Central Mongolia Research Articles

The influence of dusts on radiation and temperature over the eastern Asia with a regional climate model

In order to investigate the climate effects of dusts, a regional climate model (RegCM 4.6) with the dust scheme was used to simulate the direct radiative forcing and air temperature response at 2 m near surface of dusts over the eastern Asia. Two sets of experiments were conducted, one with and one without dust aerosols. The experiment covered the main dust occurrence months from March to May for 8 years (2011−2018), and the simulation results were evaluated against ground station, reanalysis and satellite data. The model captured the spatiotemporal distribution of dust AOD and mass loading over the eastern Asia. However, it tended to underestimate the dust AOD and mass loading over the downwind of the dust source region and the Taklimakan Desert, and overestimate them over the north Xinjiang. The direct net radiative forcing including shortwave and longwave was up to −20 W·m−2 at the surface and −10 W·m−2 at the TOA over the dust source region due to the dominant negative shortwave forcing. The only exception of positive forcing at the TOA was observed along the western boundaries of the Tibetan Plateau due to the semi-persistent ice and snow cover. The dusts tended to warm the atmosphere more than 18 W·m−2 and cool the surface locally up to −0.7 °C. Among the 5 sub-areas, the largest averaged regional direct radiative forcing induced by dusts appeared over the central Inner Mongolia in May with the value of −3.0 ± 2.1, −12.2 ± 4.1 and 9.2 ± 4.4 W·m−2 at the TOA, surface and in the atmosphere, respectively. The results indicated that the model simulation for dusts should be further improved and the dust effects should be included in the estimates of climate change over the eastern Asia.

Chariots in the Bronze Age of Central Mongolia based on the materials from the Khoid Tamir river valley

The issue of using chariots in the culture of the Bronze Age population of Central Mongolia was studied on the materials of archaeological sites from one micro-region in the Khoid Tamir river valley, drawing primarily from images on rocks and stone stelae. Systematic analysis of rock art styles and burial traditions based on radiocarbon dates of burials and ritual deposits of bone enabled us to distinguish two periods of chariots' usage here: 1)prior to ca. 1200 BCE, in the Sagsai culture; 2) after ca. 1200 BCE, with the DSK culture. The study of the chariot image, its parts, and attributes of charioteers in visual compositions allowed us to reconstruct its role in the life and beliefs of herders. On deer stones, a charioteer's attributes (belt plates with a pair of hooks) are always adjacent to individual sets of weapons, which indicates the use of chariots by warriors. At the same time, images of the chariot and chariot draught teams on rocks and stelae of both periods appear connected with burial rites and ideas about the posthumous path to the afterlife. An important role in this transition was performed by a male deer, which led the deceased and his horses to the sky. Veneration of the deer image increased significantly during the second period, which is reflected in the composition of deer stones of the Mongol-Transbaikal type.

The impact of teleconnections on the temporal dynamics in aboveground net primary productivity of the Mongolian Plateau grasslands

AbstractTemporal dynamics in aboveground net primary productivity (ANPP) are significant for environmental protection and economic development in the Mongolian Plateau grasslands (MPGs). Climate control of ANPP's temporal variations has intensified in response to local meteorological conditions, while the contributions of large‐scale atmospheric circulations to ANPP variations are poorly understood in the MPGs. First, we explored the temporal dynamics in annual ANPP, and then, we analyzed correlations among annual ANPP, local meteorological variables, and three different teleconnections during 1982–2015 in this study. Our analytical results indicated that (a) ANPP exhibited an increasing trend during the entire study period. However, the increasing trend did not persist, and two reversals occurred in 1998 and 2007. (b) ANPP variations were primarily influenced by summer precipitation in most regions and by summer precipitation and temperature together in other regions of the MPGs. (c) The Atlantic Multidecadal Oscillation (AMO) in winter negatively dominated annual ANPP variations by influencing summer precipitation and summer temperature in central Mongolia. The North Atlantic Oscillation (NAO) in winter exerted strong positive impacts on ANPP variations by influencing summer precipitation in Inner Mongolia, China. The East Atlantic Western Russia (EAWR) in spring controlled annual ANPP variations by influencing summer precipitation in western and eastern Mongolia. (d) The winter AMO, winter NAO and spring EAWR significantly dominated the annual ANPP variations in 49.78% of the MPGs, with values of 18.90, 9.81 and 21.07%, respectively. (e) Reversals of the winter AMO, winter NAO and spring EAWR between negative and positive phases resulted in two reversals of ANPP trends. This study will improve our understanding of the role of large‐scale atmospheric circulations in regulating ANPP variations and will be valuable in guiding the development of grazing land management in Mongolia and Inner Mongolia, China.

