Central Mongolia Research Articles

New findings of the female reproductive structures of Umaltolepis Krassilov and associated leaves of Pseudotorellia Florin in the Lower Cretaceous of Mongolia

Female reproductive structures of Umaltolepis are recorded in the Huhteeg (=Khukhtyk or Khukhteeg) Formation (Aptian–Albian) of the Baganuur coal mine (Central Mongolia) for the first time. These structures, preserved as dispersed cupules, are very similar to U. mongoliensis from the Tevshiin Govi Formation (Aptian–Albian) of the Tevshiin Govi locality in Central Mongolia. In the Baganuur locality, cupules of Umaltolepis were found in association with Pseudotorellia leaves, described here as a new species Pseudotorellia baganuriana, sp. nov. Leaves of this species are lanceolate, they are distinctive in the elongated epidermal cells of the adaxial leaf side similar across costal and intercostal zones, smooth periclinal walls of the ordinary epidermal cells, stomata arranged in bands on the abaxial leaf side, and the rare presence of small proximal papillae on some subsidiary cells of the stomata. Leaves of the new species differ considerably from the Pseudotorellia leaves associated with U. mongoliensis in the Tevshiin Govi locality. Despite this, we describe the Bagannur cupules as U. mongoliensis since we did not find any significant differences from the Tevshiin Govi material. Based on the updated species composition of Pseudotorellia in the Bureya Basin in Russia Far East (Nosova et al., 2021), we discuss here the type species Umaltolepis vachrameevii and associated leaves.

The genetic origin of Huns, Avars, and conquering Hungarians

Huns, Avars, and conquering Hungarians were migration-period nomadic tribal confederations that arrived in three successive waves in the Carpathian Basin between the 5th and 9th centuries. Based on the historical data, each of these groups are thought to have arrived from Asia, although their exact origin and relation to other ancient and modern populations have been debated. Recently, hundreds of ancient genomes were analyzed from Central Asia, Mongolia, and China, from which we aimed to identify putative source populations for the above-mentioned groups. In this study, we have sequenced 9 Hun, 143 Avar, and 113 Hungarian conquest period samples and identified three core populations, representing immigrants from each period with no recent European ancestry. Our results reveal that this "immigrant core" of both Huns and Avars likely originated in present day Mongolia, and their origin can be traced back to Xiongnus (Asian Huns), as suggested by several historians. On the other hand, the "immigrant core" of the conquering Hungarians derived from an earlier admixture of Mansis, early Sarmatians, and descendants of late Xiongnus. We have also shown that a common "proto-Ugric" gene pool appeared in the Bronze Age from the admixture of Mezhovskaya and Nganasan people, supporting genetic and linguistic data. In addition, we detected shared Hun-related ancestry in numerous Avar and Hungarian conquest period genetic outliers, indicating a genetic link between these successive nomadic groups. Aside from the immigrant core groups, we identified that the majority of the individuals from each period were local residents harboring "native European" ancestry.

Rayleigh wave tomography of central and southern Mongolia

The Mongolian Plateau located between the Siberian Craton and the North China Craton developed after multiple tectonic evolutions. It is proposed to be related to the far-field effect of the Indo-Asian collision in the Cenozoic. In this study, we inverted for high-resolution S wave velocity structures of Mongolia using Rayleigh wave tomography to constrain the plateau evolution. In particular, we obtained crustal and upper mantle seismic structures under Gobi Desert by combining Mongolian and Chinese datasets. The study reveals strong low-velocity anomalies in the lower crust immediately beneath the Hangay Dome, while the low-velocity zones are imaged beneath the dome margins in the upper mantle. The results imply that the Hangay Dome was formed by mantle upwelling into the crust from major faults following lithospheric delamination. Under the South Gobi Desert, we imaged several inclined high-velocity patches in the upper mantle, indicating the subducted slabs formed in the Paleozoic. The ancient structures in the upper mantle led the Indo-Asian collision to propagate further to southern Mongolia.

