10 papers in Geology in China won "Frontrunner 5000——Top Articles in Outstanding S&T Journals of China "
"Geology in China" indexed in World Journal Clout Index (WJCI) Report of Scientific and Technological Periodicals (2021)
"Geology in China" selected as the Source Journal of "Outstanding S&T Journals of China (2020) "
Editor in Chief：HAO Ziguo
Established in：1953
ISSN： 1000-3657
CN： 11-1167/P
Domestic postal code：2-112
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SI Qinghong, ZHU Qiang, MIAO Peisen, LI Jianguo, ZHAO Hualei, WANG Zhixiang
2024,51(5):1455-1468, DOI: 10.12029/gc20210416001
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This paper is the result of mineral exploration engineering. Objective The faded alteration of uranium–bearing rock series in the redbed is closely related to reductive alteration, and the analysis of the characteristics of faded alteration and its genetic fluid is of great significance for understanding the uranium ore–forming fluids and ore–forming mechanism. Methods This study is based on analyzing the sedimentary characteristics and faded alteration characteristics of sandstones in Luohe Formation by means of core logging, element geochemical test, electron microscope scanning, electron probe analysis, XRF scanning and core infrared spectrum scanning. Results The sandstones in the Luohe Formation are basically formed in aeolian sedimentary with oxidation conditions mineral assemblages enriched in uranium minerals, pyrite and gypsum but little trivalent iron oxides, and uranium and sulfur elements show obvious migration. Then, the redox state of sandstone and the correlation between uranium mineralization and faded alteration were discussed. Conclusions The main body of Luohe Formation sandstone was formed in aeolian deposits under oxidation conditions, and its color, Fe2O3/FeO, Th/U and Cu/Zn reflect that the environment has been changed from oxidation to reduction with the increase of sandstone faded degree. The characteristics of the consistency between faded alteration and uranium mineralization in Luohe Formation in space, mineral association and redox state suggest that their genesis is related to the same reducing fluid.
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ZHAO Yan, GUO Changlai, CUI Jian, ZHANG Yanfei, LI Ying, LI Xuguang, YU Huiming
2024,51(5):1469-1484, DOI: 10.12029/gc20220829001
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This paper is the result of environmental geological survey engineering. Objective To investigate the distribution characteristics of heavy metals and provide a scientific basis for local characteristic agricultural development, comprehensive tourism, and soil heavy metal pollution control. Methods Through geological investigation, the soil parent material was identified, and topsoil samples were collected. Soil environmental quality evaluation was carried out based on the distribution characteristics and enrichment degree of element content. The degree of heavy metal pollution was evaluated using the ground accumulation index method. The Hakanson ecological risk index method was used to identify the degree of potential ecological risk in the study area. Furthermore, Pearson correlation analysis and cluster analysis were employed to quantitatively determine the main sources of different heavy metals. Results The average values of Cr and Pb in the soil of the Beizhen agricultural area were lower than the background values of the Liaohe River Basin in Liaoning Province. The enrichment degree of heavy metals in the topsoil, from high to low, was Hg > As > Cd > Pb > Zn > Cu > Cr > Ni. The soil quality in the study area is generally good. The proportion of Cd, Cu, and Zn contents exceeding the risk screening values in the exceeding standard samples was 45.56%, 29.11%, and 11.47%, respectively, accounting for 86.12% of the total number of exceeding standards. The evaluation results of heavy metal pollution showed that As and Cd were in a mildly polluted state, most heavy metals in soil samples were in no to mild pollution, and only Hg elements had strong to extremely strong pollution at individual sampling points. The order of potential ecological risk of single indices from high to low is Hg > Cd > As > Cu > Ni > Pb > Cr > Zn. The distribution range of the potential ecological risk comprehensive index (RI) of surface soil in the whole region is 29.7 to 2358.16, with an average value of 141.9, primarily indicating low risk, followed by moderate risk. The results of correlation analysis and cluster analysis show that Ni, Cr, As, and Pb are mainly affected by the natural weathering of the parent rock, while Cu, Zn, Cd, and Hg are influenced by agricultural production, industrial production, transportation, and even construction activities. Conclusions The enrichment of substances produced by the unreasonable application of agricultural substances, atmospheric deposition, industrial production, domestic garbage, and coal combustion in the soil may pose pollution risks to the ecological environment quality of the study area. In the future, it is necessary to strengthen the monitoring and research on the enrichment trend of Hg, Cd, Cu, and Zn elements in different plots.
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ZHAO Liyuan, KONG Linghao, ZHAO Zhigang, ZHOU Wenhui, QIU Jiandong, HUANG Jianhua, GENG Baili, YANG Maosen, HAN Xiangcai, LI Yachao, GU Songsong, ZHAO Mingjie, SHAN Kai
2024,51(5):1485-1500, DOI: 10.12029/gc20230622001
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This paper is the result of environmental geological survey engineering. Objective This paper collected 34 surface soil samples to analyze and determine the concentrations of eight heavy metal, including Hg, Cd, As, Pb, Cu, Cr, Zn, and Ni. The objective was to characterize the heavy metal pollution in the soil around a gold mine, identify the sources of heavy metals in the soil, and conduct a risk assessment. Methods Correlation analysis and principal component analysis were used to explore the sources of heavy metals in the soil. Single pollution evaluation and geo–accumulation index method were employed to determine the degree of pollution. Potential ecological risk assessment and human health risk assessment methods were utilized to evaluate the risks. Results (1) Only three point source pollutions were found in the study area: one for Hg contamination and two for Cd contamination. (2) Nickel, chromium, and arsenic mainly originated from soil parent materials, while lead, cadmium, zinc, and mercury primarily came from mining activities. Copper was derived from both soil parent materials and agricultural activities. (3) Some localized areas demonstrated high potential ecological risks, mainly due to Hg and Cd, while other elements posed minimal risks. (4) Human health risk assessment indicated that the heavy metal elements in the soil did not pose significant health risks to humans. Conclusions The soil around the gold mine was influenced by mining activities and exhibited localized pollution, albeit at a low level. The risks were manageable, but monitoring and assessment of heavy metals in this area should be strengthened.
