage basin of the Pacific Ocean. In a context of the study goal the hydroclimatic fluctuation in eastern Mongolia resulted from Lake Yakhi is presented here. Result from changes in lake area of Lake Yakhi shows it decreased from 79.72 km2 in 1970 to 53.76 km2 in 1986 and 35.03 km2 in 2018. The hydraulic dynamics and field observation show that Lake Yakhi is shifting into a playa lake. For shrinking Lake Yakhi, shifting toward a playa lake is directly related to the global warming, i.e., it implies the lake is extremely sensitive to climate change in the late Holocene. This coincides with those conditions of large lakes in the Govi region in southern Mongolia (Orkhonselenge et al., 2018). The major element compositions of the lake sediments show that the core Y18-1 is dominated by SiO2, Al2O3, K2O and Na2O, while the cores Y18-2 and Y18-3 largely contain SiO2, Al2O3, CaO and Fe2O3. In addition to the dominant semimetal and transition metal, presence of oxides of alkali earth metals in the core Y18-1 and of alkaline earth metals in the cores Y18-2 and Y18-3 show a derivation of intermediate sedimentary and volcanic rocks in the drainage basin of Lake Yakhi. This coincides with the tectonostratigraphic terrane structure of the cratonal clastic sedimentary rocks (Badarch et al., 2002) in the Lake Yakhi area. Further detail geomorphological and geochronological records from Lake Yakhi would not review only the hydrogeochemical evolution, but the paleoclimate changes in eastern Mongolia. Leading the dates would precisely determine the paleohydroclimatic fluctuations in eastern Mongolia.
This study reconstructs the Late Quaternary paleoclimate history of Mongolia based on multiple-proxy sedimentary records from lakes in Mongolia. Mongolia archives important paleoclimatic records in Central Asia, because it is located in the center of the Eurasian continent. Mongolia has an extremely dry extra-continental climate developing under the interaction of the Siberian high- and Asian low-pressure cells, and the Westerlies, which modulated by the North Atlantic Oscillations. Despite the importance of paleoenvironmental changes in Mongolia for our understanding of large-scale regional paleoclimatic changes, the temporal and spatial paleoenvironmental sequences within Mongolia itself have not been established well (An et al., 2008). To date, studies on lake in Mongolia have only focused on lake genesis, lake level fluctuations, morphometric evolution of lake basin and chemical composition of lake water, and not on any important implications for paleoenvironmental history from lacustrine sediments. The paleoclimatic records show that in the Late Pleistocene, the cold and dry and cold and wet climates dominated western and northern Mongolia, respectively. In the Holocene, climates in Mongolia differ from region to region depending on each landscape driven by local atmospheric circulations.
Тус судалгааны ажлын хүрээнд Хэнтий аймгийн Дэлгэрхаан сумын нут агт орших Тосон болон Бүрд нуурын устай талбайн өөрчлөлтийг (NDWI) тодорхойлж, усны найрлагыг тогтоож, бохирдлын зэргийг тодорхойлов. Тосон нуур нь олон төрлийн эрдэсжилттэй давстай нуур учир эмчилгээнд ашигладаг төдийгүй 1969 оноос Тосон нуурын дэргэдэх Аваргын рашаанд түшиглэн “Аварга Тосон” амралт сувиллын газар бий болжээ. Сүүлийн жилүүдэд амрагчдын тоо ихсэж, нутгийн удирдлагуудын хараа хяналт багассанаар тус нуур нь бохирдож эхэлсэн байна. Иймд Тосон, Бүрд нуур болон нуурын эргэн тойрон дахь бохирдол ямар түвшинд байгаа, бохирдлоос шалтгаалан талбайн хэмжээ өөрчлөгдөж байгаа эсэх болон бохирдолд нөлөөлөгч хүчин зүйлсүүд нууруудад ямар нөлөө үзүүлж байгааг шинжлэх ухааны үндэслэлтэйгээр тогтооход судалгааны ажлын зорилго оршино. 2016 оны 8 сард Тосон, Бүрд нуурын уснаас тус тус нэг нэг дээж авч дээж бүрт химийн задлан шинжилгээ хийж найрлагыг тодорхойлсон. Тосон, Бүрд нууруудын устай талбайн хорогдлыг Landsat хиймэл дагуулын сансрын зургийг ашиглан AcgGis 10.4 програм дээр боловсруулалт хийж 2000 оноос хойш нууруудын талбай хорогдож орчны уст цэгүүд тасарсныг тогтоосон. Судалгааны үр дүнд нуурын усанд хийсэн геохимийн шинжилгээгээр Тосон, Бүрд нуурууд маш их бохирдолтой гэдэг нь тогтоогдсон ба бохирдлын шалтгаан нь уур амьсгалын хуурайшилт болон хүмүүсий н буруутай үйл ажиллагаа зэрэг юм.
