Minerals

A complete series of the calcite–otavite solid solutions [(Ca_1−xCd_x)CO₃] were prepared, and their dissolution processes lasting nine months were experimentally investigated. For the dissolution in the N₂-degassed water, the Ca concentrations of the aqueous phases increased up to the steady states after 5040 h of dissolution, and the Cd concentrations of the aqueous phases increased up to the highest values and then decreased gradually to the steady states of 0.017–6.476 μmol/L after 5040 h of dissolution. For the dissolution in the CO₂-saturated water, the Ca and Cd concentrations of the aqueous phases increased up to the peak values and then decreased gradually to the steady states of 0.94–0.46 mmol/L and 0.046–9.643 μmol/L after 5040 h of dissolution, respectively. For the dissolution in the N₂-degassed water at 25 °C, the mean solubility products (log K_sp) and the Gibbs free energies of formation (ΔG_f^θ) were estimated to be −8.45–−8.42 and −1129.65–−1129.48 kJ/mol for calcite [CaCO₃] and −11.62–−11.79 and −671.81–−672.78 kJ/mol for otavite [CdCO₃], respectively. Generally, the log K_sp values decreased non-linearly, and the ΔG_f^θ values increased linearly with the increasing Cd/(Ca+Cd) mole ratio (X_Cd) of the (Ca_1−xCd_x)CO₃ solid solutions. In the Lippmann diagrams constructed for the sub-regular (Ca_1−xCd_x)CO₃ solid solutions with the estimated Guggenheim coefficients a₀ = −0.84 and a₁ = −3.80 for the dissolution in the N₂-degassed water or a₀ = −1.12 and a₁ = −3.83 for the dissolution in the CO₂-saturated water, the (Ca_1−xCd_x)CO₃ solid solutions dissolved incongruently, moved progressively up to the quasi-equilibrium curves for otavite and then along the quasi-equilibrium curve from right to left, approached the solutus curve and finally reached the minimum stoichiometric saturation curve for calcite. The considerably Cd-poor aqueous phases were finally in equilibrium with the CdCO₃-rich solid phases. Full article

Natural minerals and earths with coloring properties have been widely used as artistic pigments since prehistoric times. Despite being extensively studied, the complex chemistry of earth pigments is still unsatisfactory described with respect to their mineralogical and structural variability and origin. In this study, a large group of earth pigments from various geographical locations was investigated using easily accessible spectroscopic techniques and multivariate analysis with the aim to identify distinctive mineralogical and chemical characteristics of natural pigment sources. Portable X-ray fluorescence (p-XRF), Fourier transform infrared spectroscopy (FTIR) and fiberoptic Raman spectroscopy were used for the elemental, molecular and structural characterization of the investigated pigments. Diagnostic spectral features and chemical patterns (fingerprints) were identified and discussed with respect to their geological sources. Due to the occurrence of similar accompanying minerals, it was observed that the differentiation of red and yellow ochers is more challenging compared to green, brown and black pigments. However, for some of the investigated pigments, the presence of certain accessory minerals and/or of certain chemical patterns can have diagnostic value. Principal component analysis (PCA) of the FTIR and XRF data matrices showed promising results in terms of geological attribution, highlighting a promising tool for provenance research. The results of the study demonstrate the potential benefits of this rapid and nondestructive approach for the characterization and differentiation of earth pigments with similar hues coming from different geological sources. Full article

The cost, complexity, lack of filling space and time create challenges in the longwall backfill operation, resulting in poor subsidence control and reduced productivity. This paper proposes an automated continuous mining and continuous backfill (CMCB) method by examining its key requirements and investigates the optimum sequence of coal panel (such as drifts) excavation to ensure ground strata control at relatively high productivity. The automated CMCB adopts the highwall mining technique underground, which enables easier automation at the workface. A numerical simulation of the Changxing coal mine in China was undertaken, and five different sequences of coal excavation were investigated, using the automated CMCB excavation parameters (assuming a 4 m width cut, 5 m mining height for a 200 m long coal slice) to determine the optimum sequence of resource excavation. The plastic zones and vertical displacement across the five models were analyzed. Simulation results of the 5 m high coal seam excavation show that the odd-even slice (OES) mining sequence, which has a vertical ground displacement of 74 mm, is the most efficient excavation method, due to its effective stress redistribution and lower induced ground displacement. Full article

