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Studying surface geochemical anomalies is important for detecting the presence of mineral deposits. However, distinguishing inconspicuous geochemical anomalies is a challenge for geochemists. This paper studies geochemical quantitative prediction for Pb–Zn metallic mineral deposits by identifying inconspicuous surface geochemical anomalies mainly associated with the Permian and Jurassic strata in the middle-southern Da Hinggan Mountains metallogenic belt. Some new methods are employed to highlight weak surface geochemical anomalies. The weak surface geochemical anomalies of Pb and Zn are effectively highlighted by the average contrast values of Pb–Zn–Ag–Cd. The similarity coefficient with the large typical discovered deposits is used to identify new Pb–Zn mineralized anomalies and delineate new prospecting target areas. The denudation degree of mineral deposit is determined by the ratio of (W × Sn)/(As × Sb). The analogy method and areal productivity method are employed for resource prediction. Thirty-six prediction areas with Pb–Zn resources of 307.73 million tons are delineated. Five prediction areas are verified, and some new mineral deposits are proven by drilling. The verification results show that the predicted resources are very reasonable and credible. This paper is a successful case of quantitative prediction assessment of mineral resource potential, which can be used as a reference for future prospecting activities. [ABSTRACT FROM AUTHOR]

Metal migration and precipitation in hydrothermal fluids are important topics in economic geology. The Hongling polymetallic deposit comprises one of the most important parts of the Huanggangliang–Ganzhuermiao polymetallic metallogenic belt, which is in eastern Inner Mongolia. Except for lead–zinc skarn, minor cassiterite in the skarn and disseminated W–Sn mineralization in granitic rocks have also been found. The dominant Sn–W mineralization is in the northern part of the deposit, occurring as disseminated wolframite and cassiterite in aplite hosted in Mesozoic granite porphyry. The aplite together with pegmatite K-feldspar–quartz comprises vein dikes hosted in the granite porphyry, providing evidence for the transition from melt to fluid. The veins, dikes, and Sn–W mineralization in the aplite provide an opportunity to investigate fluid exsolution and the mechanics of metal precipitation. Based on field observations, the micrographic and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) results of the vein dikes, chronology, and the whole-rock geochemistry of the host rock, together with the fluid inclusion results, this paper discusses the characteristics of the causative magma, the mechanics of fluid exsolution and W–Sn precipitation. Our results show that the causative magma is of highly fractionated A-type granite affinity and has an intrusive age of late Mesozoic (133.3 ± 0.86 Ma). The magmatic evolution during shallow emplacement led to immiscibility between highly volatile, high-silica, and W- and Sn-enriched melts from the parent magma, followed by fluid exsolution from the water-rich melt. The alkaline-rich fluid exsolution led to a change in the redox state of the magma and the chilling of the melt. Fluid boiling occurred soon after the fluid exsolution and was accompanied by the degassing of CO2. The boiling and escape of CO2 from the fluid led to changes in fluid redox and W and Sn precipitation; thus, the W and Sn mineralization are mostly hosted in causative intrusions or peripheral wall rocks, which can be used as indicators for Sn–W exploration in the area. [ABSTRACT FROM AUTHOR]

This paper presents scientific analyses of the wall paintings in Wudang Lamasery, which is located in the Baotou area of Inner Mongolia, China. Raman spectroscopy was used to analyze the pigments of the mural of the Lam rim Hall. The results show that vermilion, red lead, chrome yellow, emerald green and synthetic ultramarine were used. The existence of synthetic pigments provides a clue for the date the mural was painted. [ABSTRACT FROM AUTHOR]

