10 research outputs found
Study of Tuvans in Xinjiang: an annalistic review
No full textAuthor presents an array of studies in ethnic history, language, folklore, material and intellectual culture of Tuvans in Xinjiang Uyghur Autonomous Region of China that had been conducted by the Russian scientists during the past 20 years
Integrated Geophysical and geochimestry investigations at the Ondurnaran lode gold deposit
No full textUndurnaran deposit (1090 34’ 23.1 E, 440 40’ 51.7” N) locates in Saikhandulaan soum of Dornogovi province. Detailed geological prospecting work using scale of 1:10000 was carried out from 2009 up to 2011. Mineralization of the Undurnaran deposit is related to Upper Carboniferous Gunbayan formation volcanogenic-sedimentary rocks and Late Carboniferous Mandakh complex diorite. Microquartzite, quartzite and carbonate veins contain gold micrograins. Sometimes gold is included in meta-andesite and diorite. Alteration zone with a little arched form directs from southeast to northward. Size of the alteration zone is ranging from 20 meters up to 30 meters in wide and its length continues approximately 500 meters. Gold grade reaches approximately 3.5-4.5 g/t within mineralization zone. Gold mineralization is mainly controlled by Saikhandulaan abyssal fault which continues from northeast to southwest
Impact of faulting on the depression morphology of Ulaagchinii Khar Lake in Mongolia
No full textThe geomorphology of the Ulaagchinii Khar Lake depression is predominantly governed by tectonic faulting. Morphometric analysis identifies a distinct network of orthogonal faults that are prominently manifested in both topographic and bathymetric patterns. These fault systems primarily trend northwest-southeast and north-south, intersecting near the lake’s central region. This central zone is characterized by pronounced linear formations and abrupt shifts in elevation, as depicted in isobath profiles, indicative of tectonic subsidence along fault zones. The lake depression exhibits strong tectonic control, supported by a high hypsometric integral (HI=0.91) and a notably elongated basin shape index (Bs=2.81). Further evidence for a tectonic origin includes a major east-west oriented fault extending 40.8 km with a steep inclination of 35°, and a vertical relief energy of 274 m. Significant depth variations, reaching up to 47 m in the lake’s western sector, further reinforce the influence of faulting on its morphological configuration. Complementary geomagnetic anomaly data also correspond with these structural features, affirming the presence of active tectonic processes within the depression. The orthogonal fault systems have not only shaped the physical structure of the depression but have also influenced its hydrological regime by enhancing groundwater infiltration, thereby contributing to the lake’s freshwater characteristics. This research underscores that the current morphology and hydrological compartmentalization of Ulaagchinii Khar Lake are the result of an interplay between tectonically controlled fault activity and Late Quaternary dune deposition
Effect of coal type on aerosol optical properties at Ulaanbaatar city
No full textIn this study, seasonal characteristics of aerosol optical properties at Ulaanbaatar station of the international network of SKYNET are investigated using ground-based skyradiometer from the years extending from 2017 to 2023. The aerosol optical thickness (AOT) at 500nm wavelength and Angstrom exponent (AE) were determined in winter to evaluate the decrease in air pollution in Ulaanbaatar since implementing the government\u27s decision to use coal briquettes for household heating. During the study period, the monthly mean AOT at 500nm varied throughout the year, with the maximum value of 0.178±0.004 obtained in winter due to households burning large amounts of biomass, and the highest AOT (0.183) was obtained in February. The mean AOT was 0.21 in the winter of 2017-2019, which decreased by 15 per cent to 0.18 in the winter of 2019-2023
Effect of coal type on aerosol optical properties at Ulaanbaatar city
No full textIn this study, seasonal characteristics of aerosol optical properties at Ulaanbaatar station of the international network of SKYNET are investigated using ground-based skyradiometer from the years extending from 2017 to 2023. The aerosol optical thickness (AOT) at 500nm wavelength and Angstrom exponent (AE) were determined in winter to evaluate the decrease in air pollution in Ulaanbaatar since implementing the government's decision to use coal briquettes for household heating. During the study period, the monthly mean AOT at 500nm varied throughout the year, with the maximum value of 0.178±0.004 obtained in winter due to households burning large amounts of biomass, and the highest AOT (0.183) was obtained in February. The mean AOT was 0.21 in the winter of 2017-2019, which decreased by 15 per cent to 0.18 in the winter of 2019-2023
