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Current Status and Recommendations of Offshore CO 2 Geological Storage Monitoring LI Qi, LI Yanzun, XU Xiaoyi, LI Xiaochun, LIU Guizhen, YU Hang, TAN Yongsheng Geological Journal of China Universities    2023, 29 (1): 1-12.   DOI: 10.16108/j.issn1006-7493.2023008 Abstract （2400）      PDF （1583KB）（485）       Knowledge map    Save Marine carbon dioxide (CO 2) storage is an important means to cope with greenhouse gas emissions in China’s coastal areas, and is an indispensable key technology to achieve the goal of “emission peak and carbon neutrality”. The coastal areas of China are industrially developed and rich in carbon sources. Owing to the good physical properties and reservoirs and trap characteristics, offshore basins have huge storage potential. At present, the first marine demonstration project of China has been officially launched in the Pearl River Estuary Basin in the South China Sea. As an important part of CCUS technology, CO 2 monitoring runs through the whole life cycle of CO 2 geological storage and is a necessary method to ensure the safety and rationality of storage works. However, China’s CO 2 marine storage technology is in its infancy, and the task of marine storage monitoring is quite challenging. For this reason, this paper reviews the relevant representative research and demonstration project cases of international CO 2 marine storages, summarizes the monitoring indicators, technologies and schemes, and puts forward the screening and optimization methods of monitoring CO 2 marine storage and suggestions for monitoring technology. The outcome of this study provides a reference for the development of CO 2 marine storage demonstration projects in China. Related Articles | Metrics

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Progress of Methods for Assessing CO 2 Mineralization Storage Potential in Basalt GAO Zhihao, XIA Changyou, LIAO Songlin, YU Xiaojie, LIU Muxin, LI Pengchun, LIANG Xi, DAI Qing, HUANG Xinwo Geological Journal of China Universities    2023, 29 (1): 66-75.   DOI: 10.16108/j.issn1006-7493.2022099 Abstract （2022）      PDF （1109KB）（588）       Knowledge map    Save CO 2 geological storage is an important technology to reduce CO 2 emissions, which can safely store CO 2 in geological formations for millions of years. Conventional CO 2 storage reservoirs include deep saline aquifers and depleted oil and gas reservoirs. Basalt is a new type of CO 2 storage reservoir that has been attracting attention in recent years. CO 2 storage in basalt would increase the technical method and potential of CO 2 geological storage. Storage potential assessment is one of the fundamental works of CO 2 geological storage study. This paper systematically examines the current methods for assessing the storage potential of CO 2 in basaltic rocks, and analyzes the principles and application scenarios of various methods. Then, the study takes the basalt of Icelandic Active Rift zone as an example to compare each of the methods. The study suggests that the current CO 2 mineralization storage potential assessment methods generally include three categories: ① Unit rock storage potential assessment method, which evaluates carbon sequestration potential based on the reaction volume or area of rocks; ② Mineral replacement storage potential assessment method: based on the volume of minerals that can react with CO 2 in basalts. ③Pore filling storage potential assessment method, which evaluates the proportion of secondary minerals that can fill reservoirs’ pore space after CO 2 mineralization. The authors note that the first method requires special experimental analysis, making it more challenging, the second method is more appropriat for basalts with high porosity and low reactive mineral content, while the third method is more suitable for basqlts with low porosity and high reactive mineral content. Related Articles | Metrics

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Research on Tortuosity Fractal Characteristics of Sandstone Pores Based on Nuclear Magnetic Resonance Imaging Technology XIANG Lei, WANG Huimin, SHENG Jinchang, LUO Yulong, ZHAN Meili, TAO Kai, TIAN Jiali Geological Journal of China Universities    2023, 29 (1): 120-127.   DOI: 10.16108/j.issn1006-7493.2022074 Abstract （1778）      PDF （2582KB）（185）       Knowledge map    Save Under the context of “double carbon” emission reduction, saline aquifer of sandstone is the most potential medium for carbon dioxide storage. The study of pore-structure characteristics determines the fluid migration and storage efficiency, which has great scientific significance. Fractal dimension is usually used to quantitatively characterize the distribution of sandstone pore structures in three-dimensional space. However, when studying the fractal dimension of sandstone pores in the past, the fractal dimension was calculated based on the characteristic values such as porosity, average pore radius, and average tortuosity, which could not well reflect the heterogeneity and arrangement of pore structures. Therefore, in this paper, pore structures of sandstone are generalized into capillaries with tortuosity. First, the image of rock slices is obtained by means of nuclear magnetic resonance imaging (MRI) technology, and the fractal dimension of pore distribution obtained by the box-counting dimension method is used. The fractal dimension of the pore distribution is the target parameter, and the fractal dimension of the tortuosity is calculated iteratively by combining the fractal scalar relationship between the number of capillaries and the pore size under different tortuosities. Compared with the traditional fractal dimension calculation method, the fractal dimension of tortuosity determined in this paper is larger, and the difference between different rock samples is more obvious, which can better reflect the heterogeneous characteristics of pore distribution. Related Articles | Metrics

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Effects of Physical Parameters of Shale on CO 2 Storage Capacity with Different Mechanisms YIN Shuguo, YANG Guodong, FENG Tao, MA Xin, CAO Wei, HUANG Mian, GUO Tianqing Geological Journal of China Universities    2023, 29 (1): 37-46.   DOI: 10.16108/j.issn1006-7493.2022071 Abstract （1753）      PDF （1157KB）（207）       Knowledge map    Save CO 2 enhanced shale gas recovery (CO 2-ESGR) can not only increase CH4 production, but also store CO 2. In order to investigate the effects of physical parameters of shale on CO2 sequestration mechanisms, a dual-porosity, dual-permeability homogeneous model was established using CMG-GEM based on the shale of Yanchang Formation in Ordos Basin. This study analyzed the effects of vertical permeability to horizontal permeability ratio (Kv/Kh), water saturation and porosity of shale on CO 2 storage capacity with different mechanisms in CO 2-ESGR. Moreover, 27 sets of orthogonal tests were designed to investigate the extent of influence of these three factors by range analysis. The results showed that Kv/Kh increase in the range of 0.1 to 1 leads to enhanced CO 2 storage capacity with different mechanisms, and the maximum storage capacity can increase by 69.96%, of which the adsorption storage capacity can increase by 97.96%. Water saturation increase in the range of 0-0.9 induces the total CO 2 storage to show an increase first and then a decrease. The maximum storage capacity can reduce by 67.12%, of which the dissolved storage capacity can reduce by 83.35%, with the largest range fluctuation. Shale porosity increase in the range of 0.1- 0.99 leads to the reduction of total CO 2 storage capacity, and the maximum storage capacity can reduce by 95.38%, of which the adsorption storage capacity can reduce by 99.99%. Range analysis showed that water saturation has the largest impact on the amount of structural trapping, residual trapping and solubility trapping, porosity has the largest impact on total CO 2 storage capacity and adsorption storage capacity, and Kv/Kh has the least effect on CO 2 storage capacity with different mechanisms. For CO 2 storage in shale reservoirs, shale with low water saturation, low-porosity and high Ky/Kh ratio is suggested to obtain the maximum storage capacity. Related Articles | Metrics

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Analysis of Monitoring Technologies of Offshore CO 2 Geological Storage in Japan’s Tomakomai and Its Enlightenment XU Xiaoyi, LI Qi, TAN Yongsheng, LIU Guizhen, LI Xiaying Geological Journal of China Universities    2023, 29 (1): 13-24.   DOI: 10.16108/j.issn1006-7493.2022096 Abstract （1715）      PDF （3566KB）（342）       Knowledge map    Save Offshore carbon dioxide (CO 2) capture and storage (CCS) is one of key technologies to cope with global climate change and reduce greenhouse gases such as CO 2, and also an important solution to achieve carbon neutrality goal of China. Offshore sedimentary basins of China have huge storage potential, and the first offshore CO 2 geological storage demonstration project has been officially launched in the Pearl River Mouth Basin of the South China Sea in 2022. Japan’s Tomakomai CCS project is the most successful offshore CO 2 geological storage project in Asia so far, and its monitoring work provides important practical references and technical experiences for the development of China offshore CCS projects. Based on this consideration, this paper comprehensively reviews the case of Tomakomai CCS project, analyzes its implementation, site monitoring items and distribution, monitoring facilities and technologies, monitoring results, etc., summarizes the successful experience of the Tomakomai CCS project and the multi-level and all-round monitoring system of land-wellbore-marine integration, aiming to help offshore CCS projects of China run smoothly, and to ensure the security and safety of the marine ecological environment. Related Articles | Metrics