Gallium (Ga) and germanium (Ge) critical elements have a wide range of applications and market value. Extracting critical elements from coal gangue and combustion products can alleviate pressures on primary mining resources. Understanding the transformation behavior of Ga and Ge during coal gangue combustion processes is significant for resource utilization and environmental protection. Coal gangue from Xing'an League, Inner Mongolia, was chosen to explore how combustion temperatures (600 °C to 1000 °C) and particle sizes (50, 80, 10, 140, and 200 mesh) influence Ga and Ge migration during combustion. Techniques such as ICP-MS, XRD, XRF, SEM, TG-DSC, and sequential chemical extraction were employed to analyze the transformation of minerals and to quantify the contents and occurrence forms of Ga and Ge. Smaller gangue particle sizes were associated with higher concentrations of Ga and Ge. Approximately 99.19% of Ga and Ge in coal gangue were found in the residual, organic/sulfide-bound, and metal-oxide-bound modes. High temperatures promoted element volatilization and changed the reactions and interactions between elements and minerals. As combustion temperatures rose from 600 °C to 1000 °C, Ga and Ge contents in the products declined progressively. Under high temperatures, minerals like kaolinite, illite, and pyrite in gangue converted to silicate glass phases, mullite, and hematite. Minerals like kaolinite, calcite, and pyrite melted, leading to increased cohesion and agglomeration in the products. Over 90% of Ga and Ge in the combustion products existed in the residual, organic/sulfide-bound, and metal-oxide-bound forms. Moreover, Ga was enriched in combustion products, with its content exceeding critical extraction levels. The results may provide a useful reference for developing critical elements enrichment, extraction, and separation technologies from coal gangue. [ABSTRACT FROM AUTHOR]

The Aolunhua Mo deposit is a typical porphyry deposit, which is located in the middle southern section of the Da Hinggan Range metallogenic belt. Here, we report LA-ICP-MS zircon U-Pb age data from the Mo-associated granitoid, together with the element geochemistry of the zircons, discussing the source material of the ore-forming rock of the deposit. The zircon data constrain the crystallization age of the granite porphyry as 135.0 ± 1.0 Ma, correlating it with the widespread Yanshanian intermediate–felsic magmatic activity. The Th/U ratio of the zircon is greater than 0.1, with a significant positive Ce anomaly (Ce* = 1.72–188.71) and a negative Eu anomaly (Eu* = 0.05–0.57). The zircons show depleted LREE and enriched HREE patterns, as well as low La and Pr contents, suggesting crystallization from crust-derived magmas. Based on the geology of the ore deposit and the age data, in combination with the regional geodynamic evolution, we infer that the Aolunhua Mo deposit was formed near the peak stage of Sn poly-metallic metallogenesis in the Da Hinggan Range region at around 140 Ma, associated with a tectonic setting, characterized by the transition from compression to extension. Based on a comparison with the newly found Mo deposits along the banks of the Xilamulun River, we propose that the Tianshan–Linxi is an important Mo-metallogenic belt. It also suggests an increased likelihood for the occurrence of Mo along the north bank of the Xilamulun River. [ABSTRACT FROM AUTHOR]

Lithium (Li) is an important strategic metal mineral resource, irreplaceable in the fields of modern industry, new energy technology, nuclear fusion, and energy storage devices. Li is an important supplement to traditional strategic metal mineral resources and has become an important avenue of mineral resource exploration. Therefore, there is an urgent need to establish a cooperative exploration model of coal and Li deposits to lay a theoretical foundation from the perspective of technical optimization and economic rationality. This study is based on the distribution characteristics of the Haerwusu coal–Li deposit, and the effectiveness of the response to exploration techniques, the economical and effective exploration techniques, the reasonable exploration engineering design, and resource estimation parameters is investigated. Therefore, the cooperative exploration model of the coal–Li deposit is established. The high-Li areas in the surface of the Haerwusu Li deposit is distributed near the B1 anticline or in the middle area between the X1 syncline and the B1 anticline, and the vertical distribution of Li content is irregular. The exploration techniques, exploration engineering design, and resource estimation are reviewed and optimized. According to the geological, geochemical, and geophysical conditions, a reasonable cooperative exploration model for coal–Li deposits is established from the two aspects of the coordination of multi-mineral exploration and the coordination of various exploration technologies. The determination of the coal–Li deposit cooperative exploration model has important practical significance for improving the resource security system. [ABSTRACT FROM AUTHOR]

