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Discovery of Volcanic Clay-type Lithium Deposit in Region of Volcanic Rocks Along the Southeastern Coast of China SHAO Xiaoyang, DENG Fei, ZHANG Zhongjin, WANG Rucheng, LU Xiancai, CHE Xudong Geological Journal of China Universities    2024, 30 (04): 409-417.   DOI: 10.16108/j.issn1006-7493.2024031 Abstract （1426）      PDF（pc） （5089KB）（1257）       Knowledge map    Save We report the lithium enrichment in the late Cretaceous Yetang Formation, located in the Shirenbei Basin, northeast of Guangdong Province. The Li2O content is greater than 0.2%, and can be a target for extracting lithium. Comprehensive crosssections of the Shirenbei Basin, geochemical analyses and lithofacies interpretation suggest that the lithium-enriched layers occur in shale, mudstone and siltstone, located in Middle-Upper Yetang Formation; lithium is mainly stored in clay minerals, whose formation is closely related to volcanic activities. It was initially interpreted as a volcanic-type lithium-rich clay deposit. The basin structure provides the environment for sedimentation and concentration of lithium. The layers containing enriched lithium are approximately 226 meters thick in total, and are in great potential for extracting lithium deposit. This discovery provides fclues on investigating large-scale lithium-rich clay deposits related to volcanic activities along the southeast coast of China.  Related Articles | Metrics | Comments（0）

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The Generation of Acid Mine Drainage: Insights from Reactive Transport Modeling and Stable Isotope QIU Wenjie, DU Zhuoran, YIN Ziyue, SUN Yuanyuan, ZHU Xiaobin, WU Jianfeng Geological Journal of China Universities    2025, 31 (01): 1-13.   DOI: 10.16108/j.issn1006-7493.2024091 Abstract （430）      PDF（pc） （2327KB）（966）       Knowledge map    Save Acid mine drainage (AMD) resulting from mining activities is a global environmental issue. Investigating the acid generation mechanisms of AMD and the biogeochemical processes affecting the release, migration, and transformation of heavy metals and sulfates provides a scientific basis for quantitatively predicting AMD formation and developing remediation strategies. In this paper, a multiphase reactive transport model for water-gas two-phase flow is constructed based on the TOUGHREACT/EOS3 code to simulate the acid generation process of sulfide minerals (such as pyrite) in tailings impoundment under the influence of atmospheric precipitation and oxygen. It further considers the physical and geochemical reaction processes of associated species in the migration and transformation within the aqueous medium. The reaction network includes the release of H⁺ from the oxidation and dissolution of sulfide minerals, the migration and transformation of iron ions and sulfate, and the pH buffering processes caused by the dissolution and precipitation of major minerals. Finally, by incorporating sulfur stable isotopes into the reactive transport model, the study identifies the bacterial sulfate reduction processes and corresponding sulfur isotope fractionation occurring during the formation of AMD. The model quantitatively assesses the acid production contributions under different oxidation pathways of pyrite, revealing that simultaneously considering the parallel oxidation processes of O₂(aq) and Fe3+ increases the concentrations of acid, iron ions and sulfate. The pH is controlled by the release of H⁺ from pyrite oxidation and the neutralization reactions corresponding to mineral dissolution and precipitation. Stable isotope reactive transport model indicates significant differences in δ34S values under different fractionation kinetic enrichment factor, and using the Rayleigh fractionation model in an open system can greatly overestimate the enrichment factor. This research aids in understanding and predicting the formation and migration processes of acidic water in mining environments, which is crucial for addressing environmental pollution issues caused by mining activities.  Related Articles | Metrics | Comments（0）

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The Occurrence State of Lithium in the Middle Mesoproterozoic Wumishan Formation Lithium-rich Rock Series in Eastern Hebei Province GENG Xiaolei, LI Wei, , WANG Kebing, CAI Yuanfeng, , REN Chao, JI Shichao, WANG Jingzhao, , GAO Yanfeng, WANG Yuguang, TONG Xinen, WANG Ruiqi Geological Journal of China Universities    2024, 30 (06): 694-704.   DOI: 10.16108/j.issn1006-7493.2023072 Abstract （262）      PDF（pc） （5627KB）（925）       Knowledge map    Save In 2021, Hebei Geological Survey Institute discovered an extraordinary enrichment of lithium in the Middle Mesoproterozoic Wumishan Formation in the eastern Hebei, which is the first time that clay type lithium resources were found in Precambrian strata in China. The lithium-rich rock series has large thickness, wide distribution, stable horizon, Li2O grade of 0.1-0.42 wt%, and has great prospecting potential. As a new lithium-endowed horizon, the occurrence state of lithium is directly related to the exploration and development significance of the clay-type lithium resources discovered this time. By using X- ray diffraction (XRD), thermal analysis (TG-DTG) and Fourier transform infrared spectroscopy (FTIR), it is found that the lithium-rich rocks in the study area are mainly composed of dolomite, quartz and clay minerals such as illite and illite/smectite mixed layers. Through solid state nuclear magnetic resonance spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), clay mineral purification and Na ion exchange experiments, it is revealed that the lithium in the Wushan Formation lithium-rich rock series mainly exists in the illite and illite/smectite mixed layers in the form of isomorphic replacement, and a very small amount of lithium exists in the form of ion adsorption between the clay mineral layers or on the surface. The research results provide important theoretical basis and technical support for the selection, metallurgy and exploitation of clay-type lithium resources in eastern Hebei Province in the future. Related Articles | Metrics | Comments（0）

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The Origin of Orbicular Granitoids CAO Yufei, LI Shuting, ZHANG Shaobing, HUANG Fang Geological Journal of China Universities    2024, 30 (06): 635-645.   DOI: 10.16108/j.issn1006-7493.2023067 Abstract （440）      PDF（pc） （5289KB）（911）       Knowledge map    Save Granitoids with orbicular structure are very rare because of their unique orbicular structure. They stand as unique objects to study magma processes. When high-temperature magma contacted or mixed with low-temperature magma, due to their difference in viscosity and temperature, high interfacial tension leads the high-temperature magma to form orbicules in low-temperature magma. The temperature of orbicules decrease rapidly and result in high degrees of supercooling. Induced by exsolution of volatiles or other factors, the orbicules begin to crystallize and branched or feathery crystals are formed. The rapid crystallization in orbicules results in rapid change of local melt and the alternating crystallization of different minerals, forming dark and light rings. During this process, the crystallized minerals can exhibit branched or feathery structures. However, it is still unclear how viscosity and temperature control spheroidization, and how minerals crystallize after spheroidization, and how long the crystallization process lasts. These issues are waiting to be studied and revealed. Related Articles | Metrics | Comments（0）