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The Effect of Pre-existing Fracture Complexity on Rupture Characteristics of Tight Reservoir YIN Chen, SHI Xuewen, CAI Bo, WEN Shanshi, LIANG Tiancheng, WANG Xin, FU Haifeng, HAN Fusheng Geological Journal of China Universities    2023, 29 (1): 128-137.   DOI: 10.16108/j.issn1006-7493.2022081 Abstract （1713）      PDF （5081KB）（153）       Knowledge map    Save Pre-existing microscale fractures, cracks and pores in geological layer, which makes the rock or/and stratum heterogeneity, response the difference of rupture characteristics under artificial injection. The exploitation and development of unconventional oil and gas reservoirs represented by tight oil and gas accounts for an increasing proportion of China’s oil and gas production capacity, and artificial fractures are often produced by hydraulic fracturing to enhance oil and gas flow and achieve the scale of economic production, they also are the important target for CO2 injection and geological storage. Based on the true triaxial hydraulic fracturing experiment and the microseismic data in geological setting, this paper studies multiscale rupture process in sandstone through the temporal and spatial characteristics of acoustic event and the microseismic event. The results show that the pre-existing fractures in rock dominate the rupture pattern under the stable triaxial hydraulic fracturing stress and geological settings. Related Articles | Metrics

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Effects of CO 2 Purity on Residual Water During Carbon Sequestration in Deep Saline Aquifers HU Zhikai, LI Yi, SUO Ruiting, DIAO Yujie, LI Qi, MA Xin Geological Journal of China Universities    2023, 29 (1): 57-65.   DOI: 10.16108/j.issn1006-7493.2022061 Abstract （1686）      PDF （3124KB）（173）       Knowledge map    Save During the process of CO 2 being injected into deep saline aquifers, residual water formed in rock pore has negative impacts on CO 2 injectability, storage capacity and safety. Therefore, it is important to investigate the formation and evolution of residual water under various influencing factors. In this study, natural rock core taken from the deep reservoirs of the Ordos Basin were used to conduct core-flooding experiments using 3 sets of CO 2 purity (99.999%CO 2, 75%CO 2+25%N2 and 50%CO 2+25%N2) at 40℃ and 8 MPa to investigate the effect of CO 2 purity on residual water. The experimental results show that the order of time required to reach the breakthrough point and the drainage endpoint are, 99.999%CO 2<75%CO 2+25%N2<50%CO 2+50%N2; the order of the irreducible water saturations is: 99999%CO 2<75%CO 2+25%N2<50%CO 2+25%N2. The analysis revealed that changes in CO 2 purity lead to changes of important properties in two-phase floods, such as interfacial tension, wettability, and viscosity ratio. By analyzing the LogCa-LogM displacement stability diagram, the capillary force was determined to be the dominant factor affecting the results of experiments. This study is of great value for predicting residual water saturation under various conditions and evaluating CO 2 sequestration capacity. Related Articles | Metrics

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Research on Inter-well Interference Law of Supercritical CO 2 Staged Multi-cluster Fracturing PENG Shouchang, XU Dongsheng, GAO Yang, ZHANG Fang, SHI Leiting, ZHANG Yulong, LIU Tong, WEI Xiaochen Geological Journal of China Universities    2023, 29 (1): 47-56.   DOI: 10.16108/j.issn1006-7493.2022083 Abstract （1649）      PDF （2951KB）（143）       Knowledge map    Save The staged multi-cluster fracturing of horizontal wells is a key technology for the development of unconventional oil and gas reservoirs. While rationally using fracturing-induced stress to increase the volume of reservoir reconstruction, avoiding sand plugging and fracturing interference caused by inter-well interference is a key scientific issue in fracturing process optimization. In this paper, aiming at the problem of fracture interference and interwell interference of staged multi-cluster fracturing using supercritical CO 2, a fluid-solid coupling extended finite element method is used to establish a fracture-induced stress calculation model for studying single wells and multi-wells. We consider the flow and fluid loss of supercritical CO 2 in fractures, and systematically study the disturbance stress of fracturing operation from the lithological characteristics of unconventional oil and gas reservoirs, the distribution of in-situ stress field and construction technology, etc. The propagation mechanism and stress disturbance characteristics of multi-cluster hydraulic fractures in a single well are revealed, and on this basis, the inter-well fracture interference law of multi-wells is studied. The results show that the fracturing interference limit in reservoirs with high level of stress difference and high elastic modulus is relatively large, and the formation of low level of stress difference and low elastic modulus needs to appropriately increase the cluster spacing to reduce inter-cluster interference. After well 1# is fractured, the asymmetry coefficient of hydraulic fractures in adjacent well 2# first increases and then decreases with the well spacing; when the well spacing is equal to the fracturing interference limit, the asymmetry coefficient λ reaches the maximum, and the well circumference is reformed The range is the largest, but the asymmetry of the two wings of the fracture may lead to insufficient reservoir production. This research provides a theoretical basis for horizontal well subdivision cutting and fracturing and threedimensional well pattern design optimization, which is of great significance for the efficient development of unconventional oil and gas resources in the context of the“carbon peaking and carbon neutrality”strategy. Related Articles | Metrics

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Status and Advances of Research on Caprock Sealing Properties of CO 2 Geological Storage CHEN Bowen, WANG Rui, LI Qi, ZHOU Yinbang, TAN Yongsheng, DAI Quanqi, ZHANG Yao Geological Journal of China Universities    2023, 29 (1): 85-99.   DOI: 10.16108/j.issn1006-7493.2023010 Abstract （1535）      PDF （6425KB）（595）       Knowledge map    Save CO 2 Geological storage is one of the key technologies to address global climate changes and reduce greenhouse gas emissions. Large-scale CO 2 injection into the formation is prone to inducing CO 2 leakage problem. In particular, the leakage problem of CO 2 through caprock includes capillary leakage, hydraulic fracture and leakage along pre-existing faults crossing caprock. Therefore, evaluation of caprock seal is crucial for prediction of long-term safety and stability of CO 2 geological storage. This paper provides an overview of the current status of research on sealing mechanisms, influencing factors, and damage modes affecting caprock seal of CO 2 geological storage. It is concluded that caprock seal mechanisms include capillary seal, hydraulic seal, and overpressure seal. The main influencing factors of caprock seal characteristics include caprock lithology, mudrock-sand ratio, caprock mechanical properties, and sequestration pressure. Then, the damage modes of caprock seal during CO 2 injection are illustrated, and some insight into the shortcoming of caprock seal is provided. Related Articles | Metrics

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Carbon and Oxygen Isotopic Composition in Shell Carbonates of Modern Land Snails in China: Distribution and Climatic Response LUO Ling, SHEN Hua, BAO Rui, TAN Haolin, LI Chenglong, SHENG Xuefen Geological Journal of China Universities    2022, 28 (6): 861-873.   DOI: 10.16108/j.issn1006-7493.2021088 Abstract （1495）      PDF （2048KB）（268）       Knowledge map    Save The carbon and oxygen isotopic composition of the land snail shell can record environmental and climate information, which are important proxies for reconstructing paleoenvironment and paleoclimate. In this paper, we added the land snails’ data in Xinjiang (controlled by the westerly zone), western Sichuan (controlled by the Indian monsoon), and northeast (north end of the East Asian monsoon) under different climate conditions, analyzing the carbon and oxygen isotope composition of snail shells and combining with previous published data. The distribution and climate response of carbon and oxygen isotope composition of land snail shells in China have been evaluated. The results showed that the relationships between the carbon isotope composition of snail shells and mean annual precipitation or relative humidity are negative, whereas the relationships between the carbon isotope composition of snail shells and mean annual evaporation amount or aridity index are positive nationwide. The carbon isotope of snail shells with annual average temperature (larger than 9.5℃ ) has a negative correlation. There is no significant relationship between the oxygen isotope composition of snail shells and five climate factors, which may be caused by the different response degrees of snail shell oxygen isotope in different monsoon regions, or caused by the contrary correlations between the oxygen isotope of the snail shell and temperature in different regions. Hence the carbon isotope of snail shells can reliably record the carbon isotope variation of C3 vegetation by effective precipitation, the interpretation of the snail shell’s oxygen isotope is still unclear, and needing more studies in the future. Related Articles | Metrics

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Geochemical Characteristics of Heavy Metal Enrichment in Soil Fe-Mn Nodules in the Karst Area of Guangxi FENG Yifu, LIAO Qilin, JI Wenbing, REN Jingli, JI Junfeng, YANG Zhongfang, ZHUO Xiaoxiong, WANG Lei, LIU Yuanyuan Geological Journal of China Universities    2022, 28 (6): 787-798.   DOI: 10.16108/j.issn1006-7493.2021079 Abstract （1484）      PDF （8719KB）（264）       Knowledge map    Save The natural heavy metal contaminant is severe in the Karst area in Guangxi. In this area, the soil contains large quantities of Fe-Mn nodules. Soil Fe-Mn nodules are symbiotic products of soil formation, which is controlled by the environmental conditions. Therefore, Fe-Mn nodules is a good geological record of soil formation and development, as well as historical environmental change. Fe-Mn nodules are composed of ferromanganese oxides, which have strong capacities for heavy metal adsorption. Studying the accumulation characteristics of heavy metals in Fe-Mn nodules will improve understanding the accumulation processes of heavy metals during soil formation and provide scientific support for soil management and treatment. In this study, a series of experiments were conducted using the soil and Fe-Mn nodules from a typical Karst area in Liujiang, Guangxi. Through the determination of trace elements, the analysis shows that Fe-Mn nodules can adsorb Ni, Cu, Cd, Zn, Pb, Co, Ba, As and Cr effectively. We found concentric ring structure and regular distribution of elements in nodules by means of micro measurement methods including Raman spectrum and SEM-EDS. Combined with internal structure and elemental distribution characteristics, the formation mechanism and material source of Fe-Mn nodule was speculated. The formation of Fe-Mn nodules immobilized heavy metals and reduced heavy metal pollution in soil. However, the dissolution of Fe-Mn nodules will release large amount of heavy metals into soil especially those associated with Mn. Related Articles | Metrics