Trapiche-like quartz, which is scarcely reported, has a unique texture with a core, six arms, and quartz growth sectors. This study is based on six trapiche-like quartz from the Dongwuqi area, Inner Mongolia, China. Many experiments have been carried out to investigate the basic gemological characteristics, crystal structures, and chemical compositions. Magnification observation has demonstrated that the texture is due to the distribution of white-colored chalcedony in growth sectors. Spherical and black inclusions have been identified as iron oxides by Raman spectra and EPMA. EPMA and LA-ICP-MS data have shown that the samples were grown in an acidic environment with an average medium-high temperature of 325 °C. Combined with the crystal growth theories and infrared experiments, we propose that the trapiche-like texture is the result of dislocation glide, which is caused by the existence of water and changes in temperature. [ABSTRACT FROM AUTHOR]

Double-roadway tunneling could mitigate the contradiction between mining production needs and tunneling speed, which is pivotal to the sustainable development of underground mines. However, it is very difficult to control the stability of a mining roadway on an adjacent working face suffering from strong mining disturbance due to double-roadway tunneling, especially at a large mining height working face. In order to control the stability of the return air roadway (RAR) 23205 of a strong mining roadway at working face 23205 in the Zhuanlongwan Coal Mine in Inner Mongolia, we carried out field monitoring, theoretical analysis, numerical simulations, and engineering practice to identify the main factors influencing the deformations and the stress distribution law of the surrounding rock in order to propose countermeasures for strong mining roadways. The results show the factors influencing the large deformation of strong mining roadways include large mining height, repeated mining, stress concentration due to the large coal pillar, and a small thickness of the anchorage layer in the roof. The stress peak in the central coal pillar caused by the first and second mining is 23.19 MPa and 27.49 MPa, respectively, and the stress concentration coefficients are 4.538 and 5.379, respectively. Countermeasures (pressure relief via large-diameter boreholes in the large coal pillar and long anchorage for roof reinforcement) were created to control the stability of a strong mining roadway, i.e., RAR 23205. Field measurements indicated that deformations in RAR 23205 could be efficiently controlled. The maximum deformation of the surrounding rock was 50 mm, which meets the safety and efficient production requirements of the coal mine. In addition, new roadway layout optimization and control countermeasures are put forward to control the stability of mining roadways. [ABSTRACT FROM AUTHOR]

The super-large Baerzhe Be–Nb–Zr–REE deposit in NE China is hosted in the Early Cretaceous peralkaline granites. In this work, the newly discovered granitic dikes developed around the Baerzhe deposit were studied for the first time, focusing on their genesis and genetic relationships with the Baerzhe peralkaline granites. Zircon U-Pb dating of these granitic rocks (including the granite porphyry, rhyolite and miarolitic granite) yielded Early Cretaceous ages of 125–121 Ma. Their mineral assemblages and geochemical features suggest that they share similar features with the peralkaline A-type granites. Their geochemical data and zircon Hf isotopic compositions (εHf(t) = +3.4 to +10.5) indicate that the peralkaline granitic rocks were formed by the partial melting of dehydrated charnockite with extensive plagioclase crystal fractionation, which resulted in a peralkaline affinity. There are two types of distinct zircons in the studied samples: the type I zircon with a bright rim and dark core, which may represent a cumulate mineral phase captured together with aggregates during eruption, and the type II zircon with a higher evolution degree crystallized in the residual melts. Combined with the simulation results using whole-rock trace elements, we proposed that the peralkaline granitic dikes represent more evolved interstitial melts than the Baerzhe granitic magma. In the Early Cretaceous extensional tectonic settings, mantle-derived magma upwelled, which induced the melting of the lower crust and prolonged the evolutionary process of the magma crystal mush. [ABSTRACT FROM AUTHOR]