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Numerical Modeling of Groundwater Dynamic Response to Agricultural Irrigation in a Typical Arid Area WANG Beida, SONG Jian, YIN Ziyue, LIN Jin, WU Jianfeng Geological Journal of China Universities    2025, 31 (01): 92-103.   DOI: 10.16108/j.issn1006-7493.2024010 Abstract （199）      PDF（pc） （4614KB）（845）       Knowledge map    Save Researching the impact of agricultural irrigation on the groundwater dynamic under different crop growth conditions in arid and semi-arid area holds significant practical importance for the rational development and utilization of regional groundwater. Using the MODFLOW-NWT program and unsaturated zone simulation subroutine package UZF1 in GMS software, a numerical model was established for the northern bank of the Kaidu River in the Yanqi Basin. The model was calibrated using daily groundwater level data. Water balance analysis was also conducted. Water requirement for five typical crops (peppers, tomatoes, wheat, sugar beets, and corn) was computed using the crop coefficient method. The calibrated groundwater model was used to simulate the effects of agricultural irrigation on the groundwater depth dynamic under different planting scenarios. The results show that planting the high-water-consumption sugar beets corresponds to the greatest average groundwater depth, while planting wheat results in the smallest average groundwater depth. Average Groundwater depth are similar when planting tomatoes, peppers, and maize. During sugar beets cultivation, the average groundwater depth is 0.85 meters greater than during wheat cultivation. With a 100-millimeter-increase in water demand, the average groundwater depth increases by 0.31 meters during the growing season. It indicates that crop water requirement is a crucial factor affecting groundwater level fluctuation in study area. The finding can provide a scientific guidance for the sustainable management of water resources and the formulation of agricultural planting strategy of arid and semi-arid area.  Related Articles | Metrics | Comments（0）

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pH Swing-Evaluation of Economic Potential of Mineralized Carbon Fixation Process of Steel Slag XIE Kui, ZHAO Liang, ZHU Chen, FENG Henan, SUN Jiajia, ZHOU Yiyang Geological Journal of China Universities    2024, 30 (04): 476-484.   DOI: 10.16108/j.issn1006-7493.2023034 Abstract （1249）      PDF（pc） （1219KB）（814）       Knowledge map    Save The CO2 mineral sequestration-based ammonium slag recycling carbon sequestration process has promising economic potential and CO2 emission reduction benefits, which can help steel companies achieve high-value comprehensive utilization of steel slag solid waste and waste resources containing CO2 flue gas. Raw material loss, reaction time and impurity ion behavior directly affect the operation cost and product quality of the process, and ultimately determine its application value. In this study, the economic potential of the steel slag ammonium salt recycling carbon fixation process was evaluated through laboratory scale test data, and suggestions were made for process parameter determination and optimization directions from the cost control perspective. The results show that the freshness of the solution remains basically unchanged during 10 cycles of leaching solution, and the main reason for the loss of raw materials is the loss of solution volume; the precipitation process CO2 flow rate reaches 15-20 L/min when the precipitation time drops to 20-30 min, at this time the precipitation process is not a limiting factor of the process operation rate; no obvious enrichment of impurity ions is seen in the circulating solution, and the precipitated calcium carbonate products of ten rounds of reactions are in line with industry standards; the CO2 reduction factor of this process to produce precipitated calcium carbonate is 1.543; the profit of this process to reduce 1 ton of CO2 is 1325.25 RMB, and the profit can reach 1654.74 RMB by reducing the solution loss, which has significant economy.  Related Articles | Metrics | Comments（0）

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Using the Thickness of Delta Foredeposits to Restore the Maximum Paleo-water Depth of Lakes: A Case Study of Qinnan Sag in Bohai Bay Basin and Huizhou Sag in Pearl River Mouth Basin DANG Zhaoqing, CHEN Ying, LYU Chengfu, BAI Zhizhao, XIAO Yueye, ZHOU Qianshan Geological Journal of China Universities    2024, 30 (06): 726-736.   DOI: 10.16108/j.issn1006-7493.2023058 Abstract （265）      PDF（pc） （8320KB）（811）       Knowledge map    Save Water depth plays a decisive role in the redox conditions of a basin and plays an important role in the enrichment and preservation of organic matter in sedimentary basins. Previous studies mainly relied on paleontology, element geochemistry, stratigraphic thickness, and other methods for qualitative and semi-quantitative palaeodepth restoration. However, these methods have a high dependence on original samples and low prediction accuracy and are not suitable for Palaeogene Lake basin palaeodepth restoration in offshore basins. In this study, the depth of paleowater is mainly restored based on the thickness of the delta for deposits in seismic profiles. By using this method, the maximum palaeobathymetric during the sedimentary period of the third Member of the Shahejie Formation of the Eocene in Qinnan west subsag of Bohai Bay Basin is 595 m, and the maximum paleowater depth during the sedimentary period of Wenchang Formation in the southwest of Huizhou Sag of Pearl River Mouth Basin is 526 m. Combined with previous research results, it is found that the rate of sag-controlling fault activity is strong in the third Member of the Shahejie Formation period of Qinnan Sag and the Wenchang Formation period of Huizhou Sag, and they are during the strong rifting of the basin, which controls the formation of deep water lake basins. During this period, many Sags in Bohai Bay Basin and Pearl River Mouth Basin are in deep-water-ultra-deepwater environments, so it is inferred that the deep water environment is the result of strong fault activity. Then the redox conditions of the lake basin are controlled, and more organic matter is preserved in the lake basin to form high-quality source rocks.  Related Articles | Metrics | Comments（0）

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Suppression of Desiccation Cracking Behavior in Clayey Soils Using the Bio-carbonation of Reactive Magnesia Method ZHENG Hongyang, WANG Rui, LIU Yujia, TANG Chaosheng Geological Journal of China Universities    2024, 30 (06): 705-713.   DOI: 10.16108/j.issn1006-7493.2023066 Abstract （252）      PDF（pc） （4623KB）（763）       Knowledge map    Save Upon drying, the generated cracks on the soil surface can greatly weaken the mechanical properties of soils, thereby causing various geological engineering problems. Based on the bio-carbonation of reactive magnesia (RMC) method, this study investigated the feasibility of the spraying method in suppressing desiccation cracking and explored the effects of curing agent composition, urea concentration, RMC dosage and spraying sequence on the anti-cracking performance of soils. The results show that: (1) The formation of hydrated magnesium carbonates (HMCs), and the bio-carbonation product of RMC could enhance the cementation of soil particles and establish a bio-carbonation layer on the sample surface, which enables to effectively inhibit the desiccation cracking behavior of soils through decreasing the evaporation rate of moisture in the soil and increasing the tensile strength of samples; (2) The elevated urea concentration could significantly facilitate the bio-carbonation of RMC. In the case of 2.0 mol/L urea concentration, the maximum penetration resistance of the bio-carbonized sample increased by 195.5% after three wetting-drying cycles in comparison to that of the raw sample; (3) Both high RMC dosage and the post-spraying treatment of RMC solution impeded the infiltration of RMC within the soil matrix, which negatively affected the improvement of cementation performance for soil samples.  Related Articles | Metrics | Comments（0）