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Experimental Verification of Gas-operated Sampling Technology for Subsurface Fluid LI Xiaying, LIU Xuehao, LI Qi, XIAO Wei, LI Xiaochun Geological Journal of China Universities    2023, 29 (1): 138-146.   DOI: 10.16108/j.issn1006-7493.2022072 Abstract （1481）      PDF （1756KB）（143）       Knowledge map    Save Obtaining underground fluid samples with high quality is important for CO 2 leakage monitoring in CO 2 geological utilization and storage (CCUS). The gas-operated underground fluid sampler has the advantages of high sampling accuracy, low formation disturbance, and in-situ monitoring through integrating downhole monitoring technologies, and has been widely applied in several CCUS applications. However, during practical application processes, sampling volume of the sampler is unstable and greatly affected by groundwater level. In order to solve these problems, a visualized experimental device to simulate subsurface fluid sampling in a wellbore was developed. A set of fluid sampling experiments at different liquid heights were carried out to explore sampling process and sampling mechanism of the gas-operated sampler. The results show that there is no disturbance to the liquid height during the sampling process, indicating the gas-operated sampling technology is characterized by passive sampling and low interference to external environment. The sampling volume depends on the size of the storage container and the liquid height in the wellbore. The sampling volume can be calculated accurately by the liquid height and the pipeline size. The measured sampling volumes under different liquid heights are basically consistent with the theoretical values. The error between the measured volume and calculated one decreases with the increasing liquid heights. The maximum error is less than 6.6%. Both the sampling time and average sampling rate mainly depend on the injection pressure and present a power function relationship with the injection pressure with a correlation coefficient of greater than 99%. The above experimental results can help to understand the sampling mechanism of gas-driven sampler and are of great significance to feedback and guide sampling performance in field by optimizing the structure. In addition, it can improve the ability of warning environmental risks in CCUS and contaminated sites. Related Articles | Metrics

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Hirnantian (latest Ordovician) Stratigraphy and Palaeogeography of the Western Yangtze Platform, South China WANG Guangxu, WEI Xin, CUI Yunong, ZHANG Xiaole, WANG Qian, ZHAN Renbin Geological Journal of China Universities    2023, 29 (2): 298-315.   DOI: 10.16108/j.issn1006- 7493.2022051 Abstract （1421）      PDF （20684KB）（435）       Knowledge map    Save Hirnantian (latest Ordovician) rocks and fossils have still not been sufficiently documented in the western Yangtze region of South China (today’s southwestern Sichuan and northeastern Yunnan provinces, Southwest China). Compilation of published and new data results in refined Hirnantian stratigraphy and palaeogeography of the region. The lower Hirnantian is typified by the dark-grey cacareous mudstone or argillaceous limestone of the Kuanyinchiao Formation yielding cool-water Transitional Benthic Fauna 1 (TBF 1). The middle Hirnantian strata, however, can be grouped into a near-shore lithofacies belt with distinctive grainstones of the upper Kuanyinchiao Formation yielding warm-water TBF 2, and a more offshore belt characterized by black shales of the basal Lungmachi Formation. A similar facies differentiation occurs in the upper Hirnantian of the region, but the near-shore sediments are in places represented by TBF 3-bearing calcareous siltstones, for which a new lithostratigraphic unit, the Weiba Formation, is proposed. On this basis, refined Hirnantian paleogeographic reconstructions of the western Yangtze Platform are presented. Related Articles | Metrics

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Identification of the Dust and Weathering Characteristics of the Soil Weathering from Basalt in Jiangsu and Anhui Provinces CHEN Liao, LIU Lianwen, ZHU Xiaoyu, CAI Jie, JI Junfeng Geological Journal of China Universities    2022, 28 (6): 838-848.   DOI: 10.16108/j.issn1006-7493.2021065 Abstract （1379）      PDF （2411KB）（177）       Knowledge map    Save It is great significance to the identification and contribution of dust in pedogenesis，because the dust affect the global biogeochemical cycle. In this study, two typical weathering profiles (Meihua village, Mingguang County, Anhui Province and Baota village, Xuyi county, Jiangsu Province) and some surface and stream sediment samples were selected from the basaltic platform of Jiangsu Anhui Province. The main minerals, clay minerals, major and trace elements, Sr and Nd isotopic compositions of the samples were analyzed systematically. The results show that the basalt is mainly composed of plagioclase and pyroxene, and the weathered bedrock is mainly composed of montmorillonite, while the soil is characterized composed of dust minerals such as quartz and illite, which are not found in bedrock and weathered bedrock. The bedrock and weathered basalt are characterized by high Mg, low Si, K and no Eu anomaly, while the soil is characterized by high Si, K, low Mg and negative Eu anomaly. Relative to soil, the bedrock and weathered bedrock have a much higher εNd and much lower 86Sr/ 87Sr value. All mineral, element and isotope evidences show that the dust can serviced as important component of soil. Calculated by the Nd isotope mixing model, it can been foundthat the contribution of dust to the soil is more than 60%. The weathering of basalt is characterized by complete montmorillonization and significant removal of Ca and Mg. In Meihuacun section, Ce negative anomaly appears in the surface soil, while Ce positive anomaly appears in the lower layer. It is also found that the content of Si and K in the soil increases due to the accretion of wind dust. Affected by relatively large elevation difference, basalt weathering products and settled wind dust are easily eroded by precipitation, resulting in thinner weathering profile, which makes basalt weathering in “supply limited” mode. This work provides new geological evidence for the weathering mechanism of basalt and the role of wind dust in the element geochemical cycle. Related Articles | Metrics

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Enhanced Chemical Weathering in the Yukon River Basin in North America under the Background of Global Warming NIE Haoyang, LI Shilei, CHEN Yang, WANG Hongtao Geological Journal of China Universities    2022, 28 (6): 825-837.   DOI: 10.16108/j.issn1006-7493.2022067 Abstract （1378）      PDF （3167KB）（264）       Knowledge map    Save The feedback of silicate weathering to climate change and tectonism may play an important role in regulating longterm climate change, quantitative evaluation of this feedback process will help us to more accurately understand how Earth’s carbon cycle works. It is generally believed that there are two weathering types called “supply-limited” and “kinetic-limited”. Global warming may accelerate chemical weathering in the basin under the “kinetic-limited” regimes, however, it remains poorly constrained. The Yukon River Basin is a typical “kinetic-limited” regime. Studying the response of Yukon River weathering to climate warming will help us to deeply understand the interaction between climate and continental weathering. Forward modeling is an important means to distinguish end-members of river weathering. This study estimates the decadal variations in chemical weathering rates in Yukon River Basin with a forward model based on a dataset of major ion composition of the riverine dissolved from 1975 to 2019. The results show that the water chemical properties of the Yukon River basin are mainly controlled by carbonate weathering and silicate weathering. The average annual CO2 consumption rates by silicate weathering and carbonate weathering are 2.1×10 11 mol/yr and 4.1×10 10 mol/yr, respectively, which are in the middle level of the world’s large rivers. More importantly, during the same period, with a 2.2℃ temperature rise and an increase in discharge by 13.7%, the total flux of cation in the basin is increased by 35.7%. And the cation flux of silicate and carbonate weathering increased by 41% and 35% respectively, the sensitivity of cation flux/weathering rate to climate is in good agreement with the results from Iceland. Corresponding to the accelerated weathering rate, the carbon flux of silicate weathering increased by 59.6%. Although the increase of carbon sink is insignificant in terms of absolute flux compared with anthropogenic carbon emission by contemporary fossil combustion, the additional CO 2 sequestration may have an important impact on global climate during Earth’s history, given the increased rates of global silicate weathering within the tectonic scale, especially in the relatively cold high latitude area. Related Articles | Metrics

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Risk Transmission Characteristics of Carbon Dioxide Geological Storage Based on Social Network Analysis JING Meng, LIU Guizhen, LI Qi, XU Xiaoyi, LI Xiaochun Geological Journal of China Universities    2023, 29 (1): 100-109.   DOI: 10.16108/j.issn1006-7493.2023009 Abstract （1372）      PDF （1300KB）（134）       Knowledge map    Save As an essential and necessary means for emission reduction, carbon dioxide geological storage technology is of great significance for ecological and environmental protection, promotes international cooperation on global medium and long-term climate changes, and advances green, recycling and low-carbon development. This study summarizes 46 risk factors that may emerge throughout a lifecycle of carbon dioxide geological storage projects. A risk network relationship model was created using the social network analysis method to investigate the transmission relationship between risk factors associated with carbon dioxide geological storage projects. By analyzing the of overall local risk network parameters, this study identifies key factors such as key initial node, key risk-causing node, and key transmission node in the risk transmission processes. The following three potential risk transmission chains are identified: (1) Geologic hazard → Unexpected disruptions of CO 2 supply, access or transportation → Unexpected changes in construction or operation costs; (2) Insufficient knowledge of an operator or lack of corresponding qualification → Man-made leakage → Environmental damage of the project → Public participation → Unexpected construction or operation cost changes; (3) Improper departmental coordination → Talent recruitment and management risk → Operator’s lack of knowledge or lack of corresponding qualification → Unexpected construction or operation cost changes. The findings of this study can serve as a theoretical and technical reference for risk research in carbon dioxide geological sequestration projects and promote the healthy development of carbon dioxide capture, utilization and storage (CCUS) projects. Related Articles | Metrics

