Abstract:Early Precambrian basement is well developed in western Shandong Province of the North China Craton. This paper shows a systematic study of the monzogranites from Culai Mountain,western Shandong, revealing the evolution history of Precambrian crust in the eastern part of North China Craton. LA-ICP-MS zircon U-Pb isotopic dating shows that the monzogranites from Culai Mountain were formed at about 2.48 Ga, which also restricts the time limit of metamorphism-anatexis in Culaishan area. The rocks have high Si, Na and K, low P, a A/CNK ratio of 0.94～1.10, and belong to the high-K calc-alkaline series. The monzogranites exhibit enriched light rare earth elements (LREEs) with no δEu anomalies, and are enriched in large ion lithophile elements (LILEs) (e.g., Rb, Sr and Ba), and depleted in high field strength elements (HFSEs) (e.g., Nb, Ta, P and Ti). Based on comprehensive analysis, it is believed that the monzogranite from Culai Mountain originated from partial remelting of the about 2.7 Ga thickened lower crust (tonalite TTG rocks). Formed in an extensional environment after collisional orogenesis, it marks that the completion of the collage of micro-land masses in western Shandong in the late Neoarchean, and together with other regions to formed a stable North China Archean Craton.

Abstract:Beryl is an important Be-Al silicate mineral with high economic and industrial value. Laojunshan gneiss dome is located in the joint of South China block and Indosinian block, which has experienced multi-stage tectonic-magmatic action and developed Sn, Cu, Zn and other polymetallic deposits and emerald deposits. This study focuses on the detailed analysis of macro- and micro-structural characteristics of beryl and its symbiotic quartz veins in the region, and limits the temperature environment of formation and deformation through fluid inclusions and quartz EBSD fabric. The results show that beryl and quartz are rich in fluid inclusions, in which beryl has low temperature-high salinity two-phase and high temperature-low salinity three-phase fluid inclusions, and quartz has low temperature-low salinity two-phase fluid inclusions. The deformation characteristics of the quartz associated with beryl mainly develop rhombal <a> superimposed by secondary prim <c>, indicating low-temperture (350～400℃) deformation environment, superimposed by local high-temperture deformation. The magmatic fluid in the middle and late Yanshanian was accompanied by the uplift/exhumation of gneiss dome, which brought rich ore-forming elements, including the main Be elements of beryl mineralization. The exhumation process of regional gneiss dome from deep to shallow provides an important structural ore-bearing fluid channel for mineralization. With the occurrence of fluid immiscibility, the pH value of ore-forming fluid increases, thus promoting the occurrence and precipitation of ore-forming elements.

Abstract:The Yangchang phosphate deposit is located within the shallow marine strata of the Meishucun Formation (∈₁ms) in the southwestern Yangtze block. Investigating the sedimentary environment evolution of the Meishucun Formation in this mining area holds significant implications for regional prospecting. This study conducts geochemical analyses of major and trace elements from the Meishucun Formation in the Yangchang phosphate mining area to explore the sedimentary evolution process and phosphate enrichment sites. The results indicate that the Meishucun Formation contains relatively high concentrations of CaO and MgO, with elevated loss on ignition. Notably, P₂O₅ is enriched in the upper part, while SiO₂ is enriched in the lower part. The first member of the Meishucun Formation (∈₁ms¹), formed during the early to mid-Cambrian transgression, exhibits multi-element enrichment characteristics. Specifically, the enrichment coefficients of U and Mo in the lower submember (∈₁ms^1-1) exceed 60 times the average crustal value, whereas those in the upper submember (∈₁ms^1-2) exceed 10 times the average crustal value. Significant differences in peak values of U and Mo enrichment are observed between the two submembers. The lower submember (∈₁ms^1-1) shows no Ce anomalies and weak negative Eu anomalies, while the upper submember (∈₁ms^1-2) displays weak negative anomalies for both Ce and Eu. These findings suggest that the first member of the Meishucun Formation was deposited in a subtidal low-energy environment, transitioning from a relatively anoxic environment in the lower submember (∈₁ms^1-1) to a relatively oxidized environment in the upper submember (∈₁ms^1-2). The second member of the Meishucun Formation (∈₁ms²), composed of endogenous sediments hosting phosphate ores, was formed in an intertidal or subtidal high-energy environment. Trace element characteristics suggest an anoxic environment, while negative Ce anomalies indicate an oxidized environment. This implies that the collophanite in the phosphorite of the second member crystallized and precipitated from supersaturated phosphorus-rich seawater above the subtidal oxidation-reduction interface under arid and hot conditions, subsequently depositing in a closed or semi-closed anoxic environment on the seafloor. The third member of the Meishucun Formation (∈₁ms³), consisting of endogenous sediments formed at the upper part of the supratidal or intertidal zone, inherits trace and rare earth element characteristics from the second member, indicating an oxidizing environment under dry and hot climatic conditions. In summary, the sedimentary environmental evolution of the Meishucun Formation can be divided into four stages: early transgression, middle transgression, late transgression, and regression, corresponding to climatic changes from arid or semi-arid and hot to warm and humid, then back to arid and hot. The seafloor also underwent four stages of sedimentary processes: reduction, oxidation, mainly focused on reduction, reduction and oxidation alternate with each other, and oxidation. We conclude that the Yangchang phosphate mining area was situated in the underwater intertidal or subtidal high-energy zones within the shallow shoals of the eastern Yunnan epicontinental sea, Yangtze Craton, where the formation and enrichment of collophanite are more favorable in relatively closed or semi-closed reducing environments or semi-reducing environments of seawater.