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Numerical Simulation and Software Development of Fracture Flow and Reactive Transport Based on Upscaled Discrete Fracture Matrix Model LIU Dianguang, YANG Yun, YUAN Yiliang, DOU Zhi, WU Jianfeng, WU Jichun Geological Journal of China Universities    2025, 31 (01): 14-23.   DOI: 10.16108/j.issn1006-7493.2024089 Abstract （255）      PDF（pc） （3852KB）（695）       Knowledge map    Save Reactive transport simulation in fractured media is a prominent and challenging research area in the fields of geosciences and environmental engineering. Traditional equivalent porous media models and discrete fracture networks have certain limitations in accurately characterizing groundwater flow and solute transport processes within complex fracture networks. This paper presents the development of FracRTM, a numerical simulation software for groundwater flow and reactive transport in the fractured media. FracRTM, based on Discrete Fracture Network (DFN) modeling, employs the Upscaled Discrete Fracture Matrix Model (UDFM) to construct continuum meshes and calculate equivalent permeability and porosity. The software integrates open-source reactive transport simulation programs to model the physical and chemical processes of groundwater flow, solute transport, and chemical reactions within fractured-matrix systems. This paper describes the overall design and functional modules of FracRTM , followed by a numerical simulation case study of acid mine drainage migration, which is used to validate the software’s effectiveness. Related Articles | Metrics | Comments（0）

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Heat Flow and Deep Temperature Distribution in Kuqa Foreland Basin, Northwestern China FENG Guanzhong, LIU Shaowen, ZHU Chuangqing, LI Xianglan Geological Journal of China Universities    2024, 30 (04): 460-475.   DOI: 10.16108/j.issn1006- 7493.2023021 Abstract （1112）      PDF（pc） （6800KB）（691）       Knowledge map    Save Geothermal regime of the sedimentary basins is key for understanding the formation and evolution of the basins and assessing hydrocarbon and geothermal energy, and has attracted much attention from the academia and industrial circles. Kuqa Foreland Basin, located between the Tarim Basin and Southern Tianshan Mountain, is one of major hydrocarbon exploration targets in China, and accurate knowledge of geothermal regime of this basin is beneficial for hydrocarbon potential assessment. Here we integrate updated steady-state temperature logs and oil testing temperature, with thermal properties data, to decipher the thermal characterization of the Kuqa Foreland Basin. The geothermal gradient of the basin ranges from 17.3 to 25.7 ℃ /km, with an average of 21.5±2.6 ℃ /km; while the heat flow varies from 27.4 to 57.9 mW/m2, with a mean of 40.9±7.2 mW/m2. The range and average of estimated formation temperatures at 1000-6000 m in the basin are 26-49 ℃ (36±4.6 ℃ ), 42-82 ℃ (59±7.5 ℃ ), 64-113 ℃ (82±10.3 ℃ ), 85-127 ℃ (102±11.6 ℃ ), 98-140 ℃ (119±12.8 ℃ ) and 110-155 ℃ (133±13.9 ℃ ), respectively. Generally, the present-day thermal state of the Kuqa Foreland Basin is relatively low and the thermal pattern is characterized by hot in the north and east, cold in the south and west, which is attributed to the east-west differences in the thickness of the Cenozoic sediments and the lateral variations in the intensity of active deformation associated with the far field effects of the Indo-Asian continental collision. The large thickness of the sediments in the western part of the basin, which forms the thermal blanketing effects owing to their low thermal conductivities, preventing the transport of heat from the deep to the surface. In addition, the active deformation in the eastern part of the basin is more intense, and the friction heating effect of fault movements is obvious. These two factors are combined to account for the observed present-day geothermal field pattern of Kuqa Foreland Basin. Related Articles | Metrics | Comments（0）

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Parameter Sensitivity Analysis of Landscape Evolution Models: An Example from the Kumarak River Basin WU Qihui, ZENG Xiankui, WU Jichun Geological Journal of China Universities    2024, 30 (05): 585-592.   DOI: 10.16108/j.issn1006-7493.2023049 Abstract （345）      PDF（pc） （1780KB）（684）       Knowledge map    Save Landscape evolution model is the basis for quantitative research on landscape evolution, but it involves complex processes and numerous model parameters. In order to alleviate the difficulty of parameter identification and improve the reliability of model parameter setting, identifying the key driving mechanisms and parameters of the landscape evolution model has become the focus of current research. In this study, the Kumarak River Basin in the Tarim River Basin of Xinjiang was selected as the study area, and the landscape evolution model of the study area was established based on the LE-PIHM (Landscape Evolution-Penn State Integrated Hydrologic Model). The parameter sensitivities of the LE-PIHM model were identified by the global sensitivity analysis method, Sobol method. The surface elevation of three typical landforms in the study area was used as the objective function for the sensitivity analysis, and the results showed that the key model parameters for the landscape evolution of the mountainous areas in the study area were the weathering rate of bare bedrock (P0), the fitting coefficient for bedrock weathering equation (α) and the rate of tectonic uplift (U), which were mainly related to the weathering effect of the bedrock and the tectonic uplift effect. Meanwhile, in the plain area of the study area, the model parameters have high sensitivity except for aquifer porosity (ng), and the elevation change in the plain area is mainly controlled by the interaction between the parameters. In the riverine area of the study area, the sensitivity of the model parameters is similar to that in the plain area, but the soil porosity (ns) and aquifer horizontal hydraulic conductivity (KHg) have significantly stronger sensitivities, which are related to surface watergroundwater interactions and aquifer permeability properties, respectively. Related Articles | Metrics | Comments（0）

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Mechanism Governing on Different Hydrochemical Evolution Processes for Two Types of Travertine and Silica Sinters in Shannan, Tibet CONG Tingting, TAN Hongbing, CONG Peixin, SHI Zhiwei, XUE Fei, ZHANG Yu Geological Journal of China Universities    2024, 30 (06): 646-659.   DOI: 10.16108/j.issn1006-7493.2023073 Abstract （361）      PDF（pc） （3558KB）（679）       Knowledge map    Save The Tibet Plateau is rich in geothermal resources. Among them, in Chaka and Quzhuomu areas of Shannan, under similar background of geohistorical evolution, geothermal springs with significantly different water chemical compositions were formed, and two different types of springs, silica and travertine, were deposited on a large scale. In this paper, the causal mechanisms of the differences in hydrochemistry between the two types of geothermal systems are discussed through the comparative analysis of the parameters of the two types of geothermal springs, normal and trace chemical compositions, and the stable isotopes of H and O. The results show that Quzhuomu geothermal springs are recharged by meteoric water, and the components source is mainly water-rock interaction, and the water chemical type is mainly HCO3-Ca-Na type. Due to the long hydrochemical evolution process of Chaka and the mixing of a higher proportion of magma residual fluid, the water chemical type evolves into Cl-Na type. The estimation results of various geothermal thermometer show that the thermal reservoir temperature of Quzhuomu is between 98.8-181.3 ℃ , and the proportion of cold water mixing before excretion is 43.4%, while the thermal reservoir temperature of Chaka (183.2-204.3 ℃ ) is significantly higher than that of Quzhuomu. Compared with Quzhuomu, the longer water cycle evolution process of Chaka geothermal springs, the mixing of a higher proportion of magma residual fluid and the higher thermal reservoir temperature, are the main cause mechanism that controls the large-scale deposition of silica during the discharge process of geothermal springs and the abnormal enrichment of some typical incompatible elements in the water body. Related Articles | Metrics | Comments（0）

