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Overview of the Application and Prospect of Common Chemical Weathering Indices LI Xulong, ZHANG Xia, LIN Chunming, HUANG Shuya, LI Xin Geological Journal of China Universities    2022, 28 (1): 51-63.   DOI: 10.16108/j.issn1006-7493.2020118 Abstract （3324）      PDF （1109KB）（4268）       Knowledge map    Save Common chemical weathering indices such as the Weathering Index of Parker (WIP), the Chemical Index of Alteration (CIA), the Index of Compositional Variability (ICV), CIX index and αAlE are often used to evaluate the chemical weathering intensity of source areas. But the factors which controlling the above chemical weathering indices should be considered, otherwise the results of the weathering evaluation will be distorted. This paper argues that the geological survey of source area should be known when chemical weathering indices are used to study the chemical weathering process. The selection of fine sediments or suspended matter can weaken the influence of grain size on chemical weathering indices. The impurities in the sediments are removed by acid treatment. Then, the Sc/Th-CIA diagram was used to reflect the material source information, Th/SC-Zr/Sc diagram was used to further distinguish the control effect of sedimentary differentiation and sedimentary recirculation, and then the samples with ICV value less than 1 were selected to eliminate the interference of recirculation. The A-CN-K diagram or the formula proposed by Panahi (2000) were used to correct the potassium metasomatism, and the strength of chemical weathering of source rocks was evaluated by CIA eventually. To ensure that the calculation of chemical weathering indices can accurately reflect the weathering situation of the source area, SPSS software can be used to analyze the proportion of some factors which affecting the CIA to construct characteristic weathering index of the study area. Related Articles | Metrics

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Active Source Seismic First-arrival Pickup Method Based on Small Sample Convolutional Neural Network YU Zhihan, WANG Tao, SUN Pengyuan, WANG Wenchuang, GUO Zhenbo Geological Journal of China Universities    2022, 28 (3): 414-423.   DOI: 10.16108/j.issn1006-7493.2021060 Abstract （341）      PDF （3646KB）（393）       Knowledge map    Save The interpretation of seismic travel-time imaging depends on the accuracy of picking up first arrivals, and it is low efficiency and high cost to pick up arrivals manually. Previous studies showed that deep learning can be applied for automatically picking, but the methods often need a large number of arrivals as the training set. In this study, we trained the U-Net with multichannel images and found that the root mean square error (RMSE) of first P arrivals decreases with the increase in the number of training sets. The errors of 35 and 597 shots are 11.4 and 6.5 ms, respectively. Referring to data augmentation methods in semisupervised learning, we selected methods (Random Crop, Random Erase, etc.) suitable for seismic data and applied them to the training set. After random erase of the training sets of 35 shots, the RMSE is less than 5.5 ms (about 3 sampling points), which is 51% less than the error with the original training set. Compared with previous deep learning methods, the augmentation methods can be implemented to pick up the first arrivals with higher precision in the case of small samples. Related Articles | Metrics

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Advances in the Study of Biogeochemical Cycles of Phosphorus ZHOU Qiang, JIANG Yunbin, HAO Jihua, JI Junfeng, LI Wei Geological Journal of China Universities    2021, 27 (2): 183-199.   DOI: 10.16108/j.issn1006-7493.2020002 Abstract （1844）      PDF （2398KB）（1840）       Knowledge map    Save Phosphorus is an essential element for life and an important limiting factor for food production. The biogeochemical cycles of phosphorus not only regulate marine primary production, but also has an impact on the global climate system; it also determines the formation and distribution of phosphate resources and affects the continuity of life on earth. The current theory of “earth system science” integrates the subsystems of atmosphere, hydrosphere, lithosphere (crust and upper mantle) and biosphere, providing a broader view for studying the global phosphorus cycles. Based on the existing research and combined with the theory of “earth system science”, the following important understandings of the biogeochemical cycles of phosphorus has been obtained: The evolution of phosphorus in geological history determines the current cycle pattern of phosphorus on a global scale (terrestrial ecosystems and marine ecosystems); Human industrial and agricultural activities, as an important geological agent, has changed the biogeochemical cycles of phosphorus, resulted in resource crisis of phosphate depletion and environmental problem of eutrophication of water bodies; The key to solve the resource crisis problem of phosphorus shortage and environmental pollution problem of phosphorus surplus lies in regulating the biogeochemical cycle process that cause these problems.  Related Articles | Metrics