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BAO Liran, LI Yu, ZHANG Fenglei, YUE Fujun, LUO Kai, DENG Hai, YAN Mingshu
2024,51(5):1501-1512, DOI: 10.12029/gc20230505002
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This paper is the result of environmental geological survey engineering. Objective Natural geological carbon sinks mostly consist of soil and karst carbon sinks, and the main form of carbon’s participation in the carbon cycle in soil is organic carbon. Therefore, the study of topsoil organic carbon has great significance for increasing soil carbon sink and achieving the "carbon peaking and carbon neutrality" goal. Methods Based on the data of a multi–objective regional geochemical survey, this paper analyzed the spatial distribution of topsoil organic carbon density in Chongqing with the geostatistical method, studied the influencing factors and importance of soil organic carbon density by one–way ANOVA and classification regression tree and evaluated the carbon sequestration and emission reduction potential of the farmland soil with the model approach. Results The average density of topsoil organic carbon in the study area was 2.75 kg/m2 , and the spatial distribution had a moderate degree of spatial autocorrelation, showing a distribution pattern of being high at the north and south ends and low in the middle. Altitude, temperature and soil type were the main factors affecting the organic carbon density, followed by precipitation and land use method. The carbon sequestration potential of farmland topsoil was about 36.88 Tg C, equivalent to 24.10% of Chongqing's carbon emissions from energy consumption in 2018. Conclusions The soil organic carbon density was relatively high in cool and humid high–altitude areas, in Chongqing; and forests, grasslands, and paddy fields can help with the accumulation of soil organic carbon among different land use methods. Before the carbon balanceis achieved, the farmland soil, has a "carbon sink" effect as a whole, absorbing carbon from the air.
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LI Wenpeng, SHI Xiaolong, LIU Jianzhang, CHEN Shuang, CAI Kui, SONG Zefeng, TIAN Haofei
2024,51(5):1513-1526, DOI: 10.12029/gc20211126003
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This paper is the result of environmental geological survey engineering. Objective This study aimed to understand the stability of heavy metal pollution in farmland soils surrounding industrial zones. A total of 100 surface soil samples were collected and analyzed for the total concentration and speciation of Pb, Cr, As, Cd, and Hg as well as their association with clay minerals. Methods The extent of pollution and stability of farmland soils and health risks associated with the soil and wheat cultivated in these soils around Wuji Tannery, Xinji Tannery, Handan and Wuan Metallurgy, Guangping Chemical Plant, and Neiqiu Chemical Plant were evaluated. The evaluation was conducted using the single–factor index method, soil mineral evaluation method, and health risk assessment model. Results The analysis revealed high concentrations of Cr in Wuji Tannery soil, Hg in Neiqiu and Guangping Chemical Plant soil, and Cd and Hg in Wuan Metallurgy soil. A significant correlation was observed between heavy metals, particularly those in the residual fraction, and clay minerals such as montmorillonite, chlorite, and illite. Clay minerals exhibited high retention of Cd and Hg but low retention of Pb and As. Additionally, clay minerals in two soil samples from Wuji exceeded the Cr retention capacity Human health risk assessments indicated that soils posed a noncarcinogenic risk (1.02) to children via oral and dermal exposure. Moreover, the cancer risk index, with wheat as the intake medium, exceeded the acceptable limit (1×10-4) for both adults (5.16×10-4) and children (6.44×10-4). Conclusions There is a positive relationship between heavy metals and clay minerals. Therefore, residents in industrial areas, particularly those who rely on wheat as a staple food, should pay close attention to the Cd content in wheat.
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WEI Shuaichao, ZHANG Wei, FU Yong, LIU Feng, YUAN Ruoxi, YAN Xiaoxue, LIAO Yuzhong, WANG Guiling
2024,51(5):1527-1553, DOI: 10.12029/gc20230214001
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This paper is the result of mineral exploration engineering. Objective In recent years, lithium has become a key mineral in the world's major economies, as demand has grown rapidly in the emerging and low–carbon technology industries. Especially under the "carbon peaking and carbon neutrality" goals, the demand for lithium resources is also becoming more urgent in China, but the security of lithium supply seriously restricts the development of new energy industry. At present, our lithium resources are mainly developed by the brine type and pegmatite type, but the geothermal brine type also has a certain resource potential. Therefore, it is necessary to study the distribution characteristics of lithium element in geothermal water. Methods Based on the results of investigation and study of geothermal water in China by predecessors, this paper introduces and discusses the distribution characteristics of lithium content in geothermal water, influencing factors, lithium extraction technology of geothermal water and geothermal exploration technology. Results We analyzed the lithium content of geothermal water in the main heat storage of 30 provinces and cities, and actually calculated that the annual discharge of lithium metal in the 1989 geothermal water was 789 t, and estimated that the annual discharge of lithium metal in the geothermal water was 3233 t, indicating that the geothermal water lithium resources have certain potential. Conclusions It is found that the main factors influencing the lithium content of geothermal water are the characteristics of surrounding rocks and thermal reservoir rocks, temperature, water–rock interaction, etc. It is also found that lithium isotopes have good potential in tracing the sources of geothermal systems, water–rock interactions, and material sources in continental areas. Lithium–rich geothermal water enrichment mechanism in China is mainly divided into the Himalayan geothermal belt type and Sichuan basin type, the former is related to the type in the crust remelting magma upwelling, while the latter is related to the dissolution and filtration of gypsum and halite in the strata. In addition, it is pointed out that the future prospecting direction of lithium–rich geothermal water in China will be concentrated in the Tibetan Plateau, Sichuan Basin, Jianghan Basin and oil (gas) field water. "Simultaneous exploration of geothermal water and lithium" and "simultaneous mining of geothermal water and lithium" to maximize the utilization of resources, and multiple geothermal exploration technologies will also contribute to the development of geothermal industry.