Lithium-ion batteries (LIBs) are dangerous to recycle, as they pose a fire hazard when cut and contain various chemical hazards. If recycled safely, LIBs provide a rich secondary source for metals such as lithium and cobalt, while reducing the environmental impact of end-of-life LIBs. Discharging the spent LIBs in a 5 wt.% NaCl electrolyte at room temperature enables their safe dismantling. A sludge was observed to form during the LIB discharging, with a composition of 34.9 wt.% Fe, 35 wt.% O, 17.7 wt.% Al, 6.2 wt.% C, and 4.2 wt.% Na. The average electrolytic solution composition after the first discharge cycle contained only 12.6 mg/L Fe, 4.5 mg/L Li, 2.5 mg/L Mn, and trace amounts of Ni and Co. Separating the active cathode powder from the aluminum cathode with a 10 wt.% NaOH leach produced an aqueous filtrate with an Al metal purity of 99.7%. The leach composition consisted of 9558 mg/L Al, 13 mg/L Li, 8.7 mg/L Co, and trace amounts of Mn and Ni. The hydrometallurgical sample preparation processes in this study enables the production of a pure black mass with less than 0.05 wt.% Co, 0.2 wt.% Li, 0.02 wt.% Mn, and 0.02 wt.% Ni losses from the active cathode material. Full article

A short-term side-effect of CO₂ injection is a developing low-pH front that forms ahead of the bulk water injectant, due to differences in solute diffusivity. Observations of downhole well temperature show a reduction in aqueous-phase temperature with the arrival of a low-pH front, followed by a gradual rise in temperature upon the arrival of a high concentration of bicarbonate ion. In this work, we model aqueous-phase transient heat advection and diffusion, with the volumetric energy generation rate computed from solute-solvent interaction using the Helgeson–Kirkham–Flowers (HKF) model, which is based on the Born Solvation model, for computing specific molar heat capacity and the enthalpy of charged electrolytes. A computed injectant water temperature profile is shown to agree with the actual bottom hole sampled temperature acquired from sensors. The modeling of aqueous-phase temperature during subsurface injection simulation is important for the accurate modeling of mineral dissolution and precipitation because forward dissolution rates are governed by a temperature-dependent Arrhenius model. Full article

The Mesozoic Xuefengshan Orogen (XFSO) in South China hosts abundant gold ore deposits. The XFSO records a history of polyphase tectonic deformation and the structural controls on gold mineralization are poorly understood. The recently discovered quartz-vein type Huanggou gold deposit in the southern XFSO is characterized by multiple stages of deformation and represents an excellent natural laboratory for deciphering structural controls on gold mineralization in a complex orogenic belt. A systematic structural analysis indicates that the geometry of the Huanggou gold deposit and adjacent areas mainly resulted from four stages of deformation: (1) D₁ top-to-the-NW sense of shearing; (2) D₂ SE-directed back-folding and back-thrusting; (3) D₃ NW–SE upright folding; and (4) D₄ NW–SE normal faulting and fracturing. Two sets of quartz veins are exposed in the deposit: (1) SE-dipping Au-bearing quartz veins; and (2) NW-dipping non-mineralized quartz veins. The SE-dipping Au-bearing quartz veins were likely formed by the main deformation phase of the XFSO. During D₁ top-to-the-NW simple shearing, these synkinematic Au-bearing quartz veins progressively evolved into sigmoidal shapes and rotated to a preferred SE-dipping orientation. Subsequently, D₂ SE-directed back-folding and back-thrusting resulted in the formation of synkinematic NW-dipping non-mineralized quartz veins. D₃ upright folding locally steepened the dips of both Au-bearing and non-mineralized quartz veins. Our results may provide new insights into the structural controls of gold mineralization in the XFSO. Full article

Global sensitivity analysis (GSA) is a fundamental tool for identifying input variables that determine the behavior of the mathematical models under uncertainty. Among the methods proposed to perform GSA, those based on the Sobol method are highlighted because of their versatility and robustness; however, applications using complex models are impractical owing to their significant processing time. This research proposes a methodology to accelerate GSA via surrogate models based on the modern design of experiments and supervised machine learning (SML) tools. Three case studies based on an SAG mill and cell bank are presented to illustrate the applicability of the proposed procedure. The first two consider batch training for SML tools included in the Python and R programming languages, and the third considers online sequential (OS) training for an extreme learning machine (ELM). The results reveal significant computational gains from the methodology proposed. In addition, GSA enables the quantification of the impact of critical input variables on metallurgical process performance, such as ore hardness, ore size, and superficial air velocity, which has only been reported in the literature from an experimental standpoint. Finally, GSA-OS-ELM opens the door to estimating online sensitivity indices for the equipment used in mineral processing. Full article