Carboniferous magmatic records of central Mongolia and its implications for the southward subduction of the Mongol–Okhotsk Ocean

ABSTRACT The now-extinct Palaeozoic to Mesozoic Mongol–Okhotsk Ocean is evidenced by the Mongol–Okhotsk suture, which stretches from central Mongolia to the Sea of Okhotsk. The geodynamics of southward subduction of the Mongol–Okhotsk Ocean remain enigmatic, especially whether the subduction began during the Carboniferous is highly debated. In this paper we present new zircon U–Pb ages and whole-rock geochemical data for the Carboniferous magmatic rocks in Northeast Mongolia. Zircon U–Pb dating indicates that the Adaatsag dacite, Northern Bayanjargalan gabbro-diorite and Bagannur pluton were emplaced at ca. 325 Ma, ca. 316 Ma, and ca. 305 Ma, respectively. Occurrences of these rocks together constitute a Carboniferous magmatic belt to the northwest of the Middle Gobi volcanic-plutonic belt. The ages of trapped zircon xenocrysts within the Bagannur pluton indicate that the basement of this magmatic belt is the Ereendavaa terrane. Geochemical analysis indicates that these magmatic rocks were formed in an Andean-type active margin, which provides robust evidence for southward subduction of the Mongol-Okhotsk Ocean during the Late Carboniferous. By combining all the available data, we argue that the onset of the Central Mongolia–Tsagaan Uul continental collision during the Late Carboniferous – Early Permian may have triggered the beginning of an active margin of the Mongol-Okhotsk Ocean along the northern coast of the Central Mongolia microcontinent.

Holocene Temperature Variations in Semi-Arid Central Mongolia—A Chronological and Sedimentological Perspective From a 7400-year Lake Sediment Record From the Khangai Mountains

Semi-arid Mongolia is a highly sensitive region to climate changes, but the region’s Holocene paleoclimatic evolution and its underlying forcing mechanisms have been the subject of much recent debate. Here we present a continuous 7.4 ka sediment record from the high-altitude Shireet Naiman Nuur (Nuur = lake) in the central Mongolian Khangai Mountains. We extensively dated the sediments and analyzed elemental composition and bulk isotopes for lake sediment characterization. Our results show that 14C-dating of bulk organic carbon and terrestrial macrofossils provide a robust and precise chronology for the past 7.4 ± 0.3 cal ka BP at Shireet Naiman Nuur and 14C-ages are mostly in stratigraphic order. The 14C-based chronology is confirmed by paleomagnetic secular variations, which resemble the predictions of spherical harmonic geomagnetic field models. The very good chronological control makes paleomagnetic secular variation stratigraphy a powerful tool for evaluating and refining regional 14C-chronologies when compared to the record presented here. The lake sediment proxies TOC, N, log (Ca/Ti) and log (Si/Ti) reveal increased lake primary productivity and high growing season temperatures from 7.4 ± 0.3 to 4.3 ± 0.2 cal ka BP, which is likely the result of stronger summer insolation and pronounced warming. Reduced summer insolation thereafter results in decreased productivity and low growing season temperatures at Shireet Naiman Nuur from 4.3 ± 0.3 cal ka BP until present day. The globally acknowledged 4.2 ka event also appears as a pronounced cooling event at Shireet Naiman Nuur, and additional abrupt cooling events occurred during minima in total solar irradiance at ∼3.4, 2.8 and 2.4 ka BP. Low lake primary productivity and growing season temperatures are likely the result of longer ice cover periods at the high-altitude (2,429 m a.s.l.) Shireet Naiman Nuur. This leads to shorter mixing periods of the lake water which is supported by more positive δ13CTOC because of increased incorporation of dissolved HCO3− by aquatic producers during periods of longer ice cover.

Characteristics and driving forces of vegetation dynamics in Inner Mongolia Autonomous Region from 1992 to 2018

Human activities related with construction and destruction are one of the important drivers for vegetation dynamics. Using remote sensing to explore the quantitative monitoring process and driving force of vegetation succession can well reveal the impacts of human activities on ecological background. Based on the vegetation formation group and vegetation formation scales, this study used the European Space Agency's annual land cover data and geo-information TUPU analysis to investigate vegetation succession direction, succession speed, and succession sequence in the Inner Mongolia from 1992 to 2018. The vegetation succession characteristics and its driving forces were then clarified. Results showed that vegetation structure changed dramatically with increasing vegetation and decreasing barren during the study period. The specific annual growth rate was cultivated land (353.10 km2) > grassland (243.92 km2) > forest (-16.22 km2) > shrubland (-120.37 km2) > desert (-556.31 km2). There was a trade-off between the area changes of adjacent grasslands, deserts, and shrublands. Vegetation succession presented a spatial pattern of vegetation expansion and desert reduction, with the succession hotspots concentrated in the West Liaohe River Plain, the desert-grassland junction of central Inner Mongolia, and along the Yellow River. The structure of vegetation succession sequence was complex with progressive succession and regressive succession intermixed. The retention rate of succession flow differed among different communities. Most of the succession flow was intercepted by the grassland and shrubland community of vegetation formation group and the grassland and cropland rainfed community of vegetation formation. The core driving forces of vegetation dynamic succession are agriculture and animal husbandry production, economic development level, population size, ecological engineering, and climate change. As a case study of plantsociology and landscape ecology, our results could provide scientific guidance for optimizing vegetation patterns and enhancing the spatial division and succession level of ecological measures.