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Late Mesozoic Bansin and Range Framework and the Related Tectono-Magmatism of Southeast China DONG Changchun, SHU Limin, SHU Liangshu Geological Journal of China Universities    2023, 29 (2): 223-239.   DOI: 10.16108/j.issn1006-7493.2021053 Abstract （1352）      PDF （2209KB）（359）       Knowledge map    Save The Southeast China Block was located in the back margin of the Late Mesozoic Japan-Taiwan volcanic arc. The middle Jurassic-late Cretaceous extensional basins and volcanic-intrusive rock series are widely developed in the Southeast China region as a response of ancient Pacific Plate subduction toward the eastern Asia Continent leading the back-arc expansion. The types of basin include the middle Jurassic rifts, the late Jurassic-early Cretaceous volcanoclastic and lava faulted-depression basins and the late Cretaceous-Paleogene redbed faulted-depression basins. The igneous rock series consists mainly of granitoids, bimodal magmatic rocks, A-type granites, metamorphic core complexes and doming-shape plutons, which were formed in the early Cretaceous with a peak value of 140-110 Ma). The basins coexist together with coeval plutons and constituted the Early Cretaceous Southeast China Basin and Range tectonics. This study summarized the principal geological features of the Late Mesozoic Southeast China basin and range geomorphology and analyzed the petrological and geological structural marks and the constraint factors forming the Southeast China bansin and range framework. Finally we discussed the Late Mesozoic geodynamic process of the Southeast China region. Related Articles | Metrics

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Analysis of CO 2 Geological Storage Condition in Jiangsu Province and Offshore Area ZHU Qianlin, CHEN Dongbao, GONG Yijie, CHEN Fu, SANG Shuxun, LIU Shiqi Geological Journal of China Universities    2023, 29 (1): 25-36.   DOI: 10.16108/j.issn1006-7493.2022080 Abstract （1320）      PDF （7423KB）（339）       Knowledge map    Save The analysis of the geological condition in Jiangsu Province and offshore area shows that the Subei-Southern South Yellow Sea basin developed in the Lower Yangtze block is a potential site for CO 2 geological storage in Jiangsu Province. The suitable formation for CO 2 storage lithology is analyzed according to the stratigraphic and lithological data. On this basis, according to the drilling and seismic survey profile data, the suitability of CO 2 storage space is discussed through the thickness of CO 2 storage suitable stratum in 800-3500 m depth range of each tectonic unit. The results show that the sandstone layers in lower Yancheng formation, Sanduo formation, Dainan formation, the first and third members of Funing formation, and Chishan formation have good CO 2 storage space. The Chishan formation is less distributed in the basin, and the Yancheng formation, Sanduo formation, Dainan formation and Funing formation are widely distributed. Jinhu depression, Gaoyou depression, Qintong depression, Hai’an depression, Baiju depression, Funing depression, Yancheng depression, Naner depression, Nansi depression, Nanwu depression, Nanqi depression and the Naner low uplift have good CO 2 storage potential. The CO 2 storage potential of Hongze Sag, Linze Sag, Liannan Sag, Lianbei Sag, Nansan Sag and Nanliu Sag is relatively poor. Related Articles | Metrics

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Numerical Simulation of Compressional Deformation of Pre-existing Passive Salt Diapir in Keshen Area of Kuqa Depression WU Chao, XU Wenqiao, LI Qing, WANG Wei, CHEN Weili, YIN Hongwei, QU Yuanji Geological Journal of China Universities    2023, 29 (2): 240-250.   DOI: 10.16108/j.issn1006-7493.2021057 Abstract （1273）      PDF （14318KB）（127）       Knowledge map    Save Kuqa fold-thrust belt is a typical complex salt-bearing fold-thrust system. In this paper, based on seismic interpretation, two discrete element models are designed to explore the influence of pre-existing passive salt diapir on the structural geometry and evolution of double-detachment fold-and-thrust belts, as well as the causes behind the different salt structural deformation characteristics and mechanism of the strike segment in Keshen 5 structural area, and the slip displacement of subsalt faults are analyzed finely. The simulation results show that the pre-existing salt diaper, as the priority location of compressional structural deformation and the priority area of stress release, affects the sequence of faults in subsalt layer and the slip displacement of subsalt faults, proceeding to control the differential evolution of structures along the strike. Comparing the simulation results and structural features of Keshen 5 structural area in Kuqa depression, we suggest that the Tuzimazha anticline is the result of the subsequent compressional deformation of the pre-existing passive diapir in the salt basin. The Tuzimazha anticline absorbs most of the shortening, resulting in a significant uplift of the adjacent subsalt fragments, and a wide and gentle syncline is formed on the north side of the anticline under the influence of syntectonic deposits, which suppresses the formation of disordered faults in the syncline. The pre-existing salt diapir structure is the main controlling factor controlling the tectonic deformation in Keshen 5 area. There is no pre-existing salt diapir in the eastern part of the study area, Kumugelemu anticline and Kasangtuokai anticline are developed in turn, the amplitude of which decreases towards the basin, and the slip intensity of subsalt faults weakens towards the basin. The western part of the study area contains pre-existing passive salt diapir. Tuzimaza anticline is developed, and the activity intensity of subsalt faults under pre-existing passive salt diapir is stronger than that of adjacent faults. Related Articles | Metrics

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Current Research Status and Tendency of Hydrogen Production Coupled CCUS Technology Based on Bibliometrics CAO Xiaomin, LI Qi, XU Liang Geological Journal of China Universities    2023, 29 (1): 110-119.   DOI: 10.16108/j.issn1006-7493.2022073 Abstract （1220）      PDF （2996KB）（145）       Knowledge map    Save Hydrogen energy is the “ultimate form” of energy in the future. Currently, industrial production of hydrogen mainly relies on fossil fuels. Carbon capture, utilization and storage (CCUS) is an important way to realize the transformation from “grey hydrogen” to “blue hydrogen” and “dual carbon goals”. In this paper, related literatures were collected from the Web of Science core collection. CiteSpace software was used to analyze the literature source, research strength, research hotspots and research frontiers in the coupling field of hydrogen production and CCUS technology. The results show that China ranks the first in the number of publications and also has extensive cooperation with other countries. The main research forces at home and abroad are research institutes and universities. Sorption enhanced steam methane reforming (SESMR) hydrogen production technology, chemical looping combustion (CLC) hydrogen production technology, catalysts, adsorbents and oxygen carriers are the main research hotspots. Metal oxygen carriers are at the forefront of research. Development of composite catalysts with catalytic and adsorption functions and application of electricity-hydrogen generation technology combining CLC technology and coal gasification in the thermal power industry are the two main research directions in the future. Considering the industry-wide adoption of “dual carbon goals”and the additional cost of carbon tax, the hydrogen production technology accompanying CCUS is still a preferred option. Related Articles | Metrics

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One-stop Sharing and Service System for Geoscience Knowledge Graph ZHU Yunqiang, DAI Xiaoliang, YANG Jie, WANG Shu, SUN Kai, QIU Qinjun, LI Weirong, QI Yanmin, HU Lei, LYU Hairong, WANG Xinbing, ZHOU Chenghu Geological Journal of China Universities    2023, 29 (3): 325-336.   DOI: 10.16108/j.issn1006-7493.2023029 Abstract （1220）      PDF （7167KB）（631）       Knowledge map    Save As the most effective way of knowledge organization and service at present, knowledge graph has become the cornerstone of artificial intelligence and has been widely used in semantic search, machine translation, information recommendation and so on. In the era of big data, there is an urgent need of Geoscience knowledge graphs for integrating, mining and analysis of scattered, multi-source and heterogeneous Geo-data and its unknown knowledge intelligent discovery. To promote the construction and application of Geoscience knowledge graphs, the Deep-time Digital Earth (DDE) International Big Science Program has taken knowledge graph as its one of the core research contents since its launch in 2019. After more than three years of construction, DDE has built a large number of Geoscience knowledge graphs, and it strong needs one-stop sharing and service system of these knowledge graphs. Firstly, this paper introduces the content framework, composition as well as characteristics of the DDE knowledge graphs. On this basis, the design of the one-stop sharing and service system for the Geoscience knowledge graph is designed that include the design of the system functional and technical architecture. Finally, the development and operation environment & tools, and key technologies of the system are discussed in detail. The practice has proved that the system can effectively realize the one-stop sharing and open access of DDE knowledge graphs. Meanwhile, it sets an example for other fields or domains’ knowledge graph integrating and sharing systems. Related Articles | Metrics