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Petrogenesis of the Biotite Quartz Monzonite from Shangshuiqiao Fluorite Deposit, North Wuyi Area: Constraints from Geochronology and Geochemistry ZENG Xianghui, MENG Delei, ZENG Runling, JIANG Qibao, OUYANG Yongpeng Geological Journal of China Universities    2024, 30 (05): 559-576.   DOI: 10.16108/j.issn1006-7493.2024040 Abstract （505）      PDF（pc） （4598KB）（644）       Knowledge map    Save Shangshuiqiao fluorite ore is a newly discovered medium fluorite deposit with great exploitation prospect in northern Wuyi area in recent years. However, little research has been carried out on this deposit. In this paper, petrographic, zircon U-Pb chronological and whole-rock geochemical analyses have been carried out on the biotite quartz monzonite from the the Shangshuiqiao fluorite deposit. The zircon LA-ICP-MS U-Pb ages show that the biotite quartz monzonite was formed at  235~236 Ma, which is the product of Indosinian magmatism. According to the geochemical analyses, the biotite quartz monzonite samples are characterized by high alkali (Na2O+K2O), Mg and Fe contents and low P and Ti contents. They have high σ values (2.59 and 3.61) and low A/CNK ratios (0.96 to 1.16), belonging to the typical high-K series with metaluminous to weakly peraluminous. In terms of trace and rare earth elements, the biotite quartz monzonite is enriched in Rb, Th, U, K and light rare earth elements (LREEs), but depleted in Ba, Sr, Nd, Ta, P, Ti and heavy rare earth elements (HREEs), as well as high rare earth elements (ΣREE varying from 356×10-6 to 448×10-6) and weak negative Eu anomalies (Eu/Eu* between 0.61 and 0.76). Besides, the biotite quartz monzonite displays high Zr+Nb+Ce+Y content (varying from 381×10-6 to 546×10-6) and Ga/Al ratio (104×Ga/Al between 2.60 and 3.07), with lower Rb/Sr (0.31 to 0.82), Rb/Ba (0.11 to 0.18) and TFeO/MgO ratios (2.02 to 2.22), belong to post-orogenic (PA type) aluminous A-type granites. In addition, based on the results of geochemical mapping and characteristics of regional magmatism and sedimentation, we suggest that the biotite quartz monzonite from Shangshuiqiao fluorite deposit may be formed in the postorogenic extensional tectonic environment at the end of intracontinental orogeny under the background of multi-plate convergence. During the mineralization stage, the biotite hydrolysis and sericitization of plagioclase in biotite quartz monzonite may provide F and Ca sources for fluorite mineralization. Related Articles | Metrics | Comments（0）

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Sedimentary Environment and Organic Matter Enrichment Mechanism of the Yuertusi Formation Source Rocks during Early Cambrian Period SUN Houxue, HAO Fang, WANG Qi, TIAN Jinqiang Geological Journal of China Universities    2024, 30 (05): 622-633.   DOI: 10.16108/j.issn1006-7493.2023055 Abstract （527）      PDF（pc） （1628KB）（641）       Knowledge map    Save The development mechanism of source rocks of the early Cambrian Yuertusi Formation is one of the key points of deep oil and gas exploration in the Tarim Basin. The completion of ultra-deep drilling of pre-Cambrian strata in the basin in recent years provides an ideal window for the study of the development mechanism of Cambrian source rocks in the basin. In order to investigate the sedimentary environment and paleo-productivity during the deposition of source rocks and clarify the enrichment mechanism of organic matter, a systematic analysis of TOC, major and trace elements and carbon and oxygen isotopes was carried out in a typical well of the Tabei area. The results show that the lower part of the Yuertusi Formation was in anoxic-sulfuration environment with high primary productivity. In comparison, the upper section was formed in the oxygen-poor sedimentary environment, and the productivity was gradually weakened to a low productivity level. Carbon and oxygen isotopes indicate that the lower member of the Yuertusi Formation was deposited under the background of extensive transgression with upwelling. The coupling of upwelling currents and mild hydrothermal activities provides abundant nutrients for the bloom of primary productivity during this period, and the enrichment of organic matter was mainly controlled by high productivity and good preservation conditions. There was basically no hydrothermal activities in the upper member of the Yuertusi Formation when it was deposited, the productivity level gradually decreased, and the reductibility of the water body also began to weaken, which was manifested in the low productivity level and the depositional environment of the upper system domain in the upper member, and eventually resulted in the low abundance of organic matter. Related Articles | Metrics | Comments（0）

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Carbon Sequestration Effect and Prospects for Artificial Sinking Enhancement of Marine Diatoms ZHU Huaxi, XUAN Kun, ZHOU Lingling, ZENG Zhihong, GE Chendong, HU Rong Geological Journal of China Universities    2025, 31 (02): 152-164.   DOI: 10.16108/j.issn1006-7493.2024008 Abstract （260）      PDF（pc） （1560KB）（623）       Knowledge map    Save The ocean, as the largest active carbon reservoir in the Earth surface system, presents a huge potential for carbon sequestration. Owing to their unique physiological structure, widespread distribution, efficient carbon sequestration mechanisms, and strong proliferative capacity, diatoms contribute about 40% of ocean primary productivity and 40% of particulate organic carbon export, playing an important role in the marine biological carbon pump. These organisms exhibit robust carbon sequestration efficiency and exceptional adaptability through powerful CO2 concentrating mechanisms (CCMs) and efficient biophysical and biochemical carbon fixation processes. They also offer opportunities for Carbon Capture, Utilization, and Storage (CCUS), presenting innovative avenues for biological carbon sequestration technology. Identifying and cultivating fast-growing diatom species, optimizing growth conditions, and enhancing photosynthesis efficiency are critical aspects. Current research has employed indoor physiological experiments to decipher factors influencing their physiological activities and carbon sequestration efficiency and further assessed the response of diatoms to global change from the perspective of global biogeochemical cycling. This provides an important theoretical basis for evaluating diatom-mediated natural carbon sequestration and their artificial augmentation prospects. Envisioned as a “microbial carbon sequestration factory”, diatoms hold promise in maximizing carbon sequestration capabilities while generating commercially valuable products. If the cost of carbon sequestration can be effectively reduced, diatom-driven carbon sequestration will be a technologically sustainable solution to support the “Dual Carbon Plan” in the future. Related Articles | Metrics | Comments（0）

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Experimental Study on Seepage and Heat Transfer of A Single Fracture in Sandstone during Shallow Geothermal Extraction WU Hongtao, WANG Huimin, ZHENG Huifeng, SHENG Jinchang, HUANG Tairen, TIAN Jiali, SHENG Danna Geological Journal of China Universities    2024, 30 (05): 593-602.   DOI: 10.16108/j.issn1006-7493.2023056 Abstract （319）      PDF（pc） （2395KB）（549）       Knowledge map    Save The development and utilization of shallow geothermal energy is related to the successful achievement of the “doublecarbon” target. The study on seepage and heat transfer characteristics of the rock fracture in the target reservoir is critical to the effectiveness of the groundwater source heat pump system. However, most of the previous studies on seepage and heat transfer in fractures considers a single factor such as rough surface, flow velocity, confining pressure, temperature for the evaluation of its heat transfer efficiency. The understanding of the evolution mechanism of seepage and heat transfer and its contribution degree by the change of shallow geothermal reservoir (confining pressure and rock temperature) at multiple flow rates have not been systematically investigated. Therefore, based on a self-developed seepage and heat transfer system of fractured rocks, this paper carried out the seepage and heat transfer test under multiple flow rates for sandstone with a single fracture. Subsequently, the evolution characteristics of single fracture seepage and heat transfer under multiple flow rates were analyzed. Finally, the influenced mechanism and contribution degree of sensitive parameters (confining pressure and rock temperature) in shallow geothermal on seepage and heat transfer were discussed. The test results show that: (1) The trends of outlet water temperature and convective heat transfer coefficient with the increase of water flow rate have obvious transition stages. (2) The increase of confining pressure leads to the fracture closing and the thinning of flow boundary layer, while the increase of temperature gradient causes a higher outlet water temperature and convective heat transfer coefficient due to the increase of heat flux density. (3) The contribution of rock temperature is significantly higher than that of confining pressure. Especially when the temperature increases from 60 ℃ to 70 ℃ , the convective heat transfer coefficient increases dramatically. Related Articles | Metrics | Comments（0）