English

Myxobacteria can produce rich and varied biological active substances against bacteria, fungi and viruses, which have great development and research value in medicine and agriculture. In this study, the diversity of culturable myxobacteria in central Inner Mongolia in China was studied and the effects of soil utilization mode, soil type and environmental parameters on the distribution of myxobacteria in this region were analyzed. Furthermore, the activities of myxobacteria against potato late blight pathogen were tested. The results showed that Myxococcus, Corallococcus, Pyxidicoccus, Cystobacter, Archangium and Mellittangium were the dominant genera of myxobacteria in this region. Soil utilization mode and soil types have obvious influence on the distribution of myxobacteria. The populations of myxobacteria were abundant in grassland and cultivated land samples, but few in woodland and unused land samples. The diversity of myxobacteria in the soil samples from fuvo-aquic soils, grey-cinnamon soils, castanozems, and bog soils was relatively rich, while the richness of myxobacteria in aeolian soils, solonetzs, skeletol soils and castano-cinnamon soils was poor. There was no significant correlation between myxobacteria distribution and soil environmental parameters (including the water content, pH value, content of organic matter, content of available phosphorus, content of hydrolytic nitrogen and content of available potassium). Most of the myxobacterial strains isolated in this area (83%) showed the activity against P. infestans, among which the proportion of the disease-resistant strains belonging to Myxococcus and Corallococcus was high, the proportion of the strains belonging to Cystobacter and Mellittangium in the medium, and the proportion of the strains belonging to Pyxidicoccus and Archangium low. The completion of this work will enrich the myxobacteria resource bank in Inner Mongolia and lay a foundation for the further study on myxobacteria and the development of biological pesticide against potato late blight. © 2021 Friends Science Publishers

‘Tears of Rejoicing Spirits’

Abstract Accounts of Mongol mountain sacrifices (ovoo takhilga) variously focus on transactional offerings that elicit benefits from local spirits and on the patron-like position held by spirits towards those who supplicate them. In contrast this article explores how, in such ceremonies, human–spirit relations are shaped through the enactment of emotions: in this context, happiness. Bringing classic literature on sacrifice into dialogue with recent studies of happiness as a social phenomenon, we argue that the generation of happiness (bayarluulakh; bayasgakh) in local spirits is of great importance in mediating the distance between spirits and their human neighbours. This mediation allows for the shaping of optimal post-sacrificial relations between these two categories of being. Our argument is made through an analysis of ethnographic and linguistic data relating to an ovoo takhilga in a Khalkha area of central Mongolia.

Age, origin and tectonic implications of Late Carboniferous-Early Permian felsic magmatic rocks from central Inner Mongolia, south-eastern Central Asian Orogenic Belt

ABSTRACT Permo-Carboniferous felsic magmatic rocks are widely exposed on the northern half of the south-eastern Central Asian Orogenic Belt. However, their origin and spatiotemporal distribution are unknown. Herein, zircon U-Pb-Hf isotopic data, major and trace element compositions of the whole-rock, and Sr-Nd isotopic data derived for felsic volcanic rocks and granites of the Chaganaobao and Baiyinaobao areas in central Inner Mongolia are combined with the data from previous studies. The integration of these results reveals that the Uliastai Continental Margin, Erenhot-Hegenshan Ophiolite Belt, and Northern Orogenic Belt have coeval magmatic lull or trough at c. 307 Ma, which overlap with the closure timing of the Hegenshan Ocean. The Latest Carboniferous−Early Permian (c. 303−295 Ma) felsic volcanic rocks in the Chaganaobao area of the Uliastai Continental Margin comprise dacite, trachydacite, and rhyolite, while demonstrating positive whole-rock εNd(t) (+2.9 to +4.7) and zircon εHf(t) values (+7.65 to +13.78). Early Permian granites of the Baiyinaobao area located within the Northern Orogenic Belt show positive εHf(t) values (+ 2.70 to +11.33) and low TFe2O3 + MgO + TiO2 contents. The geochemical composition reveals that those felsic magmatic rocks mainly originate from the partial melting of juvenile crustal components with subordinate input of mantle-derived melts. Those c. 305−275 Ma felsic magmatic rocks from the north of the south-eastern Central Asian Orogenic Belt exhibit affinities of post-collision type granites in geochemical nature. Therefore, the flare-up of the Early Permian magmatism surrounding the Erenhot-Hegenshan Ophiolite Belt could be related to the extension after the final closure of the Hegenshan Ocean.