Abstract:A thick layer of mirabilite was deposited in the lower part of the potassium-bearing strata of the Mahai Salt Lake in the Qaidam Basin. Unlike potassium salts, which usually formed in dry and hot climate, mirabilite is mostly formed under extremely cold conditions. Therefore, the study of the sedimentary characteristics and genesis of thick-layer mirabilite is of great significance for understanding the evolution of ancient environments and their impact on potassium salt mineralization. The article takes the stratigraphic profile of thick-layer mirabilite developed in the Mahai mining area of the Qaidam Basin as the research object, through systematic sampling, thin section identification, chemical composition, mineral type, and sulfur isotope analysis were carried out to study the changes in the chemical composition, mineral type, and sulfur isotope of the profile. The results show that the salt minerals in this section are main stone salt, gypsum, mirabilite, and glauberite, the maximum deposition age of the mirabilite layer is 275.3 ±47.9 ka BP, the research section shows the characteristic of evolution from thick-layer pure mirabilite to gypsum-bearing stone salt from bottom to top. The lower part is mirabilite layer, and glauberite appears in the middle and lower parts. The highest content of stone salt is in the middle and upper parts, while the content of stone salt in the upper part relatively decreases and the content of gypsum increases. Correspondingly, the content of potassium, magnesium, and calcium in the chemical composition of sediments steadily increases, while the overall content of sulfate ions and sodium decreases. During the period of thick-layer mirabilite deposition, Mahai Salt Lake was in a continuously dry and cold climate, which was beneficial to the continuous enrichment and increase of potassium and magnesium in the brine of the salt lake, which laid a foundation for the formation of solid potassium ore through local enrichment.

Abstract:In order to determine the geochemical characteristics and paleosedimentary environment of the Lower Cretaceous Yixian Formation and Jiufotang Formation in the northern part of the Naiman sag, petrographic analysis was conducted on N10 and NA-2 wells located near the sedimentary center in the north. Samples of mudstone and evaporite were tested for major and trace elements, carbon and oxygen isotopes, organic carbon, pyrolysis, and group composition. The paleoredox conditions, paleosalinity, paleowater depth, paleoclimate, and lake water sealing characteristics of the study area were systematically analyzed. The study shows that they were volcanic facies in the early sedimentary period of Yixian Formation in the northern part of the Naiman sag, mainly fan delta-lacustrine depositional-lake facies sedimentary systems in the middle and late sedimentary period, and local shore-shallow lacustrine facies of different types of evaporites in the late sedimentary period. Sensitive elements or element ratios such as Cu/Zn, Sr/Ba, Sr/Cu, Rb/Sr, Fe₂O₃/MnO, Ga, Sr indicate that the climate of Yixian Formation changed from semi-humid-semi-arid to arid from the middle period to the end period, the water environment also changed from semi-closed-semi-open with partial oxidation to completely closed with weak oxidation-weak reduction, and the sedimentary geochemistry environment changed from freshwater-brackish deep lake to brackish shallow lake. The Jiufotang Formation is a semi-enclosed deep lake sedimentation of oxidized fresh water with a climate similar to that of the middle of the Yixian Formation. The sedimentary environment during the middle and late periods of the Yixian Formation and the Jiufotang Formation were suitable for biological reproduction, which were favorable for the development of argillaceous source rocks. And for the development of pores and intercrystalline pores of thick-layer evaporites, which can become good reservoir spaces, they are favorable for oil and gas enrichment.