The Bayan Obo deposit is the largest REE resource in the world. Although many isotopic dating methods have been applied, ages based on petrography and closure temperatures still lack discussion. In this study, three digital petrographic images were created based on full-scanning microscopy, BSE, and TESCAN integrated mineral analysis (TIMA), providing a more scientific method for analyzing the mineral types, distributions, and content of the Bayan Obo deposit. By combining the full-scan images, monazites were selected in thin sections and dated in situ. The monazite in the body ores sample yields three 207Pb intercept ages of 657 ± 25 Ma (MSWD = 1.06), 763 ± 16 Ma (MSWD = 1.3), and 689 ± 22 Ma (MSWD = 8.1), and the monazite in one section yields maximum and minimum ages of 1393 ± 142 Ma and 429 ± 24 Ma, respectively. Combined with previous studies, the earliest and major stages of carbonatites, REE, and dikes in the Bayan Obo deposit area were dated at ~1.4 Ga and ~1.3 Ga, respectively. Due to the multiple subduction and accretion events related to the Paleo-Asian Ocean and North China Craton, the Bayan Obo deposit is intensely overprinted, with a tectonic-thermal event recorded at ~1.0–0.2 Ga. The multiple or protracted isotopic ~1.4–0.4 Ga ages in the Bayan Obo deposit account for five reasons. First, the separate thermal events and the partial recrystallization of monazite. Second, the diffusion of daughter products from the host mineral over time. Third, differences in the closure temperatures of different minerals and isotopic chronologies. Four, resetting of the closure system due to high temperature and hydrothermal alteration. Five, the minerals and transformed ores that formed in the Paleozoic. The in situ monazite U–Pb ages in thin sections provide insight into formation sequences from the giant Bayan Obo Fe–REE–Nb deposit. [ABSTRACT FROM AUTHOR]

Intra-oceanic subduction is a fundamental process on Earth, the study of which can improve the understanding of plate tectonic processes and the history of continental growth. Here, we report on newly recognized trondhjemite in the north of Diyanmiao ophiolite belt in North China. The trondhjemite was found along the Erenhot-Hegenshan suture zone. U-Pb zircon dating revealed that the trondhjemite crystallized at 309 ± 2.1 Ma. The trondhjemite had a high amount of SiO2 (68.94–76.45 wt %), Al2O3 (13.37–15.90 wt %), and Sr (232–601 ppm); and a low amount of K2O (1.57–2.70 wt %), Y (6.91–9.39 ppm), Ni (1.10–4.19 ppm), and Cr (1.55–13.50 ppm). The Na2O/K2O ratios were 1.90–4.37. There was a lack of negative Eu anomalies. It was relatively enriched in large-ion lithophile elements (LILEs) such as Rb, Ba, K, and Sr; was depleted in high-field-strength elements (HFSEs) such as Nb, Ta, Ti, and P; and had low total rare-earth element (REE) contents (27.73–49.63 ppm) with distinct REE fractionation (chondrite-normalized (La/Yb)N of 5.76–10.52), which was similar to adakitic rocks formed by partial melting of subducted oceanic crust. The trondhjemite, together with Diyanmiao ophiolite (335.6 Ma), may have formed during the stages of intra-oceanic subduction, suggesting that in the Early Carboniferous–Late Carboniferous, the southern Paleo-Asian Ocean was in its subduction stage. [ABSTRACT FROM AUTHOR]