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Assessment of Carbon Dioxide Mineralization Sequestration Potential of Volcanic Rocks in Leizhou Peninsula, Guangdong Province, China LI Pengchun, JIANG Jinglian, CHENG Jinhui, ZHAO Minghui Geological Journal of China Universities    2023, 29 (1): 76-84.   DOI: 10.16108/j.issn1006-7493.2022078 Abstract （1206）      PDF （1188KB）（196）       Knowledge map    Save Mineral carbon sequestration by volcanic rocks, providing a permanent sequestration solution for reducing atmospheric CO 2, is one of an economic and safe way of carbon capture and storage (CCS). Volcanic rocks are widely distributed in China, but research on the carbon sequestration potential of volcanic rocks is still very limited. In this paper, we selected the volcanic rocks of Leizhou Peninsula, Guangdong Province as the study area, and used MapGis software to establish a vector geographic information database of the thickness distribution of volcanic rocks in Leizhou Peninsula, and interpolated to obtain a three- dimensional gridded data body. The results show that the total area of volcanic rocks in Leizhou Peninsula is approximately 3940 km 2, with a total volume of 257 km 3, and calculated results of the theoretical CO 2 mineralization storage capacity ranges from 1.9 to 45.9 billion tons. Among them, the volcanic rocks in the Leinan area have the largest potential, with the theoretical storage capacity ranging from 1.3 to 32.6 billion tons, followed by volcanic rocks in the area east of Suixi County in Leibei and west of Zhanjiang City, with the capacity from 0.2 to 5.6 billion tons. Although the theoretical storage capacity of volcanic rocks in the Donghai Island area is relatively small (0.15 to 3.5 billion tons), they have a good source-to-sink matching condition due to their proximity to the surrounding industrial emission sources, and so they also have good CCS prospects. The results of this study not only provide an important basis for the screening site of CO 2 mineralization volcanic rocks, but also offer support for future development of regional CCS projects or industries. Related Articles | Metrics

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The Earliest Denudation Record of the Dabie Orogenic Belt Evidenced from the Middle Triassic Huangmaqing Formation in the Ningwu Basin LI Chao, HU Xiumian Geological Journal of China Universities    2022, 28 (4): 527-538.   DOI: 10.16108/j.issn1006-7493.2020104 Abstract （1172）      PDF （3914KB）（124）       Knowledge map    Save Due to post-orogenic multi-stage tectonic events and long-term massive denudation, there are poor precise constraints to limit the initial denudation time of the Dabie orogen, that is, timing of starting to provide a source for the peripheral basins. In this work, we conduct field investigations on the Huangmaqing Formation, a set of Middle Triassic delta facies terrigenous clastic rock in Ningwu Basin, northeastern South China, and presents sedimentologic and provenance analysis. Lithologies of the Huangmaqing Formation are dominated by the litho-quartzose sandstone and feldspathic-litho-quartzose sandstone, with quartz of 76%-84%, lithic fragment of 10%-14%, and feldspar of 6%-11%. Among the lithic fragments, quartz-rich metamorphic rock fragments or metapelite grains rock debris are dominant, indicating the existence of special sources of metamorphic rocks. The detrital zircon age spectrum shows the main peaks at 350-250 Ma、420-400 Ma、900-700 Ma、2000-1600 Ma、2500-2100 Ma. The Susong Complex belt located in the southern orogenic belt is the main source of the Huangmaqing Formation. Compared with the sedimentary records of other early Mesozoic basins around the Dabie orogen, it is found that these basins have similar provenance in the Middle-Late Triassic. The early exhumation of the lower metamorphic belts in the Dabie orogenic belt led to the initial denudation of the orogenic belt. At least part of the sediments of the Huangmaqing Formation were derived from the early uplift and denudation of the orogenic belt. Related Articles | Metrics

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Discussion on the Main Controlling Factors of the Structure of Baikal Rift: Insights from Physical Modeling WANG Mengnan, LI Jianghai, LIU Chen, LIU Leixin Geological Journal of China Universities    2023, 29 (2): 251-260.   DOI: 10.16108/j.issn1006-7493.2021059 Abstract （1164）      PDF （6688KB）（104）       Knowledge map    Save Baikal Rift is located in the center of the largest continental area in the world, far away from any active plate boundary, but it is one of the most active and complex tectonic areas on earth today. The main controlling factors of its formation and evolution have been widely discussed. Yet, it is still the subject of intense debate concerning. In this paper, the process of lithospheric deformation under the background of local tension is studied by means of physical modeling. Baikal rift is located at the joint of the strong Siberian craton and the weak Sayan-Baikal fold belt. The Siberian craton is characterized by a strong lithosphere where the crust and mantle are mechanically coupled. The experimental results show that stress tends to accumulate on the craton side under the regional tension, and a deep and large fault first developed near the edge of the craton at the weak suture between the craton and orogenic belt. With the continuous extension of the lithosphere, the stress is transferred to the side of the orogenic belt, and the faults also migrate to the side of the orogenic belt, presenting an echelon arrangement. Compared with the young fold belt, the old craton has a cold and hard rigid basement, which determines the narrow and deep depression characteristics of Baikal rift and the asymmetry of its structure. Related Articles | Metrics

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Genesis Process of the Cretaceous Daqushan Pluton in Zhejiang Province: Crystal-Melt Separation and Magmatic Recharge HE Chen, XIA Yan, XU Xisheng, QIU Jiansheng, XU Hang, ZHANG Zhi, ZHAO Sidi Geological Journal of China Universities    2023, 29 (5): 657-678.   DOI: 10.16108/j.issn1006-7493.2022018 Abstract （1149）      PDF （11167KB）（1042）       Knowledge map    Save The models of trans-crustal magmatic system and crystal mush provide new insights into the study of Cretaceous magmatism in northeast China. The Daqushan pluton is located in the northeast of coastal Zhejiang and Fujian. It is mainly composed of K-feldspar granite with abundant melanocratic microgranular enclaves (MME) and is locally traversed by several mafic-intermediate dikes. A small outcrop of monzonite is exposed near the Chaotoumen. MME have a fine-grained texture with acicular apatites. Zircon U-Pb dating results show that the rock samples in the Daqushan pluton (including the K-feldspar granite, MME, monzonite, and mafic-intermediate dikes) crystallized at ~100 Ma. The K-feldspar granite are highly silicic (SiO2=68.45%-73.82%). While the miarolitic granite (DQS-7) without MME has the higher silica (76.27%), and its whole-rock geochemical and Sr-Nd isotope compositions are similar to those of coeval high silica granites (SiO2>75%) exposed around the Daqushan pluton. Daqushan K-feldspar granite bearing aggregates of plagioclase and K-feldspar exhibit“complementary”trace element geochemical characteristics with Daqushan miarolite and surrounding high silica granites. Further researches show that the Daqushan K-feldspar granite and miarolite were formed by felsic magma which originated from the partial melting of the ancient crustal basement and was recharged by mantle-derived magma. Such felsic magma underwent fractional crystallization and the extraction of high silica melt. Then, the residual silicic cumulate of the crystal mush and high silica melt crystallized and formed the Daqushan K-feldspar granite, miarolite and the surrounding coeval high silica granites. The mafic dikes of Daqushan are enriched in LILEs and depleted in HFSEs and are derived from the partial melting of the enriched mantle metasomatized by subducted dehydration fluids. The results of EPMA analyses indicate that the plagioclase in the K-feldspar granite and MME has a core-mantle-rim texture with low- An in the core (27-36, 25-41) and rim (17-32, 18-26) and relatively high-An in the mantle (28-57, 27-65). Integration of the element geochemical characteristics and Sr-Nd-Hf isotopic results, monzonite and intermediate dikes should be the product of magma mixing of mantle-derived mafic magma and felsic magma, while MME are the product of magma mingling of the two endmembers. The results of the Al-in-hornblende geobarometer show that the crystallization depth of MME is 1.8- 3.0 km, hornblende in monzonite develops core-mantle-rim texture, the crystallization depth of hornblende core and mantle is 17.0-21.2 km, and the depth of hornblende rim is 1.9-4.5 km. Based on the study of the origin and genetic relationships of K-feldspar granite, MME, miarolite, monzonite and mafic-intermediate dikes, and compared with the surrounding coeval high silica granites, this study establishes a model of trans-crustal magmatic systems for Daqushan pluton. The rollback of the subducting paleo-Pacific plate, the back-arc extension in the coastal area and the upwelling of the asthenosphere led to the underplating of the mantle-derived mafic magma, and further induced the partial melting of basement rocks in the lower crust to produce felsic magma. The continuous recharge and heating of mantle-derived magma favor the existence of long-lived melt-bearing regions in magma chambers, promoting magma differentiation and crystal-melt separation and thus forming two magma chambers with depths of 17-21 km and 2-3 km, respectively. K-feldspar granite, high silica granites, monzonite, MME and intermediate-mafic dikes were formed by magma mingling/mixing and crystal-melt separation in two connected magma chambers at different depths. Related Articles | Metrics