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PAN Zhaoshuai, ZHANG Zhaozhi, CHE Dong, ZHANG Tao, ZHANG Lanying, YANG Wei
2024,51(5):1554-1569, DOI: 10.12029/gc20221113002
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This paper is the result of mineral exploration engineering. Objective Silver, as an important precious metal, has both industrial and financial properties and is crucial to promote national economic and social development. It is important to systematically analyze the characteristics of silver resources and demand trends for emission reduction and resource security in China. Methods From the perspective of the development of the silver industry, the characteristics of the application, geology, supply and demand and market of silver are summarized in China. According to the demand driven difference between industrial silver and non–industrial silver, the demand of silver is predicted using S–curve and ARIMA models in China from 2022 to 2035. Results Based on the resource status and demand forecast results of silver mines, the following results are obtained: (1) Silver mines have the geological characteristics of "four more and four less". It means that the total amount of resources is large and the available resources are few; more small deposits, less large deposits; more lean ore, less rich ore; more concomitant deposits, fewer independent deposits; (2) With the continuous growth of silver application field, domestic mine resources and renewable resources cannot meet the demand, so it is necessary to import silver ore and other concentrates (used to produce silver by–products, such as lead concentrates, zinc concentrates, etc.) to supplement the gap; (3) From 2022 to 2035, the demand for silver in China will continue to grow, from 5800 t to 9500 t, with an average annual growth rate of about 3.7%; (4) From 2022 to 2035, the demand for industrial silver in China will grow rapidly, from 3800 t to 7000 t, with an average annual growth rate of 4.4%. Photovoltaic systems are the main field driving the growth of industrial silver demand; (5) From 2022 to 2035, the demand for non–industrial silver in China will grow slowly, from 2000 t to 2500 t, with an average annual growth rate of 1.7%. Conclusions Based on the above research results, in order to promote the development of the silver industry chain, the following suggestions are put forward: (1) The position and role of silver in the future national economy should be paid more attention; (2) A variety of ways should be adopted to ensure the supply capacity of silver resources; (3) The added value of industrial silver products should be improved to provide guarantee for energy transformation and high–end manufacturing by increasing technological innovation and carrying out deep processing; (4) The national and private silver reserve and security system should be established to avoid large fluctuations in silver prices.
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LI Yang, SONG Yang, TANG Juxing, CHEN Wei, SUN Hao
2024,51(5):1570-1600, DOI: 10.12029/gc20230227001
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This paper is the result of mineral exploration engineering. Objective Antimony (Sb) is one of the strategic minerals in China, thus it is imperative to construct a new antimony resource base. This study analyzes and summarizes the geological characteristics, deposit types, spatial and temporal distribution, and ore–forming sources of Sb、Sb–Au、Sb–Pb–Zn deposits in Tibet, and preliminarily summarizes the metallogenic laws of antimony deposits in Tibet, which is of great significance for guiding the new round of ore prospecting breakthroughs. Methods This paper collected and investigated the data of Sb deposits in Tibet from published literatures around the world, and combined with the latest regional geological survey results, to clarify the relationship between the mineralization of Sb deposits (prospects) in Tibet and the formation and evolution of the Tibetan Plateau from factors of geological characteristics, genetic types and geochemistry. Results The Sb deposits in Tibet are mainly of hydrothermal type. The ore bodies are mainly endowed in clastic rocks and carbonate rocks. The mantle materials have contributions to the Sb mineralization. The mineralization age is mainly from the Early Cretaceous to the Miocene (about 20 Ma). The Sb mineralization is mainly related to the collisional granitic magmatism and the post–collisional extensional magmatism. The distribution of Sb deposits in Tibet is controlled by various layered structures, faults, folds and other tectonic structures, and the ore–bearing strata are late Triassic and Jurassic–Cretaceous strata. Conclusions The Sb deposits in Tibet have the characteristics of zonal distribution, which can be divided into four major Sb metallogenic belts from west to east: western Tibet, southern Tibet, northern Tibet and eastern Tibet. The Cenozoic era is the most important metallogenic period of Sb deposits in Tibet, and the intracontinental extensional background after the strong uplift of the Tibetan Plateau is conducive to the Sb mineralization. According to the metallogenic characteristics of Sb deposits in Tibet, an applicable exploration model is proposed to provide a scientific basis for the prospecting breakthrough of Sb deposits.