The Hetaoping ore district in Baoshan City, Yunnan Province, is one of the major localities of Pb-Zn polymetallic skarn deposits in China, where geophysical and geochemical surveys play an important role in exploring Pb-Zn polymetallic mineral resources. Based on the exploration and prospecting carried out at the periphery of the Hetaoping Pb-Zn polymetallic deposit, this study proposed an aero-ground joint exploration method to determine the metallogenic model of distal skarns in the Hetaoping ore district, achieving ideal prospecting results. The steps of this method are as follows. First, the locations of ore-induced anomalies were determined using high-amplitude aeromagnetic anomalies. Then, the ore-induced anomalies were determined to be anomalies of Pb-Zn polymetallic deposits through geochemical surveys of soil samples and ground geophysical surveys. Based on these data, a quantitative analysis and metallogenic potential assessment of ore bodies and their surrounding rocks were conducted using the interactive 2.5D magnetic inversion. In addition, the 3D inversion of regional gravity data was also performed in order to determine the spatial location of the deep magma chamber. Accordingly, the metallogenic geological process in this area was analyzed by determining the spatial morphology of the deep magma chamber, and a prospecting model of the Pb-Zn polymetallic deposits was finally built. The results show that the aero-ground joint exploration method, which first conducts a rapid scanning survey using the aeromagnetic method and then locates, distinguishes, and assesses significant aeromagnetic anomalies by combining comprehensive verification means such as ground geophysical, geochemical, and geological surveys, is efficient and economical. This study will guide regional metallogenic research and the exploration and prospecting of Pb-Zn polymetallic deposits. Full article

The problem of spent fluid catalytic cracking (SFCC) catalyst resource utilization, draws more and more attention to system analysis. SFCC was leached in an oxalic solution for comprehensive utilization. The results showed that for a D50 ≤ 17.34 μm, the catalyst leached for 240 min at 95 °C in the presence of a 2 mol/L oxalic acid solution, and the extent of leaching of V, Ni, Fe, and Al was 73.4%, 32.4%, 48.2%, and 36.8%, respectively. Studies on the occurrence state of the main ions (V, Ni, Fe, and Al) in the leaching solution were presented. Additionally, the separation of the main ions from such a solution by the “solvent extraction-stripping-hydrothermal precipitation-comprehensive recovery of valuable metal” process was studied. The immobilization rates of vanadium and nickel in geopolymers can be obtained using the toxicity characteristic leaching procedure (TCLP) test, and the geopolymers prepared by SFCC leaching residues can be considered a non-hazardous material. A process diagram of the comprehensive utilization of SFCC catalysts is presented. Full article

A geoenvironmental assessment methodology was developed to estimate waste quantities and disturbances that could be associated with the extraction of undiscovered uranium resources and identify areas on the landscape where uranium and other constituents of potential concern (COPCs) that may co-occur with uranium deposits in this region are likely to persist, if introduced into the environment. Prior to this work, a method was lacking to quantitively assess the environmental aspects associated with potential development of undiscovered uranium resources at a scale of a uranium resource assessment. The mining method of in situ recovery (ISR) was historically used to extract uranium from deposits in the Goliad Sand of the Texas Coastal Plain. For this reason, the study’s methodology projected the following types of wastes and disturbances commonly associated with ISR based on historical ISR mining records: the mine area, affected aquifer volume, mine pore volume, water pumped and disposed during uranium extraction and restoration, and radon emissions. Within the tract permissive for the occurrence of undiscovered uranium resources, maps and statistics of factors were derived that indicate the potential contaminant pathways. The percentage of days meeting the criteria for air stagnation indicate the potential for radon accumulation; the geochemical mobility of COPCs in groundwater in combination with effective recharge indicates the potential for infiltration of surface-derived COPCs; the geochemical mobility of COPCs in groundwater combined with hydraulic conductivity indicates the propensity for transmitting fluids away from contaminated or mined aquifers; and finally, geochemical mobility of COPCs in surface water combined with the factor for climatic erosivity (R factor) indicates the potential for COPCs to persist in surface waters due to runoff. This work resulted in a new methodology that can be applied to any undiscovered mineral resource to better understand possible wastes and disturbances associated with extraction and identify areas on the landscape where COPCs are likely to persist. Full article