The large Bayanbaolege Ag polymetallic ore deposit is located in the Tuquan-Linxi Fe (Sn)-Cu-Pb-Zn-Ag-Nb (Ta) polymetallic metallogenic belt, which is an important part of the Great Xing'an Range metallogenic province, northeast China. The sulfide–quartz vein-type orebodies in the deposit are mainly hosted in the Cretaceous granodiorite porphyry and Late Permian Linxi formation. The U-Pb dating of the zircon from the post-ore diorite porphyrite yields an age of 124.8 ± 1.1 Ma, which constrains the mineralization time at the Early Cretaceous. The Sr-Nd isotope values (87Sr/86Sr)i = 0.708576~0.710536; εNd (t) = −0.51~+0.69; the Hf isotope values 176Hf/177Hf = 0.2827278~0.2830095, the εHf (t) = +3.1~+11.2, TDM2 = 615~1341 Ma of the metallogenic granodiorite porphyry. The Hf isotope values 176Hf/177Hf = 0.2828596~0.2829451, and the εHf (t) = +5.7~+8.8 of the diorite porphyrite, TDM2 = 827~1108 Ma, indicating that the ore-forming materials were the possible involvement of heterogeneous juvenile sources including moderately depleted mantle and newly underplated lower crust. The major and trace elements (including REEs) implied that these intrusions are the I-type granite and linked intimately to the westward subduction of the Paleo-Pacific Ocean plate. From these whole-rock major and trace elements and zircon U-Pb ages, as well as Sr-Nd-Hf isotope data, we conclude that the ore-associated I-type granites in the Bayanbaolege deposit formed in an extensional tectonic setting of the Early Cretaceous, and are compactly related to the retreat of the Paleo-Pacific Ocean subducted plate linked intimately to the westward subduction of the Paleo-Pacific Ocean plate rather than the closure of the Mongol–Okhotsk Ocean. Furthermore, by integrating geological background work and previous research work, implying the mineralization age of the Bayanbaolege deposit should have been formed in the 125–130 Ma. [ABSTRACT FROM AUTHOR]

Multiple stages of igneous rocks occur in the recently discovered Nianzigou Mo deposit in Chifeng, Inner Mongolia, which can provide insights into the late Mesozoic geodynamic evolution of the southern Da Hinggan Range. The mineralization age is similar to the age of local granites, but there are few detailed studies of the tectonic setting during Cu-Mo mineralization in this area. The Nianzigou Mo deposit is located close to the northern margin of the North China Craton and in the eastern Central Asian Orogenic Belt and is a typical quartz-vein-type Mo deposit in the Xilamulun Mo ore belt. The granite in this deposit has high SiO2, Al2O3, K2O, and Na2O contents, and low MgO, CaO, and Fe2O3t contents. The granite is characterized by enrichments in large-ion lithophile elements and depletions in high-field-strength elements and, in particular, Sr, Ti, and P. The granite has high contents of rare-earth elements, is enriched in light rare-earth elements, and has marked negative Eu anomalies. The granite is an alkaline and calc-alkaline and metaluminous A-type granite. The zircon U-Pb ages of the monzogranite and granite porphyry are 157.2 ± 0.3 and 154.4 ± 0.4 Ma. The model age obtained by Re-Os isotopic dating is 154.3 ± 1.7 Ma, indicating that molybdenite mineralization also occurred during the Late Jurassic period. Given that the molybdenite Re contents are 7.8–24.9 ppm (average = 16.8 ppm), the ore-forming materials of the Nianzigou Mo deposit had a mixed crust–mantle source, but were mainly derived from the lower crust. Based on the geology and geochemistry, we propose that the Nianzigou Mo deposit formed in a postorogenic extensional tectonic setting associated with the southward subduction of the Mongol–Okhotsk oceanic plate. [ABSTRACT FROM AUTHOR]

A field trial was conducted in Inner Mongolia to evaluate the stabilization effects of phyto-stabilization, biochar-stabilization, and their coupled stabilization for As, Cu, Pb, and Zn in soil. Stabilization plants (Achnatherum splendens, Puccinellia chinampoensis, and Chinese small iris) and biochar (wood charcoals and chelator-modified biochar) were introduced in the field trial. The acid-extractable fraction and residual fraction of the elements were extracted following a three-stage modified procedure to assess the stabilization effect. The results after 60 days showed that the coupled stabilization produced a better stabilization effect than biochar-/phyto- stabilization alone. Achnatherum splendens and Puccinellia chinampoensis were found to activate the target elements: the residual fraction proportion of As, Cu, Pb, and Zn decreased while the acid-extractable fraction proportion of Cu and Zn increased in the corresponding planting area. Neither type of biochar produced a notable stabilization effect. The residual fraction proportion of As (20.8–84.0%, 29.2–82%), Pb (31.6–39.3%, 32.1–48.9%), and Zn (30.0–36.2%, 30.1–41.4%) increased, while the acid-extractable fraction proportion remained nearly unchanged after treatment using Chinese small iris-straw biochar or Achnatherum splendens-straw biochar, respectively. The results indicate that phyto-stabilization or biochar-stabilization alone are not suitable, whereas the coupled stabilization approach is a more efficient choice. [ABSTRACT FROM AUTHOR]