Tectonic geomorphology of the lake depressions in the Mongolian Altai mountains, western Mongolia
No full textThis study explores the tectonic geomorphology of lake depressions in the Mongolian Altai Mountains (MAM), focusing on three prominent lakes: Tolbo, Achit, and Uureg. These lakes are situated within tectonically active zones in the westernmost part of Mongolia, providing valuable insights into the interplay between geological processes and geomorphological evolution. The study investigates the structural characteristics and faults influencing lake depressions, utilizing satellite imagery, morphometric analysis, and geomorphological criteria interpretation. The morphometric analysis reveals significantly high HI (%) values for the Uureg, Achit, and Tolbo lake depressions, suggesting active tectonic movements in these regions. Additionally, the Smf, Bs, RSl, and Re indices support the evidence of ongoing tectonic processes. Since the northern MAM are located within a transpressional stress regime, the associated basins are expected to reflect this tectonic setting. Accordingly, all intermontane basins in the region are characterized as half-ramp, remnant low, or ramp basins. Each depression is shaped by different fault regimes, including thrust, strike-slip, and tilted thrust faults. These depressions are controlled by neotectonic processes associated with the Indian–Eurasian plate collision. Their dynamic nature underscores their significance as key tectonic features in the MAM. This case study deepens our understanding of the dynamic interplay between tectonics and lake depression formation in seismically active regions. It contributes valuable insights into the geomorphological evolution of mountainous landscapes
Mesozoic–Tertiary exhumation history of the Altai Mountains, northern Xinjiang, China: New constraints from apatite fission track data
No full textThis study uses apatite fission track (FT) analysis to constrain the exhumation history of bedrock samples collected from the Altai Mountains in northern Xinjiang, China. Samples were collected as transects across the main structures related to Palaeozoic crustal accretion events. FT results and modeling identify three stages in sample cooling history spanning the Mesozoic and Tertiary. Stage one records rapid cooling to the low temperature part of the fission track partial annealing zone circa 70 ± 10 °C. Stage two, records a period of relative stability with little if any cooling taking place between 75 and 25–20 Ma suggesting the Altai region had been reduced to an area of low relief. Support for this can be found in the adjacent Junngar Basin that received little if any sediment during this interval. Final stage cooling took place in the Miocene at an accelerated rate bringing the sampled rocks to the Earth's surface. This last stage, linked to the far field effects of the Himalayan collision, most likely generated the surface uplift and relief that define the present-day Altai Mountains
Great Jurassic thrust sheets in Beishan (North Mountains) Gobi areas of China and southern Mongolia
No full textJurassic thrust sheets with minimum displacements of 120-180 km have been discovered within the 'Hercynian-Indosinian' orogenic belt of the Beishan of China and south Gobi area. The thrusts strike E-W, extend over 1200 km in length, and carried Meso-Proterozoic massive dolomitic limestones over strata ranging from Neo-Proterozoic (Cryogenian and Terminal Proterozoic) to Lower-Middle Jurassic. Slip-linear plots based on kinematic indicators, such as slickenlines and groove lineations, fiber lineations and 'drag folds' adjacent to the fault surface. vergence of folds and imbricated thrusts in the upper plate, indicate northward movement in the Beishan area to the west and southward movement in the South Gobi area to the east. The two major thrust faults, the Beishan thrust and South Gobi thrust, are presumably separated by a major tear fault, the Ruo Shui fault. The major thrust faults were later deformed into a series of E-W antiforms and synforms and the sheets are separated, due to erosion, into a number of klippen mainly located on synforms of the major faults. The Ar-40-Ar-39 metamorphic core complex, which is a result of an extensional event that postdates the thrust event, yields an Ar-40-Ar-39 plateau age of 155.1 +/- 10 Ma, and Rb-Sr isochron age of 153 +/- 6.2 Ma. The thrust sheets formed during the late Middle Jurassic, long after the closure of any oceans in the study area previously reported for this region, and are ascribed to a phase of intracontinental deformation. The closing of the Jurassic Tethys or retroarc deformation behind an active continental margin at the southern edge of Asia, prior to the Tethyan collision, or/and the closing of Mongolo-Okhotsk oceans might be responsible for this event. Copyright (C) 1996 Elsevier Science LtdGeosciences, MultidisciplinarySCI(E)EI66ARTICLE91111-11261
