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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 （6532）      PDF（pc） （1109KB）（7805）       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 | Comments（0）

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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 （3721）      PDF（pc） （2398KB）（3348）       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 | Comments（0）

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Analysis of Deformation Characteristics and Parameters of Clay Layers in South Subsidence Area of Beijing YOU Binhao, YE Shujun, TIAN Fang, LUO Yong Geological Journal of China Universities    2023, 29 (4): 590-599.   DOI: 10.16108/j.issn1006-7493.2021083 Abstract （3570）      PDF（pc） （2292KB）（895）       Knowledge map    Save The land subsidence in Beijing is divided into north and south areas, and the southern area mainly includes Lixian-Yufa subsidence zone. The subsidence rate in this area has accelerated in recent years and reached 50-75 mm/a during 2017-2019, showing new subsidence characteristics. Based on the subsidence and water level observation data of 7-year time series from 2011 to 2017 at Yufa Subsidence Monitoring Station, the only subsidence observation station in the south subsidence area. The deformation characteristics of soil layers, especially clay layers, are systematically analyzed. Then the elastic and inelastic specific storage, vertical hydraulic conductivities and deformation lag time of the clay layers are estimated by the stress-strain diagram method and the type curve method. The results show that there are both elastic deformation and plastic deformation in each soil layer, and the plastic deformation is the main deformation with obvious deformation hysteresis. However, the deformation rate of each soil layer presents different characteristics. The results of the stress-strain diagram method show that the inelastic specific storage of the first and second clay layers is between 1.49×10-5 and 2.10×10-5, the elastic specific storage is between 3.93×10-5 and 8.38×10-5, the inelastic specific storage is 2-4 times of the elastic specific storage, the vertical hydraulic conductivity is between 6.20×10 -6~4.39×10-5 m/d, and the soil deformation lag time is 2.1-12.8 years. The specific storage of the shallow layers in the study area estimated by the type curve method is about 4.8×10-4, and that of the deep layer is between 1.08×10-4 and 2.05×10-4. The specific storage of shallow layer is 2-4 times of that of deep layer, and the vertical hydraulic conductivities are 1-2 orders of magnitude larger than that of the deep layers. Related Articles | Metrics | Comments（0）

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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 （3523）      PDF（pc） （4975KB）（3169）       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 | Comments（0）

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Current Status and Recommendations of Offshore CO2 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 （3126）      PDF（pc） （1583KB）（1035）       Knowledge map    Save Marine carbon dioxide (CO2) 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, CO2 monitoring runs through the whole life cycle of CO2 geological storage and is a necessary method to ensure the safety and rationality of storage works. However, China’s CO2 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 CO2 marine storages, summarizes the monitoring indicators, technologies and schemes, and puts forward the screening and optimization methods of monitoring CO2 marine storage and suggestions for monitoring technology. The outcome of this study provides a reference for the development of CO2 marine storage demonstration projects in China. Related Articles | Metrics | Comments（0）

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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 （3093）      PDF（pc） （11167KB）（1229）       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 | Comments（0）

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Progress of Methods for Assessing CO2 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 （2962）      PDF（pc） （1109KB）（2722）       Knowledge map    Save CO2 geological storage is an important technology to reduce CO2 emissions, which can safely store CO2 in geological formations for millions of years. Conventional CO2 storage reservoirs include deep saline aquifers and depleted oil and gas reservoirs. Basalt is a new type of CO2 storage reservoir that has been attracting attention in recent years. CO2 storage in basalt would increase the technical method and potential of CO2 geological storage. Storage potential assessment is one of the fundamental works of CO2 geological storage study. This paper systematically examines the current methods for assessing the storage potential of CO2 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 CO2 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 CO2 in basalts. ③Pore filling storage potential assessment method, which evaluates the proportion of secondary minerals that can fill reservoirs’ pore space after CO2 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 | Comments（0）

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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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Study on the Evolution of Groundwater Storage Variations in the Tarim River Basin Based on GRACE and GLDAS CHEN Danhong, ZENG Xiankui, WU Jichun, GUI Dongwei, SUN Yuanyuan Geological Journal of China Universities    2022, 28 (6): 894-901.   DOI: 10.16108/j.issn1006-7493.2021012 Abstract （2768）      PDF（pc） （6807KB）（631）       Knowledge map    Save Located in the arid area of northwest China, the Tarim River Basin(TRB) is characterized by scarce precipitation and fragile ecology. Water resource is the key factor to maintain the social and economic development and ecological health of TRB. Here we identify the groundwater storage (GWS) variations in the Tarim River Basin from 2003 to 2019 using the Gravity Recovery and Climate Experiment (GRACE) satellite data and Global Land Data Assimilation System (GLDAS) data, and analyzes its spatial and temporal distribution. The results show that the GWS in TRB presents a decreasing trend during 2003 to 2019 , at a rate of -2.13 mm/a. The decline trend of GWS variations decrease gradually from north to south, and the GWS depletion is largest in the middle part of the southern Tianshan Mountains while the GWS increases significantly in the lower reaches of Tarim River, which was related to the emergency ecological water transport in the past decade. Besides, the GWS variations in the TRB are consistent with annual precipitation anomalies. With less precipitation, i.e., 2004, 2006-2009，GWS in the TRB decreases significantly，while increases correspondingly during rainy year. The method based on GRACE and GLDAS data has great potential applications in analyzing GWS variations for monitoring groundwater resources in the Tarim River Basin, which lacks of groundwater monitoring networks. Related Articles | Metrics | Comments（0）