Abstract:The Ordovician weathered crust reservoir in the Ordos Basin is affected by calcites of different stages,so clarifying the genesis and influence of calcites can help to understand the mechanism of reservoir formation. Minera-logical,geochemical and isotope chronological results of calcites from the Ordovician weathered crusts in the Fuxian area of the Ordos Basin demonstrate that these calcites can be divided into white primary calcite, red secondary calcite and white secondary calcite. The white primary calcite filled in the pores and crevices of the paste mold,whereas the cleavage of calcite in the dissolved pores is much more developed than those in the dissolved seams. Geochemistry shows obvious negative Ce anomalies, a few calcites filled in the pores have positive Eu anomalies. They have red and orange-red cathodoluminescence, and their U-Pb ages are 333.3±3.3 Ma and 332.8±3.5 Ma, respectively, indicating that this type of calcite was formed in the early Carboniferous near surface environment. Gypsum was dissolved by atmospheric freshwater to form Ca²⁺, which reacted with atmospheric freshwater rich in CO^2-₃ at the gypsum mold pores and dissolution fractures. Red calcite is the secondary calcite of metasomatic dedolomitization, with dolomite crystal type mostly and orange-red cathodoluminescence. It is formed by metasomatic dolomite crystals in the atmospheric freshwater equimolarly from surface to near-surface environment, with high Mn,low Sr,high Sr isotopes and negative C and O isotopes. White secondary calcite is poikilitic,and medium-grained crystals,with developed cleavage, orange-red cathodoluminescence, high Sr concentration and high Sr isotopes, negative Ce and C anomalies, relatively stable O isotope,and U-Pb age of 212.0±19.0 Ma. The results indicate that this type of calcite was formed by the reaction of acidic fluids with Ca²⁺ during the Late Triassic hydrocarbon expulsion period. All kinds of calcite are the products of different diagenetic fluids in different diagenetic stages, which are easy to develop in the relative low-lying stagnant areas and result in the reduced rock porosity. Therefore, more attention should be paid to the high parts of paleo-karst geomorphology for effective reservoirs.

Abstract:Magmatic sulfide and oxide deposits rarely commonly appear due to their different genetic mechanism, and the studies about their co-existence mechanism are important for understanding the mineralization of mantle-derived magmas. Chengde, Hebei Province is an important magmatic mineral resource rich area in China. Sulfides coexisting with magnetite appear in Habaqin iron deposit, and the magnetite has been studied, but few studies on sulfide are involved. We carried out the major and trace elements, and in situ S isotopes of sulfides as well as in situ Sr isotopes of amphibole and apatite on the basis of petrography of host hornblendite, to reveal the genesis of sulfides. The hornblendite shows cumulate texture and consists of amphibole (80%~85% by volume), magnetite (10%~15%), apatite (3%~5%), and minor sulfides (<5%). The magnetite appears as granular aggregates and sulfides as sparse disseminations (<5%). The sulfides are mainly pyrite with inclusions of magnetite and apatite, suggesting that sulfides crystallized at late stage. The contents of S and Fe in pyrites range from 52.0% to 53.0% and 45.4% to 46.5%, respectively, with higher concentration of Co (up to 1.68%), suggesting its formation is controlled by magmatic segregation, accompanied by slight magmatic hydrothermal process. The initial ⁸⁷Sr/⁸⁶Sr ratios of amphibole and apatite range from 0.705 82 to 0.708 30 and 0.706 16~0.708 09, respectively, and the δ³⁴S values of pyrites range from -2.8‰ to +1.3‰, suggesting that the hornblendite and its sulfur mainly originate from an enriched lithospheric mantle; sulfur saturation is primarily controlled by the fractional crystallization of the parental magma. The crystallization of magnetite leads to delayed sulfide saturation, and weak assimilation and contamination of crustal material results in weak sulfides separation compared to oxides.