Interrelations between relief, vegetation, disturbances, and permafrost in the forest‐steppe of central Mongolia

AbstractIn semi‐arid central Asia, relief has a strong impact on the distribution of vegetation and discontinuous permafrost. Our aim was to analyse causal chains and inter‐relationships that control the spatial patterns of forest and permafrost in the forest‐steppe of the northern Khangai Mountains in Mongolia. For this purpose, we conducted soil‐profile descriptions, ground‐penetrating radar sounding, and vegetation mapping to gain information about forest and permafrost distribution. We integrated remote‐sensing analysis and field‐mapping data, including soil properties, vegetation cover, forest fires and anthropogenic forest use. We developed and applied a technique for spatial delineation of permafrost distribution, based on the parameters Topographic Wetness Index (TWI), incoming solar radiation and Normalized Difference Vegetation Index (NDVI). Key outcomes of this study are that the occurrence of discontinuous permafrost within 1 m depth is limited to forest stands larger than 100 ha on north‐facing slopes. Dense ground vegetation supports permafrost, whereas sandy soil texture leads to greater depth of the permafrost table. As the seasonal ice in the active layer progressively melts down during summer, meltwater interflow above the permafrost table provides additional soil moisture downslope. This process is reflected in enhanced vitality of the steppe vegetation on toe slopes below forests with permafrost. This effect can in turn be used to indirectly detect permafrost in forest stands by remote sensing. Permafrost mostly disappears after forest fires and other severe disturbances, but it may re‐establish during forest regrowth. However, climate warming is presently leading to a loss of permafrost regeneration potential after disturbance, and to a shift from climate‐induced and ecosystem‐driven permafrost to entirely ecosystem‐protected permafrost. These trends will result in a further decrease of permafrost area after forest disturbance.

Geodynamic Modeling of Lithospheric Removal and Surface Deformation: Application to Intraplate Uplift in Central Mongolia

AbstractIntraplate surface deformation is enigmatic and the underlying mechanisms responsible are not fully understood. We use thermo‐mechanical numerical modeling to explore the conditions under which lithospheric removal processes can occur and investigate the timing and amplitude of consequent surface deformation. We allow lithospheric removal to develop dynamically and self‐consistently by applying a phase transition and density jump that is hypothesized to be a consequence of metamorphic eclogitization in a thickened crust, rather than simply imposing an initial dense block. By systematically varying parameters, we test their influence and control on lithospheric removal. We confirm that a weak and dense lower crust, a hot crust‐mantle boundary, and a convergent regime are critical requirements for delamination‐style removal. We apply these results to central Mongolia, which is an ideal natural laboratory for studying intraplate surface uplift because of its high topography and location in the continental interior. We determine that the physical parameters and structure inferred in this region match the conditions for delamination. Thus, model outputs are evaluated against the available observational evidence. We find that the removal of the lithosphere by delamination can explain: the dome‐shaped topographic pattern and elevated surface; the thin lithosphere and its structure; the elevated temperature at the crust‐mantle boundary. Additionally, it is hypothesized that delamination leads to magmatism due to mantle decompression melting, consistent with intraplate volcanism. Ultimately, the results suggest that lithospheric removal by delamination is a physically plausible mechanism and a potential explanation for intraplate uplift.