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Discovery of Paleogene Mudanjiang High-Mg# Andesites from Northeast China and Their Petrological Characteristics XIONG Qiao, ZENG Gang, ZHENG Zhichong, ZHANG Huili, ZHOU Zhongbiao, WANG Xiaojun, LIU Jianqiang, CHEN Lihui Geological Journal of China Universities    2023, 29 (2): 161-173.   DOI: 10.16108/j.issn1006- 7493.2021109 Abstract （2573）      PDF（pc） （3283KB）（507）       Knowledge map    Save Cenozoic high-Mg# andesites (HMAs) are generally distributed in the active continental margin and island-arc setting, but they are rare in the intraplate setting. In recent years, intracontinental HMAs erupting at 20.6-0.3 Ma (Neogene- Quaternary) have been found in Wuchagou of western Songliao Basin and Xunke, Menluhe and Russian Far East of northern Songliao Basin. The discovery of these intracontinental HMAs is important to understand the nature and fate of recycled crustal materials in the mantle. Here we, for the first time, report Paleogene HMAs erupting at 49.2-36.3 Ma in Mudanjiang area, eastern Songliao Basin. These volcanic rocks have SiO2 contents of 54.75-58.95 wt% and Mg# values of 45.18-51.72, falling into the scope of HMAs. They are mainly basaltic andesites and andesites belonging to subalkaline series with a small variation of the major element compositions. Based on petrographic observation and MELTS_Excel calculation, plagioclase and orthopyroxene phenocrysts were crystal phases at the earliest stage and mineral phases in the groundmass (such as orthopyroxene, clinopyroxene and titanomagnetite) appeared successively. The results of MELTS_Excel calculation indicate that the crystal phases have not been separated from the magma system and the composition of these rocks can represent the primary magma composition. The crystallizing pressures of the Mudanjiang HMAs are 169-570 MPa by using the orthopyroxene-melt barometer, suggesting a depth of 5.6-18.8 km. The crystallizing temperatures of these rocks are 1109-1181 ℃ by using the orthopyroxene-melt and melt thermometers, which are consistent with other Cenozoic HMAs (Xunke, Menluhe and Wuchagou) in northeast China (1132-1192 ℃) and are higher than island-arc andesites (950-1050 ℃). The pre-eruptive melt H2O contents vary from 0.3 to 1.0 wt% calculated by the plagioclasemelt hygrometer, which are in the range of Cenozoic HMAs in other parts of northeast China (0.3-1.4 wt%), yet tend to lower H2O than island-arc andesite (2-9 wt%). Therefore, the chemical composition, petrographic characteristics, magmatic physical properties (temperature and H2O content) and evolutionary characteristics of the Mudanjiang HMAs are similar to Cenozoic HMAs found in other areas of Northeast China, which all belong to intracontinental HMAs. The discovery of Mudanjiang HMAs suggests that these intracontinental HMA-type magmatism continued from Eocene to Pleistocene and are distributed throughout northeast China. Related Articles | Metrics | Comments（0）

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Status and Advances of Research on Caprock Sealing Properties of CO2 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 （2459）      PDF（pc） （6425KB）（2121）       Knowledge map    Save CO2 Geological storage is one of the key technologies to address global climate changes and reduce greenhouse gas emissions. Large-scale CO2 injection into the formation is prone to inducing CO2 leakage problem. In particular, the leakage problem of CO2 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 CO2 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 CO2 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 CO2 injection are illustrated, and some insight into the shortcoming of caprock seal is provided. Related Articles | Metrics | Comments（0）

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Effects of Physical Parameters of Shale on CO2 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 （2421）      PDF（pc） （1157KB）（778）       Knowledge map    Save CO2 enhanced shale gas recovery (CO2-ESGR) can not only increase CH4 production, but also store CO2. 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 CO2 storage capacity with different mechanisms in CO2-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 CO2 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 CO2 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 CO2 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 CO2 storage capacity and adsorption storage capacity, and Kv/Kh has the least effect on CO2 storage capacity with different mechanisms. For CO2 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 | Comments（0）

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Ce-in-zircon Oxybarometer and the Redox State of the Early Earth XIAO Luyi, YANG Xiaozhi Geological Journal of China Universities    2022, 28 (4): 484-492.   DOI: 10.16108/j.issn1006-7493.2020114 Abstract （2407）      PDF（pc） （1097KB）（958）       Knowledge map    Save Oxygen fugacity (f O2), a quantitative factor in rendering the redox state of a given system, is a key thermodynamic parameter in Earth sciences. The oxygen fugacity of the early Earth and its variation with time, which is a prime goal of Earth sciences, plays important roles in understanding the origin and evolution of the atmosphere, hydrosphere, biosphere and even the whole Earth. Zircon provides the oldest samples yet found on the planet, and is almost the only survivor of the Hadean period. Studies in recent years have demonstrated that the Ce content of zircon is able to record the prevailing f O2 of its parent magma, leading to the so-called Ce-in-zircon oxybarometer. This provides a unique probe into the redox state of the early Earth. We provide a brief introduction of this technique, and then outline the recent advances on the redox state of the early crust and mantle, followed by a discussion on the f O2 evolution of the early atmosphere, crust and upper mantle and the coupling relation of f O2 between them. Related Articles | Metrics | Comments（0）

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Analysis of Monitoring Technologies of Offshore CO2 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 （2376）      PDF（pc） （3566KB）（826）       Knowledge map    Save Offshore carbon dioxide (CO2) capture and storage (CCS) is one of key technologies to cope with global climate change and reduce greenhouse gases such as CO2, 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 CO2 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 CO2 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 | Comments（0）