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Predevonian Tectonic Evolution of South China: from Cathaysian Block to Caledonian Period Folded Orogenic Belt SHU Liang-shu J4    Abstract （2115）      PDF （501KB）（4262）       Knowledge map    Save The interpretation of Predevonian tectonics of South China is controversial long time both on its age and distribution. Based on the middle-high grade metamorphic rocks, ductile slipping rheologic structures exposed in the the Zhejiang- Fujian-Jiangxi-Guangdong domain and high quality dating data published recently, the author believes that an ancient continental block existed certainly in South China, which is composed of Proterozoic schist, gneiss and migmatite with an oldest age of 2 Ga, their protolites are clastic rocks, volcanic rocks and plutons. This old land is temporarily called as Cathaysian Continental Block which is limited in the domain between Shaoxing-Jiangshan-Pingxiang fault and Zhenghe-Dapu fault, and its scope is less than that defined by Grabau. During 800-900 Ma, following the closure of paleo-South China ocean, Cathaysian block collided with Yangzi block and then became a part of Rodinia supercontinent. Not long time after converging, by affection of breakup of Rodinia supercontinent, proto-Cathaysian continental block was split into three sub-blocks, namely the southeastern Zhejiang-northwestern Fujian, the central-southern Jiangxi and the Yunkaidashan, and several rifts or sea channels occurred among them. From Early Sinian to Late Ordovician, these sea channels were expanded and were filled by 10000-20000 m thick clastic rocks (containing limestone) and turbidites. However coeval ophiolite and volcanic rocks are absent, implying extended fault did not reach to upper mantle. New geochronological results indicate that the ophiolite and volcanic rocks in the study areas, which were described as Early Paleozoic by previous researchers, yielded pre-Sinian ages, concentrating mainly between 800 Ma and 900 Ma. Thus, the previous Early Paleozoic tectonic framework needs to be re-constructed. In Silurian, a strong tectono-thermal event took place in South China, causing closure of Sinian-Early Paleozoic sea channels and folding-uplifting of mega-thick sediments. The South China Caledonian fold and orogenic belt was formed on the Proterozoic metamorphic basement. In the study area, folding deformation and ductile slipping rheology are very common, including thrust and strike-slip deformation, the peak period of deformation is 420-400 Ma. At the same time, a violent granitic magmatism was started, forming numerous strongly peraluminous S-type granites with A/CNK (molar Al2O3/[CaO + Na2O + K2O]) > 1.1, and I-type granitoids is rare. Peak period of granitic magmatism took place in the 430-400 Ma. Then, the whole South China Caledonian folded geological bodies were overlain unconformably by Late Devonian conglomerate and coarse sandstone, indicating termination of folding and orogeny. From Late Devonian, a united paleo-geographic and sedimentary environment occurred really in the study domain and its neighboring areas. Related Articles | Metrics

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Enzyme-induced Calcium Carbonate Precipitation (EICP) and Its Application in Geotechnical Engineering CAO Guanghui, LIU Shiyu, YU Jin, CAI Yanyan, HU Zhou, MAO Kunhai Geological Journal of China Universities    2021, 27 (6): 754-768.   DOI: 10.16108/j.issn1006-7493.2020200 Abstract （1867）      PDF （4975KB）（1384）       Knowledge map    Save The technique of improving soil by enzyme-induced calcium carbonate precipitation is called EICP, which has attracted more and more attention over the past decade due to its wide application. The article describes the mechanism of EICP and summarizes the extraction methods of plant urease and bacterial urease. In addition, the influence of factors such as urease, calcium source, urea, skimmed milk powder, temperature and pH on the cementing effects of EICP is explored. Furthermore, methods for testing the strength, calcium carbonate content, microstructure and composition of EICP reinforced samples are summarized, and the application of EICP in geotechnical engineering is evaluated. The purpose of this article is to summarize the current status of EICP research and potential problems that need to be overcome in future research. 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 （1109）      PDF （2519KB）（505）       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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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 （1361）      PDF （2209KB）（380）       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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An Overview of Characteristics and Prospecting of Gold Ore Deposits in China WANG Bin，LI Jingchao，WANG Chengxi，ZHENG Xiao，SUN Kefeng Acta Metallurgica Sinica    2020, 26 (2): 121-.   DOI: 10.16108/j.issn1006-7493.2019033 Abstract （587）      PDF （2571KB）（925）       Knowledge map    Save Based on the geodynamic settings of gold metallogenesis and the basic geological features of gold ore deposits, China’s gold deposits can be classified into 11 categories. Among these categories, the structurally-fractured altered-rock type, inner and outer contacting belts type of plutonic intrusives, the Carlin or quasi-Carlin type, hydrothermal type within low-grade metamorphic clastic rocks, and continental volcanic rock types are the types of interest in prospecting. As far as metallogenic ages concerned, those that occurred in Mesozoic and Cenozoic are the major types. According to their geotectonic units, geological evolution, metallogenic geological conditions, spatial-temporal distribution, gold deposit types, regional metallogenic factors, and volumes of mineral resources, totally 42 gold ore concentration areas, which are spatially distributed in clusters, have been preliminarily identified on the basis of China’s III-graded classification scheme of metallogenic zones (belts). According to gold prospecting borehole quantities per unit area, China’s gold ore concentration areas can be categorized into 3 levels, i.e., highly, moderately, and lowly developed. The highly developed ones are mainly distributed in Central and Eastern China. Except the placer gold deposits, about 88.12% boreholes for primary gold (rock gold or associated gold) deposits are less than 500 m with deep in China, suggesting that the quantities and depths of gold exploration drillings in China are less and shallower than in other countries. As for the gold resources exploration potentials, we propose that (1) in Central and Eastern China, the deep parts and the peripheries of the existing gold mines are key locations to be focused on; (2) for Western China, the gold ore concentration areas, which are located especially in Xinjiang Uygur Autonomous Region, Qinghai Province, and Tibet Autonomous Region, are the future key regions with immense potentials for unexplored gold resources. Related Articles | Metrics

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Chloritization Sequences in Mudstone during Diagenesis and Its Geological Significance FU Yu, DING Qingfeng*, WU Changzhi Acta Metallurgica Sinica