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ZHAO Chenhui, WANG Denghong, WANG Chenghui, LIU Shanbao, QIN Jinhua, ZHU Zeying, ZHAO Yunbiao, LIU Ze, LIU Jinyu, LI Yang, LIU Xinxing
2024,51(5):1601-1616, DOI: 10.12029/gc20230309006
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This paper is the result of mineral exploration engineering. Objective Recently, leucogranites have become a hot spot in the study of petrogenesis and rare metal metallogeny. However, the spatiotemporal distribution characteristics of global leucogranite are still unclear. For further prospecting of rare metals in China, it is essentially to clarify the spatiotemporal distribution of leucogranite and the metallogenic specialization between leucogranite and rare metal deposits. Methods We collect 1155 geochemical data from 115 leucogranites worldwide, and combine with our recently achievements from the Nanling Region, Western Sichuan, Southern Tibet, and Altai. Results In reference to the composition, this study reveals that the content of SiO2 in leucogranite is exceed 1% higher than the global average value of granite, while the REE content of the rocks with rare metal mineralization is extremely low. Spatially, the content of SiO2 and ALK (Na2O+K2O) of leucogranites in the Hercynian orogenic belt in Central and Western Europe are lower than those of the Himalayan leucogranites, as well as those of Western China. Meanwhile, the SiO2 and ALK content of leucogranite in Western China are lower than Eastern China. Both leucogranites in Central and Western Europe and North America are rich in P2O5. The highest values of Li, Be, Nb, Ta, Ga, Rb and Sn in the samples appear in Central and Western Europe, while the highest values of W present in eastern China. Cenozoic SiO2 and ALK content of leucogranite were higher than Paleozoic but lower than Mesozoic. Notablely, Paleozoic leucogranite are enriched in P2O5. Besides, tourmaline is a vital indicator of Neoproterozoic leucogranite. Conclusions The mineralized leucogranite are generally lack of magmatic garnet. Those leucogranite with feature of A/CNK>1.2. Rb/Sr>1, ΣREE>10×10–6 are mostly related to Sn–W–Nb–Ta mineralization, while Rb/Sr>1, ΣREE<10×10–6 of leucogranite more akin to Li–Sn–Nb–Ta–Be mineralization. All the data indicate that the Mesozoic leucogranites in Eastern China are the most evolved leucogranites worldwide and the best mineralization potential.
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LI Siyuan, HOU Qingye, YANG Zhongfang, YU Tao
2024,51(5):1617-1643, DOI: 10.12029/gc20230910002
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This paper is the result of environmental geological survey engineering. Objective Nitrogen (N) is a key nutrient across Earth's terrestrial ecosystems and one of the pollution elements that cause water eutrophication. Owing to the continuous improvements of analysis and testing techniques, nitrogen stable isotope technology has developed into a common research method and analysis mean, and has been widely used in nitrogen biogeochemical cycle, water eutrophication and groundwater pollution source identification. Methods In this paper, the relevant literatures on nitrogen stable isotope in the field of ecological environment domestic and overseas in recent years were reviewed, and the research status of nitrogen isotope fractionation mechanism, nitrogen stable isotope analysis technology and nitrogen isotope applications in ecological environment were summarized, the development of remediation technologys of nitrate pollution in groundwater were briefly described. Results (1) A mature system of nitrogen isotope mass spectrometry and nitrogen isotope tracer technology has been established. (2) Nitrification and denitrification are the main mechanisms of soil nitrogen conversion cycle. Nitrogen input is realized by biological nitrogen fixation, and nitrogen output is mainly through nitrogen gas or ammoniation produced by plants or microorganisms, which is accompanied by different degrees of nitrogen isotope fractionation. (3) Nitrogen isotopes can be used to measure soil nitrogen turnover rates and N2O emission rates, improve biological nitrogen fixation, indicate changes in atmospheric nitrogen deposition, investigate the interaction between plant and soil and determine nitrogen uptake and utilization by plants, and identify crop area sources and pollution in groundwater and atmosphere. Conclusions Future researches should focus on improving the ability of quantitative detection of uncertainty sources in the nitrogen cycle, identifying undiscovered nitrogen input, accumulation and loss pathways, and perfecting and developing ecosystem nitrogen cycle model.
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CHEN Wudi, LIU Xiaohuang, LI Hongyu, SUN Xingli, WANG Yugang, LIU Xiaojie, XING Liyuan, WANG Ran, LUO Xinping, WANG Chao, ZHAO Honghui
2024,51(5):1644-1663, DOI: 10.12029/gc20231121001
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This paper is the result of ecological geological survey engineering. Objective Under the background of global climate change and the continuous expansion of human activities, natural ecosystems and their service functions are facing increasingly serious threats and recessions.In order to address this challenge, it is critical to identify and protect key sites that are of great value to ecological sustainability. Ecological security pattern refers to a comprehensive strategy and method to ensure regional ecological sustainability. Methods Based on the In–VEST model, PLUS model and circuit theory, this study evaluated the dynamic changes of ecosystem services and ecological security pattern (ESP) in the Tianshan Mountains in the arid region of Northwest China. Results The spatial distribution of land use type (LUCC) was basically stable from 1990 to 2050. In the past 30 years, the total conversion area was 32.52×103 km2, which was mainly the conversion between wasteland and grassland. Compared with 2020, the total land conversion areas under the scenarios of Natural development scenario (ND), Ecological protection scenario (EP) and Urban development scenario (UD) in 2050 are 21.43×103 km2, 23.09×103 km2 and 22.87×103 km2, respectively. Among them, the net increase of forest land area is the most, which is mainly transformed from grassland. The area of forest land, grassland and water body increased under EP scenario. In the other two scenarios, the area of construction land and cultivated land has expanded significantly. Compared with ND and UD scenarios, the ecosystem service function of EP scenario is greater. There are obvious spatial differences in ESP in the Tianshan Mountains from 1990 to 2050. The larger ecological sources and smaller resistance corridors are mainly distributed in the central and northern parts of the Tianshan Mountains with higher ecosystem service functions. On the contrary, broken ecological sources and large resistance corridors are mostly distributed in the western region blocked by sand, bare land or mountains. The southeast is a desert area, with no ecological source and lack of ecological corridors. In the past 30 years, the area of ecological source area has decreased by 1.84×103 km2, showing a trend of fragmentation, and the ecological network is more complex. Compared with 2020, the area of ecological source and pinch point under EP scenario in 2050 will increase by 10.53×103 km2 and 0.11×103 km2 respectively, and the area of ecological barrier zone will decrease by 0.38×103 km2. In addition to the EP scenario, the ecological source area of the other two scenarios also increased, but lower than the EP scenario. Conclusions Ecological protection scenarios play a vital role in shaping LUCC and are of great significance for maintaining ecological security and ecosystem integrity.