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Exploration of New Methods in Marine Strontium Isotope Stratigraphy CAI Yue Geological Journal of China Universities    2024, 30 (03): 253-268.   DOI: 10.16108/j.issn1006-7493.2024015 Abstract （2301）      PDF（pc） （2031KB）（1024）       Knowledge map    Save Strontium Isotope Stratigraphy (SIS) is an important tool for establishing age models for oceanic sedimentary deposits. It has wide applications in many fields including oil and gas exploration and paleoclimate reconstructions. SIS is based on the premise that global seawater is homogeneous relative to Sr isotopes but with variations through time. A key assumption of SIS is that the samples retain the Sr isotope composition of the original seawater where they form. However, diagenesis and loosely attached impurities can alter the Sr isotope composition of the fossil samples, thereby undermining the meaningfulness of the SIS age. Therefore, sample selection and preparation are crucial for obtaining meaningful SIS ages. This article evaluates existing methods for SIS, including sample preparation and Sr isotope analysis. In recent years, to precisely extract the composition of ancient seawater, studies using Nd, Pb, and Li isotopes in carbonates have thoroughly investigated different methods of sample preparation. Based on these technical advances, this paper thoroughly investigated an oyster sample with independent age constraints from the Miocene shallow-marine deposits of the Gulf of Suez, Egypt. By comparing the elemental composition of sequential leachates of the oyster with those of present-day organisms, this paper proposes a new protocol for SIS sample preparation. This paper also compiles and compares the accuracy and precision of Sr isotope data measured using Thermo-ionizing mass spectrometry (TIMS) vs. Multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). While for samples with abundant Sr, the new generation of MC-ICP-MS can reach similar precision and accuracy as the old generation TIMS, for smaller samples and samples that require higher precision, the new generation TIMS is still the best choice for SIS research. Finally, this paper makes some suggestions for Sr analysis on the MC-ICP-MS.  Related Articles | Metrics | Comments（0）

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Niobium Mineralization in the Miaoya Alkaline Complex, Hubei Province: Constraints from Rutile Mineralogy and Geochronology YING Yuancan, CHEN Wei, LIU Jiajun, YANG Fan, JIANG Shaoyong Geological Journal of China Universities    2024, 30 (03): 345-361.   DOI: 10.16108/j.issn1006-7493.2024019 Abstract （2264）      PDF（pc） （6817KB）（582）       Knowledge map    Save The Miaoya alkaline complex is mainly composed of syenite and carbonatite enriched in Nb and REE, with a verified Nb2O5 reserve of 0.93 Mt @ 0.12%. It is the second largest carbonatite-hosted Nb-REE deposit in China, second only to Bayan Obo. Previous studies have focused on the genesis of carbonatite and the process of REE enrichment, but the occurrence and enrichment mechanism of Nb in syenite are still unclear. Based on field geological surveys, detailed petrography, mineral chemistry, and U-Pb dating of the Nb-bearing minerals in syenite were obtained using TIMA, EMPA and LA-ICP-MS analyses. The results show that the main Nb-bearing mineral in the Miaoya syenite is rutile, which can be divided into magmatic and hydrothermal generations based on texture and chemical composition. Magmatic rutile is rare, while hydrothermal rutile is common in various syenites, mostly disseminated along the edges or fissures of primary rutile or closely associated with biotite and ilmenite. Magmatic rutile shows low contents of Nb2O5 (1.43%~2.56%), FeO (0.74%~1.01%), and other trace elements (e.g., Ta, Cr, V, W, Mo, Sb); while hydrothermal rutile has variable enrichments of Nb2O5 (3.48%~20.68%), FeO (1.18%~6.92%), and other trace elements. In-situ U-Pb dating of rutile illustrates that the formation age of magmatic rutile is 446±21 Ma, while the formation age of hydrothermal rutile is 240±19 Ma, indicating that Nb mineralization in syenite experienced initial enrichment during the early Paleozoic magmatic stage and secondary enrichment during the Triassic hydrothermal metasomatic stage. In summary, we believe that Nb enrichment and mineralization in the Miaoyao complex are controlled by both magmatic and hydrothermal processes. During the early Paleozoic magmatic stage, niobium within syenite is mainly hosted by rutile, biotite and Ti-bearing minerals (e.g., ilmenite); in the Triassic hydrothermal metasomatic stage, hydrothermal fluids can decompose biotite to form secondary Nb-rich rutile and columbite, or metasomatize primary rutile and ilmenite to generate hydrothermal Nb-rich rutile.  Related Articles | Metrics | Comments（0）

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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 （2243）      PDF（pc） （2411KB）（553）       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 | Comments（0）

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Influence of Flow Velocity and Dip Angle on Perchloroethylene Migration in Fractured Media LU Yue, LIU Yichao, XU Hongxia, SUN Yuanyuan, WU Jichun Geological Journal of China Universities    2022, 28 (4): 554-564.   DOI: 10.16108/j.issn1006-7493.2020223 Abstract （2185）      PDF（pc） （2834KB）（434）       Knowledge map    Save Perchloroethylene (PCE) was selected as the representative dense non-aqueous phase liquid (DNAPL) to investigate its migration and distribution characteristics under different flow velocities and dip angles in single fractured media. By using the light transmission method, we could monitor the migration and saturation distribution of PCE dynamically, and therefore the change process of PCE source zone architecture could be characterized. The results showed that PCE separated from the injection needle in the form of lumps, and was nearly elliptical and not continuous with each other in the process of migration. In this paper, Fs refers to the square of the initial pollutant separated from the injection needle. The larger the flow velocity was, the larger Fs was, and the smaller PCE centrifugal rate e was; the larger the dip angle was, the smaller Fs was, and the smaller the centrifugal rate e was. When the infiltration process became stable, the area and centrifugal rate of agglomerated PCE decreased  significantly. The increase of flow velocity and dip angle promoted the vertical migration of PCE, which accelerated the front-end migration rate of PCE and made PCE move to the bottom of the fracture system more quickly. The increase of flow velocity promoted the distribution of PCE, and the peak saturation decreased, while the increase of dip angle suppressed the distribution and made the peak saturation increase during the process. Related Articles | Metrics | Comments（0）