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Paleosalinity Characteristics and Geological Significance of the Upper Bayingobi Formation in Yingejing Depression, Bayingebi Basin GAO Hongxia, LIU Xiaodong, LIU Pinghui, MENG Pinghong, XIANG Long, RAO Gengwei Geological Journal of China Universities    2022, 28 (4): 539-553.   DOI: 10.16108/j.issn1006-7493.2021072 Abstract （1106）      PDF （3420KB）（199）       Knowledge map    Save The mudstone of the upper Bayingobi formation in Bayingobi basin is one of the research targets for the deep geological disposal of high-level radioactive waste in China. At present, the combination characteristics of clay minerals and the factors affecting the paleosalinity of the mudstone are less studied. In this paper, the paleosalinity of the upper Bayingobi formation is comprehensively distinguished by the methods of B content, Sr/Ba ratio, Rb/K ratio, Na+K mass fraction and X-ray diffraction. The results are as follows：(1) The upper member of Bayingobi formation is dominated by semi deep lake-deep lake sedimentary environment with thick dark grey mudstone developed. And it mainly ranges from semi deep lake to deep lake facies. (2) The lithologic characteristic of the target formation in the study area is argillaceous and silty. Illite, montmorillonite and mixed layer of illite and montmorillonite are well developed while chlorite and kaolinite are relatively rare. (3) The values of Sr/BA, Rb/K, B/GA and Na+K of the selected samples are similar to the paleosalinity changes restored by Couch formula, and the water is mainly featured by brackish and saline water. (4)With increasing sample depths from TZK-1 and TZK-2 boreholes, the paleosalinity changes regularly, with the characteristics of increase-decrease, which is consistent with the change of illite content. The paleosalinity change is coupled with paleoclimate and redox research in this lithologic section. The results show that: The study of paleosalinity in the target formation is not only conducive to the restoration of paleosedimentary environment in the lake basin, but also helps to reveal the influence of paleosalinity variation on clay mineral assemblage characteristics and evolution. These results may provide a certain basis for the later in-depth study of clay mineral’ s nuclide adsorption performance and nuclide migration in mudstone. Related Articles | Metrics

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Overview of New Taxa on Global Vertebrate Fossil during 2017-2021 WANG Haohan, ZHU Min, SHI Xiaodong, PAN Zhaohui Geological Journal of China Universities    2023, 29 (5): 788-794.   DOI: 10.16108/j.issn1006-7493.2022026 Abstract （1100）      PDF （2181KB）（287）       Knowledge map    Save Biodiversity data of vertebrate fossils is important information source for studying earth history and life evolution. The species list of vertebrate fossils is an essential basis for studying the diversity of global vertebrate fossils. Reviewing new taxa and literature on vertebrate fossils can reveal the research hotspots of vertebrate fossils diversity and grasp disciplinary development directions on a time scale. Based on the DeepBone Database, this study reviews the annual variation characteristics of taxa and literature, distribution countries of the holotype, published journals, and significant contributing institutions of new taxa on the different categories of global vertebrate fossils during 2017-2021 using bibliometrics analysis. The result shows that 2662 new taxa emerged, and 1946 literature were published on global vertebrate fossils during 2017-2021. New taxa and literature on vertebrate fossils have decreased since the outbreak of COVID-19 at the end of 2019. Countries with a high distribution of the holotype of new taxa for global vertebrate fossils during 2017-2021 and are rich in vertebrate fossil resources, are strong in the economic and scientific research, mainly including the United States, China, New Zealand, Argentina, and Germany. Journal of Vertebrate Paleontology, Cretaceous Research, Historical Biology, PeerJ, and Journal of Systematic Palaeontology are the prominent journals on new taxa of vertebrate fossils. The institutions with a high contribution to the new taxa for vertebrate fossils are the Chinese Acad Sci, Russian Acad Sci, Consejo Nacl Invest Cient & Tecn, Nat Hist Museum, and the research cooperations of various institutions are very close. The study of taxonomy on vertebrate fossils in China has reached a high level in the world. We should continue to strengthen the accumulation of primary data on vertebrate fossils diversity to provide the DeepBone database for exploring the origin and evolution of bio diversity in the future.  Related Articles | Metrics

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Surface and Subsurface Chemical Weathering in Tropical Hainan Island: Implications for Global Carbon Cycle and Seawater Sr Isotope Evolution PENG Jingcheng, ZHENG Xu, WU Weihua Geological Journal of China Universities    2022, 28 (6): 849-860.   DOI: 10.16108/j.issn1006-7493.2021018 Abstract （1095）      PDF （1601KB）（197）       Knowledge map    Save The chemical weathering of tropical volcanic island/arc plays an important role in global carbon cycle and Sr isotope evolution of seawater. In this paper, a comprehensive study of river water, groundwater, rainwater, bedrock and sediment was carried out in some small basaltic and granitic watersheds in Hainan Island, China. The element contents and 87Sr/86Sr ratios of water and solid samples were analyzed. The results show that there is a certain relationship between the chemical alteration index (CIA) and 87Sr/ 86Sr, which is mainly attributed to the different stages of weathering: in the early stage dominated by biotite weathering, 87Sr/ 86Sr is relatively high. After that, plagioclase begins to be weathered and 87Sr/ 86Sr decreases gradually. In the middle weathering stage, after a large amount of plagioclases are decomposed, the weathering of various K-rich minerals is intensified, and the 87Sr/ 86Sr value rises to the highest point. In the stage of high weathering degree, the stable weathering residual materials are dominant as the decrease of K-rich minerals, and the 87Sr/ 86Sr value declines gradually. Compared with the young active volcanic islands, for example, the Lesser Antilles Islands in the Caribbean Sea and the Reunion Island in the Indian Ocean (the subsurface chemical weathering rate is 2-5 times higher than the surface weathering rate), the underground water flow and total dissolved solids (TDS) in Hainan Island are much lower due to the relatively low rainfall and the low porosity of the old inactive volcano. As a result, the subsurface chemical weathering rate of Hainan Island is lower than that of the surface weathering, only close to the Kamchatka active volcanic island in high latitude, 6%-25% of the Lesser Antilles and Reunion Islands in tropical zone, and is one of the regions with the lowest contribution of subsurface weathering in the world. The surface chemical weathering and CO 2 consumption rates of basalt area in Hainan Island are higher than those of Massif Central, France and Siberia, slightly lower than those of Hawaii and Deccan Trap, and significantly lower than those of Java and Luzon Island in Southeast Asia. Under the condition of similar temperature, runoff has an obvious control over the chemical weathering rate. The CO 2 consumption capacity of Hainan Island in the tropical region is only in a global average range due to the low annual runoff. Related Articles | Metrics

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Macroscopic and Mesoscopic Investigation on the Physical and Mechanical Characteristics of Coral Limestone at Different Depths MA Linjian, LIU Huachao, ZHANG Wei, LI Qi, ZHU Honghu, WU Jiawen Geological Journal of China Universities    2023, 29 (3): 471-478.   DOI: 10.16108/j.issn1006-7493.2021074 Abstract （1070）      PDF （2519KB）（469）       Knowledge map    Save In order to investigate the physical and mechanical characteristics of coral reefs with different depth in the South China Sea, scanning electron microscopy (SEM) and X-ray tomography (CT) technology are used to characterize the micro morphology and internal pore structure characteristics of shallow and deep reef limestone. Quantitative relationships between P-wave velocity and porosity as well as density were established. Uniaxial compression tests on dry and saturated reef limestone were also carried out. Results show that shallow reef limestone is porous with excellent pore connectivity, and the main mineral composition is aragonite, which belongs to the biological sedimentary rock. While deep reef limestone is dense with poor pore connectivity, and the main mineral composition is calcite, belonging to the metamorphic rock. The porosity of deep reef limestone is about 1/10, with an average peak compressive strength of about 4.8 times and an average elastic modulus of about 4.5 times that of shallow reef limestone. Reef limestone belongs to soft or extremely soft rock, characterized by brittle destruction property. The typical damage pattern is multiple rupture surface destruction along the primary pore, growing line of corals and weak bond surface, with high  residual strength. The hydrogenic effect of reef limestone is significant, and the water rationality of deep reef limestone is stronger than shallow reef limestone. The significant difference of physical and mechanical performances in shallow and deep reef limestone are mainly due to the variety in mineral components, pore structure and lithology caused by the varying degree of rock cementation with different depths. Related Articles | Metrics