Lithology identification is an essential fact for delineating uranium-bearing sandstone bodies. A new method is provided to delineate sandstone bodies by a lithological automatic classification model using machine learning techniques, which could also improve the efficiency of borehole core logging. In this contribution, the BP neural network model for automatic lithology identification was established using an optimized gradient descent algorithm based on the neural network training of 4578 sets of well logging data (including lithology, density, resistivity, natural gamma, well-diameter, natural potential, etc.) from 8 boreholes of the Tarangaole uranium deposit in Inner Mongolia. The softmax activation function and the cross-entropy loss function are used for lithology classification and weight adjustment. The lithology identification prediction was carried out for 599 samples, with a prediction accuracy of 88.31%. The prediction results suggest that the model is efficient and effective, and that it could be directly applied for automatic lithology identification in sandstone bodies for uranium exploration. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) are considered critical elements in modern society due to their irreplaceable role in new innovative and energy technologies. The giant carbonatite-related Bayan Obo deposit contributes most REE resources in the world's market, while its origin is still unclear because of the complicated and diverse REE ore mineralogy and texture. Thescanning electron mircroscopy SEM)-based automated mineralogy allows for the numeric assessment of rocks and ores' compositional and textural properties. Here, we use TIMA (TESCAN Integrated Mineral Analyzer) to quantitatively characterize REE ore mineralogy from the deep drill core within the H8 unit ("dolomite marble") to better understand the deposit. The mineral composition, occurrence, and Ce elemental deportment of the borehole ores at different depths (i.e., 1107 m, 1246 m, 1406 m, 1546 m, and 1682 m) were obtained. The results show that the main types of ores in the investigated samples can be divided into banded REE-Fe ores, banded REE ores, disseminated REE-Fe ores, and veined REE ores. REE and gangue minerals vary significantly in abundance and occurrence. Monazite-(Ce) and bastnäsite-(Ce) are the primary REE host minerals, and both contribute the most to the REE budget. Other REE minerals, such as parisite-(Ce)/synchysite-(Ce), cerite-(Ce), huanghoite-(Ce)/cebaite-(Ce), and aeschynite-(Ce), are significant contributors. The gangue minerals generally include fluorite, barite, magnetite, pyrite, quartz, magnesio-arfvedsonite, and minerals of the biotite and apatite groups, among others. Combined with the newly published mineral-scale chronological and isotopic geochemical analyses, it is reasonable to conclude that the later hydrothermal fluids remobilized and redistributed the original Mesoproterozoic carbonatitic REE minerals and formed a high variable ore mineral assemblage. Furthermore, it is demonstrated that the mineralogical study using TIMA can provide accurate and reliable mineralogy data for the comprehensive interpretation of the complex REE ores, and extend our understanding of the deposit. [ABSTRACT FROM AUTHOR]

Clay rock in the Tamusu (TMS) area in the Inner Mongolia province is one candidate as a geological disposal site for highly radioactive waste in China. The diffusion behavior of HTO and Se(IV) in Tamusu clay rock was studied by through-diffusion (TD) experiments and numerical analysis to determine the spatial and temporal variation. A minimum error analysis was conducted to determine the HTO and Se(IV) diffusion coefficients in compacted TMS clay. The TD experimental results and numerical analysis showed that the diffusion of HTO and Se reached a steady state within 7 and 50 days, respectively, and the apparent diffusion coefficients (Da) decreased with the increases in the compacted density. In fact, there was retardation of Se diffusion in intact TMS clay rock. A two-site sorption model for Se was applied to simulate fast and slow sorption behavior quantitatively. [ABSTRACT FROM AUTHOR]