Abstract:In the early days of the porcelain industry in Jingdezhen, the porcelain capital, a single raw material—porcelain stone was used. During the developing process of porcelain industry, the ancestors of Jingdezhen porcelain invented the binary-compositions formulation: mixing porcelain stone and kaolin in a certain proportion to form porcelain raw materials, which greatly improved the quality and efficiency of porcelain production. However, we still do not know why ancient porcelain stones could become suitable raw materials for ancient porcelain making. For this purpose, this article conducted detailed microstructural studies and electron probe mineral composition analysis on porcelain stone samples taken from the rock walls of ancient mining pits in Gaoling Mountain. The results show that the porcelain stone from Gaoling Mountain is a special type of leucogranite, consisting of albite, K-feldspar, quartz, a small amount of biotite, and Fe-muscovite (?), and develops a micro fracture grid structure partially filled by chlorite. This composition and structural characteristics make porcelain stone an early excellent raw material for porcelain production that is easy to mine and process. Combined with the recently published experimental results of high-temperature crystallization of water rich acidic magma, we suggest that the Jingdezhen porcelain stone is a kind of leucogranite formed by dynamic crystallization of a water-saturated granite melt under the lower cooling-rate and lower undercooling degree conditions, with a mineral combination sequence of albite (+biotite) → K-feldspar+quartz →Fe-muscovite (?). Fe-muscovite (?) may be a new mineral, and further research is needed to determine its crystal structure and lattice parameters. The discovery of Fe-muscovite(?) in porcelain stones will help to understand the relationship between changes in the composition of ancient porcelain bodies and changes in porcelain-making formulas, and thus more reasonably infer the onset time of the emergence of binary formula technology.

Abstract:Time is a basic physical parameter to describe a geological process or geological event. Each radionuclide has a particular half-life, hence, they are applied to investigate different time scales of geological processes according to their half-lives. The occurrence of geological events and the duration of geological processes can restrict their causes and mechanisms, which is the key to reconstruct the geological processes. Currently, many isotope decay systems have been developed to achieve high-precision isotope dating, however, U-Pb chronology system containing double decay system, which is the first tool that precisely restricted the exact age of the earth. From the early solution analysis method to the present in-situ U-Pb geochronology analysis by laser ablation analysis or secondary ion mass spectrometry, U-Pb system has developed vigorously. The only tool for the calibration of all in-situ U-Pb geochronology standards is the double-spike diluent method of thermal ionization mass spectrometry (ID-TIMS). Therefore, this study reviewed the development of high-precision ID-TIMS U-Pb geochronology in detail, where we focused on the milestone events in its development process. Finally, the potential applications of high precision geochronology for ore deposit research are discussed.

Abstract:Carbonates play a crucial role in transporting surface carbon-bearing materials into the Earth's deep mantle through subduction. The recycling process of subducted carbonates is considered a pivotal process in the deep carbon cycle within subduction zones. During subduction, carbonates undergo decarbonation reactions to varying extents, releasing carbon-bearing fluids or melts into the mantle, thereby significantly impacting its composition and redox state. Today our comprehension of the carbonate recycling process in subduction zones largely stems from restricted investigations of (ultra) high-pressure metamorphic rocks, mantle xenoliths of different depths, experimental petrology and molecular dynamics conducted under conditions of high temperature and high pressure. A thorough understanding of the processes involved in subducting carbonate recycling is crucial for deciphering the geochemical and dynamic behavior of carbon in the deep Earth. This paper provides a comprehensive review of the subducting carbonate recycling process. It examines various decarbonization mechanisms, including metamorphic decarbonation, dissolution decarbonation, melting decarbonation, and redox decarbonation. By integrating these mechanisms with the thermal structure of global subduction zones, the paper investigates the distribution of carbon states and its migration patterns. Furthermore, it explores the impacts of these processes on the oxidation processes within both shallow and deep Earth environments.

Abstract:High-purity quartz is widely used in high-tech industries such as semiconductors, photovoltaics, optical communication, and light sources. It plays an important role in national strategic emerging industries, economic security, and national defense security, and is a scarce resource in the world and China. Vein quartz is one of the ideal raw materials for processing high-purity quartz raw materials. Based on extensive collection and research of vein quartz exploration results, this article divides the mineralization zones of vein quartz deposits in China according to their tectonic environment, distribution characteristics, mineralization characteristics, and controlling factors, and briefly describes the mineralization characteristics of each mineralization zone; Summarized the ore-forming laws of vein quartz deposits in China. The main types of vein quartz deposits are magmatic hydrothermal vein type, followed by metamorphic hydrothermal vein type, and pegmatite vein type. The main mineralization periods are Yanshanian, followed by the Hualixi, Caledonian, Jinning, and Indosinian periods. 27 vein quartz mineralization zones have been preliminarily divided, and it is proposed that 5 vein quartz mineralization zones, including the Lüliang, South Qinling, Tongbai-Dabie, East China Sea-Ganyu, and Altai blocks, are important high-purity quartz vein quartz mineralization zones in China. The summary of the mineralization rules of vein quartz and the division of mineralization zones provides a theoretical basis for the exploration and deployment of vein quartz.