This study aims to reconstruct paleoclimatic changes in eastern Mongolia inferred from lacustrine sedimentation in Lake Yakhi, being included in a drainage basin of the Pacific Ocean, covering analytic works of sedimentation rate and dating. In a frame of the study goal the preliminary results are presented here. Lake Yakhi, having an inflow Gal River, is a mineral lake elevated at 670 m a.s.l. in a tectonically originated depression (Tserensodnom, 1971). Three cores of lake sediments were collected and major element compositions of the lake sediments were analyzed at the Division of Radionuclide Analysis, the Central Geological Laboratory in Mongolia using the Axios Max X ray fluorescence (XRF) spectrophotometer. The preliminary result presents that cor e Y18 1 is enriched with SiO2, Al2O3, Na2O and K2O, and cores Y18 2 and Y18 3 contain higher contents of SiO2, Al2O3, CaO and Fe2O3. The core Y18 1 is dominated by the presence of oxides of alkali earth metals due to its geographical location in the mouth of inflow, however the cores Y18 2 and Y18 3 show a derivation of intermediate volcanic and volcaniclastic rocks indicating sedimentary peculiarity in central parts of Lake Yakhi. This coincides with the tectonostratigraphic terrane structure (Badarch et a l., 2002) of the cratonal non marine clastic sedimentary rocks distributed in the Lake Yakhi area. More investigations with detail geochemical and geochronological analyses are needed from Lake Yakhi and its inflow to review the hydrogeochemical evolution and paleoclimatic changes in eastern Mongolia.
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 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.
Spanning a northern sector of continental Central Asia, the Altai Mountains contains a rich record of glaciation. Still,therearefewstudiesreconstructingthedynamicsandtimingofformerglaciersintheregion.Weinvestigated the glacial history of two paleoglaciers, residing on opposite flanks of the Ikh-Turgen Mountains, straddling the border between Russia and Mongolia, using a combination of remote sensing, terrain analysis, field investigations and 10Be surface exposure dating. On the eastern side (Mongolia) of Ikh-Turgen, mean arithmetic exposure ages from a latero-frontal moraine indicate deglaciation during Marine Isotope Stage (MIS) 3 (45.3±2.7 ka, n=5) and MIS 2 (22.8±3.5 ka, n=4). These age constraints are consistent with other paleoclimate records from the region. Cold and wet conditions during early MIS 2 and MIS 3 likely triggered glacier expansions but the transition to a drier climate resulted in more restricted paleoglacier extents during MIS 2 than during MIS 3. Well-constrained MIS 3 glacier expansions in Central Asia are rare. We therefore speculate whether the climatic and topographic setting of the eastern flank of the Ikh-Turgen Mountains has allowed for a better preservation potential of these moraines, making them more suitable for surface exposure dating than other regions of Central Asia, or whether MIS 3 moraines occur more widespread but await to be robustly dated. Corresponding surface exposure ages, from the western side (Russia) of Ikh-Turgen, indicate a more complex story with large scatter (∼14–53 ka, n=8) making paleoclimate inference and comparison to other proxies difficult. Owing to their proximity, the paleoglaciers of Ikh-Turgen, should have responded similarly to climate forcing, yet they exhibited distinctly different behaviours. We discuss the connection between paleoglacier dynamics and style of moraine deposition and propose that differences in glacier dynamics caused differences in ice-marginal depositional environments, explaining the scatter in exposure ages on the western side. This study shows the importance of style of deposition in chronological studies of glacial landforms and demonstrates that certain moraine types can be difficult to use as paleoclimate proxies.
This study aims to reconstruct paleoclimatic changes in southern Mongolia lying in intercontinental Central Asia based on geomorphological, geochemical and geochronological methods applied to the sediments of the Tsagaan Suvarga. Stratigraphy of the Tsagaan Suvarga is bounded by a paleochannel in the northeast and low hills in the south, and extends from west to east. Physical properties of the stratigraphy are varied with grain size and shape of the sediments. Totally, 19 samples (TS15-1 – TS15-18) were taken from the stratigraphy of the Tsagaan Suvarga. Colors of the sediments transform from brown and yellowish brown to reddish in the upper part, from reddish to green in the middle part, and from green to brown in the lower part, respectively. Grain size shows that sediments consist of fine gravels, coarse sands, fine gravels, coarse sands, fines sands and clays along a transection from upper part to lower part. Dating of the sediments using radiocarbon (14C) shows that sediments TS15-05 and TS15-09 were deposited 790±20 and 8360±30 yr cal. BP, respectively. Results from the stratigraphy of the Tsagaan Suvarga indicate three paleoclimatic periods along a transection from lower to upper parts: А (Early Holocene or 8360±30 yr cal. BP), B (Middle Holocene or between 8360±30 and 790±20 yr cal. BP), and C (Late Holocene or since 790±20 yr cal. BP). Geochemical analyses show the sediments of the Tsagaan Suvarga deposited in the paleoclimatic cycles of wet and warm with ratios of Fe2O3/NaO, and Rb/Sr and Sr/Cu, respectively.