Ground penetrating radar for soil-water measurement in a semi-arid climate in the Orkhon River basin, central Mongolia

In this paper, we present a velocity analysis technique using ground-penetrating radar (GPR) data to estimate near-surface soil-water content affected by topography and solar radiation on a mountain peak, mountain mid-slope, and alluvial plain sites in a semi-arid climate area in central Asia. By making precise measurements of reflected EM wave velocity, the water content in the near-surface soil was determined. The GPR experiments at several frequencies were carried out in two sequential phases (comprising common-offset and multi-offset methods) to obtain the soil-water content and illustrate the subsurface structure. We then tried to determine the relationship between near-surface moisture content and permafrost thawing. Therefore, we used several different methods including time-domain reflectometry and a resistivity survey. We also confirmed via the GPR data that vegetation cover indicates soil-water content in the near-surface soil. The results evaluated in this study provide meaningful information about soil water as well as subsurface structures. The GPR data acquired at the survey sites indicated a large range of near-surface water content due to the topography of the survey lines.

Late Pleistocene Expansion of Small Murid Rodents across the Palearctic in Relation to the Past Environmental Changes.

We investigated the evolutionary history of the striped field mouse to identify factors that initiated its past demographic changes and to shed light on the causes of its current genetic structure and trans-Eurasian distribution. We sequenced mitochondrial cyt b from 184 individuals, obtained from 35 sites in central Europe and eastern Mongolia. We compared genetic analyses with previously published historical distribution models and data on environmental and climatic changes. The past demographic changes displayed similar population trends in the case of recently expanded clades C1 and C3, with the glacial (MIS 3–4) expansion and postglacial bottleneck preceding the recent expansion initiated in the late Holocene and were related to environmental changes during the upper Pleistocene and Holocene. The past demographic trends of the eastern Asian clade C3 were correlated with changes in sea level and the formation of new land bridges formed by the exposed sea shelf during the glaciations. These data were supported by reconstructed historical distribution models. The results of our genetic analyses, supported by the reconstruction of the historical spatial distributions of the distinct clades, confirm that over time the local populations mixed as a consequence of environmental and climatic changes resulting from cyclical glaciation and the interglacial period during the Pleistocene.

Petrogenesis and tectonic setting of the Early Permian gabbro–granite complex in the southeastern Central Asian Orogenic Belt, central Inner Mongolia, China

Gabbro–granite complexes formed in active continental margins provide critical constraints on magmatic processes, crust–mantle interactions, and tectonic evolution. The petrogenesis and tectonic setting of the Early Permian igneous rocks in the southeastern Central Asian Orogenic Belt have been a subject of dispute for a long time. This contribution presents an integrated study on the field occurrence, petrology, petrography, zircon U–Pb ages, in situ zircon Hf isotopes, whole-rock geochemistry, and Sr–Nd isotopes of the Early Permian Yiheshaorong gabbro–granite complex, Xi Ujimqin Banner, central Inner Mongolia. Lithologically, the Yiheshaorong complex consists predominantly of gabbro, pyroxene diorite, and alkali feldspar granite. Results of LA–ICP–MS zircon U–Pb dating suggest that crystallization ages of the gabbro, pyroxene diorite, and alkali feldspar granite are 281–280, 278, and 281–280 Ma, respectively. Silica (SiO2) content varies from 41.26 to 79.64 wt% and exhibits a gap between 56.84 and 75.45 wt%, displaying a good bimodal geochemical distribution. Geochemically, the gabbros and pyroxene diorites are characterized by enrichment of large ion lithophile elements (LILEs; e.g., Ba and K) and depletion of high field strength elements (HFSEs; e.g., Nb, Ti, and P). These rocks show similar homogeneous zircon Hf isotopic (positive εHf (t) values from +7.8 to +10.1) and whole-rock Sr–Nd isotopic (low initial 87Sr/86Sr ratios from 0.7044 to 0.7051, positive εNd (t) values from +3.7 to +4.7) compositions. The gabbros and pyroxene diorites originated from partial melting of depleted asthenospheric mantle metasomatized by subduction slab fluids; and they experienced various degrees of crystallization differentiation during ascension. The alkali feldspar granites are ferroan, alkali-calcic–calc-alkalic series rocks marked by high SiO2, K2O + Na2O, and FeOT/MgO; and low Al2O3, CaO, and MgO contents. Their trace elements are marked by enrichment of LILEs (such as K and Rb); depletion of HFSEs (such as Nb and Ti), Ba, Sr, and P; and strongly negative Eu anomalies (Eu/Eu* = 0.17–0.57), with coincident distribution patterns forming a seagull-type distribution form, showing an A-type granite affinity. The alkali feldspar granites are characterized by positive εHf (t) values (+8.6 to +10.3, young TDM2 ages, 645–758 Ma) and εNd (t) values (+3.5 to +3.8 as well as young TDM2 ages, 667–687 Ma). All these geochemical characteristics indicate that the alkali feldspar granites originated from the partial melting of juvenile crust under high temperature and low pressure condition. The Yiheshaorong complex was most likely formed in a back-arc spreading basin. Such an extensional regime can likely be attributed to the upwelling of asthenospheric mantle caused by the rollback and break-off of a subducted Paleo-Asian Ocean slab in the Early Permian, which induced large-scale extension and magmatism in the study area.