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Research Progress and Prospect of the Gangdese Magmatic Belt in Southern Tibet MENG Yuanku, YUAN Haoqi, WEI Youqing, ZHANG Shukai, LIU Jinqing Geological Journal of China Universities    2022, 28 (1): 1-31.   DOI: 10.16108/j.issn1006-7493.2020057 Abstract （653）      PDF （2414KB）（1068）       Knowledge map    Save The Gangdese magmatic belt is the product of the northward subduction of the Neo-Tethys oceanic lithosphere beneath the Lhasa terrane and subsequent India-Asia collision. The Gangdese magmatic arc belongs to the typical continental magmatic belt and is the target area for studying plate accretion, crustal growth and reworking and collisional orogeny. Numerous lines of evidence indicate that the Neo-Tethys oceanic lithosphere experienced four distinct stages of evolution: the early-stage subduction (>152 Ma), late-stage subduction (100 to 65 Ma), main-collisional (55 to 40 Ma), and post-collision extentional stages (23 Ma to present). Multiple studies were carried out in the Gangdese belt and much progress has been made during past decades. However, the formation and evolution of the Neo-Tethys Ocean and magma source of igneous rocks are still debated, especially the detailed petrogenetic dynamic processes. This paper reviews the evolution history and tectonic background, and then summarizes related scientific problems from thirteen aspects. It is shown that the Gangdese magmatic belt is a typical magmatism-tectonismmineralization-deformational metamorphism belt and experienced multi-stage evolution processes rather than a simple continental magmatic arc aggregated in the Lhasa terrane. The review shows that (1) the Gangdese magmatic belt is a natural laboratory for studying the evolution history of the Neo-Tethys, and provides better constraints on the styles of the subducting slab. (2) The different-stage granitoid stocks and batholiths might be formed by multiple additions and incremental assembly of magmas over a span of millions of years or even longer. Therefore, we should use a mush model to reconstruct petrogenesis and petrogenetic secnarios of granitoid rocks in detail. (3) The mantle nature of the Gangdese region shows complicated features that are characterized by geochemical heterogeneity along the arc strike direction. (4) The reversed isotopes exist in the Gangdese belt, probably indicating an ancient nucleus. (5) The Gangdese belt is tilting and has different crustal compositions that are characterized by lower crustal compositions in the eastern segment and middle-upper crustal compositions in the middle-western segment. Crustal tilting of the Gangdese region suggests a differential and imbalanced exhumation process. (6) At present, numerous studies are focused on igneous rocks with methods mainly including radioactive Sr-Nd-Hf isotopes, whereas non-traditional stable isotopes (Mg-O-Li-B-Mo) are rarely reported. In addition, research topics are mainly associated with petrogenesis and geochronology, but few studies focus on the magma emplacement and post-magmatic deformation and uplifting-denudation processes. (7) Research in structural geology of the area is few and usually tectonic evolution is inferred from magmatic evolution in the Gangdese belt, southern Tibet. Finally, we also provide future prospects based on the current research status of the Gangdese magmatic belt in southern Tibet. Related Articles | Metrics

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Research Progress of Methane Bio-mitigation Technology in Landfill Cover SUN Wenjing, KONG Yi, CHEN Xueping, LIU Xiaoyang Geological Journal of China Universities    2021, 27 (6): 775-783.   DOI: 10.16108/j.issn1006-7493.2020107 Abstract （645）      PDF （1348KB）（544）       Knowledge map    Save During the service life of landfills, large amounts of methane will be released due to the degradation of organic matter by microorganisms. Even with the gas collection devices, methane still escapes into the atmosphere. Methane gas is one of the important gases that cause the greenhouse effect. Methane-oxidizing bacteria is a microorganism that takes methane as the only carbon source, and has an excellent methane oxidation efficiency. In small and medium-sized landfills, old landfills and large landfills where it is no longer economical to turn on gas collecting devices, the landfill final cover soil can be mixed with methaneoxidizing bacteria to oxidize methane gas and reduce the release of methane from landfill, so as to reduce the greenhouse effect and achieve the purpose of environmental protection The relevant research on methane oxidation efficiency of methane oxidizing bacteria at home and abroad was reviewed. The classification of methane-oxidizing bacteria and its mechanism of methane oxidation, the factors that affect the oxidation efficiency of methane-oxidizing bacteria and the application of methane-oxidizing bacteria in landfill sites are summarized, and the future research and application area of methane-oxidizing bacteria is outlined. Related Articles | Metrics

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Review and Advancements of Studies on Silicate Weathering and the Global Carbon Cycle WU Weihua, ZHENG Hongbo, YANG Jiedong, LUO Chao J4    2012, 18 (2): 215-.   Abstract （1939）      PDF （436KB）（3474）       Knowledge map    Save Silicate weathering is a major sink of the atmospheric CO2, which directly affects the global carbon cycle and the climate. Since the pioneering work of Walker et al. (1981), studies on“ silicate weathering, carbon cycle and climate changes” have sprung up in recent years. Many advancements have been obtained from computer models to river water geochemistry andfrom large rivers with a drainage area exceeding to 106 km2 to monolithologic small watershed with tens/hundreds km2 drainagearea,. In the global scale, atmospheric CO2 consumption from silicate weathering is about 0.138-0.169 Gt per year. Compared tothe current atmospheric carbon content of 800 Gt, at first glance, this CO2 consumption rate seems so slow that silicate weatheringwould play only a negligible role in the global carbon cycle. However, atmospheric CO2 removed from silicate weathering istransported by rivers and thereafter precipitated in the ocean as carbonate minerals, and the residence time of carbon in carbonaterocks is in excess of millions of years. Therefore, silicate weathering is an important mechanism that modulates the long-termcarbon cycle. Moreover, researches show that the small watersheds draining basalts/ophiolites in the tropical zones have thehighest silicate weathering and CO2 consumption rates. It is estimated that CO2 consumption from volcanic rocks in the tropicalzones represents about 10% of the global export of carbon by silicate weathering, while the tropical volcanic arcs correspond toonly~1% of the exorheic drainage area worldwide. Related Articles | Metrics