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Hydroclimate Changes in Southwestern China Over the Past 800 Years and its Dynamics ZHAO Bin, CUI Yingfang, KONG Xinggong, ZHAO Kan, WANG Yongjin Geological Journal of China Universities    2024, 30 (06): 747-755.   DOI: 10.16108/j.issn1006-7493.2023063 Abstract （312）      PDF（pc） （7662KB）（517）       Knowledge map    Save Southwestern China is a high-risk area of drought. However, hydroclimate behavior and its mechanism on various timescales in southwestern China are still unclear, largely due to scarce long-term high-resolution hydrological reconstructions. Moreover, the speleothem-based oxygen isotope record shows an ambiguous relationship between Asian summer monsoon variation and regional hydrological change. Here, we present a nearly 800-yr-long (1180-1969 AD) annually resolved and accurately dated regional hydroclimate record based on annual laminae thickness data from a stalagmite (NO. DX1) in Dongge Cave, Guizhou Province. The regional climatic conditions are dominantly influenced by the Asian summer monsoon and the Intertropical Convergence Zone (ITCZ). In the continuously-growing section (from 0-58.2 mm), regular laminations can be observed under a microscope. The microscopic features of the lamina resemble those from Shihua and Hulu caves in the monsoonal regions of China. Therefore, we obtain a layer-counting timescale and an annual laminae thickness record from 1180 to 1969 AD. The close similarity between the annual laminae thickness and δ13C records suggests that annual laminae thickness of stalagmite DX1 can serve as a proxy for regional hydroclimate. Centennial-scale hydroclimate changes are broadly similar to the Northern Hemisphere (NH) temperature variations, with a significant drought event (-1540-1630 AD) during the Little Ice Age (LIA), supporting that the NH temperature has an important influence on low-latitude hydrological changes, via meridional shifts of the ITCZ. The mathematical analyses reveal that the regional hydrological changes display significant -3-year and -7-year periodicities (accounting for -44% of the total variance), likely related to the interannual El Niño-Southern Oscillation (ENSO) variations. In addition, the 31-yr running biweight variance for the regional hydroclimate gradually decreased from the Medieval Warm Period to the LIA, reached the minimum during the coldest LIA interval (-1540-1630 AD), then gradually increased, and became unusually high during the Current Warm Period. This hydroclimate variance is largely consistent with the reconstructed ENSO variance and further modulated by secular NH temperature background states. Our observation implies that the ENSO and low-latitude hydrological variance will increase, and the frequency and amplitude of extreme climate events will increase under the scenario of continuous global warming. Related Articles | Metrics | Comments（0）

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Zircon Geochronology, Geochemical Characteristics and Geological Significance of Meta-Sedimentary Rocks in the Yingyangguan Group, Eastern Guangxi LAN Yuanchun, SHI Yu, TANG Yuanyuan, ZHOU Yuxi, WENG Boyin Geological Journal of China Universities    2024, 30 (05): 541-558.   DOI: 10.16108/j.issn1006-7493.2023057 Abstract （428）      PDF（pc） （3483KB）（491）       Knowledge map    Save This study presents new geochemical, zircon U-Pb and Lu-Hf isotopic data for the Neoproterozoic meta-sedimentary rocks of the Yingyangguan Group in eastern Guangxi. Geochemical data show that the meta-sedimentary rocks of the Yingyangguan Group have moderate composition maturity and weathering extent, and their rare earth element (REE) patterns are similar to that of the Post-Archaean Australian Shale (PAAS), with moderate Eu negative anomalies. The trace element distributions diagram shows that some samples are depleted in U, with higher Co and Ni contents compared with those of the meta-sedimentary rocks in the Nanling range, suggesting that the provenance was mostly intermediate to mafic rocks. The matrix of the Yingyangguan tectonic mélange contains a component of meta-sedimentary rocks. The detrital zircon U-Pb dating results give a maximum depositional age (660 Ma) of the matrix part of the tectonic mélange. Combined with previous results, we suggest that the Yingyangguan tectonic mélange was formed in the Middle-Late Neoproterozoic, and resulted from reworking by the Early Mesozoic thermal events. Provenance analysis reveals that the Neoproterozoic meta-edimentary rocks of the Yingyangguan Group are mainly of felsic components, combined with zircon cathodoluminescence image characteristics, zircon U-Pb geochronological characteristics, Hf model age of the second stage (TDM2) and relevant regional geological data, we suggest that the intermediate to mafic provenance in the meta-sedimentary rocks mainly originated from the Yingyangguan area or the adjacent terranes, suggesting a close affinity of the Yingyangguan Group with the Cathaysia Block. Combined with the characteristics of regional tectonic evolution, it is inferred that the Neoproterozoic meta-sedimentary rocks of the Yingyangguan Group were deposited in a post-orogenic extension rift basin. Related Articles | Metrics | Comments（0）

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Study on Soil Suction Measurement Method Using PSYPRO Dew Point Water Potential Technique ZHANG Dazhan, TANG Chaosheng, XU Jinjian Geological Journal of China Universities    2024, 30 (04): 451-459.   DOI: 10.16108/j.issn1006-7493.2023020 Abstract （1041）      PDF（pc） （1760KB）（486）       Knowledge map    Save Soil suction measurement is crucial for the stability assessment of geotechnical engineering, real-time and accurate measurement of suction changes in soil from saturated to dry state has always been a hot topic and challenge in the field of unsaturated soil mechanics. Dew point water potential technique is a novel measurement method of soil suction. This paper detailly introduces the working principle of the PSYPRO dew point water potential meter and the significance of the required debugging parameters, and combines the calibration test and the evaporation test to give the optimal time parameter setting recommendations for the PSYPRO dew point water potential meter to measure different soil suction intervals. In this paper, the PST-55 psychrometer was firstly calibrated with different concentrations of NaCl solutions and the correction coefficient was obtained, and then the laboratory soil evaporation test was carried out, the PST-55 psychrometer and ML3 soil moisture sensor were used to measure the drying process. The changes in soil suction and water content verified the feasibility and accuracy of dew point water potential technique for real-time continuous monitoring of soil suction.  Related Articles | Metrics | Comments（0）