Permo-Carboniferous provenance shifts at the northern margin of the North China Craton and their tectonic implications: Detrital zircon U–Pb–Hf records from central Inner Mongolia

Permo-Carboniferous provenance shifts at the northern margin of the North China Craton (NCC) were reconstructed. The reconstruction was based on the detrital zircon U–Pb–Hf data from Late Paleozoic sandstones from Ondor Sum and Wude in the Southern Orogenic Belt (SOB) of the Southeast Central Asian Orogenic Belt (SE CAOB). Sandstone samples from the Lower Devonian Naqing Formation, Upper Carboniferous Hailasiamu Formation, and the first and second members of the Upper Carboniferous Amushan Formation in Ondor Sum present a nearly unimodal detrital zircon age grouping (c. 380–520 Ma), and they have similar zircon Hf isotopic compositions with igneous rocks in the SOB, implying that their provenance was from the SOB region. In contrast, samples in the same area from the third to fifth members of the Lower Permian Amushan Formation and the Lower Permian Sanmianjing Formation contain multimodal age groupings, with the ages mainly concentrated at the Late Carboniferous–Early Permian, Neoarchean, and Paleoproterozoic. The coexistence of Neoarchean and Paleoproterozoic grains suggests that the NCC could be a reliable source. In addition, the Hf isotopic composition of the Late Carboniferous–Early Permian zircons overlap with those from the NCC, and therefore, it is concluded that there were Permo-Carboniferous provenance shifts from the SOB to the NCC for the sandstones from the Upper Paleozoic in the Ondor Sum area. Late Carboniferous and Early Devonian sandstone samples from Wude had sediment contributions from both the SOB and the NCC, with detrital zircon grains from the SOB constituting the majority. Whereas, the Early Permian samples from this area contained sediment contributions predominantly from the NCC. We suggest that the Permo-Carboniferous provenance shifts were the result of significant local subsidence of the SOB, and the uplift of the Inner Mongolia Paleo-Uplift after the Early Devonian collision between the Bainaimiao arc belt and the NCC.

High‐Resolution Crustal and Uppermost Mantle Structure Beneath Central Mongolia From Rayleigh Waves and Receiver Functions

AbstractIn this study, I present a high‐resolution 3‐D Vs model of the crust and uppermost mantle beneath central Mongolia, based on seismic data recorded at the Central Mongolia Seismic Experiment array and some other networks. The model is constructed by a Bayesian Monte Carlo inversion that jointly interprets Rayleigh wave phase speeds and receiver functions. The Rayleigh wave dispersion measurements are derived from both ambient noise and teleseismic earthquake data. To improve ambient noise data coverage, a recently developed three‐station interferometry (Zhang et al., 2020, https://doi.org/10.1093/gji/ggaa046) technique is applied to produce high‐quality three‐station interferograms that augment the ambient noise data base. There are several prominent geological and tectonic features captured by the model, including (1) the Khövsgöl rift system is imaged as a high‐speed anomaly in the upper crust, whose southern edge follows the Bulnay fault. (2) The estimated crustal thickness map identifies relatively thick crust beneath the Khövsgöl rift system, the Hangay Dome, and the Gobi‐Altai Mountains. (3) A crustal high‐velocity anomaly is imaged beneath the Taryatu‐Chulutu volcanic field, which is interpreted as a solidified intrusive magma body. (4) Dispersed low‐velocity anomalies in the mantle identify locations with possible partial melting. The melting zones could be related to small‐scale asthenospheric upwelling and convective removal of lithosphere, which produces uplift of the Hangay Dome.