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End Member Model Analysis of Sediments Grain-size from Erlongwan Maar Lake and Corresponding Environmental Implication in the Past 100 Years LIAO Dongxia, GUO Haiting, WU Mengmeng, PAN Shaoming Geological Journal of China Universities    2023, 29 (2): 316-324.   DOI: 10.16108/j.issn1006-7493.2021051 Abstract （1064）      PDF （1623KB）（246）       Knowledge map    Save Sediment grain size contains paleo-environmental information such as regional precipitation intensity, water level fluctuation and sediment provenance. The end-member modeling analysis can extract the end members representing different sedimentary dynamic processes. We collected two sediment cores from the center and the shore of the Erlongwan Maar Lake. 137Cs activities were measured by Coaxial High Purity Germanium Detector GMX30P-A Series, particle size was measured by the Malvern Mastersizer 2000. The parametric EMA modeling was used to analyze the grain size data of sediment cores in Erlongwan Maar Lake. Based on the results, we analyzed the sediment source and the sedimentary environment of Erlongwan Maar Lake in the past 100 years. The results indicate that the parametric EMA modeling has recognized three end members. The sediments in Erlongwan Maar Lake are thought to be aqueous mainly, and the eolian deposits are relatively less. From EM1 to EM3, the mode particle size increases successively. EM1 represents eolian deposits and fine-grained materials carried into the lake by flowing water. EM2 comes from the erosion of debris in the basin by surface runoff, which is the major component of sediments. EM1 and EM2 indicate a closed lake sedimentary environment with weak hydrodynamics, and EM3 indicates a process of strong surface runoff transport. The detrital material derived from continent is the main source of sediments. The distant clayey particles carried by the upper westerly wind and the near dust particles carried by meso-scale regional wind also contribute to the sediments. The sedimentary environment is relatively stable during recent 100 years. The sedimentation rate of the lake core is lower than that of the lakeshore. After 1963, the content of fine-grained materials increased, while the proportion of coarse-grained components decreased. This means the improvement of ecological environmental and the decrease of surface materials loss, which indicates that the establishment of Jilin Longwan National Nature Reserve plays an important role in soil and water conservation.  Related Articles | Metrics

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Classification of Heavy Metal Contamination Risk in Typical Agricultural Soils by Visible and Near Infrared Reflectance Spectroscopy LI Quankun, ZHAO Wanfu, WEN Yubo, GUO Chao, LIU Lianwen, JI Junfeng Geological Journal of China Universities    2022, 28 (6): 799-813.   DOI: 10.16108/j.issn1006-7493.2021086 Abstract （1056）      PDF （4043KB）（154）       Knowledge map    Save The contamination of heavy metals in agricultural soils caused by natural or anthropogenic factors strengthens the importance of soil environmental quality survey and managements. Nevertheless, the conventional methods of sampling and analysis are time-consuming and costly. Visible and near-infrared (Vis-NIR) reflectance spectroscopy is a rapid and inexpensive alternative to measure soil physical and chemical parameters. This study explored the capacity of Vis-NIR reflectance spectroscopy models for soil heavy metal contamination risk classification. We collected 390 agricultural soils from a typical anthropogenic contaminated area (Wenling, Zhejiang) and a typical high geological background area (Hengxian, Guangxi), examining the concentrations of eight soil heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn), soil pH values, as well as soil Vis- NIR reflectance spectroscopy. Partial least square regression (PLSR) and support vector machine (SVM) algorithms were used to calibrate regression models for predicting the concentrations of soil heavy metals and pH values. Based on the predicted values of spectral models, soil heavy metal contamination risk types were classified. Results showed that, the regression prediction deviation (RPD) values of spectral models for Cd and Cu, the major pollutant elements in Wenling soils, were 1.23 and 1.19, respectively. The spectral prediction mechanism is the correlation between Cd and Cu with organic matter. The two major pollutant elements in Hengxian soils are As and Cd, which had the RPD values of 1.98 and 1.93, respectively. The spectral prediction mechanism is the correlation between As and Cd with iron oxides and clay minerals. In the high geological background soils at Hengxian, there were generally strong positive correlations between soil heavy metals and iron oxides, where spectral models gave more accurate predictions for heavy metals. The RPD values of spectral models for soil pH values were 1.76 at Wenling and 1.68 at Hengxian. Spectral classification of soil contamination risk has reliable overall accuracy (75.0%~100% at Wenling, 80.0%~100% at Hengxian). Therefore, the spectral method combining with remote sensing technology is helpful for rapid classification of heavy metal contamination risk in agricultural soils. Related Articles | Metrics

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Tectonic Attributes and Continental Affinities of the Precambrian Blocks in the Southwestern Central Asian Orogenic Belt WANG Bo, SUN Zhaochen, SONG Fang, NI Xinghua, CAO Tingting, LIU Jiashuo Geological Journal of China Universities    2023, 29 (3): 439-454.   DOI: 10.16108/j.issn1006-7493.2021073 Abstract （984）      PDF （2285KB）（178）       Knowledge map    Save Numerous ribbon-like micro-plates develop in the southwestern part of the Central Asian Orogenic Belt (CAOB), they are important constituents of the Kazakhstan microcontinent, understanding of their tectonic attributes, continental affinities and crustal evolution is essential for the reconstruction of the accretionary history and geodynamic processes of the CAOB. The controversies remain for a long time about the basement compositions, tectonic settings and affinities of the micro-plates. This paper compiles recently published geological and isotopic chronological data, and summarizes rock assemblages, ages and tectonic settings of the Precambrian basement, and further analyzes the tectonic attributes of the micro-plates and their possible affinities with the surrounding continental plates. The available data indicate that the Meso- and Paleoproterozoic crystalline basement only develop in a few micro-plates (such as Chinese Central Tianshan, Kyrgyz Middle Tianshan, Issyk-Kul, Zheltau and Kokchetav), but are not recorded in the other micro-plates (such as South Yili, North Yili-Aktau, Chu-Ili, Karatau, Baikonur, Erementau and Ulutau) in the SW CAOB. However, similar Neoproterozoic metamorphic and magmatic rocks were documented in all these micro- plates and form the comparable metamorphic and crystalline basement. A comprehensive comparison and analysis allow us to conclude that these micro-plates may have different origins, but they experienced similar tectonic and magmatic evolution since Neoproterozoic, and underwent comparable paleogeographic environment, suggesting Early Neoproterozoic convergent orogenesis, Late Neoproterozoic continental rifting and formation of passive continental margins during the opening of the Paleo-Asian Ocean. Related Articles | Metrics

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Structural Characteristics and Deformation Mechanisms of Multipledetachments in Luzhou area, Southeastern Sichuan Basin ZHAO Shengxian, XU Wenqiao, YANG Xuefeng, YIN Hongwei, LI Bo, WANG Wei, ZHANG Chenglin, JIA Dong, LIU Yongyang, XIE Wei, ZHANG Dongjun, LI Changsheng Geological Journal of China Universities    2023, 29 (5): 726-734.   DOI: 10.16108/j.issn1006-7493.2022029 Abstract （939）      PDF （7113KB）（274）       Knowledge map    Save In recent years, shale gas exploration and development in southeastern Sichuan has gradually expanded to the deep areas. The Luzhou area shows great potential of shale gas exploration and development with the depth over 3500 m. In order to further clarify the characteristics and evolution mechanism of various structural deformation in Luzhou area, the main controlling factors of fold belt were explored by using discrete element numerical simulation based on structural analysis of seismic data, and the evolution process of Mesozoic and Cenozoic was restored. And the following research results show that multiple detachment layers and regional tectonic compression are the main controlling factors of structural deformation in Luzhou area. Influenced by multiple detachment layers, Luzhou area has developed low steep thin-skinned structure and obvious vertical stratification, forming complex structure such as fault-propagation folds, detachment folds, buried folds and duplex structures between detachment layers. Among them, the lower Cambrian gypsum rock plays a major role in controlling the deformation, and the gypsum rock and shale slippage coordinate and accumulate towards the core of the anticlines. Since the late Yanshanian, the multi-detachment allochthonous succession with regional compression in Luzhou area were developed the thin-skinned comb-shaped folds. The fold belt rose again in Himalayan, the displacement of the original fault sand shear zones increased, and a series of secondary faults and buried folds formed between the detachment layers. The reservoirs are easy to be destroyed at anticline zones, while the syncline areas are a favorable area for shale gas exploration. The relatively simple deformation for syncline composed of ramp thrusts results in comparable stable internal stress distribution. Related Articles | Metrics

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Comparative Analysis and Enlightenment of Geoscience Knowledge Graphs: A Perspective of Construction Methods and Contents ZHU Yunqiang, SUN Kai, LI Weirong, WANG Shu, SONG Jia, CHENG Quanying, YANG Jie, MU Xinglin, GENG Wenguang, DAI Xiaoliang Geological Journal of China Universities    2023, 29 (3): 382-394.   DOI: 10.16108/j.issn1006-7493.2021111 Abstract （915）      PDF （1366KB）（349）       Knowledge map    Save Geoscience knowledge graphs (GKGs) formally represent geoscience knowledge in a way of directed graph and have strong capabilities in knowledge representation, openness and interconnectivity, and reasoning and prediction. GKGs have been one of the important infrastructures for the development of combining geoscience and artificial intelligence, thereby becoming one of the important research focuses in geoscience. Therefore, many international scientific organizations or groups have successively carried out studies in this domain, and constructed some representative GKGs. However, there is a lack of an in-depth study and analysis of these existing GKGs. To this end, this paper makes a systematic comparative analysis on their general information, construction methods, and main contents. On this basis, some enlightenments about future research of GKGs are discussed. In terms of the construction method, a unified representation framework for GKGs should be built, the source of geoscience knowledge should be enhanced by conflating multi-source and multimodal data, and methods for the representation and computation of geoscience knowledge should be studied. Regarding the contents of GKGs, complex spatiotemporal characteristics, relations, and reasoning rules should be considered. From the perspective of application, methods for assessing quality and making correction for geoscience knowledge should be developed, and application effects of GKGs should be improved. Related Articles | Metrics