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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 （2181）      PDF（pc） （2414KB）（2152）       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 | Comments（0）

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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 （2181）      PDF（pc） （2582KB）（417）       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 | Comments（0）

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Characteristics of Cryptoexplosive Breccia from the Chating Copper-Gold Deposits, Xuancheng, Anhui Province and Its Metallogenic Significance XIE Qiaoqin，SUN Rui，XU Xiaochun，XU Xinyue，AN Yuhua，QIAN Shilong Acta Metallurgica Sinica    2020, 26 (3): 255-264.   DOI: 10.16108/j.issn1006-7493.2019045 Abstract （2159）      PDF（pc） （6839KB）（1770）       Knowledge map    Save The Chating copper-gold ore in Xuancheng region is a newly discovered large ore deposit in the Mesozoic-Cenozoic volcanic-sedimentary Nanling-Xuancheng basin in recent years, where the deposits are located at shallow depths of the Middle-Lower Yangtze River. This study is focused on the cryptoexplosive breccia pipe developed in the intrusives of quartz-dioriticporphyrite in the Chating copper-gold ore deposits. Based on the detailed core observations and petrographic analysis, characteristics and types of cryptoexplosive breccia are determined, and the relationship between the cryptoexplosive breccia and the copper-gold mineralization is discussed. The cryptoexplosive breccia in the ore deposits can be divided into three types: cryptoexplosivemelt-crystal-lithicbreccia, cryptoexplosive hydrothermal breccia, and cryptoexplosive fracture breccia based on its textures, compositions and abundance of rubbles. The cryptoexplosive breccia appears as an irregular pipe enveloped by the quartz-dioriticporphyrite and shows a regular spatial distribution. From the center of breccia to wall-rock are quartz-dioriticporphyrite, cryptoexplosivemelt-crystal-lithicbreccia, the cryptoexplosive hydrothermal breccia, and the cryptoexplosive fracture breccia, respectively. The spatial relationship between the alterated, mineralized and the cryptoexplosive breccia pipe shows that there exists a genetic link between formation of cryptoexplosive breccia and mineralization. The cryptoexplosion of the melt, liquid and gas originated from intermediate-acid magma induced the formation of large amount rubbles and fractures which can cause sudden temperature and pressure changes of ore-forming fluids. In addition, the cryptoexplosive breccia may provide room for migrating, mixing, and ore-forming material unloading for ore-forming hydrothermal fluid that arose from magmatic hydrothermal fluid. The geological features of the Chating copper-gold deposit are similar to those of the porphyry deposits including the intermediate-acid porphyrite host rocks, the alteration types, and zonation of wall rocks, as well as fine-grained dissemination and fine-veined, and net-veined mineralization. However, the mineralization enrichment site is consistent with the cryptoexplosive breccia pipe. Also, the geological features such as breccia, veined, agglomerated mineralization and hydrothermal anhydrite developed intensively in the vein are distinctly different from typical porphyry deposits. Therefore, based on these characteristics, we suggest that the Chating copper-gold ore deposit is a cryptoexplosive breccia type deposit closely related to intermediate-acidic hypabyssal intrusion. Related Articles | Metrics | Comments（0）

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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 （2124）      PDF（pc） （1237KB）（1758）       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 | Comments（0）

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Trace Element Characteristics and Geological Significance of Sphalerite in Xiwan Lead-Zinc Deposit, Luzong Basin, Anhui Province ZHANG Hongqiu, HAN Shanchu, ZHANG Yong, PAN Jiayong, ZHANG Yanqun, ZHAO Bibo, DING Yong, JIANG Yao, HU Shengping Geological Journal of China Universities    2023, 29 (5): 693-704.   DOI: 10.16108/j.issn1006-7493.2022028 Abstract （2098）      PDF（pc） （2751KB）（692）       Knowledge map    Save The Luzong volcanic basin is an important part of the metallogenic belt in the middle and lower reaches of the Yangtze River. In recent years, a large-scale Xiwan lead-zinc deposit has been discovered in the East Ma’anshan Formation on its northern margin. Previous studies have shown that sphalerite in this deposit is enriched in certain dispersed elements, but there are few in-depth studies on its content and distribution characteristics and comprehensive evaluation of dispersed elements is lacking. Therefore, in this paper, the LA-ICP-MS analytical method was used to study the characteristics of trace elements in sphalerite of No. Ⅳ and Ⅴ ore bodies in the Xiwan lead-zinc deposit and discuss its geological significance. The results show that (1) Sphalerite is rich in Fe, Mn, Cd, Pb elements, and depleted in In, Tl, Se, Te, Sn elements, among which dispersed Cd element has certain comprehensive utilization values; (2) The substitution mechanisms of trace elements in sphalerite mainly include single element and multi-element coupling. Among them, the substitution mechanism of single element mainly includes Fe2+ instead of Zn2+, Cd2+ instead of Zn2+, etc. The multi-element coupling substitution mechanism mainly includes (Cu++Ge3+) instead of 2Zn2+, (2Cu++Ge4+) instead of 3Zn2+, etc.; (3) The composition characteristics of Fe, Mn, Cd, In and other trace elements (dispersed elements) in sphalerite show that the metallogenic temperature of the Xiwan lead -zinc deposit is medium to low temperatures, which belong to the epithermal deposit.  Related Articles | Metrics | Comments（0）