Petrogenesis and Tectonic Significance of Carboniferous Granites on the North Side of the Solonker Suture, Central South Mongolia

AbstractThe central part of South Mongolia, located to the north of the Solonker Suture, is a key region for studying the late Paleozoic tectonic evolution of the Central Asian Orogenic Belt (CAOB). Voluminous late Paleozoic granitic rocks, especially of Carboniferous age, were intruded in this area. However, these granitoids have not been well studied and there is a lack of precise ages and isotopic data. This has hampered our understanding of the tectonic evolution of southeastern Mongolia, and even the entire CAOB. In this paper, we provide new U‐Pb isotopic ages and geochemical analyses for these Carboniferous granites. One granite from the Ulaanbadrakh pluton yielded a zircon U‐Pb age of 326 Ma, which indicates emplacement in the Early Carboniferous, and three other granites from the Khatanbulag region gave zircon U‐Pb ages of 316 Ma, 315 Ma, and 311 Ma, which indicate emplacement in the Late Carboniferous. The Early Carboniferous granite has SiO2 contents of 70.04–70.39 wt% and K2O + Na2O contents of 6.48–6.63 wt%, whereas the Late Carboniferous granites have more variable compositions (SiO2 = 65.29–77.91 wt% and K2O + Na2O = 5.30–7.27 wt%). All the granites are weakly‐peraluminous I‐types that are relatively enriched in U, Th, K, Zr, Hf, and LREEs. The whole rock Sr‐Nd and zircon in situ Lu‐Hf isotope analyses for the Early Carboniferous granite gave positive values of ∊Nd(t) (2.87) and ∊Hf(t) (4.31–12.37) with young Nd (TDM = 860 Ma) and Hf (TDMc = 1367–637 Ma) two‐stage model ages, indicating derivation from juvenile crustal material. In contrast, the Late Carboniferous granites had more diverse values of ∊Nd(t) (–4.03 to 2.18) and ∊Hf(t) (–12.69 to 5.04) with old Nd (TDM = 1358–1225 Ma) and Hf (TDMc = 2881–1294 Ma) depleted mantle two‐stage model ages, suggesting derivation from remelting of Precambrian basement. Based on the existing results, the tectonic setting of the Late Carboniferous granites in the central part of South Mongolia is known for its diversity, and this paper believes that the tectonic background of the carboniferous granite records the tectonic transition from a continental‐margin‐arc to a post‐collisional extensional setting during the Late Carboniferous–Permian.

The conservation patterns of grassland ecosystem in response to the forage-livestock balance in North China

Being a key ecological security barrier and production base for grassland animal husbandry in China, the balance between grassland forage supply and livestock-carrying pressure in North China directly affects grassland degradation and restoration, thereby impacting grassland ecosystem services. This paper analyzes the spatiotemporal variation in grassland vegetation coverage, forage supply, and the balance between grassland forage supply and livestock-carrying pressure from 2000 to 2015 in North China. We then discuss the spatial pattern of grassland ecological conservation under the impacts of grassland degradation and restoration, and livestock-carrying pressure. Over the last 16 years, the total grassland area in North China decreased by about 16,000 km2, with vegetation coverage degraded by 6.7% of the grasslands but significantly restored by another 5.4% of grasslands. The provisioning of forage by natural grassland mainly increased over time, with an annual growth rate of approximately 0.3 kg/ha, but livestock-carrying pressure also increased continuously. The livestock-carrying pressure index without any supplementary feeding reached as high as 3.8. Apart from the potential livestock-carrying capacity in northeastern Inner Mongolia and the central Tibetan Plateau, most regions in North China are currently overloaded. Considering the actual supplementary feeding during the cold season, the livestock-carrying pressure index is about 3.1, with the livestock-carrying pressure mitigated in central and eastern Inner Mongolia. Assuming full supplementary feeding in the cold season, livestock-carrying pressure index will fall to 1.9, with the livestock-carrying pressure alleviated significantly in Inner Mongolia and on the Tibetan Plateau. Finally, we propose different conservation and development strategies to balance grassland ecological conservation and animal husbandry production in different regions of protected areas, pastoral areas, farming-pastoral ecotone, and farming areas, according to the grassland ecological protection patterns.