The stability of surrounding rock is the basic guarantee of underground space engineering safety. The large deformation of a roadway’s surrounding rock is a very common phenomenon during the underground excavation of coal mine roadways or coal mining, especially in deep soft rock mining roadways. With the increase in mining depth and mining stress, it is very important to prevent disasters caused by surrounding rock deformation. This work aims to conduct an optimization design of roadway support for deep soft rock in coal mines using a full-space synergy control technology. FLAC3D-based orthogonal numerical experiments are adopted to study the influence of bolt parameters and plastic yield zone variation on the deformation of roadway surrounding rock, which provides a basis for optimizing the support design of coal mine roadways. According to the results of the numerical analysis, the optimal support parameters are determined as 20 mm, 2.2 m and 700–900 mm for diameter, length and interval of the bolt, respectively. Finally, the determined bolt-shotcrete net beam support scheme from the full-space synergy control idea is used in a study case. Results illustrate that this study can provide reliable guidance for the stability control of deep soft rock roadways in mining fields under high stress, and it can work well to keep the surrounding rock deformation within the safe limits. Full article

Considering the shortcomings of the currently used time functions for dynamically predicting surface mining subsidence and calculating its parameters, a novel time function is proposed on the basis of an in-depth analysis on the movement characteristics of mining surface points in a fully mined area and the measured mining subsidence data in the field during the course of the mining process. The proposed function can be used to effectively characterize the surface subsidence, the subsidence velocity, and the acceleration of the mining area. All the parameters involved in the function have their physical meaning, and their influence on the function was also analyzed in this study. A parameter calculation method is proposed for the new time function based on the normalization method and least square principle. Taking the measured dynamic subsidence data of 22,618 working faces in a coal mine as an example, the reliability of the new time function model was verified by comparing the measured data with the predicted results. The results show that the average relative root-mean-square error was 5.2%, and the prediction accuracy was improved compared with the Knothe time function, double-parameter Knothe time function, and piecewise optimized Knothe time function. Full article

The Great Altai region, located at the boundary of Russia, Mongolia, China, and Kazakhstan, belongs to the system of the Central Asian Orogenic Belt. It has undergone a long complex geological and metallogenic history. Extremely rich resources of base, precious, and rare metals (Fe, Cu, Pb, Zn, Ag, Au, Li, Cs, Ta, Nb, REE, etc.) maintain developed mining and metallurgical industry, especially in East Kazakhstan, which is the key metallogenic province. The East Kazakhstan province comprises the Rudny Altai, Kalba-Narym, West-Kalba, and Zharma-Saur metallogenic belts, each having its typical mineralization profiles and deposits. The reconstructed geodynamic and metallogenic history of the Great Altai province, along with the revealed relationships between tectonic settings and mineralization patterns, allowed us to formulate a number of geodynamic, structural, lithostratigraphic, magmatic, mineralogical, and geochemical criteria for exploration and appraisal of mineral potential in Eastern Kazakhstan. Geodynamic criteria are based on the origin of different mineralization types in certain geodynamic settings during the Late Paleozoic–Early Mesozoic orogenic cycle. Structural criteria mean that the location of base-metal deposits in Rudny Altai, gold deposits in the West Kalba belt, rare and base metals in the Kalba-Narym and Zharma-Saur zones is controlled by faults of different sizes. Lithostratigraphic criteria consist of the relation of orebodies with certain types of sedimentary or volcanic-sedimentary rocks. Magmatic criteria are due to the relation between mineralization types and igneous lithologies. Mineralogical and geochemical criteria include typical minerals and elements that can serve as tracers of mineralization. The joint use of all these criteria will open new avenues in prospecting and exploration at a more advanced level. Full article