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Marine Redox Fluctuation during the Early Cambrian Age 10: Evidence from U Isotopes QIU Chen, WEI Guangyi, MIN Siyu, CHEN Xi, LING Hongfei Geological Journal of China Universities    2022, 28 (1): 40-50.   DOI: 10.16108/j.issn1006-7493.2020038 Abstract （2087）      PDF（pc） （2251KB）（1344）       Knowledge map    Save The marine animal diversity was generally low during late Cambrian and early Ordovician. Biogeochemical studies suggest that it may have been related with fluctuations in oceanic redox conditions, despite still lack of evidence. Well-preserved marine carbonates could record the geochemical characters of ancient seawater, and their uranium isotope compositions (δ238U) can be used to reconstruct the global oceanic redox conditions. In this study we analyzed the uranium isotope compositions of marine carbonates of the basal Cambrian Stage 10 from Wa’ergang section, South China. Our data show that the δ238U profile has three negative excursions with minima of -0.8‰ , -0.55‰ and -0.60‰ , respectively, which indicates three intervals of oceanic anoxia expansion. Modeling results based on the uranium isotope mass balance model suggest that about 22%, 3.5% and 5% of the global sea-floor were covered by anoxic water during these three intervals, respectively. We speculate that the first anoxic interval may have been related with increase in primary productivity due to enhanced weathering input of nutrients, and the latter two may have been induced by upwelling of deep anoxic water during the transgressions. Related Articles | Metrics | Comments（0）

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Reactive Transport Numerical Modeling for Deep Geological Sequestration of Brine Wastewater DU Zhuoran, DU Song, YANG Yun, SONG Jian, WU Jianfeng, WU Jichun Geological Journal of China Universities    2023, 29 (4): 571-579.   DOI: 10.16108/j.issn1006-7493.2021110 Abstract （2076）      PDF（pc） （2212KB）（1043）       Knowledge map    Save Brine wastewater deep well injection in China is still at the stage of access demonstration. The transport of liquid waste in deep reservoirs involves variable density drive, water-rock chemical reactions and variable-parameter synergistic physical-chemical interactions. How to quantitatively characterize these processes is one of the key scientific and technological challenges to be solved in deep well injection. Consequently, this paper selected a certain injection zone in Ordos Basin as prototype, used PFLOTRAN to construct a variable-density and variable-parameter reactive solute transport model to predict and evaluate the migration, transformation and evolution of reservoir minerals, as well as the change of reservoir properties after the brine wastewater injection to the deep geological body. As the simulation results showed, the injection of brine wastewater into the injection zone contributes to secondary minerals precipitation, such as anhydrite, calcite and fluorite; the geological storage capacity decreases by 1.51% approximately in the simulated 100 years; and the contamination area is around 2.57 km2. This model provides a simulation tool to quantitatively characterize the migration and transformation process of brine wastewater components after the deep well injection. Related Articles | Metrics | Comments（0）

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Precipitation-induced Pressure Wave Propagation in Unsaturated Zone and Its Effect on Rapid Groundwater Discharge DANG Lei, XIE Yueqing, WANG Chuan, CHANG Yang, ZENG Xiankui, WU Jichun Geological Journal of China Universities    2023, 29 (4): 580-589.   DOI: 10.16108/j.issn1006- 7493.2021104 Abstract （2067）      PDF（pc） （1977KB）（424）       Knowledge map    Save A large number of studies, using water chemistry and stable isotopes to conduct hydrograph separation, indicate that majority of stream water during rainfall is derived from ‘old water’ that is stored in the catchment before the rainfall. This phenomenon is known as ‘old water paradox’. Pressure wave in unsaturated zone driven by precipitation is regarded as a potential underlying mechanism. In this study, we established four numerical soil column experiments with different soil types (sand, loamy sand, sandy loam and loam). We attempted to explore pressure wave propagation and the possibility of rapid groundwater discharge driven by the pressure wave with demonstrative experiments. Our results show that after the first intensive rainfall, pressure wave were generated in the four columns and were observed at the bottom after 1.86, 2.84, 5.24 and 7.46 days. In comparison, the relevant soil water arrived at the bottom after 6.12, 10.33, 18.05 and 30.00 days. The differences between celerities and velocities are 74.71, 51.05, 27.08 and 20.13 cm/d. Our study indicates that celerities and velocities are strongly affected by soil hydraulic conductivities and soil retention curves, and pressure waves in sand can be propagated more easily than those in other soil types. As the thickness of unsaturated zone is usually linearly proportional to the distance from river bank, pressure wave generated during precipitation can propagate into groundwater and drive rapid groundwater discharge. This process would be easier in more permeable soils. Overall, this study advances our understanding of catchment hydrology and helps discover underlying mechanisms in a theoretical manner.  Related Articles | Metrics | Comments（0）

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Research on Inter-well Interference Law of Supercritical CO2 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 （2048）      PDF（pc） （2951KB）（394）       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 CO2, 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 CO2 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 | Comments（0）