Abstract:The coal measure resources in Antarctica possess great potential yet have received limited research. The discovered coal measures are predominantly Permian strata, with a few being Mesozoic-Cenozoic strata. The coal measures are essentially distributed in the Transantarctic Mountains and Prince Charles Mountains, with some parts found in West Antarctica. The coal-abundant strata in the Transantarctic Mountains are mainly Permian-Triassic Victoria Group of the Bacon Supergroup, and the coal-abundant strata in the Prince Charles Mountains are mainly Permian Bainmedart Coal Measures of the Amery Group. The coal in Antarctica exhibits the characteristics of a high thermal order and is mostly thermal metamorphic coal. The coal in the Transantarctic Mountains is mostly anthracite, super anthracite, or natural coke, which has the characteristics of high alteration. The coal in the Prince Charles Mountains region has the characteristics of high volatility and low sulfur. The vitrinite reflectance, which represents the maturity of coal measures, gradually decreases to a relatively stable trend as the formation age from old to new in the Bainmedart Coal Measures. The development of major coal measures in Antarctica reveals that during the Late Paleozoic and Early Mesozoic, the Antarctic was warm and humid with lush vegetation, and the sedimentary environment was vastly different from that of today. The existing coal measures were mostly developed at the intersection of river and lake sedimentary facies. The development and history of the thermal evolution of coal measure disclose that the formation of Antarctic thermal metamorphic coal measure is related to the breakup of Gondwana. The linear distribution along the Transantarctic Mountains of the Ferrar Large Igneous Province is coupled with the location of typical Permian coal measures, and the dike formed by the Jurassic short-term concentrated thermal event can be regarded as the signal of the commencement of thermal alteration of the coal measure, while the heat rise caused by the further breakup of Gondwana at the end of Cretaceous may be the main cause of the high coal rank and high maturity of the Antarctic coal measure.

Abstract:Soil organic carbon pools are one of the hot topics in carbon cycle research, among which dissolved organic matter (DOM) is the most mobile and active, and clay-grained minerals are the most active mineral components in soil. Clay-grained minerals have a significant impact on the stability of DOM. Therefore, the adsorption characteristics and control mechanisms of three common soil clay-grained minerals, allophane, kaolinite and hematite, on DOM were explored in detail from the perspectives of adsorption kinetics and thermodynamics. The results indicate that three minerals can effectively adsorb PDOM, and the adsorption capacity of allophane on PDOM is higher than that of kaolinite and hematite, but its adsorption capacity per unit area is weaker than the other two; Kinetic and thermodynamic data indicate that the PDOM uptake by allophane may be largely controlled by physical means, while that by kaolinite and hematite are chiefly through chemical forces. Differences in the interfacial properties of the three minerals lead to different absorption characteristics. Among them, the specific surface area is the main factor leading to the difference in the total amount of adsorption, while the adsorption strength depends on the pH value of the reaction system, the density and availability of the adsorption sites. This study provide a basis for understanding the sequestration of organic matter by soil clay-grained minerals.

Abstract:In the process of treating landfill leachate using the upflow anaerobic sludge blanket (UASB), microbial mineralization products can deposit and block the circulation and effluent pipes. Repeatedly replacing pipes to remove blockages is a labor-intensive process and exerts a negative impact on the stable operation of the system. The mineralogy and microscopic structural features of scaling in UASB system pipelines were investigated by mineralogical characterization methods in this study. The mechanism of scaling formation was explored. It provides a theoretical foundation for the prevention, inhibition, and cleaning of scaling in UASB reactor pipelines. The results indicated that the pipe scaling constituted a complex mixture of microbial mineralization products and organic matter, primarily consisting of acid-soluble materials. The main crystalline phases were monohydrocalcite and struvite. Struvite presented columnar crystals with diameters ranging from 0.2 nm to 0.5 mm, and arranged in bundles or radiating patterns. Monohydrocalcite appeared as spherical particles with diameters ranging from 50 nm to 350 nm. The anaerobic process producing methane production of landfill leachate consumed H⁺ and generated a large amount of CO₂, which increased the carbonate alkalinity of the anaerobic digestate. Meanwhile, organic nitrogen was ammonified, and organic phosphorus was converted into phosphate. In the digestion, phosphate, magnesium, and ammonium ions combine to crystallize into struvite, while calcium ions and carbonate ions combine to crystallize into calcite. Although the ion concentrations in the anaerobic digestate were supersaturated for hydroxyapatite and calcite, the presence of magnesium ions and high concentrations of organic matter in the anaerobic digestate may inhibit their nucleation and crystal growth. In the UASB system, struvite undergoes heterogeneous nucleation on the pipeline surface, growing into large columnar crystals. Monohydrocalcite filled the gaps between struvite crystals, incorporating a small amount of organic matter. Then, struvite and calcium carbonate were cemented together, forming pipe scaling with a certain level of strength resisting to fluid flushing. Considering the use of an in-situ acid dissolution method with 5% acetic acid to remove pipe scale, the residual acidity of the acid wash solution will keep as low as possible without altering the pH of the liquid inside the large-scale UASB reactor. Additionally, Low concentration acetic acid can serve as a substrate for methane-producing bacteria to enhance methane production.