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Anomaly Data Identification Method for Geological Disaster Monitoring Based on Generate Adversarial Network LIU Jiangcheng, HAO Guangyao, TAO Hong, XU Yanyan, WANG Heng, JIANG Xianhui, CHEN Qun Geological Journal of China Universities    2025, 31 (02): 174-184.   DOI: 10.16108/j.issn1006-7493.2024002 Abstract （167）      PDF（pc） （769KB）（482）       Knowledge map    Save Reliable geological hazard warning depends on accurate sensing data. In order to solve the problems of large noise and long time sequence characteristics of geological monitoring sensor data, we propose a method to identify abnormal data of geological disaster monitoring based on generative adversarial network. Firstly, the RandAugment algorithm is used to enrich the diversity of training data and improve the robustness to noise. Secondly, multi-head self-attention mechanism is used to extract long time series features, and the stability of early warning performance is improved by adversarial training mechanism. Experiments on four real-time series sensor data streams extracted from hidden geological disaster points in Shaanxi Province show that the proposed method has a 5%-10% improvement in AUROC and F1 indexes, compared to widely used machine learning methods.  Related Articles | Metrics | Comments（0）

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Strain Characteristics and Tectonic Significances of the Sanjiang Ductile Shear Zone in the Junction Area of Northern Guangxi and Western Hunan GUAN Rongfang, QIN Ya, FENG Zuohai, GOU Xiaofang, XING Quanli, KANG Zhiqiang, HU Qiaofan, WU Jie Geological Journal of China Universities    2024, 30 (06): 678-693.   DOI: 10.16108/j.issn1006-7493.2023062 Abstract （208）      PDF（pc） （7826KB）（476）       Knowledge map    Save The strain characteristics and tectonic significance of the Sanjiang ductile shear zone are studied by analyzing the macro-micro structures, magnetic fabrics and quartz EBSD fabrics to constrain the Early Paleozoic orogenic processes of the Yangtze and Cathaysia block. The Sanjiang ductile shear zone has typical macro-micro scopic ductile deformation fabrics, including S-C fabric, tensile lineation, A-type fold, domino structure, mechanical twin, permeable foliation, core-mantle  structure and quartz dynamic recrystallization. The magnetic fabrics and macro-micro structure show that the Sanjiang ductile shear zone extends more than 40 km in NNE direction with a width of 3.7-7.5 km. The mylonitic C-foliation strikes 262°-321° with the dip at 31°-87° and the overall average is 295 °∠ 69°. The mean of 36 groups of magnetic foliations with susceptibil ity anisotropy (Pvalue)≥1.05 is 304°∠ 83°. The clockwise rotation of the magnetic foliation relative to the C-plane foliation of mylonite indicates a sinistral sense of the Sanjiang ductile shear zone. Macro-micro structures show that the Sanjiang ductile shear zone is dominated by sinistral thrust shear and dextral normal slip shear. The rock strain of the Sanjiang ductile shear zone is mainly flattening and tensile strain. At the same time, it shows both pure shear and simple shear. Quartz EBSD fabric analysis reveals that the Sanjiang ductile shear zone is characterized by the late mid-low temperature deformation (300-500 ℃ ) superimposed on the early midhigh temperature deformation (480-600 ℃ ). Based on the research of macro-micro structures, magnetic fabrics and quartz EBSD fabrics, combined with regional geological data, it is considered that the Sanjiang ductile shear zone was formed in the tectonic background of compression and extrusion of the Cathaysia block from SE toward the Yangtze block. In the early extrusion and collision stage, the Sanjiang ductile shear zone underwent mid-high temperature sinistral thrust shear. After the late orogenic extension, the Sanjiang ductile shear zone experienced dextral normal slip shear at mid-low temperature. The above analysis reveals the strain characteristics, deformation temperature and dynamic background of the Sanjiang ductile shear zone and provides new constraints for better understanding of the Early Paleozoic tectonic events in South China. Related Articles | Metrics | Comments（0）

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Modification of Pretreatment Method of Phosphate Oxygen Isotope Analysis in Phosphorus-poor, Silicon-rich Freshwater System WU Kedi, WEI Haizhen, RUAN Xiaohong Geological Journal of China Universities    2024, 30 (05): 526-540.   DOI: 10.16108/j.issn1006-7493.2023047 Abstract （295）      PDF（pc） （5614KB）（476）       Knowledge map    Save Phosphorus is the limiting element of the trophic states for most freshwater systems. Therefore, the identification of the main phosphorus sources is essential to the efficient control of phosphorus pollution as well as the prevention of eutrophication. Phosphate oxygen isotope (δ18OP) is proved to be effective in source identification. However, freshwater habitats are always of low phosphorus concentrations and complex compositions. For example, water bodies in silicate rocks exposed areas can be characterized by having little phosphorus while abundant silica. The later can easily precipitate and adsorb PO43-, making it difficult to obtain valid δ18OP through existing methods. In this study, the widely used Mclaughlin pretreatment method was modified to deal with the phosphorus-poor, silicon-rich water, the phosphorus-poor sandy sediments and soils. The efficient enrichment and purification of PO43- in freshwater are achieved with the following improvements: (i) reduction in the proportion of reagents added at the PO43- enrichment step; (ii) graded pH adjustment prior to CePO4 precipitation; (iii) multiple steps of fine pore membrane filtration to reduce the silica content; (iv) dynamic ion-exchange to remove cations. For phosphorus-poor sandy sediments and soils, an increase of the sample amount and the concentration of the extraction solutions, combined with the purification steps of water samples have been used to precipitate sufficient pure Ag3PO4 for δ18OP determination. The phosphate recovery of significant procedures relating to precipitation or cation are above 80%, and the precision is ±0.6‰ . The analytical accuracy was evaluated by comparing the δ18OP of Ag3PO4 generated with the modified methods and the pure phosphate solution directly. The modified methods have been applied to the δ18OP determination of samples from Danjiangkou Reservoir basin, providing technical support for tracing phosphorus in this basin. Related Articles | Metrics | Comments（0）

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Sensitivity Analysis of Controlling Factors for Earth Fissures in Aquifer Systems with Abrupt Thickness Changes ZHANG Huolian, HE Shenlin, ZHANG Yongwei, YU Dejie, GONG Xulong, YE Shujun Geological Journal of China Universities    2024, 30 (04): 442-450.   DOI: 10.16108/j.issn1006-7493.2023041 Abstract （1149）      PDF（pc） （1568KB）（467）       Knowledge map    Save The “groundwater pumping type” earth fissure disasters caused by excessive exploitation of groundwater widely occur worldwide. Their developments are contributed by both excessive exploitation of groundwater and complex geological and hydrogeological conditions. The type of earth fissure in aquifer system with abrupt thickness change is a general type of earth fissures. In order to achieve a deeper understanding of the mechanism of this type of earth fissures, the paper designs a numerical experimental test in which earth fissure developes in an aquifer system with abrupt thickness change. Firstly, the finite element method is used to calculate the stress-strain distribution of the aquifer system, and the interface element method is used to calculate rupture development. Then the Sobol global sensitivity analysis method is applied to quantify the impact of four control factors, including aquifer thicknesses ratio, changes in pore water pressure, compression coefficient, and cohesion, on the depth of earth fissure development. The results of numerical test indicate that during the process of pumping groundwater, due to the decrease of pore water pressure, differential compaction and shear stress concentrate continuously increase at the location with abrupt changes in aquifer thickness, which leads to the formation of earth fissure on the ground and further downward expansion. The sensitivity analysis results indicate that the aquifer thicknesses ratio is the most sensitive control factor for the development of earth fissures, the sensitivity of pore water pressure changes is second, the sensitivity of compression coefficient is weak, and cohesion is an insensitive control factor. There is an obvious collaboration between the thicknesses ratio and the changes in pore water pressure. The greater the difference in thickness between aquifers, combined with the greater decrease in pore water pressure, the deeper the development of earth fissures. Related Articles | Metrics | Comments（0）