Temporal and Spatial Changes in Evapotranspiration and Its Potential Driving Factors in Mongolia over the Past 20 Years

Evapotranspiration (ET) plays an important role in the study of regional long-term water cycles. The water cycle in Mongolia has been seriously affected by global warming and the intensification of human activities. A significant relationship exists between climate factors and ET. In this paper, the temporal and spatial fluctuations and stability of ET in Mongolia from 2001 to 2020 were studied by using MOD16A2 ET, MOD13A2 NDVI and the climate data of ERA5-Land. ET trends were analysed by using the Breaks for Additive Season and Trend (BFAST) software package, Theil–Sen median trend analysis, Mann–Kendall method and Hurst index. The correlations between ET and temperature (Tem), precipitation (Pre), net solar radiation (Nsr), soil moisture (Swl) and human activities were determined by partial correlation analysis and a geographic detector. In the past 20 years, ET increased significantly in 49.4% of Mongolia, and NDVI also showed a significant increasing trend. BFAST detected two mutation years. ET decreased rapidly from 2006 to 2007 and increased rapidly from 2015 to 2016. In addition to winter, the meteorological factor that had a significant positive impact on ET in the east and west was Pre, whereas the impact of Tem was more obvious in central Mongolia. In winter, Tem had a great impact on ET. In the vegetation growing season, the joint action of NDVI and Pre greatly positively contributed to ET. The geographical detector showed that the influence of annual human factors on ET was weakened by changes in NDVI and Pre. In the growing season, Tem and Nsr increased nonlinearly to ET, and other natural and human factors showed bivariate enhancement. These results will help to understand the responses of ET changes to natural factors and human activities in Mongolia and provide data support for future research on ET and the water cycle.

Transport Patterns and Potential Sources of Atmospheric Pollution during the XXIV Olympic Winter Games Period

The attainment of suitable ambient air quality standards is a matter of great concern for successfully hosting the XXIV Olympic Winter Games (OWG). Transport patterns and potential sources of pollutants in Zhangjiakou (ZJK) were investigated using pollutant monitoring datasets and a dispersion model. The PM2.5 concentration during February in ZJK has increased slightly (28%) from 2018 to 2021, mostly owing to the shift of main potential source regions of west-central Inner Mongolia and Mongolian areas (2015–18) to the North China Plain and northern Shanxi Province (NCPS) after 2018. Using CO as an indicator, the relative contributions of the different regions to the receptor site (ZJK) were evaluated based on the source-receptor-relationship method (SRR) and an emission inventory. We found that the relative contribution of pollutants from NCPS increased from 33% to 68% during 2019–21. Central Inner Mongolia (CIM) also has an important impact on ZJK under unfavorable weather conditions. This study demonstrated that the effect of pollution control measures in the NCPS and CIM should be strengthened to ensure that the air quality meets the standard during the XXIV OWG.

Two Phases of Metamorphism in the High-Pressure Schists in Central Inner Mongolia, China: Implications for the Tectonic Transition From Terminal Subduction of the Paleo-Asian Ocean to Continental Collision

High-pressure (HP) rocks exhumed from subduction zones usually record much warmer geotherms than numerical modelling results, as their peak mineral assemblages are always modified during the exhumation process. The decompressional metamorphic evolution of HP rocks should be considered carefully if using their P–T records to constrain the thermal structure of a subduction zone. The Ondor Sum Group, known as mélanges containing various high P/T metamorphic rocks in central Inner Mongolia, represents a fragment of subducted oceanic crust in the Early Paleozoic, However, the thermal structure of the subduction zone is unavailable due to an absence of exhumed HP rocks with P–T estimates. In this study, the HP schists were newly discovered in the Ondor Sum Group at Airgin Sum in the central Inner Mongolia. The HP schists include a garnet–phengite schist (sample EL01) and a garnet–amphibole schist (sample EL08). The petrography of these rocks and phase equilibrium modelling using THERMOCALC suggest two phases of metamorphism, both of which are characterized by clockwise P–T evolutions involving pre-peak prograde stage, peak-stage, and post-peak decompression stage. The peak P–T conditions of the early-phase metamorphism are constrained by P–T pseudosections to be ∼18 kbar/∼535°C for sample EL01 and 18 kbar/∼500°C for sample EL08. The peak P–T conditions of the late-phase metamorphism are constrained by P–T pseudosections to be ∼8 kbar/532°C in EL01 and ∼7.0 kbar/495°C in EL08. Available U–Pb data of zircons from the HP schists and a granodiorite vein using LA–ICP–MS constrain the timing of early-phase HP metamorphism in the early Paleozoic and the late-phase metamorphism supposed to be in the Devonian based on the previous reported ages. The peak P–T conditions for the early-phase metamorphism were high-P/T conditions with a thermal gradient of ∼8°C/km, pointing to a warm oceanic subduction. The overprinting late-phase metamorphism represents medium-P/T conditions with a geothermal gradient of 22–25°C/km, which we attribute to a collisional thickening process. As a result, we suggest that the HP schists in the Ondor Sum Group represent the terminal stage of subduction of the Paleo-Asian oceanic plate, and that the schists were involved in the continental collision after the closure of the Paleo-Asian Ocean in the Devonian.