Global patterns in monthly activity of influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus: a systematic analysis
No full textAbstract: Background Influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus are the most common viruses associated with acute lower respiratory infections in young children (= 65 years). A global report of the monthly activity of these viruses is needed to inform public health strategies and programmes for their control. Methods In this systematic analysis, we compiled data from a systematic literature review of studies published between Jan 1, 2000, and Dec 31, 2017; online datasets; and unpublished research data. Studies were eligible for inclusion if they reported laboratory-confirmed incidence data of human infection of influenza virus, respiratory syncytial virus, parainfluenza virus, or metapneumovirus, or a combination of these, for at least 12 consecutive months (or 52 weeks equivalent); stable testing practice throughout all years reported; virus results among residents in well-defined geographical locations; and aggregated virus results at least on a monthly basis. Data were extracted through a three-stage process, from which we calculated monthly annual average percentage (AAP) as the relative strength of virus activity. We defined duration of epidemics as the minimum number of months to account for 75% of annual positive samples, with each component month defined as an epidemic month. Furthermore, we modelled monthly AAP of influenza virus and respiratory syncytial virus using site-specific temperature and relative humidity for the prediction of local average epidemic months. We also predicted global epidemic months of influenza virus and respiratory syncytial virus on a 5 degrees by 5 degrees grid. The systematic review in this study is registered with PROSPERO, number CRD42018091628. Findings We initally identified 37 335 eligible studies. Of 21 065 studies remaining after exclusion of duplicates, 1081 full-text articles were assessed for eligibility, of which 185 were identified as eligible. We included 246 sites for influenza virus, 183 sites for respiratory syncytial virus, 83 sites for parainfluenza virus, and 65 sites for metapneumovirus. Influenza virus had clear seasonal epidemics in winter months in most temperate sites but timing of epidemics was more variable and less seasonal with decreasing distance from the equator. Unlike influenza virus, respiratory syncytial virus had clear seasonal epidemics in both temperate and tropical regions, starting in late summer months in the tropics of each hemisphere, reaching most temperate sites in winter months. In most temperate sites, influenza virus epidemics occurred later than respiratory syncytial virus (by 0.3 months [95% CI -0.3 to 0.9]) while no clear temporal order was observed in the tropics. Parainfluenza virus epidemics were found mostly in spring and early summer months in each hemisphere. Metapneumovirus epidemics occurred in late winter and spring in most temperate sites but the timing of epidemics was more diverse in the tropics. Influenza virus epidemics had shorter duration (3.8 months [3.6 to 4.0]) in temperate sites and longer duration (5.2 months [4.9 to 5.5]) in the tropics. Duration of epidemics was similar across all sites for respiratory syncytial virus (4.6 months [4.3 to 4.8]), as it was for metapneumovirus (4.8 months [4.4 to 5.1]). By comparison, parainfluenza virus had longer duration of epidemics (6.3 months [6.0 to 6.7]). Our model had good predictability in the average epidemic months of influenza virus in temperate regions and respiratory syncytial virus in both temperate and tropical regions. Through leave-one-out cross validation, the overall prediction error in the onset of epidemics was within 1 month (influenza virus -0.2 months [-0.6 to 0.1]; respiratory syncytial virus 0.1 months [-0.2 to 0.4]). Interpretation This study is the first to provide global representations of month-by-month activity of influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus. Our model is helpful in predicting the local onset month of influenza virus and respiratory syncytial virus epidemics. The seasonality information has important implications for health services planning, the timing of respiratory syncytial virus passive prophylaxis, and the strategy of influenza virus and future respiratory syncytial virus vaccination. Copyright (C) 2019 The Author(s). Published by Elsevier Ltd