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The Quantitative Analysis Methods for Iron Oxides in Sediment and Their Application in Cretaceous Oceanic Red Beds LI Xiang, CAI Yuanfeng J4    2014, 20 (3): 433-.   Abstract （837）      PDF （1087KB）（2425）       Knowledge map    Save Hematite and goethite are the most stable iron oxides in nature and widely present in different compartments of the global system. They are responsible for the color origin of many types of sediment. In addition, the formation and preservation of hematite and goethite have been used to track palaeoenvironmental information. There are several approaches to characterizing and distinguishing hematite and goethite, but the quantifying of the concentrations of hematite and goethite in natural samples has been restricted by low concentration, relative poor crystalline and fine-grained as well as the limits of specific analysis methods used. In this paper, the most common quantitative methods of hematite and goethite, including X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS), have been introduced. Based on the qualitative analysis of the Cretaceous Oceanic Red Beds (CORBs) samples, we used the K-value method to quantify the hematite contents in the red shale samples from the Chuangde section in Tibet and obtained the hematite contents ranging from 3.81% to 8.11%. Analysis using DRS with multiple linear regression was performed to obtain the absolute contents of iron oxides within Aptian-Albian cyclic oceanic red beds in ODP Hole 1049C 12X Core, North Atlantic. The results reveal that the brown beds contain 0.13~0.82% hematite and 0.22~0.81% goethite. The orange beds contain 0.19~0.46% hematite and 0.29~ 0.67% goethite. The comparison of the calculated results with the test data shows that both methods were feasible for the quantitative analysis of iron oxides in CORBs. In actual practice, the accuracy of qualitative analysis of iron oxides must firstly be improved by the combination of XRD with DRS and then the choosing of quantitative analysis method can be achieved through the comprehensive analysis of both the predicted contents and crystalline of iron oxides. Related Articles | Metrics

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Petrogenesis of Ophiolite-type Chromite Deposits in China and Some New Perspectives HU Zhenxing, NIU Yaoling, LIU Yi, ZHANG Guorui, SUN Wenli, MA Yuxin J4    2014, 20 (1): 9-.   Abstract （921）      PDF （1391KB）（1872）       Knowledge map    Save Ophiolites of varying ages are widespread in China, some of which contain chromite deposites of industrial value. However, compared with some of the world’s large ophiolite chromite deposites (e.g., Kempirsai, Bulquiza, Guleman), the Chinese chromite deposits are small (e.g., Sartohay, Dongqiao, Luobusa). Recent research recognizes that most ophiolites with significant chromite reserves are all formed in a surpasubduction zone environment. Melt-rock interaction is a popular interpretation for the origin of podiform chromite deposits, but the actual mechanism in this model for chromite enrichment remains unclear. It remains the primary task to understand process or processes of chromium enrichment towards the formation of chromite deposits. Is the formation of chromium-rich melts necessary? If so, when, where, how, and under what conditions could this take place? These are additional processes beyond the well-understood aspects of the petrogenesis that need to research towards an effective chromite mineralization model. Related Articles | Metrics Cited: Baidu(3)

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Paleogeographic Reconstruction Driven by Big Data: Challenges and Prospects ZHANG Lei, ZHONG Hanting, CHEN Anqing, ZHAO Yingquan, HUANG Keke, LI Fengjie, HUANG Hu, LIU Yu, CAO Haiyang, ZHU Shengxian, MU Caineng, HOU Mingcai, JAMES G. Ogg Geological Journal of China Universities    2020, 26 (1): 73-.   DOI: 10.16108/j.issn1006-7493.2019091 Abstract （522）      PDF （1094KB）（677）       Knowledge map    Save Paleogeography is a typical data-reliable subject. Paleogeographic reconstruction focuses on the characteristics of geographic, life, and climate changes on the Earth's surface through geological history. In the new era of big data, the continuous accumulation of massive paleogeographic data and the rapid development of computer science technology make it possible to reconstruct the paleogeographic history using more standard and intelligent tools and software. The current paper reviews the major databases and research groups related to paleogeography, and proposes the following key components of big data-driven paleogeographic reconstruction: (1) A standard paleogeographic knowledge system; (2) An open and interactive paleogeographic data platform with new technologies such as natural-language understanding to expand data sources; (3) Paleogeographic data quality control mechanisms; (4) Various types of paleogeographic reconstruction models contructed with artificial intelligence technology; (5) Visual outputs as time-sliced maps or animations. Related Articles | Metrics

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Geology and Geomorphology of Tarim Basin and Its Evolution in the Cenozoic LI Jianghai，WUTongwen，LEI Yuting Acta Metallurgica Sinica