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Detrital Zircon U-Pb Geochronology and Geological Significance of the Triassic Strata from Aolaoshan Area, in the West Section of North#br# Qaidam Basin WANG Bo, WU Zhixiong, HU Junjie, MA Licheng, MA Yinsheng, SHI Hui Geological Journal of China Universities    2024, 30 (04): 397-408.   DOI: 10.16108/j.issn1006-7493.2023038 Abstract （1158）      PDF（pc） （4132KB）（462）       Knowledge map    Save A dispute whether there was Triassic sedimentation or not in Qaidam Basin and its later evolution are continuous as yet. Via systematic analysis of detrital zircon geochronometry, rock assemblages and regional stratigraphic correlation on the Triassic strata from Aolaoshan area, in the west section of north Qaidam Basin, this study aiming at providing evidence for the Triassic stratigraphic framework in the northern margin of Qaidam. The average age of young zircons in the lower part of Tb Triassic Formation is 248 Ma. Considering paleontological data from the underlying Ta strata, the deposition time limit of the Aolaoshan Triassic deposits was Early to Middle Triassic. The detrital zircon U-Pb ages were between 243-260 Ma, 414-538 Ma, 678-857 Ma, 1064-1642 Ma and 1700-2836 Ma. Respectively, indicating that the sedimentary materials may derived from Indosinian magmatic rocks, Upper Devonian recycle material, North Qaidam tectonic belt, Shaliuhe Group and Dakendaban Group. The study area has the same sedimentary characteristics as the Triassic in the Huaitousala area, and they both are markedly different from the Triassic stratigraphic division in Qilian and West Qinling areas. It is suggested that a series of continuous or intermittent sedimentary strata were developed in the northern margin of the Qaidam Basin during the Triassic period. In the early Triassic, influenced by the subduction of the Zongmurong Ocean to the south, the northern margin of the Qaidam Basin began to uplift rapidly. Several sets of sedimentary strata and crystalline basement in the early period were rapidly denudated, and the sedimentary strata dominated by alluvial and alluvial facies were formed near the source fault depression. In the Middle Triassic, the activity intensity of the peripheral tectonic belt tended to be stable on the whole, and the northern margin of the Qaidam basin was in the shallow sea shelf platform sedimentary system with thick-bedded limestone as the main deposits. Until the late Triassic, with the strong continental collision between East Kunlun and Qaidam terrane, the whole Qaidam Basin was rapidly uplifted, and the weakly consolidated Triassic in the basin was large-scale denudated. Some of the weakly consolidated Triassic in the basin was transported eastward to Gonghe Basin, and only part of the depressions were preserved.  Related Articles | Metrics | Comments（0）

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Geochemical Characteristics and Source Analysis of Late Permian Rare Earth Earth-Rich Rock Series in the Qixi Area of Western Guizhou LUO Xiangjian, QIN Ying, LU Shufan, ZHANG Jiawei, HUANG Qin, WANG Biao, GONG Daxin, TIAN Enyuan, LIU Guodong Geological Journal of China Universities    2024, 30 (04): 418-430.   DOI: 10.16108/j.issn1006-7493.2023035 Abstract （1432）      PDF（pc） （9212KB）（445）       Knowledge map    Save Geochemical characteristics and sources of ore-forming material of different lithological sections of the rare earth element (REE)-rich rock series at the base of the first member of the Late Permian Xuanwei Formation in the western Guizhou region are still unclear. This study conducts geochemical analyses of major, trace, and REEs of typical profiles in the western Guizhou and Qixi regions, and explores the geochemical characteristics and sources of ore-forming material of different lithological sections of REE-rich rock series. The results show that the REE-rich rock series can be divided into iron rock section, aluminum rock section, and clastic rock section from bottom to top. Among them, the aluminum clay rock section shows the highest rare earth content, up to 0.76%. The REE-rich rock series is mainly composed of SiO2, Al2O3, FexOy, and TiO2 with a total content of 83.93% to 87.24%; Large ion lithophile elements such as Cs, Rb, Ba, V are depleted, while high-field strength elements such as Zr, Hf, Nb, Ta are stable; The REE distribution patterns are all displayed as right dipping with different lithological sections being characterized by moderate differentiation of light and heavy REEs in the iron rock section, no δCe anomalies, and weak negative δEu anomalies; The degree of differentiation between light and heavy REEs in the aluminum rock section is significant, showing negative δCe and δ Eu anomalies; The light and heavy REE fractionation in the clastic rock section is moderate with a weak positive δCe anomaly and a negative δ Eu anomaly. Based on the ICV values of the samples, La/Sc-Co/Th diagrams, and REE distribution patterns, it is determined that the main sources of the aluminum clay rock section and the clastic rock section are moderately acidic volcanic rocks (not volcanic ash) that were eroded, transported, and deposited, while the source of the iron rock section is nearby basalts. Related Articles | Metrics | Comments（0）

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Application of Fractal Characteristics of Drill Hole Karst Geology in Analyzing the Degree of Karst Development TAN Yao, QI Jihong, XU Mo, ZHENG Tongxin, WANG Zhongyu, WANG Shuai Geological Journal of China Universities    2024, 30 (05): 603-612.   DOI: 10.16108/j.issn1006-7493.2023052 Abstract （290）      PDF（pc） （3780KB）（442）       Knowledge map    Save The existing analysis of the degree of karst development is mainly based on the general understanding of regional scale, but under the influence of topography, landform, groundwater runoff and other factors. The degree of karst development in the same geological unit varies and the regional general understanding of karst development often cannot meet the requirements of site-scale karst development degree analysis. A drill hole data is an important source for studying karst development characteristics at the engineering site. But various factors such as the core recovery rate and the large long steep dip-vertical karst fractures can influence the estimates for the karst development degree using the traditional karst statistical methods. By collecting drill holes data within the scope of the project and using the karst fractal theory, this paper combined the borehole image recognition system and the graphic fractal calculation program to determine the karst development degree discriminant index (IKAF), and proposed a site-scale, high-precision karst development degree identification method. The drill hole data of a reservoir site in the left bank mountainous area of the middle and upper reaches of the Shiting River basin in Mianzhu were analyzed using this method. The results show that this method can quickly and accurately identify the morphology of karst development in the drilling hole, reducing errors in determining the karst rate caused by the development of long and steep to vertical karst fractures. The degree of karst development obtained using this method is basically consistent with the degree of karst development reflected by the karst phenomena such as sinkholes and karst caves obtained from field investigations. This method is a beneficial addition to the traditional method in analyzing the degree of karst development.  Related Articles | Metrics | Comments（0）