Depositional environment and petroleum source rock potential of Mesozoic lacustrine sedimentary rocks in central Mongolia

Middle Jurassic (five samples from one location) and Lower Cretaceous (thirty-two samples from eight locations) lacustrine sedimentary rocks of central Mongolia were studied to determine their depositional environments and petroleum source rock potential. The Middle Jurassic shale contains sufficient organic matter (OM) with Type II/III kerogen to represent a mixed oil and gas potential source rock. Tmax and biomarker maturity indices suggest a thermally immature level. Pristane/phytane and the gammacerane index indicate that the shale accumulated in an oxic, freshwater environment. Terrigenous OM with input from algae and macrophytes was a major contributor as indicated by long-chain n-alkanes and the abundance of C29 regular steranes. The stable carbon and nitrogen isotope compositions and kerogen types agree with land plant derived OM. Lower Cretaceous shales are highly oil-prone but thermally immature, reflected by Rock-Eval data and biomarker parameters. Carbon preference index (CPI), n-alkane distributions, and C27/C29 ratios suggest that OM in Lower Cretaceous shales is a mixture of phytoplankton, macrophyte, and land plant. The contribution from algal OM is variable. Lower Cretaceous shales were deposited in stratified lakes with anoxic bottom waters and the salinity of paleolakes was variable, indicated by Pr/Ph and the gammacerane index, respectively. Organic geochemical characteristics and depositional environments of Middle Jurassic and Lower Cretaceous sedimentary rocks studied herein are similar to those of Jurassic source rocks in western Chinese basins and Lower Cretaceous source rocks in eastern Mongolian basins, respectively.

Analysis of Current and Qualified Major Grain Producing Areas in China in the Last 30 Years

China’s grain production has been on a pathway parallel to urbanization in the last 30 years. When the balance between the grain supply and demand is considered, contradiction between farming suitability and actual deviation provides warning of a crisis regarding China’s food security. In this study, we constructed a set of topologic maps to summarize the basic distribution of the farming conditions in China, and Kernel density and Local Moran’s I analyses were con-ducted to investigate the spatial-temporal pattern of China’s regional grain production based on the grain output at the county level from 1985 to 2019. The results show that the high-output zones were concentrated in the regions with superior physical conditions in 1985, and by 2019, the high-output zones had increased in the northern regions (i.e., Northeast China Plain) and decreased in the southern regions (i.e., Southern China). The surplus zones of per capita grain output were concentrated in the regions with high total outputs during 1985–2019. The shortage zones were distributed in the regions with low total outputs and low total outputs or large populations. Based on the above three results, several typical commodity grain bases have lost their dominant role (i.e., the Pearl River Delta); furthermore, the qualified commodity grain bases were compiled at both the national and regional level based on overlay analysis (i.e., the Tarbagatay Prefecture as well as eastern and central Inner Mongolia).