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Numerical Simulation on the Size Effect of Compressive Strength and Deformation Parameters of Rock Materials Under Different Confining Pressures TANG Wei, ZHAO Xiaobao*, LEI Jiyuan, Yuan Bin, LIU Hanwen J4    2016, 22 (3): 580-.   Abstract （700）      PDF （2987KB）（1062）       Knowledge map    Save The compressive strength and deformation parameters of rock materials are important indices of rock engineering. Because a rock is a typical heterogeneous material, its strength and deformation parameters vary with sample sizes. In this paper, the size effects of rock materials under different confining pressures were numerically studied using PFC2D code. The simulation results indicate that (1) rock strength, peak strain and compressive modulus decrease with increasing specimen sizes, whereas the change of specimen size has little effect on the failure mode of these rock specimens. (2) rock strength, peak strain and compressive modulus increase with the confining pressures. Among them, the rock strength and peak strain have linear relations with the confining pressures. In addition, the failure of rock specimens gradually changes from the splitting mode into shear failure mode with the increase in confining pressures. (3) the increments of rock strength and peak strain for different size specimens at the same confining pressure range are approximately the same. Meanwhile, these two parameters increase with confining pressures. Therefore, the size effect of the rock strength and peak strain at high confining pressure becomes weak. In addition, the increasing ratios of compressive modulus for the corresponding scenarios are similar, which causes the confining pressure to have little impact on the size effect of compressive modulus. Related Articles | Metrics

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Progress in High Precision Analytical Approaches of Silicon Isotope WANG Junlin, WANG Wei, WEI Haizhen Geological Journal of China Universities    2021, 27 (3): 275-288.   DOI: 10.16108/j.issn1006-7493.2021033 Abstract （768）      PDF （1355KB）（759）       Knowledge map    Save With the modification of Alkali fusion method for digesting silicates and the development of the multi-collection inductively coupled plasma mass spectrometer (MC-ICP-MS), the silicon isotopic analysis methods have been significantly improved in recent years. The analytical precision of δ 30Si (2SD) is better than ±0.10‰, compared with ±0.15‰-±0.30‰ by gas mass spectrometer (GS-MS) in earlier studies. It enables us to distinguish the minor fractionation of Si isotopes during the high temperature processes; and also avoid using hazardous chemical such as fluoride. For the in situ determination of δ 30Si, the analytical precision of secondary ion mass spectrometry (SIMS) and femtosecond laser ablation (fs LA) also have been modified to be ±0.10‰-±0.22‰. This article reviewed the progress in silicon isotope analysis in the past decades, and discussed the establishment of high precision silicon isotope analysis method under wet plasma condition using MC-ICP-MS. Then we compared the silicon isotopic compositions of standard reference materials in different laboratories, and finally summarized the range of δ 30Si in major geological reservoirs, e.g., BSE, Earth crust and Meteorites. Related Articles | Metrics

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Types and Characteristics of Geoheritage Resources in the Shungeng Mountain, Huainan, Anhui Province ZHANG Zikang, GU Chengchuan, WU Jiwen, ZHAO Ming, ZHAN Run, SHAO Qingqing, ZHANG Yuanyuan Geological Journal of China Universities    2024, 30 (01): 89-99.   DOI: 10.16108/j.issn1006-7493.2022063 Abstract （61）      PDF （4598KB）（125）       Knowledge map    Save The Shungeng Mountain in Huainan, Anhui Province, is tectonically located in the southern thrust-napped belt of the Huainan Coalfield within the North China Craton (NCC) and hosts many natural and artificial exhumed geoheritages. According to the field geological survey, 62 major geoheritage sites have been identified in the Shungeng Mountain, which can be divided into 3 major categories, 8 categories and 14 subcategories. Among them, typical Cambrian-Ordovician sections of the NCC, karst topography, fault structures and mining heritages are well developed and are of high scientific research and ornamental value. Based on the previous studies, the genesis and regional geological background of these geoheritages in the Shungeng Mountain are discussed, which provide a theoretical basis for the proper exploitation of the geoheritage resources. In light of the problems existing in the protection and exploitation of geoheritage resources in the Shungeng Mountain, this paper puts forward suggestions for long -term planning. Related Articles | Metrics

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Recent Advancement in Methods of Estimating Geothermal Reservoir Temperature: A U.S. National Geothermal Data System-based Study JIANG Shu, CHEN Guohui, ZHANG Yuying, ZHANG Luchuan, KUANG Jian, LI Chun, CHENG Wanqiang Geological Journal of China Universities    2021, 27 (1): 1-17.   DOI: 10.16108/j.issn1006-7493.2020096 Abstract （568）      PDF （2072KB）（1174）       Knowledge map    Save Estimation of geothermal reservoir temperature plays a key role in the geothermal system research. This study employs geothermometers of geochemistry, mineral equilibria, mixing model with cold meteoric water, and gas to evaluate the reservoir temperature of different geothermal fields with data archived in the National Geothermal Data System (NGDS), which concludes the limitations of applications of different methods for determining the reservoir temperature and provides benchmarks for choosing the appropriate methods to calculate the geothermal reservoir temperature. The results reveal that: 1) The geochemical geothermometer method is reliable when the geothermal fluids reach the equilibrium between ions and minerals; the SiO2 (silica) geothermometer is more reliable than the cation geothermometer when the geothermal fluids have not reached the equilibrium; 2) The saturation index of the mineral equilibria can provide benchmarks choosing the geothermometers even if it cannot calculate the accurate reservoir temperature due to the selection of limited saturated minerals. For example, the chalcedony geothermometer is better than SiO2 geothermometer to estimate the reservoir temperature of due to the oversaturation of silica based on the multi-mineral equilibrium plot. For the vapordominated high temperature geothermal reservoirs, the minerals and ions cannot reflect the properties of geothermal reservoir, and the gas thermometer will be more successful in predicting the subsurface temperature in high-temperature geothermal systems. The mixing models usually overestimate the reservoir temperature since they pick up the temperature before the hot water gets mixed with the cold water. There is no universal geothermometer since each method has its own assumptions and works for specific geothermal setting. The best approach is to employ various suitable geothermometers and validate the results. Related Articles | Metrics