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ZHANG Surong, WANG Daming, YANG Junquan, ZHANG Jing, WANG Jianhua, ZHANG Donghui, TONG Yunxiao, JIN Zhibin, CHEN Donglei
2024,51(5):1664-1675, DOI: 10.12029/gc20231011002
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This paper is the result of agricultural geological survey engineering. Objective Soil quality is closely related to human activities. Given that traditional methods fall short in achieving the large–scale dynamic monitoring of soil quality, the quantitative inversion of elements in soils using hyperspectral remote sensing, which proves macroscopic, real–time, in–situ, and fast, has emerged as a hot topic and challenge in the field of remote sensing application. Methods This paper explores three methods for quantitative remote sensing inversion of elements in soils: direct quantitative inversion, indirect quantitative inversion using correlations among the elements, and quantitative inversion based on plant spectra. Specifically, this paper systematically summarizes the primary principles, advantages, and current research status of these methods and proposes future trends in relevant fields from the perspective of interdisciplinary integration. Results The commonly used methods for the quantitative inversion of elements in soils face challenges when applied on a large scale. Among these, the indirect inversion based on the spectra of plant leaves or canopies is considered the most reliable. Achievements in ecological geochemistry enable the identification of the unique spectral effects of target elements in different plants, which assists in determining the principle of the plant spectrum–based quantitative inversion of elements in soils. Conclusions More in–depth research based on big data mining and the physicochemical properties of soils while promoting interdisciplinary integration represents a favorable direction for achieving breakthroughs in wide–area monitoring technology for elements in soils.
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KONG Xiangke, LI Yi, WANG Ping, HAN Zhantao, LIU Shenghua, ZHANG Zhaoji, WANG Yanyan
2024,51(5):1676-1685, DOI: 10.12029/gc20220312001
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This paper is the result of soil environmental survey engineering. Objective The objective is to identify the impact of characteristic pollutants (Cr (III), salt, organic matter) in the leachate of tannery sludge on the conversion of soil NH4+–N conversion and microbial community structure. It provides a theoretical basis for the safe agricultural use of tannery sludge and soil pollution prevention and control. Methods The transformation of NH4+–N to NO3––N in soil was studied through soil cultivation experiments under different pollution conditions, and the high–throughput sequencing is used to analyze the composition and structure characteristics of microbial community in soil. Results The characteristic pollution components in the tannery sludge leachate inhibit the nitrification process of NH4+–N in the soil, and the influence factors are sorted as follows: Cr(III)>saltness>organic matter. The exogenous Cr(III) pollution has a significant inhibitory effect on the transformation rate and amount of NH4+–N, whereas the saltness and organic matter only delay the start time of nitrification and reduce the nitrification rate in soil. With the increase of Cr(III) content from 100 mg/kg to 250 mg/kg, the transformation amount of NH4+–N decreases from 94.23% to 19.38% after 90 days of culture. The high Cr(III) and salinity in the leachate have a significant impact on the microbial community structure and distribution in the soil at the initial stage of pollution. With the decrease of the bioavailability of Cr(III) and the enhancement of microbial adaptation in soil aging process, the microbial community structure and composition in Cr(III), salinity, and organic matter contaminated soils become similar, and the abundances of nitrifying bacteria (Nitrosospira, Nitrosomonas and Nitrosospira) also have an obvious increase. Conclusions The results of RDA analysis show that the main characteristic factors affecting the evolution of microbial community structure in tanning contaminated soil are: Cr(III) (R2=0.53, P<0.01), NH4+–N (R2=0.59, P<0.005) and NO3––N(R2=0.53, P<0.01).
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YUAN Shuai, ZHANG Siyuan, ZHANG Xueqiong, YUAN Guoli, WANG Yongliang, BIAN Peng, TAI Surigala
2024,51(5):1686-1700, DOI: 10.12029/gc20220302002
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This paper is the result of environmental geological survey engineering. Objective This study aims to evaluate the current status of heavy metal contamination in the soil of Dashetai, Ulat Front Banner. A comprehensive sampling campaign was conducted, involving the systematic collection of 845 topsoil samples, 30 crop samples, and 17 drinking water samples. The concentrations of eight heavy metals (Arsenic (As), Cadmium (Cd), Chromium (Cr), Copper (Cu), Mercury (Hg), Nickel (Ni), Lead (Pb), and Zinc (Zn)) were analyzed to assess the extent of contamination. Methods The levels of soil heavy metal contamination, ecological risk, and associated health risks in the study area were assessed using the geoaccumulation index method, the potential ecological hazard index method, and a health risk assessment model. Results The concentrations of heavy metals in the farmland soils of Dashetai are approximately equivalent to the background levels observed in the Hetao Plain. The assessment of potential ecological risks indicated that the heavy metal contamination in the soil predominantly posed slight to moderate ecological hazards. The human health risk assessment revealed that, through oral and dermal exposure, the soil's carcinogenic risk value was calculated to be 5.69 × 10–6, which exceeds the standard threshold of 10–6. However, this level of risk is considered to pose a minimal carcinogenic threat, one that is generally deemed acceptable by public health standards. Conclusions The distribution of mercury (Hg) is significantly influenced by anthropogenic activities, with areas of medium to high risk predominantly located in Dashetai. In contrast, the distribution of other elements is primarily governed by the parent materials of the soil. Moderate–risk areas for cadmium (Cd) are concentrated along the coast of Wuliangsu Lake. Arsenic (As) was identified as the primary contributor to the health risks associated with the consumption of vegetables, grains, and drinking water.