The presence of aluminum in the weathering crust leaching rare earth ore harms the subsequent extraction and separation of rare earths. High-quality rare earth production processes must reduce the aluminum content in their feed liquid. Groups containing lone pairs of electrons can form stable insoluble complexes with metal ions under certain conditions. In this paper, 3-hydroxyphenylphosphoryl propionic acid is used to selectively separate rare earths by complexation in feed liquid. The results show that: using 3-hydroxyphenylphosphoryl propionic acid as the complexing agent, and when the amount of 3-hydroxyphenyl phosphoryl propionic acid is six times the theoretical complete reaction amount, the reaction time is 10 min, the reaction temperature is 50 °C, and the solution is adjusted to pH 1, the extraction rate of RE³⁺ is 90.48%, and the extraction rate of Al³⁺ is nearly 9.52%. The separation of rare earth and aluminum is well realized. 3-hydroxyphenyl phosphoryl propionic acid has good water solubility and low cost, and the product after complexation reaction with metal ions is solid and easy to separate. It has potential as an alternative complexing agent in the industry. Full article

Municipal solid waste incineration fly ash (FA) can represent a sustainable supply of supplementary material to the construction industries if it is pre-treated to remove hazardous substances such as chloride, sulfate, and heavy metals. In this paper, the phenomenology associated with a water washing multi-cycle treatment of FA is investigated, focusing attention upon the mineral dissolution process. The efficacy of the treatment is assessed by leaching tests, according to the European Standard, and discussed in light of the occurring mineral phases. The water-to-solid (L/S) ratio is a crucial parameter, along with the number of washing cycles, for removing halite and sylvite, whereas quartz, calcite, anhydrite, and an amorphous phase remain in the solid residue. The sequential extraction method and dissolution kinetics modelling provide further elements to interpret leaching processes, and suggest that dissolution takes place through a two-step mechanism. Altogether, multi-step washing with L/S = 5 is effective in reducing contaminants under the legal limits for non-hazardous waste disposal, while the legal limits for non-reactive or reusable material cannot be completely reached, owing to sulfate and some heavy metals which still leached out from the residue. Full article

The operational conditions, including temperature and gas composition, vary along the radial position in a blast furnace. Nevertheless, very few studies can be found in the literature that discuss how the reduction behavior of the ferrous burden varies along the radial position. In this study, the effect of the radial charging position on the reducibility of acid iron ore pellets was investigated using a laboratory-scale, high-temperature furnace in CO-CO₂-N₂ and CO-CO₂-H₂-H₂O-N₂ atmospheres up to 1100 °C. The experimental conditions were accumulated based on earlier measurements from a multi-point vertical probing campaign that was performed for a center-working European blast furnace. The main finding of this study is that the pellet reduction proceeded faster under simulated blast furnace conditions resembling those in the center area, compared to the wall area, because of a higher share of CO and H₂ in the gas. Therefore, the pellet charging position affects its reduction path in a blast furnace. Additionally, it was shown that the presence of H₂ and H₂O in the reducing gas enhanced the progress of reduction reactions significantly and enhanced the formation of cracks slightly, both of which are desirable in blast furnace operation. The reducibility data attained in this study are important in understanding how temperature and gas composition is connected to the reduction degree under realistic process conditions. Full article

The Uragen giant sandstone-hosted Zn–Pb deposit has a proven reserve of 5.90 Mt metals in the southern ore zone and potentially 10 Mt metals for the whole deposit, and orebodies are strictly confined to the bleached clastic rocks of the Lower Cretaceous red beds. The bleaching has been used to guide lead–zinc exploration; however, its nature and origin, as well as the relationship with Zn–Pb mineralization, remains unclear, although it is closely related to regional oil–gas infillings. Detailed field investigation and petrographic observation, TESCAN-integrated mineral analyzer (TIMA), and X-ray fluorescence (μ-XRF) analysis of the red and bleached sandstone at the same sedimentary layer demonstrate that the bleaching is mainly caused by the reductive dissolution of hematite pigment, which probably resulted from the interaction with H₂S formed by in situ sulfate reduction during hydrocarbon migration. The calcite cements in the bleached sandstones show δ¹³C and δ¹⁸O values of −5.36~−5.94‰ and 20.94~27.91‰, respectively, and these samples fall close to the evolution line of decarboxylation of organic matter in δ¹³C-δ¹⁸O diagram, also suggesting a genetic relationship between the bleaching and hydrocarbon-bearing fluids. Petrol–mineral composition changes and sulfide characteristics of red, bleached, mineralized zones, as well as pyrite locally replaced by coarse-grained galena in the mineralized zone, imply that the bleaching may occurred before Zn–Pb mineralization. Mass balance calculation and μ-XRF analysis indicate that large amounts of Fe and minor Zn were extracted from red beds with little or no sulfates; however, the red beds with abundant sulfates may be a sink for leached ore metals during the bleaching process. We therefore propose that the former accumulations of iron sulfides and reduced sulfur in the bleached zones may provide an ideal chemical trap for later Zn–Pb mineralization, and the bleached zones with high ∑S contents are the favorable prospective targets of the Uragen-style sandstone-hosted Zn–Pb deposits. Full article