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Study on Ecological Risk of Heavy Metals in Water and Sediments in the Heilong River Basin ZHENG Xu, GUAN Yiting, WU Weihua Geological Journal of China Universities    2022, 28 (6): 814-824.   DOI: 10.16108/j.issn1006-7493.2022005 Abstract （893）      PDF （4097KB）（236）       Knowledge map    Save As a heavy industrial base and a commodity grain base in northeast China, the heavy metal pollution of water, sediment and soil in the Heilong River Basin is very worthy of attention. We collected the samples of river water, lake water, groundwater and riverbed sediment in the Heilong River Basin from the upstream arid area to the downstream Sanjiang Plain, and then analyzed the content of heavy metal elements, in order to reveal the water resources security and the degree of pollution risk of sediments by using different indexes. The results show that in the arid area of the upper reaches of the Heilong River Basin, the content of As in some surface water and groundwater exceeds the standard for drinking water quality (up to 7 times). Therefore, the safety of water for residents in upstream areas needs to be a concern. A comprehensive assessment of the indexes of Pcom and RI shows that the overall ecological risk of sediments in the Heilong River Basin was low. Among single heavy metal elements, Cd has moderate ecological risk in most watersheds, and three sediment samples show high ecological risk. Cd, as the main heavy metal element endangering the soil quality and human health in China, also needs to be paid special attention in the Heilong River Basin. Related Articles | Metrics

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Deformation Prediction of Reservoir Landslides Using Knowledge Graph Optimized Kalman Filter HE Wangyan, ZHANG Wei, LI Houzhi, PAN Bo, DENG Lu, ZHU Honghu, SHI Bin Geological Journal of China Universities    2023, 29 (3): 372-381.   DOI: 10.16108/j.issn1006-7493.2022068 Abstract （857）      PDF （3065KB）（365）       Knowledge map    Save Reservoir landslides occur frequently in the Three Gorges Reservoir area. Predicting the deformation of the landslides is an important measure to reduce the risk. This paper constructs a Chinese reservoir landslide knowledge graph combined with multivariate Taylor series Kalman filter and proposes a knowledge graph optimized Kalman filter model KG-MTKF. Taking the Xinpu landslide in Fengjie County in the Three Gorges Reservoir area as an example, the effectiveness of the model was verified by using on-site monitoring data. Results show that compared with the monitoring data, the multivariate Taylor series Kalman filter model (MT-KF) and the knowledge graph optimized Kalman filter model (KG-MTKF) show good consistency in the stationary stage when used to predict reservoir landslides. In the initial stage and step-like stage of the landslide deformation, the prediction accuracy of KG-MTKF is higher. The error of the two models in the initial stage is relatively large, which is caused by the small initial deformation value of the landslide and the more significant influence of system noise. The errors of the two models are relatively small in the step-like stage, the stationary stage, and the entire monitoring cycle, and KG-MTKF has higher accuracy than MT-KF. For nonlinear dynamic systems like Xinpu landslides, the KG-MTKF can maintain high accuracy and strong robustness at different positions and deformation stages. Related Articles | Metrics

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Research on the Joint Extraction Method of Entity Relations in Geological Domain QIU Qinjun, WANG Bin, XU Dexin, MA Kai, XIE Zhong, PAN Shengyong, TAO Liufeng Geological Journal of China Universities    2023, 29 (3): 419-428.   DOI: 10.16108/j.issn1006-7493.2023026 Abstract （853）      PDF （1153KB）（296）       Knowledge map    Save Entity relationship extraction for the geological domain is the basis for building a geological knowledge graph, and is very important for text information extraction and knowledge base construction in the geological domain. In view of the complexity of entity relations in geological domain and the lack of a manually annotated corpus, a joint extraction model for entity relations in geological domain is proposed, focusing on the recognition of complex overlapping relations in multiple geological texts and avoiding cascading errors caused by entity recognition errors in the traditional pipeline model. In this paper, a high-quality corpus of entity relations in the geological domain is constructed, and a pre-trained language model based on BERT (Bidirectional Encoder Representations from Transformers) and BiGRU (Bidirectional Gated Recurrent Units) is proposed. Recurrent Units and Conditional Random Field (CRF) sequence annotation models to achieve joint extraction of entity relations. Experiments were conducted on the constructed dataset, and the results showed that the F1 value of the joint extraction model proposed in this paper reached 0.671 for entity relationship extraction, which verified the effectiveness of the model in this paper for geological entity relationship extraction. Related Articles | Metrics

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Stagnant Lid Tectonics in the Early Earth and Its Transition to Plate Tectonics YANG Haokun, LI Jianghai Geological Journal of China Universities    2023, 29 (6): 862-871.   DOI: 10.16108/j.issn1006-7493.2022052 Abstract （847）      PDF （958KB）（122）       Knowledge map    Save Plate tectonics has been regarded as the dominant tectonic regime on the earth today, but what was earth’s tectonic regime before the present plate tectonics began and when the present plate tectonics began are still controversial. To understand the evolution of earth and predict its future, we are required to clarify this question. Previously, researchers generally reached a consensus on an uniformitarian view that the early earth’s tectonics was similar to the present plate tectonics. However, with the accumulation of geological data and the progress of research technology, the idea of the transition from stagnant lid tectonics to modern plate tectonics was increasingly accepted. The so called “stagnant lid” refers to single plate around earth surface. In this paper, firstly we review the hypothesis of possible tectonic regime models in the early Earth under the background of stagnant lid tectonics, including heat pipe tectonics, plutonic-squishy lid model, mantle overturn and lid-and-plate tectonics. Then we review the latest research of the transition from stagnant lid tectonics to plate tectonics in early Earth. We believe that the mainstream researchers have reached a roughly consistent framework, that is, the transition from stagnant lid tectonics to plate tectonics occurred in the Meso-Neoarchean, and the modern plate tectonics may have formed in the Neoproterozoic. Related Articles | Metrics

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Construction and Application of Lithofacies Paleogeography Knowledge Graphs ZHANG Jiajia, ZHANG Lei, ZHONG Hanting, WANG Han, CHEN Anqing, LI Fengjie, REN Qiang, ZHENG Dongyu, ZHAO Hongyi, HOU Mingcai Geological Journal of China Universities    2023, 29 (3): 345-358.   DOI: 10.16108/j.issn1006-7493.2023027 Abstract （839）      PDF （2348KB）（281）       Knowledge map    Save Big data has brought new ideas and challenges to lithofacies paleogeography research. However, due to the problems of complex data types, rich semantic relationships and unclear sharing mechanisms, it is difficult to conduct in-depth data mining, analysis, and effective utilization of lithofacies paleogeographic data, which makes making many advantages of big data not fully exploited in this field. The powerful semantic processing and open interconnection capabilities of knowledge graphs, make it plays an important role in solving the problems of big data text analysis and image understanding, which and haves broad application prospects. This paper summarizes the research background of lithofacies paleogeography knowledge graphs from the perspective of construction and application; by systematically investigates investigating the construction ideas, technologies and processes of lithofacies paleogeography knowledge graphs., and The paper also lists outlines the relevant applications of knowledge graphs in lithofacies paleogeography; and points out the main problems of lithofacies paleogeography knowledge graphs, prospects for future research directions. Related Articles | Metrics

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Chinese Text-oriented Geological Semantic Information Annotation and Corpus Construction ZHANG Xueying, ZHANG Chunju, WANG Chen, LIU Wencong, PENG Ye, LU Yanxu Geological Journal of China Universities    2023, 29 (3): 429-438.   DOI: 10.16108/j.issn1006-7493.2023028 Abstract （836）      PDF （4406KB）（203）       Knowledge map    Save The structured extraction of geological information, semantic analysis, visual expression and the construction of knowledge map in text will provide a strong data foundation and technical support for the deep mining and utilization of geological big data. Whether it is a traditional statistical model or a deep learning model, the semantic analysis of geological information needs the support of tag corpus. In particular, the textual description of geological information has domain characteristics and cannot be achieved by migrating natural language corpora. Therefore, the construction of different levels of geological information annotation corpus has become the key foundation of geological semantic information analysis. Based on the analysis of the characteristics of the geological semantic information description language in Chinese text, according to the spatial and temporal characteristics and attribute description features of the geological entities, various semantic relations of geological entities are clearly expressed, and the geological semantic information is formed, formulating Chinese text labeling system and labeling specifications. The self-developed “interactive geological semantic information labeling tool”solves the shortcomings of traditional manual labeling methods such as high error rates and large workload. Using Chinese mineral resources literature and reports as data sources, a large-scale geological semantic information annotation corpus is constructed, which effectively solves the problem of the lack of large-scale standard data. Related Articles | Metrics