Strong Population Genetic Structure of Phrynocephalus versicolor in Mongolia

We examined the phylogenetic relationships and evolutionary divergence of Phrynocephalus versicolor Strauch 1876, as well as the genetic diversity and population structure in Mongolia using mtDNA variation. Phrynocephalus is one of the most diverse genera within the Agamidae family, with confusing or controversial taxonomy. This resulted in several independent suggestions for subspecies designations within Phrynocephalus versicolor. As the most dominant and abundant reptilian species in the Mongolian Gobi Desert, Phrynocephalus versicolor is ecologically important within the food chain of the ecological system it inhabits. We used 77 samples from 9 populations of P. versicolor in central and southern Mongolia. We amplified and sequenced 522–base pair (bp) –long fragment of the ND2 gene and recorded moderate levels of sequence diversity (Hd = 0.74 ± 0.023, π = 0.035 defined by 97 polymorphic sites). We conducted phylogenetic analyses using of Bayesian inference, maximum likelihood, and median-joining (MJ) network analysis that resulted in four well-supported clades (A, B, C, D) among our Mongolian samples. All of these clades, except Clade A, were population specific. The genetic distance values (mean Fst = 0.768), and analysis of molecular variance (AMOVA) also showed greater genetic distances between these clades. We ran a time-calibrated phylogenetic analysis using a strict molecular clock model with a single fossil calibration. The estimated divergence times in this study were comparable with previous findings, for example, 1.8 million years ago (mya) (1.31–2.94) for the node (Bayesian posterior probability [BPP] > 1.0 and bootstrap > 98) from which Clade A and B originated. In conclusion, our findings showed that there are at least three genetically distinct subspecies, namely P. v. versicolor, P. v. kulagini, and P. v. hispidus, with one previously unknown clade/lineage.

Numerical study on the style of delamination

Delamination of the lower crust or lithospheric mantle is one explanation for the surface uplift observed in areas of mountain building. This process describes the removal of the lower part of the tectonic plate and can occur in various ways. Different styles of delamination typically have in common that the upper material (e.g., lowermost crust or lithospheric mantle) is denser than the underlying material (e.g., asthenosphere) and therefore sinks. It has been proposed that the higher density can be caused by the formation of eclogite. In this study we apply a thermomechanical model featuring a density increase within the lithosphere by a phase transition. The model setup is designed to investigate surface uplift and mountain building in an intracontinental setting. Specifically, the model is arranged to closely resemble central Mongolia. The models give insights into the dynamically evolving flow field with respect to the style of removal, therefore the general outcome is also applicable to other orogenic regions. In addition to a systematic study on the phase transition, we also investigate the influence of convergent motion and of the rheology of the crust. Our results reveal that for the absence of a dense (eclogite) layer, delamination initially occurs as a stationary Rayleigh-Taylor instability which appears as a late and short-lived event. In comparison, for a strong density contrast an early, long-lived peeling-off removal style with a stationary slab results. The subsequent asthenospheric upwelling causes further peeling-off events for all density contrasts. For this removal style a retreating slab is observed that occasionally breaks off giving way to a periodic behaviour. The findings confirm that a strong convergence and low viscosity of the crust promote delamination. In addition, the asthenospheric upwelling yields a wide and flat surface uplift. Such dome-like features are observed to be more pronounced for high density contrasts (i.e., strong eclogitisation).

Tectonic timeline in the Mongol-Okhotsk oceanic regime: Insights from early Jurassic and early cretaceous mafic-intermediate dyke swarms in central Inner Mongolia, North China

Chronicling sequential mafic dyke swarms along convergent plate margins presents a key to outlining the tectonic timeline of complete Wilson orogenic cycles for any regional paleotectonic and global supercontinental reconstructions. This study documents two episodes of Mesozoic mafic dyke swarms from central Inner Mongolia in the combined northern China-southern Mongolia (NCSM) plate: The Gadabuqi (GDBQ) suite with an age of ca. 181 Ma from East Ujimqin and the Houtoumiao (HTM) suite with an age of ca. 131 Ma from West Ujimqin. The GDBQ suite consists of hornblende-rich appinitic rocks and ranges in SiO2 from 49.6 to 52.6%. They are calc-alkaline to high calc-alkaline and show enrichment in large ion lithophile element (LILE) and light rare earth element (LREE) but depletion in high field strength elements (HFSE), with whole-rock initial 87Sr/86Sr of 0.704608 to 0.706048, positive ƐNd(t) of +1.2 to +2.4 as well as zircon ƐHf(t) of +2.5 to +5.6 and δ18O of 5.4 to 6.5‰. These features attributed the GDBQ suite to a juvenile fluid-metasomatized lithospheric mantle source. By contrast, the HTM suite mainly comprises gabbronorites with SiO2 from 55.1 to 56.4% and shows a transitional character from high calc-alkaline to shoshonitic. They are variably enriched in LREE and LILE but depleted in HFSE, with whole-rock initial 87Sr/86Sr of 0.705656 to 0.706543, ƐNd(t) of −1.1 to +3.4 and zircon ƐHf(t) of +2.9 to +9.1 and δ18O of 6.1 to 7.8‰. These elemental and isotopic traits argued for a parental magma derivation from partial melting of a fertile asthenospheric mantle and syn-magmatic crustal assimilation and fractional crystallization. Besides representing the first recognition of two distinct basaltic underplating events in central Inner Mongolia, these two contrasting mafic dyke swarms are disposed to monitor a tectonic shift from Early Jurassic linear slab breakoff to Early Cretaceous pervasive lithospheric delamination in the Great Xing'an Range. In conjunction with polyphase magmatic records and multifarious manifestations of structural, metamorphic and sedimentological dimensions, the refined Mesozoic tectono-thermal sequence in the NCSM tract tends to encapsulate insightful testimonies for chronicling the tectonic timeline from pre-Jurassic ongoing subduction and slab roll back to prolonged post-collisional aftermath of the Jurassic to early Cretaceous times in the Mongolia-Okhotsk oceanic plate domain.