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Degradation of Trichloroethylene in Activated Sodium Persulfate System HAO Tian, ZHANG Yun Geological Journal of China Universities    2023, 29 (4): 600-607.   DOI: 10.16108/j.issn1006-7493.2021076 Abstract （2047）      PDF（pc） （1110KB）（545）       Knowledge map    Save Trichloroethylene (TCE) was taken as a target pollutant to study its degradation characteristics in the environmentally friendly chelating agents, sodium citrate (TCD) and citric acid (CA), chelating ferrous ion (Fe2+)-catalyzed sodium persulfate (Na2S2O8) system. The effects of the proportion of sodium persulfate, chelating agents, and pH value on the degradation of TCE were investigated, and the optimal proportion of all components and suitable pH value were obtained. Both TCD and CA had effectively chelated Fe2+-catalyzed sodium persulfate, which degraded TCE in water, and the degradation of TCE abided by the first-order kinetic reaction model. The optimal proportion in mole was 20:10:10:1 for Na2S2O8/TCD/Fe2+/TCE and 20:5:10:1 for  Na2S2O8/CA/Fe2+/TCE, respectively, at which both the degradation rate and the first-order reactive rate constant reached their maximum values. The maximal degradation rate was 96.7% and 97.6% and the maximal reactive rate constant was 2.48×10-2 and 2.68×10-2 min-1 for the two reactive systems, respectively. Additionally, the usage of CA for the optimal proportion was only half of TCD. For small proportion, both degradation rate of TCE and the first-order reaction rate constant increased with the increasing amount of TCE, CA, or Na2S2O8. However, excessive chelating agents could form an over-stabilized chelate with Fe2+, which reduced the catalytic effect of Fe2+ and the oxidative capacity of Na2S2O8. Excessive amount of Na2S2O8 could generate much more sulfate radicals, and these sulfate radicals could consume internally, refraining the degradation reaction of TCE. In the system of Na2S2O8/ Fe2+/TCE being 20:10:1, the catalytic effect would dwindle if the proportion in mole was greater than 10 for TCD and 5 for CA. In the system of TCD/Fe2+/TCE being10:10:1or CA/Fe2+/TCE being 5:10:1, the reaction would be refrained if the proportion in mole was greater than 20 for Na2S2O8. A suitable range of pH value was necessary for the degradation of TCE in activated sodium persulfate system. Alkaline condition refrained the degradation reaction of TCE, while acid to neutral condition was helpful for the reaction. Related Articles | Metrics | Comments（0）

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Geochronology, Geochemical Characteristics and Geological Significance of the Mesoproterozoic Diabase in Qingyuan County, Liaoning Province SU Zumin, SUN Fengyue, ZHANG Yajing Geological Journal of China Universities    2023, 29 (2): 201-212.   DOI: 10.16108/j.issn1006-7493.2021058 Abstract （2037）      PDF（pc） （3935KB）（476）       Knowledge map    Save This study presents LA-ICP-MS Zircon U-Pb dating and whole-rock geochemical analysis of a diabase dyke in Hongtoushan area of Qingyuan County, Liaoning Province, which is located in the northeastern margin of the North China Craton, to explore tectonic evolution of the North China Craton in the Mesoproterozoic. The LA-ICP-MS magmatic zircon U-Pb dating results show an age of 1293 Ma±35 Ma for the Hongtoshan diabase , which represents the emplacement age of the diabase dyke. The diabase shows SiO2=49.42%, MgO=3.56%-5.83%, Na2O+K2O=3.95%-6.2%, indicating transitional characteristics between alkaline and sub-alkaline series. The diabase is enriched in LREE, depleted in HREE and HFSE, and has no obvious Eu anomalies. The Hongtoushan diabase belongs to intraplate basalt that was formed in an extensional setting. The magma was derived from the enriched lithospheric mantle influenced by subducted materials and was assimilated by crustal rocks. Combined with available data on the Mesoproterozoic diabase dykes in the north and northeast of the North China Craton, it is suggested that the diabase was formed during the breakup of Columbia supercontinent. Related Articles | Metrics | Comments（0）

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The Petrogenesis of Baishuizhai Granitic Pluton and Its Significance to Uranium Mineralization in the Xiazhuang Area, Guangdong Province LI Kun, CHEN Weifeng, GAO Shuang, SHEN Weizhou, HUANG Guolong, LIU Wenquan, FU Shuncheng, LING Hongfei Geological Journal of China Universities    2023, 29 (4): 497-513.   DOI: 10.16108/j.issn1006-7493.2021117 Abstract （2035）      PDF（pc） （2375KB）（1917）       Knowledge map    Save The Baishuizhai pluton is one of the main ore-bearing wall rocks of the Zutongjian uranium deposit in the northwestern part of the Xiazhuang granite-related uranium ore filed, yet its petrogenetic mechanisms and its relationship with uranium mineralization are still unclear. Thus, in this study, we present zircon SHRIMP U-Pb ages, whole-rocks and mineral geochemical data for the Baishuizhai granite. Field and petrographic investigations show that the Baishuizhai granitic pluton was emplaced into the Xiazhuang granitic batholith, mainly composed of fine-grained two-mica granite and muscovite granite, and the zircon SHRIMP U-Pb dating reveals that both granites were formed during the Indochina period with ages of 229.4 Ma and 231.8 Ma, respectively. They show typical peraluminous S-type granitic geochemical characteristics that are high SiO2 contents, total alkalis contents and ACNK values ( ≥ 1.1), low FeOt+MgO+TiO2 contents and P2O5 contents, enriched in Rb, Th and U, depleted in Ba, Sr, P and Ti, and enriched in aluminum-rich minerals. Compared with the Xiazhuang granite, both types of granites in the Baishuizhai pluton show enriched in inherited zircon, higher SiO2 contents and Rb/Sr ratios, but lower FeOt+MgO+TiO2 contents, P2O5 contents, Zr/Hf ratios, and Fe2+/(Fe2++Mg) ratios of biotites, indicating that they were derived from low partial melting of reducing material-rich feldspathic meta-pelites, and are not formed by the differentiation evolution of the parent magma of the mafic meta-pelites-derived Xiazhuang granite. Furthermore, compared with the two-mica granite, the muscovite granite display significant tetrad REE patterns, lower REE, Zr/Hf ratios and Eu/Eu* values, indicating that an interaction of F-rich fluids with the magma occurred in the formation of the muscovite granite. Both types of granites in the Baishuizhai granitic pluton are enriched in uranium and can be important uranium-bearing granites in the region. Relative to the 2-mica granite in the Baishuizhai pluton, the muscovite granite is more enriched in uranium and more favorable to be uranium source rocks for hydrothermal uranium mineralization. Related Articles | Metrics | Comments（0）