ABSTRACT - This study considers sedimentological feature in Lake Ulaan, lying in the most eastern part of the Valley of Lakes, and reconstructs Holocene paleoclimatic changes of Gobi region in Mongolia. In Oct, 2015 four sediments (UN15-1a,b and UN15-2a,b) were sampled from 5 and 20 cm depths on two points in Lake Ulaan. These sediments were geochemically analyzed, and contents of oxides SiO2, TiO2, Al2O3, Fe2O3, CaO, MgO, Na2O, K2O, MnO and P2O5 and radiocarbon (14С) dating were determined in the sediments. Results show that sediments UN15-1b and UN15-2b of Lake Ulaan were deposited in middle Holocene (5969±30 yr cal. BP) and late Holocene (3397 ± 30 yr cal. BP), respectively. Chemical index of alteration indicates that weathering intensity is higher in the sediments UN15-1b and UN15-2b. This implies that humid climates dominated in the Gobi region of Mongolia between middle Holocene and late Holocene. Lower weathering intensity in the sediments UN15-1a and UN15-2a shows the presence of arid climates in the late Holocene.
The Bayan Zag succession (44º85’48’’N, 103º43’44’’E) is located at the height of 1249 m a.s.l. along the northern margin of the Gobi Desert in southern Mongolia. The Bayan Zag succession consists of moderate reddish orange sands with subordinate mudstone units and is more than 30 m thick. Although the Bayan Zag succession is geologically attractive site and provides paleoclimate history made fluvial and aeolian processes, it remains chronologically unconstrained despite the study by Dashzeveg et al. (2005). This study aims to reconstruct paleoclimate and paleoenvironmental changes in the Gobi Desert in southern Mongolia based on formation of the Bayan Zag succession. The field sampling was carried out in Oct, 2015 and bulk samples of 11 between BZ15-0 and BZ15-10 were transported to the Laboratory of Geochemistry & Geomorphology, National University of Mongolia where samples were subsampled for following analytic preparation: water content, loss of ignition, geochemical traces and 14C dating. Geochemical analyses indicate that there is no distinct pattern of spatial distribution of oxides from bottom to top along the succession, i.e., the oxides vary with large fluctuations for all samples. SiO2 and Al2O3 are dominant in all samples and some samples contain relatively high contents of CaO and loss of ignition. BZ15-4, BZ15-6 and BZ15-8 have higher chemical index of alteration (CIA) of 67% than those in other samples. Results of the 14C dating for the bulk sediments show the yellowish red sands BZ15-4 and the laminated gray mudstone lens BZ15-7 were deposited at 13250 cal yr BP and 10200 cal yr BP, respectively. The mudstone lens is expected as cross-bedded interval, occasionally exhibiting wind-ripple cross lamination during the Younger Dryas. This study infers that more dating of bottom units are thus needed to further support this result regarding the formation period of the succession and to reconstruct paleoclimate and paleoenvironmental changes in southern Mongolia. The study was supported by Asian Research Center (ARC), National University of Mongolia (grant ARC2016-09).
Алтан химэрлэг хурдас буюу салхин гарлын хурдсын физик, химийн шинжүүд нь палеогазарзүйн бүрэн дүүрэн мэдээг өөртөө агуулж байдаг. Монголын тэгш өндөрлөгийн Дөрөвдөгчийн үеийн уур амьсгалын өөрчлөлтүүдийн талаарх мэдээлэл бүрэн гүйцэд тогтоогдоогүй байгаа. Иймд энэхүү судалгаагаар Монголын орны хойд хэсгийн Дөрөвдөгчийн үеийн эртний уур амьсгалын өөрчлөлтийг илрүүлэхээр Алтанбулагийн хотгорт орших Баянтохойн хурдсын хуримтлалд давхарга зүйн судалгааг явуулсан болно. Монголын тэгш өндөрлөгийн хойд хэсэгт Дөрөвдөгчийн үед бүрэлдэн тогтсон хурдсын хуримтлалыг илрүүлж тухайн хурдсын хуримтлалын тогтоц, бүтэц, найрлага болон бүрэлдэн тогтоход нөлөөлсөн эртний уур амьсгалын нөхцөлийн харьцангуй өөрчлөлтийг тогтооход энэхүү судалгааны гол зорилго оршино. Тус судалгааны зорилгын хүрээнд (1) эолийн ландшафтаас хурдсын дээж авах, (2) хурдсын литологийн бүтэц, усны агууламж, органик материал, химийн элементүүдийн агууламж, ширхгийн хэлбэр, хэмжээ зэрэг хими, физик шинжийг тодорхойлох лабораторийн анализ хийх, (3) аналитик үр дүнд тулгуурлан эртний уур амьсгалын өөрчлөлтийг илрүүлж, бүс нутгийн үр дүнгүүдтэй харьцуулах зэрэг зорилтуудыг дэвшүүлсэн.