Late carboniferous continental arc magmatism in the southeastern Central Asian Orogenic Belt: insights from the Erenhot granitic pluton, Inner Mongolia

The closure time of the Hegenshan Ocean and its suturing scenario is debated, which hinders our understanding of the architecture and tectonic evolution of the southeastern Central Asian Orogenic Belt. We present an integrated study of in-situ zircon U-Pb isotopic ages and Hf isotope compositions, whole-rock geochemistry and Sr-Nd isotopes on the less-studied Erenhot granitic pluton in central Inner Mongolia. The <i>ca.</i> 303 to 300 Ma Erenhot pluton is composed of monzogranites, which are high-K calc-alkaline rocks and show I-type affinities. Moreover, positive correlation between Ba and Sr, along with the notably positive Rb and Pb anomalies, negative δEu and depletion in Ba, Eu, Nb and Ti, imply crystal fractionation played an important role in the magma evolution. The pluton also shows relative enrichment in light rare earth elements and large ion lithophile elements and depletion in high field strength elements, typical features of subduction-related magma. Isotopically, predominantly positive whole-rock ε_Nd(t) (0.9–3.8) and zircon ε_Hf(t) (4.50–13.66) values indicate a dominant juvenile crustal source with minor older crustal contamination. Given the mostly Proterozoic model ages (1318–543 Ma) and the presence of xenocrystic zircons, we infer that the Erenhot pluton probably was formed in a continental arc setting. Combined with the available published data, it is proposed that an east-west trending continental arc developed and was accreted onto the Uliastai Continental Margin in the Carboniferous, resulting from the northward subduction of the Hegenshan Ocean. The late Carboniferous continental arc-related magmatism (<i>ca.</i> 303–300 Ma) at Erenhot probably witnessed the waning stage of Hegenshan oceanic lithosphere subduction beneath the Uliastai Continental Margin.

Evaluation and optimization of ecosystem services under different land use scenarios in a semiarid landscape mosaic

Ecosystem services are usually influenced by physical land use changes and climate changes. The significant land use changes and polices in Inner Mongolia mainly include urban development and the ecological restoration programs of Forest Protection, the Grain for Grass and Vegetation Recovery. This study used the Dyna-CLUE model to simulate 2030 land use changes in the Central and Western Inner Mongolia, and then explored key ecosystem services and the ESs-Balanced index under four land use scenarios with the above changes. Compared with the urban development scenario, Vegetation Recovery increases NPP, soil conservation, sand fixation, the surface and bottom soil moisture by 10.84 %, 0.76 %, 4.35 %, 1.52 % and 0.12 % respectively, but it decreases water yield by 6.56%. The Grain for Grass Program increases NPP (1.12 %), soil conservation (0.43 %) and sand fixation (3.96%) at the expense of other ecosystem services, while Forest Protection only increases NPP and the surface soil moisture narrowly. The study further provided the spatially explicit land use optimization by comparing the ESs-Balanced index under four scenarios. Vegetation Recovery suits most west and south areas covered by the sandy land or Gobi, while the Grain for Grass Program is only supportable with the western sandy farmland. The results are instructive to promote key ecosystem functions and services related to serious local ecological problems, and deal with the contradictions between ecological conservation and human development in other similar arid and semiarid regions.

Spatial Transformation Characteristics and Conflict Measurement of Production-Living-Ecology: Evidence from Urban Agglomeration of China.