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ZHAO Yi, ZOU Shengzhang, SHEN Haoyong, LAN Funing, XIE Hao, LI Jun
2024,51(5):1701-1713, DOI: 10.12029/gc20221025002
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This paper is the result of hydrogeological survey engineering. Objective In order to determine the sources and control factors of main ions and dissolved inorganic carbon (DIC) in water of the Huixian karst wetland, Methods groundwater and surface water samples were collected from the Huixian karst wetland to analyze the hydrochemical ions and dissolved inorganic carbon isotope(δ13CDIC). Results The Ca–HCO3 water was identified as a main hydrochemical type in most water samples of the Huixian karst wetland. The dissolution of carbonate rock was primary contributor to Ca2+, Mg2+ and HCO3–, while NO3– was mainly derived from synthetic fertilizers and soil organic nitrogen. Moreover, K+, Na+, and Cl– were driven by the mixed inputs of synthetic fertilizer, manure, and sewage, and the acid rain and pyrite oxidation contributed more to karst water SO42–. Further, karst water DIC was respectively derived from the soil CO2 with the contribution rate of 46% and from the carbonate minerals with the contribution rate of 54% according to the obtained result from isotopic mass balance. In addition to the H2CO3 produced from CO2 and H2O, the H2SO4 derived from sulfur–containing minerals, acid rain, and anthropogenic emissions was involved in carbonate weathering in the Huixian karst wetland. Additionally, microbial nitrification processes of the reduced nitrogen fertilizers could be also ignored in the study area. For the surface water, the DIC was mainly derived from groundwater recharges, and the value of δ13CDIC was affected by the photosynthesis of aquatic plants and CO2 degassing, thereby resulting in the more enrichment of δ13CDIC compared with that in groundwater. Conclusions The obtained results provided insights into the understanding of minerals weathering and biogeochemical processes, and also highlighted the control factors of hydrogeological conditions and human activities in precisely determining hydrochemical mechanisms in the karst wetland.
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WU Zijie, ZHANG Guoren, QIU Longwei, WANG Haipeng, ZHONG Mishan, GAO Fuliang, PAN Yuqi, LUO Niangang
2024,51(5):1714-1726, DOI: 10.12029/gc20200919002
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This paper is the result of geological survey engineering. Objective The sedimentary period of the Qiaotou Formation in Liaoning is still not accurately determined, which leads to controversial discussions about its depositional background, especially the palaeoclimate. It is of great significance to discuss its depositional background by using petrogeochemical characteristics and other methods. Methods We reconstructed the palaeo–weathering climate conditions, palaeo–salinity and palaeo–oxidation–reduction conditions by analysing the elemental ratios of CaO/(CaO+Fe), Sr/Ba, and V/(Ni+V), as well as the parameters of CIA, ICV, and Ceanom from the petrogeochemical data of the sandstones of the Qiaotou Formation. Results Most of the CIA values of the sandstone samples from the Qiaotou Formation are located in the warm and humid region, while most of the ICV values are located in the cold and dry region. Most of the CaO/(CaO+Fe) and Sr/Ba values of the samples fall into the medium saline region, and a small amount is in the slightly saline region. V/(Ni+V) and Ceanom values of sandstone samples are in the reduced region, and a small amount is in the oxidised region. Conclusions The Qiaotou Formation was not deposited in the Nanhua Period, and its depositional period was generally in an anoxic reducing environment with medium saline water and a warm and humid climate.
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ZENG Xiongwei, XU Ziyi, WANG Jianpo, CHENG Long, WANG Chuanshang, WANG Zhihong
2024,51(5):1727-1734, DOI: 10.12029/gc20200606005
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This paper is the result of geological survey engineering. Objective Microbially induced sedimentary structures (MISS), one of the international research hotspots, have been paid more attentions in Precambrian rather than other period in China. Microbials flourished globally in the Early Ordovician. However, the MISS was found in the shallow water clastic rocks in France and Newfoundland of Canada, but not yet reported in China. Methods Here, we first discovered the MISS at the upper Nantsinkuan Formation of Early Tremadocian of Early Ordovician in Jieling area, Yichang, Hubei Province. Results The MISS at Jieling contained microbial mat growth features and microbial mat destruction features. It is noteworthy that the microbial mat destruction features are morphologically similar to the molar tooth that widely developed in Precambrian. Conclusions The discovery of the MISS in Jieling not only enriches the global MISS–bearing stratigraphic units, but also has important theoretical significance for the study of Phanerozoic microbialites. Moreover, it is an important supplement to the geological relics of Yichang City.
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ZHU Jiang, CHEN Chao, LI Zhanke, WU Bo, WANG Guanghong, PENG Lianhong
2024,51(5):1735-1747, DOI: 10.12029/gc20210107001
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This paper is the result of geological survey engineering. Objective To better understand the Paleo–Mesoproterozoic tectonic evolution of the Dabie orogen in the northern margin of Yangtze Block, we demonstrated the geological and geochronological characteristics for sedimentary rocks in the Lüwang–Gaoqiao mélange. Methods Geological mapping for the mélange was conducted. LA–ICP–MS zircon U–Pb isotopic analyses were carried out on the graphite–bearing quartzite. Results The graphite–bearing sedimentary rocks in Lüwang–Gaoqiao mélange are dominated by sandstones with high maturity, siliceous argillaceous rock, and carbonaceous. U–Pb dating reveals that the graphite–bearing quartzite has original deposition age of ~1.43 Ga, displaying detrital zircon age peaks at 2.55 Ga, 2.06 Ga, 1.86 Ga and 1.43 Ga. The sedimentary materials mainly came from the basement of the Yangtze Block. Conclusions The Mesoproterozoic clastic sedimentary rocks and carbonates from the Lüwang–Gaoqiao mélange were formed in a continental margin setting. They recorded an extensional regime for the Dabie orogen in the northern margin of Yangtze Block, during the break–up of the Columbia supercontinent.