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Genetic Types and Accumulation of Crude Oil in the Central Inversion Zone in the Liaoxi Depression, Bohai Sea TIAN Derui, NIU Chengmin, WANG Deying, GUO Tao, PAN Wenjing, GUO Longlong Geological Journal of China Universities    2021, 27 (4): 444-458.   DOI: 10.16108/j.issn1006-7493.2020093 Abstract （424）      PDF （1211KB）（1118）       Knowledge map    Save The central inversion zone of the Liaoxi Depression is the enrichment area of high quality light crude oil in the Liaodong Bay exploration area. However, the genetic types, source and accumulation of crude oil have not been systematically studied. Based on the analysis and comparison of the biomarkers, three sets of effective source rocks of the Shahejie Formation were distinguished. The first, third and fourth members of the Shahejie Formation, are obviously different in the source of organic matter and sedimentary environment. It is confirmed that plankton is the main component of organic matter in the three sets of source rocks. The first member of the Shahejie Formation (E2s1) has the highest plankton content and the least terrestrial organic matter input. The content of dinoflagellate in the fourth member of the Shahejie Formation (E2s4) was significantly higher than that in the first and third members of the Shahejie Formation (E2s1, E2s3). Both E2s3 and E2s4 source rocks were deposited in the freshwater and weakly alkaline reducing environment, and the E2s1 source rock was deposited in the brackish to saline alkaline strongly reducing environment. The crude oil found in the central inversion zone can be divided into three source-related types through hierarchical cluster analysis(HCA). The oil-source correlation results show that the type Ⅰ crude oil is the mixed oil originated from the E2s3 and E2s1 source rocks, which is mainly distributed in the middle block and the middle area of the east block on the central inversion zone. The type Ⅱ crude oil is originated from the E2s4 source rocks, which is distributed in the southern area of the east block on the central inversion zone. The type Ⅲ crude oil is the mixed oil originated from the E2s3 and E2s4 source rocks, which is mainly distributed in the west block and the northern area of the east block on the central inversion zone. On this basis, the main controlling factors of hydrocarbon accumulation in the central inversion zone of the Liaoxi sag were analyzed. Oil and gas reservoirs on the central inversion zone are controlled by multiple factors, including the distribution of effective source rocks and the math of fault and sand bodies. Related Articles | Metrics

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Grain-size Characteristics and Environmental Implication of Neogene Red Clays in the Chinese Loess Plateau LU Keke, CHEN Zhong, YANG Yanpeng, ZHANG Jialin, ZHAO Zhongqiang, XIA Dinghong, NI Chunzhong, SONG Yinxian, ZHANG Shitao Geological Journal of China Universities    2023, 29 (5): 713-725.   DOI: 10.16108/j.issn1006-7493.2022020 Abstract （163）      PDF （1237KB）（382）       Knowledge map    Save The aeolian origin of red clays in the Loess Plateau has been unanimously recognized. The earliest red clay was found in the late Oligocene and early Miocene, indicating that the arid environment had been formed in the inland northwest of China at the end of Paleogene. The grain size characteristics of red clay in the loess plateau show that the average grain size gradually decreases from the north to the south, indicatin g that the initial monsoon system has been established, and the winter wind played an important role in the transport of aeolian dust. The grain size distribution of red clay indiactes that it is composed of two components. The coarse grain (>20 μm) represents those transported by the near surface wind (winter wind), while the fine grain (<5 μm) represents those transported by the upper westerly wind. The grain size composition characteristics of red clays well record the development and change of atmospheric circulation. Since the end of Oligocene, the average grain size and sedimentation rate of red clays in the west of Liupanshan Mountain increased at 21.3-20.2 Ma, 16.0-13.3 Ma and 8.7-6.9 Ma, which may be related to global cooling and the Qinghai-Tibet Plateau uplift, and the 8.7- 6.9 Ma increase was mainly controlled by global cooling. In the red clay section to the east of Liupanshan, the grain size of variation characteristics shows that the grains deposited during 7.6 Ma to 6.2 Ma or to 5.4 Ma is coarse, indicating that the winter monsoon was strong. After that, the average particle size was fine up to 3.6 Ma, and the deposition rate was low, indicating that the winter monsoon was weak climate environment. From 3.6 Ma to 2.6 Ma, most profiles show an increase in mean grain size, an increase in sedimentation rates, and an increase in both winter and summer monsoon, which indicates to the transition to Quaternary glacial period. The development of the Arctic ice sheet and the uplift of the Qinghai-Tibet Plateau may have contributed to these changes. Related Articles | Metrics