Global patterns in monthly activity of influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus: a systematic analysis
No full textBackground Influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus are the most common viruses associated with acute lower respiratory infections in young children (= 65 years). A global report of the monthly activity of these viruses is needed to inform public health strategies and programmes for their control.Methods In this systematic analysis, we compiled data from a systematic literature review of studies published between Jan 1, 2000, and Dec 31, 2017; online datasets; and unpublished research data. Studies were eligible for inclusion if they reported laboratory-confirmed incidence data of human infection of influenza virus, respiratory syncytial virus, parainfluenza virus, or metapneumovirus, or a combination of these, for at least 12 consecutive months (or 52 weeks equivalent); stable testing practice throughout all years reported; virus results among residents in well-defined geographical locations; and aggregated virus results at least on a monthly basis. Data were extracted through a three-stage process, from which we calculated monthly annual average percentage (AAP) as the relative strength of virus activity. We defined duration of epidemics as the minimum number of months to account for 75% of annual positive samples, with each component month defined as an epidemic month. Furthermore, we modelled monthly AAP of influenza virus and respiratory syncytial virus using site-specific temperature and relative humidity for the prediction of local average epidemic months. We also predicted global epidemic months of influenza virus and respiratory syncytial virus on a 5 degrees by 5 degrees grid. The systematic review in this study is registered with PROSPERO, number CRD42018091628.Findings We initally identified 37 335 eligible studies. Of 21 065 studies remaining after exclusion of duplicates, 1081 full-text articles were assessed for eligibility, of which 185 were identified as eligible. We included 246 sites for influenza virus, 183 sites for respiratory syncytial virus, 83 sites for parainfluenza virus, and 65 sites for metapneumovirus. Influenza virus had clear seasonal epidemics in winter months in most temperate sites but timing of epidemics was more variable and less seasonal with decreasing distance from the equator. Unlike influenza virus, respiratory syncytial virus had clear seasonal epidemics in both temperate and tropical regions, starting in late summer months in the tropics of each hemisphere, reaching most temperate sites in winter months. In most temperate sites, influenza virus epidemics occurred later than respiratory syncytial virus (by 0.3 months [95% CI -0.3 to 0.9]) while no clear temporal order was observed in the tropics. Parainfluenza virus epidemics were found mostly in spring and early summer months in each hemisphere. Metapneumovirus epidemics occurred in late winter and spring in most temperate sites but the timing of epidemics was more diverse in the tropics. Influenza virus epidemics had shorter duration (3.8 months [3.6 to 4.0]) in temperate sites and longer duration (5.2 months [4.9 to 5.5]) in the tropics. Duration of epidemics was similar across all sites for respiratory syncytial virus (4.6 months [4.3 to 4.8]), as it was for metapneumovirus (4.8 months [4.4 to 5.1]). By comparison, parainfluenza virus had longer duration of epidemics (6.3 months [6.0 to 6.7]). Our model had good predictability in the average epidemic months of influenza virus in temperate regions and respiratory syncytial virus in both temperate and tropical regions. Through leave-one-out cross validation, the overall prediction error in the onset of epidemics was within 1 month (influenza virus -0.2 months [-0.6 to 0.1]; respiratory syncytial virus 0.1 months [-0.2 to 0.4]).Interpretation This study is the first to provide global representations of month-by-month activity of influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus. Our model is helpful in predicting the local onset month of influenza virus and respiratory syncytial virus epidemics. The seasonality information has important implications for health services planning, the timing of respiratory syncytial virus passive prophylaxis, and the strategy of influenza virus and future respiratory syncytial virus vaccination. Copyright (C) 2019 The Author(s). Published by Elsevier Ltd