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ZHONG Guangjian, QIANG Kunsheng, YANG Jianli, SUN Ming, ZHAO Jing, FENG Changmao, WANG Chao, YI Hai, ZHAO Zhongquan, YAN Pin, LIU Dameng
2024,51(5):1748-1760, DOI: 10.12029/gc20200729001
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This paper is the result of oil and gas exploration engineering. Objective The structural uplift of Chaoshan depression is controlled by the development degree of sandstone reservoir and tectonic conditions. It’s flank depression provides a source of hydrocarbon, which is the most favorable area for zones of hydrocarbon accumulation. The Mesozoic sandstone reservoirs in the Chaoshan Depression have obvious low–density characteristics based on the elastic parameters of seismic inversion to predict the oil and gas properties, while the density of other lithologies is high. Methods The elastic parameters such as density and Poisson's ratio were directly inverted from the pre–stack seismic data, and the development of sandstone reservoirs and the distribution of hydrocarbons were predicted through the density inversion results, so as to realize the prediction of the Mesozoic oil and gas content. Results The Poisson's ratio is sensitive to hydrocarbons, and the reservoir has obvious characteristics of low Poisson's ratio after hydrocarbons. Conclusions The elastic parameters of seismic inversion are used to predict the oil and gas properties, and the hydrocarbon anomalies are obvious, and the predicted structural uplift has good oil and gas properties. The pre–stack elastic parameter inversion technology greatly reduces the multi–solution and uncertainty of reservoir prediction in well–free areas, and improves the accuracy and reliability of inversion results.
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ZHANG Yu, XU Zongheng, ZHA Linglong, CHEN Yunying, TAO Zhenpeng
2024,51(5):1761-1775, DOI: 10.12029/gc20220413004
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This paper is the result of environmental geological survey engineering. Objective The cascade of disasters caused by landslide–dammed lakes is highly destructive, with its formation and outburst processes significantly influenced by the external environment. The sediment within the dammed–lake serves as a valuable tool for documenting the entire lifecycle of thedammed–lake, offering important insights into paleoenvironment and paleoclimate. Utilizing the most effective analytical methods to interpret this sediment can aid in reconstructing the sediment deposition process and understanding changes in paleoenvironment. Methods Through sediment sampling for field investigation and laboratory analysis, the suitability of statistical characteristics of dammed lake sediments is assessed using graphical and moment methods. The sediment environment of the dammed lake is reconstructed by analyzing particle size in conjunction with organic matter content, allowing for the restoration of the development process of the dammed lake. Results (1) The stratified sediment sequence of the dammed lake sediment is distinct, representing a monogenic hydrodynamic lacustrine sediment with consistent material sources rather than polygenic sediment. Analysis of the organic matter and sediment grain size variations indicates that the dammed lake has undergone four cycles of wet–dry periods, with at least three instances of blockage–overflow deposition processes resulting from the combination of climatic and geological factors. The estimated sedimentary cycle period is approximately 1750 a. It is suggested that the sedimentation history is a consequence of prolonged and intricate activities within the fault zone, as well as the combined influence of climate and river dynamics. (2) The statistical analysis results from the graphical method and the moment method indicate a high level of agreement in assessing the average grain size and sorting coefficient, suggesting that they are interchangeable. However, the partial kurtosis values obtained from the moment method are greater than those from the graphical method, necessitating a linear adjustment for practical application. Additionally, deviations from statistical expressions are observed in the skewness and kurtosis due to the reference value description. Conclusions The grain size distribution of the sediment from the dammed lake is straightforward and easily calculated, making it convenient for comparison with other sediment types. The graphical method is suggested for these calculations. The findings indicate that the grain size characteristics offer valuable insights into understanding the deposition and outburst processes of dammed lake, as well as the response of landslide disasters to climate change. This information can serve as a theoretical foundation for reconstructing the paleoenvironment and paleoclimate of the dammed lake during its deposition phase.