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Cluster Analysis of Acid Mine Drainage Pollution Characteristics Based on Self-Organizing Map Technology: A Case Study of Linkeng Coal Mine in Longyan, Fujian Province JIA Wenhui, YE Shujun, CHE Qiaohui, XU Wanqiang, ZHENG Wenming, WANG Bangtuan Geological Journal of China Universities    2025, 31 (01): 24-33.   DOI: 10.16108/j.issn1006-7493.2024088 Abstract （257）      PDF（pc） （2573KB）（411）       Knowledge map    Save Acid Mine Drainage (AMD) is one of the major environmental issues arising from coal mining, posing serious threats to ecosystems and human health. This study selected the Linkeng Coal Mine area in Longyan, Fujian as a case study and employed Self-Organizing Maps (SOM) technology to systematically analyze the pollution characteristics of AMD, aiming to accurately assess the current AMD pollution status and effectively identify the main pollution sources. The study comprehensively analyzed four water quality indicators including pH, Fe, Mn, and SO42- of 37 water samples using the SOM method, and finally divided the samples into four clusters with varying degrees of pollution, clearly revealing the spatial distribution characteristics of water bodies with different levels of pollution. The clusters, in order from the highest to the lowest pollution levels, are Cluster IV, Cluster III, Cluster II, and Cluster I. Samples in clusters III and IV show severe pollution characteristics, mainly located near coal mine water inrush points and coal waste stone stacking areas, which are key areas for future remediation efforts. Samples in cluster II are primarily affected by the influx of polluted water; cluster I contains the most samples, indicating that most of the water bodies in the area are minimally affected by AMD. The SOM method offers an effective tool for assessing AMD pollution characteristics and has the potential to be applied in other coal mine areas. Future studies need to increase monitoring frequency to capture the impact of seasonal changes on water quality. As the monitoring data continues to increase, the application potential of the SOM method will become more evident. Related Articles | Metrics | Comments（0）

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The Stability of Minerals in Foraminifera Tests under Early Diagenetic Conditions: Implications from Simulation Experiments KAN Libo, ZHOU Yuefei, LI Xiaosong, WANG Jiayu, XU Liang, XIE Qiaoqin, CHEN Tianhu Geological Journal of China Universities    2024, 30 (04): 431-441.   DOI: 10.16108/j.issn1006-7493.2023024 Abstract （1256）      PDF（pc） （6910KB）（390）       Knowledge map    Save In order to investigate the stability of carbonates in foraminifera tests under early diagenetic conditions, this study designed simulation experiments to analyze changes in morphology, structure, and chemical composition of the tests of Nonionella decora (CF1), Ammonia aomoriensis (CF2), and Ammonia tepida (CF3) after being eroded by dissolved S2-, dissimilatory-iron reducing bacterium (DIRB), and sulfate-reducing bacterium (SRB). Results showed that calcite in the tests of CF1 and CF2 can be dissolved by S2- when its concentration is above 64 mmol/L; while calcite in the test of CF3 can be dissolved only when S2- concentration is above 128 mmol/L. The dissolution occurred mainly at the place where cogwheel structure is well-developed. DIRB strongly promoted the dissolution of calcite; while such promotion was not obvious in SRB experiments. Dissolved S2- did not change the Raman spectroscopy characteristics of calcite in foraminifera tests; while DIRB and SRB led to systematic shifts of 5~7 cm-1. Dissolved S2-, DIRB, and SRB can promote the dissolution of carbonates in the tests and the homogenization of Mg. Besides, DIRB and SRB can promote the formation of Mg-enriched carbonates in the tests. The results suggest that DIRB is much stronger than dissolved S2- and SRB to change the composition and structure of foraminifera tests under early diagenetic conditions. However, the effects of SRB cannot be ignored from a long-term perspective.  Related Articles | Metrics | Comments（0）

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Macroscopic and Spectroscopic Study on Phosphate Adsorption by Ce-Al Oxide NIE Hongda, REN Chao, LI Wei Geological Journal of China Universities    2024, 30 (05): 505-513.   DOI: 10.16108/j.issn1006-7493.2023046 Abstract （435）      PDF（pc） （2775KB）（337）       Knowledge map    Save Eutrophication caused by excess phosphate in water bodies is an important issue in China and many countries (regions) around the world. Therefore, it is crucial to investigate the environmental geochemical behavior of phosphate and to explore phosphorus removal techniques and principles. In this study, a Ce-Al oxide was synthesized as the adsorbent material to investigate the adsorption behavior and mechanism of orthophosphate. The effects of system parameters such as reaction time, initial phosphate concentration, pH and ionic strength on the phosphate adsorption by the Ce-Al oxide were examined. The results showed that the phosphate adsorption reached equilibrium within 24 hours; the adsorption isotherm (pH=7) was best fitted by Langmuir adsorption mode, yielding a maximum adsorption amount of 75.5 mg·g-1; and importantly the adsorption was insensitive to pH and maintained a high efficiency in the studied pH range (i.e. pH=3-10). This study further employed zeta potential measurement, microscopic analyses (SEM and TEM) and spectroscopic methods (XRD and XPS) to investigate the phosphate adsorption mechanisms by the Ce-Al oxide. It can be concluded that surface precipitation and inner-sphere adsorption dominates the phosphate adsorption mechanisms by the Ce-Al oxide. The study demonstrates that the Ce-Al oxide is a candidate material for phosphate removal. Related Articles | Metrics | Comments（0）

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Variations Between Two Lower Cambrian Prof iles in the Upper Yangtze Region and Their Implications for Depositional Environments WANG Guozhi, ZHANG Can, LIU Dayong, QIU Linfei, LI Ziying, PENG Ping’an Geological Journal of China Universities    2024, 30 (06): 660-667.   DOI: 10.16108/j.issn1006-7493.2023071 Abstract （243）      PDF（pc） （1108KB）（324）       Knowledge map    Save Sampling of two quarry sections occurred at Zunyi, Guizhou, and Youyang, southeastern Chongqing. These samples were systematically collected from organic-rich, polymetal-enriched shales at the base of the Lower Cambrian Niutitang Formation. Analysis encompassed organic geochemistry, mineralogy, and major and trace element compositions. Despite being approximately 300 kilometers apart, both sections are situated within the Upper Yangtze Platform, facilitating comparative study. Vertical variations in TOC, δ13Corg, and major and trace element abundances suggest that these sections occupy distinct positions on the continental shelf slope. Compared to the Songlin section, samples from the Danquan section indicate proximity to the source area, characterized by higher clastic input fluxes. Although multiple depositional environment changes occurred within less than a 9-meter range from the Niutitang Formation’s base upwards in both sections, the depositional environments tended to converge with rising sea levels. The relationship between shale organic matter abundance (TOC), organic carbon isotopes (δ13Corg), and certain trace elements associated with hydrothermal activity (e.g., As, Ni, Sb) in both sections indicates different mechanisms for trace element enrichment. In the Songlin section, organic matter adsorption primarily drives trace element enrichment at the Niutitang Formation’s base, whereas in the Danquan section, mixing with codepositional hydrothermal fluids is the primary mechanism. Related Articles | Metrics | Comments（0）