Abstract:Building on previous research, we employed laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U-Pb dating method to maximize sensitivity and minimize elemental fractionation effects. This was achieved by improving the testing process, optimizing the instrument parameters, and incorporating auxiliary gas sensitization equipment, such as nitrogen. In this study, three standard zircons—Qinghu, Plešovice, and Tanz—were dated using beam spot diameters of 32, 24, and 16 μm, respectively. The experimental results reveal that with a 32 μm beam spot, standard zircon Qinghu ²⁰⁶Pb/²³⁸U age range is 162~157 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 159.5±0.8 Ma (2σ, n= 6, MSWD=0.36); Standard zircon Plešovice ²⁰⁶Pb/²³⁸U age range is 340~334 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 337.1±1.5 Ma (2σ, n=27, MSWD=0.085); Standard zircon Tanz ²⁰⁶Pb/²³⁸U age range is between 574~562 Ma, weighted average ²⁰⁶Pb/²³⁸U age 566.6±2.9 Ma (2σ, n=29, MSWD=0.070). With a 24 μm beam spot, standard zircon Qinghu ²⁰⁶Pb/²³⁸U age range is 162~157 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 159.3±0.7 Ma (2σ, n=30, MSWD=0.22); Standard zircon Plešovice ²⁰⁶Pb/²³⁸U age range is 341~334 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 337.2±1.5 Ma (2σ, n=29, MSWD=0.13); Standard zircon Tanz ²⁰⁶Pb/²³⁸U age range is 568~561 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 566.5±2.9 Ma (2σ, n=30, MSWD=0.054). With a 16 μm beam spot, standard zircon Qinghu ²⁰⁶Pb/²³⁸U age range is 163~154 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 159.5±1.4 Ma (2σ, n=25, MSWD=0.45); Standard zircon Plešovice ²⁰⁶Pb/²³⁸U age range is 340~334 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 337.3±2.0 Ma (2σ, n=30, MSWD=0.063); Standard zircon Tanz ²⁰⁶Pb/²³⁸U age range is 575~563 Ma, weighted average ²⁰⁶Pb/²³⁸U age is 567.0 ±4.3 Ma (2σ, n=30, MSWD=0.028). The weighted average ages of the three standard zircons (Qinghu, Plešovice, and Tanz) are consistent with their recommended values within the margin of error. These findings demonstrate the feasibility of using small beam spot sizes (24 μm and 16 μm) for zircon LA-ICP-MS U-Pb dating. This refined method extends the applicability of LA-ICP-MS zircon U-Pb dating, making it suitable for small zircon grains with complex structures. This model has significant theoretical research implications and economic value.

Abstract:Jingtieshan iron mine of Jiuquan Iron and Steel Group Co. is a typical complex refractory iron oxide ore. The original ore has a low iron grade, multiple types of iron minerals, and complex symbiotic relationships, making the ore extremely difficult to select. In order to improve the grade, recovery rate, filtration performance and other indicators of concentrate, starting from the perspective of process mineralogy, the differences in disseminated particle size, hardness, density and magnetic properties between raw ore and roasted ore of Jingtieshan complex refractory iron oxide ore and their washability characteristics of JISCO were analyzed to judge the advantages and disadvantages of the current mineral processing technologies. On this basis, combined with the characteristics of different beneficiation processes, ore properties, production costs, concentrate quality, and filtration performance, a new combined beneficiation process of intelligent preselection-fine breaking-dry grinding-suspension magnetization roasting-gravity separation-magnetic separation-fine sieve-reverse flotation is recommended.