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Research Progress and Prospect of the Tectonic Evolution of Okinawa Trough and Its Relationship with Magmatism, Hydrothermal Activities and Sedimentation LIU Wei，SUN Yujie，ZHENG Hanyue，XIN Mengran，HE Wei，WEI Tong，GUO Shiyue，CHEN Sifang,LIU Wenwen，FENG Yuge Acta Metallurgica Sinica    2020, 26 (6): 680-690.   DOI: 10.16108/j.issn1006-7493.2019084 Abstract （625）      PDF （2313KB）（911）       Knowledge map    Save The Okinawa Trough is a typical back-arc basin in the western Pacific Trench Arc Back-Arc system. Its unique tectonic location, magmatism, hydrothermal activities and sedimentary records have been a focus of academic research. Based on previous research, we review the controls of magmatic, hydrothermal and sedimentary activities by tectonic evolution of the Okinawa Trough. The subduction of the Philippine Sea plate led to the formation of the Okinawa Trough and the occurrence of arc volcanism, back-arc volcanism and cross-back arc volcanism. These three types of volcanism resulted in three different zones of hydrothermal activity. The magmatism and fault system caused by subduction of Philippine Sea plate provide heat sources and channels for the development of hydrothermal fluid in the Okinawa Trough. The subsidence of Zhe -Min Uplift at ~416 ka brought about the sediments in the northern Okinawa Trough to change from coarse-to fine-grained. Finally, we also provide the outlook of further research based on the current research status of the Okinawa Trough. Related Articles | Metrics

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Review on the Enzyme-Induced Carbonate Precipitation Based on Soil Stabilization LAI Hanjiang, CUI Mingjuan Geological Journal of China Universities    2021, 27 (6): 769-774.   DOI: 10.16108/j.issn1006-7493.2020071 Abstract （589）      PDF （2123KB）（531）       Knowledge map    Save Abstract：Carbonate precipitation based on soil improvement is an environmentally friendly ground treatment technology that emerges in geotechnical engineering in recent years. This technique utilizes the urease-producing bacteria (termed as Microbially Induced Calcite Precipitation, MICP) or urease enzyme (named Enzyme Induced Carbonate Precipitation, EICP) to hydrolyse urea and induce the precipitation of cementing calcium carbonate, which can bond loose soil particles together and thus enhance soil strength. Compared with the MICP method, the EICP method is free from issues related to bio-safety and oxygen availability, and can be used to treat soils with finer particles. Therefore, the EICP method is promising for applications in practical engineering. This study presents a review on the enzyme-induced carbonate precipitation based on soil stabilization from the aspects of type and sources of urease enzyme, soil treatment methods with the EICP approach, and the strength enhancement of EICP treated soil. Related Articles | Metrics

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Organic Geochemistry of Organic-rich Cherts in the Middle Permian Gufeng Formation in Chaohu, Lower Yangtze Area GENG Zi’ao，WEI Hengye Acta Metallurgica Sinica    2019, 25 (6): 823-.   DOI: 10.16108/j.issn1006-7493.2019082 Abstract （374）      PDF （4579KB）（724）       Knowledge map    Save The black cherts in the middle Permian Gufeng Formation in Chaohu area in Lower Yangtze, South China are rich in organic matter. This formation is the potential source rocks of petroleum and shale gas exploration in China. The study on the organic matter accumulation of the Gufeng Formation is important for the petroleum exploration. Here we analyze total organic carbon (TOC) content and biomarkers characteristics of organic matter in the Gufeng cherts of middle Permian in the Pingdingshan, Chaohu area, so as to address the organic matter accumulation mechanism. Our results show that the organic matter thermal mature proxy C29 ααα 20S/(20S+ 20R) ratios range from 0.37 to 0.46, and C31 22S/(S+R) ratios range from 0.53 to 0.59. These suggest that the thermal mature level is the early stage of“oil window”. The n-alkane compounds are mainly composed of short-chain n-alkanes and peak at C18. Hopane contents are higher than the terpane. C27 ααα 20R sterane is higher than the C28 and C29 ααα 20R. These suggest that the organic matter of the Gufeng Formation originates from phytoplankton algae and bacteria with a small amount of terrestrial high plant. The Pr/Ph ratios of the organic matter in the Gufeng Formation is less than 0.6, and the average gamacerane index is 0.2. These suggest that the redox conditions of paleo-water column during the deposition of the Gufeng Formation were moderate stratification and anoxia. The organic-rich Gufeng Formation is probably related to this stratification and anoxia during warm climatic conditions. Associated with the suddenly cooling, enhanced upwelling increased greatly the primary productivity greatly and yielded more large-scale organic matter accumulation. 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 （2042）      PDF （1109KB）（615）       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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3D Digitization of Geological Outcrops and Specimens：Status and Prospects XU Qi, SHEN Hanxiao, DONG Shaochun, SHI Yukun, FAN Junxuan Geological Journal of China Universities    2023, 29 (3): 403-418.   DOI: 10.16108/j.issn1006-7493.2022092 Abstract （834）      PDF （3613KB）（433）       Knowledge map    Save In the era of big data, the high techniques such as knowledge graph, artificial intelligence and virtual simulation rapidly developed, and as a result the research methods of geosciences are evolving with the times. Compared to the traditional two-dimensional images and texts, three-dimensional digital models can provide more diverse data, and therefore hold enormous potential for both the scientific research and technology fields. The digitization of geological outcrops and specimens are two typical cases of 3D modeling technology in geoscience. This paper investigated the construction of digital outcrop and 3D specimen digitization, introduced the common digitization technologies, data sharing and development services, and the current representative digital geological outcrop and 3D specimen database. The investigation results were summarized and analyzed. Moreover, some problems that exist at present were summarized, and the future development was prospected in terms of data construction standard specification, construction content and function expansion. Related Articles | Metrics