The land development by human beings has changed from the initial small-scale and low-level transformation to the comprehensive utilization of large-scale and high-intensity implementations. The contradiction between production-living-ecology space (PLES) has become increasingly prominent while drawing land dividends. As one of the important birthplaces of Chinese civilization and the ecological barrier in the northern region, the rapid urbanization and industrialization of the Yellow River Basin (YRB) make the ecological environment very fragile, and the imbalance of land and space development is extremely serious. Therefore, according to the multifunctional characteristics of land use, this paper establishes a classification system of production space (PS), living space (LS) and ecology space (ES), and discusses the spatiotemporal evolution and conflict distribution characteristics of the PLES with the help of the transfer matrix and spatial conflict index (SCI). The results are as follows. In 1990–2020, agricultural production space (APS), grassland ecology space (GES) and other ecology space (OES) yielded the largest proportion of PLES in the YRB. However, compared with 1990, the area of these spatial types decreased in 2020, while the urban living space (ULS) expanded rapidly. The distribution pattern of PLES was generally consistent, and the transformation between PLES in Ningxia, central Inner Mongolia, Loess Plateau and downstream areas was relatively intense. The conflict index of PLES showed an upward trend, but it was generally in a controllable range. The stable and controllable areas were concentrated in the upstream of the urban agglomeration, and the midstream and downstream were basic out of control and seriously out of control, respectively.

Variations in geomorphological dynamics in the northern Khangai Mountains, Mongolia, since the Late Glacial period

In semi-arid central Mongolia, geomorphological dynamics and forest distribution are commonly regarded as a result of the climatic development over the Holocene. The aim of this study was to detect variations in geomorphological activity and related eolian, periglacial, colluvial and fluvial processes since the Late Glacial, triggered by climate changes and other factors such as regional lake-level changes, fire events, and human impact. For this purpose, we investigated sediment archives in various relief positions (slope, pediment, valley bottom, dune and lake shore) in a forest-steppe region at the northern edge of the Khangai Mountains. We used a combination of geomorphological mapping and sampling of sediments, soils, paleosols, and organic layers. The samples were subjected to sedimentological analysis, luminescence and radiocarbon dating.The ages obtained for the eolian sediments showed that intense eolian activity and periglacial processes occurred during the Last Glacial Period and mitigated after 11 ka. After the Younger Dryas, geomorphological processes decreased and intensified soil formation indicated a stabilization of the soil surface simultaneously when spreading of forests around 9.5 ka was previously shown in the Khangai Mountains. The early and mid-Holocene were characterized by minor geomorphological activity and low fire frequency, as documented by sparseness of charcoal fragments and paleosols in the sediments. Only between 8 ka and 7 ka, reactivation of eolian sand transport was recorded during a drier period.Widespread distribution of late Holocene colluvial, alluvial and eolian sediments containing abundant charcoal, and periglacial features point to a distinct turning point in the Holocene landscape development around 4.5 ka, when substantially enhanced geomorphological activity started. This enhanced geomorphic activity corresponds with a period previously shown to be more humid but also more unstable, and during which forests became more susceptible to severe fire events. After a forest fire, lack of vegetation cover favored intensive erosion. Enhanced geomorphological activity points to a trend towards desertification, which was increasingly aggravated by human impact, since pastoralism emerged latest in the early Bronze Age. Increased production of steppe biomass during humid periods led to growth of population and livestock. This growth in turn resulted in overgrazing in drier years. This mechanism probably amplified the aridity signals that were detected in proxies of various paleoenvironmental archives.

Isolation and Identification of a Highly Pathogenic Avian Influenza H5N6 Virus from Migratory Waterfowl in Western Mongolia.

In April 2020, two Whooper Swans (Cygnus cygnus) and one Swan Goose (Anser cygnoides) were found dead at three different locations in western Mongolia. Virus isolation from organs taken from the carcasses and full genome sequencing revealed that all three birds were positive for highly pathogenic H5N6 avian influenza virus (HPAIV) belonging to subclade 2.3.4.4h. Confirming similar reports from central Mongolia and western China, these findings have important implications for the monitoring, control, and management of HPAIVs in wild bird and commercial poultry populations in Mongolia.

Late Carboniferous gabbro-granite suite from West Ujimqin of central Inner Mongolia: Petrogenesis and geodynamic implication