Crustal architecture of a metallogenic belt and ophiolite belt: implications for mineral genesis and emplacement from 3-D electrical resistivity models (Bayankhongor area, Mongolia)

Crustal architecture strongly influences the development and emplacement of mineral zones. In this study, we image the crustal structure beneath a metallogenic belt and its surroundings in the Bayankhongor area of central Mongolia. In this region, an ophiolite belt marks the location of an ancient suture zone, which is presently associated with a reactivated fault system. Nearby, metamorphic and volcanic belts host important mineralization zones and constitute a significant metallogenic belt that includes sources of copper and gold. However, the crustal structure of these features, and their relationships, are poorly studied. We analyze magnetotelluric data acquired across this region and generate three-dimensional electrical resistivity models of the crustal structure, which is found to be locally highly heterogeneous. Because the upper crust (< 25 km) is found to be generally highly resistive (> 1000 Ωm), low-resistivity (< 50 Ωm) features are conspicuous. Anomalous low-resistivity zones are congruent with the suture zone, and ophiolite belt, which is revealed to be a major crustal-scale feature. Furthermore, broadening low-resistivity zones located down-dip from the suture zone suggest that the narrow deformation zone observed at the surface transforms to a wide area in the deeper crust. Other low-resistivity anomalies are spatially associated with the surface expressions of known mineralization zones; thus, their links to deeper crustal structures are imaged. Considering the available evidence, we determine that, in both cases, the low resistivity can be explained by hydrothermal alteration along fossil fluid pathways. This illustrates the pivotal role that crustal fluids play in diverse geological processes, and highlights their inherent link in a unified system, which has implications for models of mineral genesis and emplacement. The results demonstrate that the crustal architecture—including the major crustal boundary—acts as a first‐order control on the location of the metallogenic belt.

Estimating spatial distribution of aridity and moisture indices of Mongolia using remotely sensed time series data

The aim of this study is to estimate the spatial distribution of aridity and moisture indices using remotely sensed time-series data. For the analysis, we have chosen two simple climatic indices. One of two indices was the De Martonne aridity index, and the other one was the Mezentsev moisture index. The study area covers the total territory of Mongolia (~1.566 × 106 km2). Both indices could be estimated from meteorological station-based air temperature and precipitation. However, meteorological station-based recorded precipitation and temperature data with long coverage are only available from a limited number of stations with insufficient spatial coverage. In other words, these datasets suffer from uneven geographic coverage, with many areas of the Earth poorly represented. In this study, therefore, we have used satellite-derived temperature and precipitation data. Monthly mean air temperature has been estimated from MODIS LSTd, LSTn, and elevation using RF regression. Precipitation data has been extracted from Climate Hazards Group Infra-Red Precipitation with Station (CHIRPS) datasets. CHIRPS is gauge-satellite combined precipitation data. Based on De Martonne and Mezensev formulas, and satellite-derived meteorological data, spatial distribution maps of aridity and moisture indices in Mongolia were generated. The study result showed that aridity was observed in all areas of southern Mongolia, and some areas in the west, and grassland areas in the east, which is largely included in the dry steppe, desert-steppe, and gobi desert zones. Moisture was observed in the forest and forest-steppe areas in north, central, northeastern, and eastern Mongolia. A comparison of the aridity index and moisture index shows the following: of the total territory, aridity is 31.9:31.4 percent, humidity 14.7:13.4 percent respectively. Dry steppe, desert steppe, and Gobi desert zones are extremely sensitive to water resource variability and availability.