Ground Penetrating Radar (GPR) is a geophysical method that uses antennas to transmit and receive high-frequency electromagnetic waves to detect the properties and distribution of materials in media. In this paper, geological observation, UAV detection and GPR technology are combined to study the recent sediments of the Yungang braided river study area in Datong. The application of the GPR technique to the description of fluvial facies and reservoir architecture and the development of geological models are discussed. The process of GPR detection technology and application includes three parts: GPR data acquisition, data processing and integrated interpretation of GPR data. The geological surface at different depths and scales can be identified by using different combinations of frequencies and antenna configurations during acquisition. Based on outcrop observation and lithofacies analysis, the Yandong Member of the Middle Jurassic Yungang Formation in the Datong Basin has been identified as a typical sandy braided river sedimentary system. The sandy braided river sandbody changes rapidly laterally, and the spatial distribution and internal structure of the reservoir are very complex, which has a very important impact on the migration and distribution of oil and gas as a reservoir. It is very important to make clear the characteristics of each architectural unit of the fluvial sand body and quantitatively characterize them. The architectural elements of the braided river sedimentary reservoir in the Datong-Yungang area can be divided into three types: Channel unit, bar unit and overbank assemblages. The geological radar response characteristics of different types of sedimentary units are summarized and their interfaces are identified. The channel sediments form a lens-shaped wave reflection with a flat at the top and convex-down at the bottom in the radar profile, and the angles of the radar reflection directional axes are different on both sides of the sedimentary interface. In the radar profile, the deposit of the unit bar is an upward convex reflection structure. The overbank siltation shows a weak amplitude parallel reflection structure. The flood plain sediments are distributed continuously and stably in the radar profile, showing weak reflection characteristics. Different sedimentary units are identified by GPR data and combined with Unmanned Aerial Vehicle (UAV) detection data, and the establishment of the field outcrop geological model is completed. The development pattern of the diara is clarified, and the swing and migration of the channel in different stages are identified. Full article

The closing time of the Paleo-Asian Ocean and the tectonic evolution of the northern margin of the North China Craton are still controversial. The geochronology and geochemistry of the Zhaojinggou monzogranite pluton provide new constraints on the late Paleozoic tectonic evolution and the closure time of the Paleo-Asian Ocean in the southern Central Asian Orogenic Belt (CAOB). The monzogranite yielded a zircon U-Pb age of 286.7 ± 1.2 Ma. Due to the characteristics of low–moderate Mg^# values (25.87–39.21), low Fe₂O₃^T values (1.13–1.72), and A/CNK > 1, we show that the pluton is weak peraluminous, high in potassium calc–alkaline series, and displays the feature of S-type granite. The total REE content is low, the distribution curve is right dipping, and the LREE is enriched; the δEu average value is 1.32 (1.11–1.54). The granite presents relatively high (⁸⁷Sr/⁸⁶Sr)_i values of 0.712345–0.713723, low ε_Nd(t) values of −8.89–−8.21 (an average value of −8.56), and a T_DM2 of 1718–1773 Ma. Furthermore, the zircon in situ Hf isotopic analysis shows ¹⁷⁶Hf/¹⁷⁷Hf ratios of 0.282342 to 0.282614, low ε_Hf(t) values of −9.27–0.38 (mean −4.74), and a T_DM2 of 1275–1887 Ma. Additionally, high field strength elements such as Nb, Ta, and Ti are depleted, and large ion lithophile elements, e.g., Rb, Ba, K, and Sr, are enriched. The above features of the Zhaojinggou monzogranite indicate that the pluton was derived from late Paleoproterozoic to Mesoproterozoic lower crustal mafic materials. By discussing the genesis and tectonic implications of the pluton massif, we propose that the Zhaojinggou monzogranite represents a magmatic event caused by the crustal–mantle interaction during the southward subduction of the eastern Paleo-Asian Ocean in the northern margin of the North China Craton during the Early Permian. Full article