Монгол орны хээрийн бүсэд явагдаж ирсэн эртний уур амьсгалын өөрчлөлт, тэр дундаа Голоцены үеийн уур амьсгал хэрхэн өөрчлөгдөж байсан талаар галт уулын гаралтай Тэрхийн Цагаан нуур болон урсгал усны гаралтай Өгий нуур зэрэг нууруудын хурдсын хими болон физик шинжүүдээр төлөөлүүлэн судаллаа. 2011 онд Тэрхийн Цагаан нуураас 4 өрмийн хурдсын дээж, Өгий нуураас 5 өрмийн хурдсын дээжүүдийг тус тус авч, тэдгээр хурдсын дээжинд усны агууламж, органик материал, карбонат, биогарлын цахиур, эрдсийн агууламж зэрэг хими болон физик шинж чанарын анализ хийсэн. Хурдсын насны дүнг тэдгээр нууруудын хурдсанд өмнө нь хийгдсэн насны дүнгүүдийг гүнээр адилтган нэгтгэсэн болно. Ерөнхийдөө Монгол орны хээрийн бүс нь Голоцений эхэн үед чийглэг, дулаан, Голоцений дунд үед хуурай, дулаан, Голоцений сүүл үед чийглэг дулаан байсан нь энэхүү судалгаагаар тогтоогдож байна. Адил өргөргийн хээрийн бүсэд орших тэдгээр нуурууд дахь хурдсын шилжилт, хуримтлалыг харьцуулан үзэхэд уулын нуурыг төлөөлөх Тэрхийн Цагаан нуурын хувьд биогарлын цахиур болон органик материал илүү агуулснараа уулын нуурыг илтгэх байгаль-газарзүйн хүчин зүйлсийн онцлог шинжийг, харин талын нуурыг төлөөлөх Өгий нуурын хувьд карборнат болон эрдсийн агууламж давамгайлж байгаа нь хурдсын эрчимжилттэнд нөлөөлөх байгалийн саадаас ангид орших нуурын ай савын гадаргын хэлбэрийн тогтцын онцлог шинжийг тус тус харуулж байна.
Two atmospheric circulation systems, the mid-latitude Westerlies and the Asian monsoon, play key roles in northern-hemisphere climatic changes. However, the variability of the Westerlies in mid-latitude Asia and their relationship to the Asian summer and winter monsoon remain unclear. We examined the variations of the grain size and elemental composition from the 30 m long loess-paleosol succession in Shaamar area, northern Mongolia, which could be recorded the interplay of the Westerlies and Asian winter monsoon for the last 30 k.y. We then compared our results with the multi-proxy paleoclimate records (e.g., eolian grain sizes, lake levels, pollen assemblages) of the Asian summer and winter monsoon regions and the Westerlies affected region. According to the compiled data of the Wang and Feng (2013), the Holocene climatic variation patterns (mainly from lake levels and pollen records) in Asia are categorized into 4 characteristic regions, such as the Summer monsoon region (southern and northeastern China), Westerlies affected region (northwestern China), Winter monsoon region (southern Siberia), and Mixture of westerlies and winter monsoon affected region (Mongolia). Specifically, summer monsoon region is characterized by dry earliest Holocene (12-11 ka), humid early to middle Holocene (11-6 ka), and the moderate-humid late Holocene (last 6 ka), corresponding to the Northern hemisphere summer insolation changes. Westerlies affected region is characterized by dry early Holocene (12-8 ka) and humid middle to late Holocene (last 8 ka). Winter monsoon region is characterized by the humid early Holocene (12-8 ka) and dry middle to late Holocene (last 8 ka). On the other hand, Mongolian records (e.g., Lake Khuvsgul, Lake Gun Nuur) demonstrate humid early Holocene (12-9 ka), dry middle Holocene (9-5 ka), and humid late Holocene (last 5 ka), which seems mixture of westerlies and winter monsoon affected region. In contrast, Shamaar loess-paleosol succession record is characterized by the humid early Holocene (12-8 ka) and dry middle to late Holocene (last 8 ka), similar to the winter monsoon region of southern Siberia. Thus, it is suggested that the eolian sediment record in Shaamar could be affected more strongly by winter monsoon influence, although Shamaar section is located closely to the mixture of westerlies and winter monsoon affected region (e.g., Lake Khuvsgul and Lake Gun Nuur).