A Review of the Genus Alloptox (Lagomorpha, Ochotonidae) from the Valley of Lakes, Central Mongolia, with Description of a New Species

A Review of the Genus Alloptox (Lagomorpha, Ochotonidae) from the Valley of Lakes, Central Mongolia, with Description of a New Species

Metallogenic Characteristics and Formation Mechanism of Naomugeng Clay-Type Lithium Deposit in Central Inner Mongolia, China

A newly discovered Naomugeng lithium mineralization area is located to the east of the Central Asian Orogenic Belt (CAOB). The lithium is hosted in the volcanic rocks of the Manketou’ebo Formation. The altered volcanic rocks mainly consist of quartz, orthoclase, chlorite, montmorillonite, calcite, and dolomite. Here, we present integrated studies of petrography, mineralogy, and geochemistry of the altered volcanic rocks (with an average Li2O content of 0.43 wt.%) collected from the drilling hole and trail trench to systematically investigate the occurrence of lithium, the mineralizing processes, and the metallogenic mechanisms. The secondary minerals of the core samples are montmorillonite, chlorite calcite, and dolomite, while the secondary minerals from the earth surface ones are montmorillonite, chlorite, and calcite. The mass change calculation and isocon analysis show that the rocks received MnO, P2O5, Co, Ni, Cu, and Li and lost Na2O, K2O, MgO, rare earth elements (REE), and Rb in the alteration process. However, other elements such as Fe, V, Co, and Ca of the core samples increased while those of the earth surface ones did not change by much. Hence, there are two zones of alterations, i.e., the montmorillonization-chloritization zone and the montmorillonization-chloritization-carbonatization zone. Lithium enrichment occurs in the zone where montmorillonization and chloritization occur. The lithium is probably enriched in altered minerals such as montmorillonite and chlorite in the forms of interlayered or adsorbed ions. The slightly negative to positive Eu anomalies of the rocks can be explained by the metasomatism of hydrothermal fluid that enriched Eu. We suggest that the Naomugeng deposit is a clay-type lithium deposit and formed under a caldera setting. The meteoric and hydrothermal fluids leach the lithium from the volcanic materials and then alter the host rocks (e.g., tuff or sediments) in the caldera basin, which forms the type of lithium clay deposit. This study analyzed the migration behavior of elements in the Naomugeng lithium deposit during a hydrothermal process, which shows that the mass balance calculation has good application in reflecting the mineralization process of clay type deposit. This study also reveals the great exploration potential of the Naomugeng deposit and has important significance for further prospecting of clay-type lithium deposits in central Inner Mongolia.

Changes in the Tree-Ring Width-Derived Cumulative Normalized Difference Vegetation Index over Northeast China during 1825 to 2013 CE

Vegetation coverage is very important in terrestrial ecosystems and climate systems. However, the observational record of the normalized difference vegetation index (NDVI), which started in the 1980s when satellites became widely used, is too short to investigate the history of variation in vegetation coverage beyond the modern observation period. Here, we present a 189 y vegetation coverage series based on a total of 349 Mongolian pine (Pinus sylvestris var. mongolica Litv) cores from seven locations from the central–western Da Hinggan Mountains (CW–DHM), northeastern China. We found a significant relationship between tree-ring width and the regional cumulative normalized difference vegetation index (CNDVI). The correlation between the ring-width chronology and the regional June–July CNDVI (CNDVIJJ) was significant, with r = 0.68 (n = 32, p &lt; 0.001) and an explained variance of 45.8% (44.0% after the adjustment for the loss of the degree of freedom). On this basis, we designed a transfer function to reconstruct the CNDVIJJ for the CW–DHM region from 1825 to 2013 CE (Common Era). During the last 189 years, there were 28 years with high CNDVIJJ values, and another 28 years with low values. We also observed CNDVIJJ fluctuations at the inter-annual and decadal time scales, including eight low value periods and nine high value periods. Based on our analysis, the variation in CNDVI is associated with climatic factors, such as temperature, precipitation and the Palmer Drought Severity Index (PDSI), which combines both temperature and precipitation. From 1950 to 2002 CE, the CNDVI showed a noticeable decreasing trend in the CW–DHM region, whereas after 2003 CE, the CNDVI exhibited an apparent increase, which has also been observed in southern Central Siberia, eastern Mongolia and northeastern and eastern China, indicating that the CNDVI change in the CW–DHM is related to climate change in the local region and in some parts of Asia.