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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 （2017）      PDF（pc） （8719KB）（640）       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 | Comments（0）

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Evolution of Oceanic Redox State during Early Ordovician Tremadocian Age Traced by Uranium Isotopes MIN Siyu, QIU Chen, LUAN Xiaocong, WU Rongchang, SHAO Qingfeng, CHEN Xi, LING Hongfei Geological Journal of China Universities    2023, 29 (2): 147-160.   DOI: 10.16108/j.issn1006-7493.2021052 Abstract （2010）      PDF（pc） （1506KB）（1431）       Knowledge map    Save The oceanic redox state is one of the important environmental factors affecting evolution of animals in the ancient ocean. The Ordovician Tremadocian Stage was the‘eve’of the Great Ordovician Biodiversification Event (GOBE), during which the biodiversity was gradually increasing. However, there has been lack of researches on evolution of ocean redox state for this key interval. Studies have proved that the U isotope compositions recorded in well-preserved carbonates can effectively trace the redox state of the global ocean redox state. In this study, we conduct systematical analyses of carbon and oxygen isotope compositions and uranium isotope compositions of carbonate samples from the Xiangshuidong section in Songzi, Hubei Province. A significant positive carbon isotope excursion event—TSICE is identified at the base of the middle Tremadocian stage. The average value of  δ238U increased from -0.64‰ ±0.12‰ to -0.26‰ ±0.15‰ across the TSICE, which indicates that the redox state of the global ocean changed from significantly anoxic (mass balance model results indicating >2.56% of the seafloor covered by anoxic seawater) to much more oxygenated before and after the TSICE. This process of environmental change is consistent with the process of increase in metazoan proportion relative to microorganism proportion in reef composition. The positive drift of carbon and uranium isotope compositions may have been related to the regression and sea-surface temperature decrease, respectively, which may have been conducive to oceanic oxidation. Related Articles | Metrics | Comments（0）

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Lithology in the Mantle Source of Jixi Cenozoic Basalts from Northeastern China ZHENG Zhichong, ZENG Gang, ZHANG Huili, LIU Jianqiang, CHEN Lihui, ZHOU Zhongbiao Geological Journal of China Universities    2023, 29 (2): 186-200.   DOI: 10.16108/j.issn1006-7493.2021063 Abstract （2000）      PDF（pc） （3152KB）（491）       Knowledge map    Save Cenozoic volcanic rocks are widespread in Northeast China, mainly surrounding the Songliao Basin. In the eastern part of the basin, volcanic rocks are distributed along Fushun-Mishan and Yilan-Yitong faults, especially near the Changbai Mountain area, and these volcanic rocks are dominated by sodium basalts. The genesis of these basalts is complex based on their significantly chemical heterogeneity found in the previous studies. Therefore, Cenozoic basalts from Jixi area in the north of Fushun-Mishan fault were selected to further identify the lithology in their mantle source. These basalts show a wide range of SiO2 (44.2~49.6 wt%) and MgO (6.7~10.6 wt%) contents, and can be subdivided into basanite, trachybasalt and basalt. In the primitive-mantle normalized incompatible element diagram, they show positive anomalies of Nb and Ta and negative anomalies of Pb and Ti, which is similar to oceanic island basalts. The calculated the primary magmas compositions of these samples are rich in MgO but poor in SiO2 and CaO; moreover, they fall in the region of silica-poor pyroxenite on the projections from or towards Diopside into the plane Olivine-Quartz-Calcium Tschermak’s (CATS). The high FC3MS (FeOT/CaO-3×MgO/SiO2) values of the basalts again indicate the presence of pyroxenite in their source. Furthermore, the olivine phenocrysts from these basalts are also analyzed, and the high-Fo olivines show lower Ca and Mn contents, and higher Ni contents and Fe/Mn ratios than the low- Fo olivines. The compositions of high-Fo olivines resemble to those olivines crystallized from pyroxenite-derived melt, strongly supporting the presence of pyroxenite in the mantle source. In summary, we highlight that pyroxenitic component, produced during the crustal recycling process, plays an important role in the formation of these mantle-derived magmas in Jixi area. Related Articles | Metrics | Comments（0）