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A Review of the Establishment Methods of Training Image in Multiple-point Statistics Modeling WANG Mingchuan, SHANG Xiaofei, DUAN Taizhong Geological Journal of China Universities    2022, 28 (1): 96-103.   DOI: 10.16108/j.issn1006-7493.2020049 Abstract （733）      PDF （1268KB）（842）       Knowledge map    Save Multiple-point statistics (MPS) modeling has been the research hotspot of reservoir modeling technology in recent years, and its practicability is restricted by training image. The quality of training image determines the accuracy and reliability of MPS modeling, and is a key factor for the successful application of MPS modeling. This study addresses the characteristics and significance of training image, and systematically introduces the establishment methods of training image creation from the definition, usage and instance, etc., including hand drawn, object-based simulation, 3D seismic information extraction or transformation, prototype- ased model, process-based simulation and 2D image method. Then, our study comprehensively compares the data sources, advantages and disadvantages of various training image creation methods, and discusses the problems caused by MPS modeling relying on training images. Combined with reviewing prior works and MPS modeling practice, the research direction of training image and its establishment methods in the future is pointed out, which provides reference for MPS modeling researchers and users, and provides some thoughts for improving MPS modeling methods. Related Articles | Metrics

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Experimental Investigation on the Interaction Between Calcite and Silica-bearing Fluid: Implications for the Formation of Silicified Carbonate Reservoir YANG Yuanxian, CHEN Qianglu, QIU Ye, YOU Donghua, WANG Xiaolin Geological Journal of China Universities    2021, 27 (2): 218-228.   DOI: 10.16108/j.issn1006-7493.2020017 Abstract （669）      PDF （2354KB）（727）       Knowledge map    Save Recent oil and gas exploration shows that silica-bearing hydrothermal fluid is an important acidic fluid in carbonate sequences. Knowledge on the interactions between silica-bearing fluid and carbonate rock is critical to understand the origin of the silicified carbonate reservoir and the prediction of reservoir distribution. In this study, experimental investigation was carried out on the interaction between calcite and silica-bearing fluid at temperatures ranging from 200 to 375℃ by using fused silica capillaries and hydrothermal reactor as the reaction chambers. In situ Raman spectroscopy was used to describe the process of the reaction. Besides, Scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS) was used to observe the morphology and to identify the composition of the quenched solids. Firstly, the temperature condition of the decarbonization reaction between silica-bearing fluid and calcite is revealed. Calcite reacts with silica-bearing fluids at temperatures above 275℃ to form CO 2, and the solid phase is non-wollastonite calcium silicate. The detailed structure of this calcium silicate needs further investigation. This result indicates that the dissolved silica itself cannot react with limestone at the reservoir temperatures. Secondly, the high salinity and the CO 2-bearing nature of the silica-bearing fluid are the important factors causing limestone dissolution. Finally, the presence of CO 2 can promote the precipitation of siliceous component, including quartz. Based on the above experiments, the formation of the silicified carbonate reservoir in the Shuntuoguole area of the Tarim basin is proposed, integrated with the previous studies. The silica-bearing hydrothermal fluid migrates upward along the deep and large faults, passing through the Sinian-Lower Ordovician dolomite layer, where the siliceous components will react with the dolomite to form magnesium-rich silicate and CO 2. CO 2 is an important acidic component, which is conducive to the dissolution of the shallow carbonate and the preservation of pores. Decrease in fluid temperature and pressure, and the presence of CO 2 result in the precipitation of quartz, forming large amounts of intercrystalline pores. Related Articles | Metrics

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Construction of Nb-Ta Deposit Knowledge Graph and Its Application RAN Yizao, DONG Shaochun, WANG Rucheng, HU Huan, FANG Siyuan, CHANG Fengnian, KONG Jia Geological Journal of China Universities    2023, 29 (3): 359-371.   DOI: 10.16108/j.issn1006-7493.2021107 Abstract （786）      PDF （4845KB）（382）       Knowledge map    Save As an important resource for emerging industries, critical metals have gradually gain attention both domestically and overseas in recent years. However there are still some bottlenecks existing in the critical metal research due to its low abundance, difficulty to trace, identify and separate. As an important infrastructure of big data and artificial intelligence, knowledge graph provides new insights to tackle these issues. Most of the research achievements related to critical metal deposits are published in academic journals, which are written in natural language and is difficult to be understood and directly used by machines. In this paper, the ontology layer of Nb-Ta deposit knowledge graph was constructed and data extracted from literatures consists of the fact layer of the Nb-Ta deposit knowledge graph. Based on the Nb-Ta deposit knowledge graph, the features and relationships among the metallogenic periods, types of Nb-Ta deposits and the co-occurrence of niobium and tantalum related minerals were analyzed. It will help to further reveal the spatio-temporal distribution and evolution characteristics of China Nb-Ta deposits.  Related Articles | Metrics