辉长岩和花岗岩组成的双峰式火成岩系列通常产出于威尔逊板块构造旋回的诸多伸展周期。基于其岩石地球化学特征示踪伸展地球动力学过程与相关壳幔相互作用的独特视角，本文报道了中亚造山带东段内蒙古中部西乌旗地区新近识别的晚石炭世猴头庙辉长岩-花岗岩系列。SIMS锆石U-Pb定年揭示辉长岩和花岗岩的侵位年龄分别为~307Ma和~305Ma。辉长岩主要由斜长石、辉石和角闪石组成；SiO₂含量介于50.4%~53.4%之间，呈现镁质、准铝质和钙碱性特征；富集大离子亲石元素，亏损高场强元素；并具有OIB型全岩Sr-Nd （I_Sr（t）=0.704249~0.704330，ε_Nd（t）=+1.73~+3.81）和锆石Hf （ε_Hf（t）=+4.58~+15.16）同位素组成，其锆石δ¹⁸O介于5.75‰~6.61‰之间。这些特征指示辉长岩可能源于俯冲板片流体交代的亏损地幔楔部分熔融。同期花岗岩主要由斜长石、钾长石、石英和黑云母组成；其SiO₂含量变化于76.3%~77.6%，高硅碱、贫铁镁、弱过铝、富钍铀、亏锶钡、Eu负异常，契合典型高分异I型花岗岩的元素地球化学特征；花岗岩具有中等放射性成因的全岩I_Sr（t）（0.704923~0.704981）、ε_Nd（t）值（-0.15~+0.57）和锆石ε_Hf（t）值（-2.63~+7.40），以及高的锆石δ¹⁸O （6.44‰~8.06‰）。鉴于元素和同位素特征指示的高分异特征和高演化源区，猴头庙高硅花岗岩可能衍生自中元古代和古生代多期增生物质所组成的复合中基性地壳的部分熔融及其后的结晶分异作用。综合区域石炭纪-早二叠世蛇绿混杂岩和岛弧岩浆岩时空展布格局，晚石炭世猴头庙辉长岩-花岗岩系列记录了内蒙古中部其时因洋脊俯冲引发的弥散性区域伸展事件。一方面，该事件既有别于建造西乌旗早-中石炭世弧-盆体系的板片回退阶段，又迥异于早二叠世大规模后碰撞伸展过程；另一方面，这些周期性伸展事件共同见证了中亚造山带东段晚古生代威尔逊造山旋回的完整历程。;Coeval bimodal igneous suites of gabbro and granite commonly typify frequent extensional episodes in the Wilson cycle of plate tectonics. With a unique view to tracing extensional geodynamic processes and related crust-mantle interactions through the petro-geochemical characteristics of such suites, this paper reports the newly identified Late Carboniferous Houtoumiao gabbro-granite suite from West Ujimqin of central Inner Mongolia, eastern Central Asian Orogenic Belt (CAOB). SIMS zircon U-Pb dating unravels the emplacement age of gabbro at ca. 307Ma and that of granite at ca. 305Ma. The gabbros mainly consist of plagioclase, pyroxene and amphibole. They range in SiO₂ from 50.4% to 53.4%, exhibiting magnesian, metaluminous and calc-alkalic affinities, with enrichment in large ion lithophile elements (LILEs) and depletion in high field strength elements (HFSEs). They possess OIB-type whole-rock Sr-Nd (I_Sr(t)=0.704249~0.704330, ε_Nd(t)=+1.73~+3.81) and zircon Hf (ε_Hf(t)=+4.58~+15.16) isotope compositions, and zircon δ¹⁸O values from 5.75‰ to 6.61‰. These features suggest that the gabbros might be derived from the partial melting of a depleted metasomatised mantle wedge from subduction-derived fluids. The coeval granites mainly comprise plagioclase, K- feldspar, quartz and biotite. They span in SiO₂ from 76.3% to 77.6%, with high alkalis, thorium and uranium but low iron, magnesium, strontium and barium. They are weakly peraluminous with negative Eu anomalies. These features are typical of highly fractionated I-type felsic magmas. With respect to isotopic compositions, the granites are characterized with medium radiogenic whole-rock I_Sr(t) (0.704923~0.704981), ε_Nd(t) (-0.15~+0.57) and zircon ε_Hf(t) (-2.63~+7.40), and high zircon δ¹⁸O (6.44‰~8.06‰). Given their highly fractionated character and highly evolved sources, the Houtoumiao granites tend to have been derived from the partial melts of the composite mafic to intermediate lower crust composed of multi-stage accretionary materials in the Mesoproterozoic and Paleozoic times, with subsequent fractional crystallization yielding the high-silica granites. Combined with the spatial and temporal distribution patterns of regional Carboniferous-Early Permian ophiolitic mélange and island arc magmatic complexes, the Late Carboniferous Houtoumiao gabbro-granite suite seems to record diffuse regional extension event due to ridge subduction in central Inner Mongolia. On one hand, this event is not only distinct from slab rollback episode of the Early-Middle Carboniferous arc-basin system in West Ujimqin, but also in contrast with large-scale post-collisional extension during Early Permian time. On the other hand, when taken together, these episodic extensional events tend to witness the complete course of the Late Paleozoic Wilson cycle in the eastern CAOB.