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Effects of CO2 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 （1999）      PDF（pc） （3124KB）（402）       Knowledge map    Save During the process of CO2 being injected into deep saline aquifers, residual water formed in rock pore has negative impacts on CO2 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 CO2 purity (99.999%CO2, 75%CO2+25%N2 and 50%CO2+25%N2) at 40℃ and 8 MPa to investigate the effect of CO2 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%CO2<75%CO2+25%N2<50%CO2+50%N2; the order of the irreducible water saturations is: 99999%CO2<75%CO2+25%N2<50%CO2+25%N2. The analysis revealed that changes in CO2 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 CO2 sequestration capacity. Related Articles | Metrics | Comments（0）

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High Precision Analytical Method for Stable Strontium Isotopes CHEN Xuqi, ZENG Zhen, YU Huimin, HUANG Fang Geological Journal of China Universities    2021, 27 (3): 264-274.   DOI: 10.16108/j.issn1006-7493.2021031 Abstract （1997）      PDF（pc） （922KB）（2109）       Knowledge map    Save Because of the development of high-precision stable Sr isotope analytical method, stable Sr isotopes have been paid more attention in recent years. Great progress has been made in studies on supergene geochemistry, paleoenvironment, archaeology, endogenesis, and meteorites. This paper summarizes the key techniques of δ88/86Sr analytical methods. Ion exchange method with Eichrom Sr Specific Resin has been widely used to purify Sr. But this specific resin is expensive and may result in contamination during the chromatographic processes. Thus it could be replaced by cation-exchange resin. MC-ICP-MS and TIMS are the instruments for isotope measurement. Normally, MC-ICP-MS has higher measurement efficiency but slightly lower precision than TIMS. Standard-Sample-Bracketing method, Zr-Empirical-External-Normalization method, and double spike method are used to correct the instrumental mass bias. The Double Spike method may have relatively high measurement precision, but there are only a few studies using this method on MC-ICP-MS. Furthermore, there is no detailed comparison of δ88/86Sr of international standard materials. Therefore, optimizing the analysis process, improving the measurement precision, and more determination of δ88/86Sr of standard materials are necessary for the future studies of stable Sr isotopes. Related Articles | Metrics | Comments（0）

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Geological Journal of China Universities    2024, 30 (03): 240-.   Abstract （1981）      PDF（pc） （466KB）（152）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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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 （1979）      PDF（pc） （2996KB）（430）       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 | Comments（0）

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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 （1921）      PDF（pc） （5081KB）（485）       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 | Comments（0）

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Characteristics of Water Saturation During Drainage and Imbibition Processes in Unsaturated Zones ZHANG Shengshan, WEI Yunbo, GU Xi Geological Journal of China Universities    2023, 29 (6): 934-944.   DOI: 10.16108/j.issn1006-7493.2022048 Abstract （1918）      PDF（pc） （2949KB）（475）       Knowledge map    Save The unsaturated zone, which is the link between the s urface water and groundwater, plays a key role in controlling water exchange and solute transport in the soils. Infiltration in the unsaturated zone is in essence a problem of twophase (air and water) immiscible displacement. A deep understanding of the airwater displacement process in the unsaturated zone is of great significance for the management and sustainable use of groundwater. A s eries of drainageimbibition experiments are carried out to study the watercontent distribution in the unsaturated zone. The light transmission method is used to monitor water content in the 2-dimensional sandbox during the drainageimbibition cycles. It is found that the lateral fluctuation of water content in the drainage process (0.145-0.175) is greater than that in the imbibition process (0.150-0.165) due to the existence of unstable drainage processes at the pore-scale. The difference of water content between drainage and imbibition means that the mechanism happened at pore-scales should also be affected by water movement at darcy-scales. Related Articles | Metrics | Comments（0）

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Influence of Fuel Pollution on Hydrogeological Parameters of Porous Media YANG Pengfei, CHEN Yudao, JIANG Yaping, YAN Jianing, ZHENG Gao, ZOU Zhikun, LIU Quan, QIN Jiaxiao Geological Journal of China Universities    2023, 29 (4): 608-616.   DOI: 10.16108/j.issn1006-7493.2021108 Abstract （1910）      PDF（pc） （1695KB）（765）       Knowledge map    Save Influence of fuel pollution on groundwater environment is an important subject. Investigating the hydrogeological parameters of contaminated sites will be helpful to understand the changes of hydrogeological parameters before and after pollution, as well as changes of the migration behavior of contaminants in groundwater. To compare the differences of parameters before and after gasoline contamination and evaluate the impacts of gasoline contamination on hydrogeological parameters, three stages of quantitative tracer experiments in sand-tank were performed. The results show that: (1) the accumulation of gasoline contamination leads to the occurrence of bioclogging, and the degree of bioclogging tends to slow down with the increasing percolation distance; there exist differences in solute dispersion in different regions of porous media, and increased solute flux in the dominant flow on the central line and the mass recovery rate ; the solute Breakthrough Curves show a lean-high pattern and a clear trailing. (2) by monitoring the gasoline contamination for 6 years, it is found that the permeability coefficients of traditional gasoline tank (TG-tank) and ethanol gasoline tank (EG-tank) were 25.4 and 20.5 m/d, respectively, which decreased to 61% and 49% of the initial permeability coefficient KII before the sand tank was contaminated; the effective porosity of TG-tank and EGtank was reduced from the initial value of 0.30 to 0.28 and 0.26, respectively. Hydrodynamic dispersion coefficient also tended to decrease. The permeability of porous media is reduced more significantly by ethanol gasoline pollution. The accumulation of organic contamination will change the hydrogeological parameters of the contaminated site, and strengthening studies of hydrogeological parameters after contamination can provide a reasonable basis for evaluating the contamination risk. Related Articles | Metrics | Comments（0）