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LIU Chunyan, LIU Jingtao, ZHU Liang, ZHANG Yuxi, JING Jihong, HUANG Guanxing, ZHOU Bing, CHEN Xi, XIE Fei, LI Bei
2024,51(5):1776-1790, DOI: 10.12029/gc20230307003
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This paper is the result of hydrogeological survey engineering. Objective Due to the limitation of terrain conditions, the ecological environment of plateau valley cities is fragile, and the strong human activities have had a severe impact on groundwater. Iron and manganese ions have become the main contribution index of super–class III groundwater in shallow groundwater in Xining, a typical plateau valley city, which seriously threatens the local ecological environment security .and the health of residents. The distribution characteristics and influencing factors of iron and manganese in shallow groundwater in plateau valley cities are deeply explored in order to provide technical support for the prevention and control measures of groundwater pollution and the alleviation of water quality safety problems in this area. Methods Based on the test results of hydrochemical composition of 144 groups of shallow groundwater samples in Xining city, combined with the geology, landform, land use type, hydrogeological investigation data and the influence of human activities, this paper studies the distribution characteristics and influencing factors of Fe and Mn in shallow groundwater in Xining city. Results The over–standard rates of Fe and Mn in shallow groundwater in the study area are 20.98% and 9.79%. Compared with 2012, the contribution rate of Fe and Mn ions to Class Ⅲ groundwater increased by 2 and 3, respectively. The excess rate of Fe and Mn in shallow groundwater of construction land is 1.4 times and 3.47 times higher than that of other land use types, respectively. There are 36 hydrochemical types of shallow groundwater in the study area, and 21 hydrochemical types of groundwater in construction land. Groundwater with high Fe and Mn is mainly enriched in HCO3–Ca·Mg type water and HCO3·SO4–Ca type water. The migration and enrichment of Fe and Mn ions in groundwater are mainly controlled by oxidation–reduction environment, and have no obvious correlation with acid–base conditions, except for the properties of overburden, ground pollution, groundwater runoff conditions. Conclusions The increase of Fe and Mn content in groundwater in the study area is mainly caused by the primary sedimentary environment, while the increase of Fe and Mn content in shallow groundwater in local construction land is caused by the primary sedimentary environment and human activities. Therefore, it is necessary to monitor the Fe and Mn content in groundwater in construction land for a long time and formulate corresponding management measures to prevent the increase of Fe and Mn content in shallow groundwater in the future.
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TANG Yuanhe, GAO Yongbao, YAN Kang, WEI Liyong, LI Guoying, YANG Ke, GUO Wendi, DU Wan'ge, SHI Lei, ZHANG Rui
2024,51(5):1791-1792, DOI: 10.12029/gc20240105002
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WANG Xueyin, FAN Xinxiang, WANG Zuogang, YANG Tao, WANG Hao, SONG Xiaohong
2024,51(5):1793-1794, DOI: 10.12029/gc20240311001
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JIANG Chen, CUI Peilong, KANG Yu, ZHAO Kang, JIN Suosuo, SHU Zhonghua, ZHANG Zhan, TIAN Bi
2024,51(5):1795-1796, DOI: 10.12029/gc20240107001
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ZHANG Honghui, WU Liang, YUAN Yongsheng, LI Suoming, LI Jinwang, ZHANG Yaotang, WANG Wanneng, LI Zhiwei, CHEN Guiren, ZHAO Jianbo, ZHENG Hongfu
2024,51(5):1797-1799, DOI: 10.12029/gc20240215001
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ZHANG Yutong, Lü Peng, LU Xiaoli, XIANG Li, HONG Jinglan, CAI Xiuhua, ZHANG Mengbo, CHAI Xinxia, LI Lu
2024,51(5):1800-1805, DOI:
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Volume 51,2024 Issue 5
In Focus
Reviews
Research Articles
短文（发现与进展）
New and Highlights
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CAI Ningbo, WANG Linlin, BAO Yiyao, LI Yipu, WAN Zexing, KANG Zhimei, LUO Shengyuan
DOI: 10.12029/gc20231019003
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Abstract:[Objective]The Yichang area of Hubei Province is one of the important frontier areas of shale gas exploration on the Middle Yangtze platform. Field investigation and drilling works in recent years show that the Cambrian Shuijngtuo Formation in this area is a shale gas exploration target with great potential industrial value. [Methods]Based on the latest borehole data in this area, the characteristics of high-quality shale reservoirs and the hydrocarbon accumulation patterns are identified by means of multidisciplinary methods. [Results]The shale of the Shuijngtuo Formation has high organic matter abundance, with TOC mainly distributed in the range of 0.56%~8.42%. Organic matter is dominated by type II1 and type I kerogen, and Ro equivalent value is distributed in the range of 2.4%~3.2%. Porosity and permeability values of shale reservoirs within the Shuijngtuo formation are mainly in the range of 0.5% ~ 9.1% and 0.019 ~ 0.540×10-3 μm2. Reservoir pore spaces of shales within the Shuijngtuo Formation mainly includes organic pores, inorganic pores and fractures. Occurrence of pore spaces is mainly related to the enrichment degree of organic matter, the content of clay minerals and the development degree of fractures. Natural gas is mainly attached to the shale reservoir in the form of adsorbed gas (45.21%~81.44%) and free gas (18.56%~54.79%), and the proportion of dissolved gas is relatively small. The gas bearing property of the shale reservoir is mainly related to the content of organic carbon, the proportion of brittle minerals and the degree of fracture development. The higher the proportion of organic carbon, the proportion of brittle minerals, and the degree of fracture development, the better the gas bearing property of the reservoir becomes. [Conclusions]Based on the geochemical, petrophysical and field measurement data, this study concluded that the shale gas of the Shuijingtuo Formation in Yichang area has great commercial value and is one of the ideal targets for shale gas exploration and development in southern China.
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ningpengyuan, WANG chunlian, Zhu pinging, Liang zhen, Yan kai, Liu dianhe
DOI: 10.12029/gc20230904002
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Abstract: [Objective] Peridotite is an important mineral resource in China, which is widely used in building materials, refractory materials and fertilizer raw materials. Studying the origin, distribution and prospecting prospect of peridotite ore deposit is an effective way to solve the shortage of olivine resources in our country, and it is an important guideline for discussing the origin and prospecting direction of chromite ore deposit. [Methods] This paper summarizes the origin,distribution, mineral deposit types, development and utilization of peridotite in China by collecting and sorting out previous research data. [Results] According to the output of olivine, peridotite includes two main types of deposit: peridotite envelope type occurring in basalt and vein filling hydrothermal type occurring in peridotite. The main mineral areas of peridotite in China are Nanyang in Henan Province, Hebei Province, Jiaohe in Jilin Province and Shangnan in Shaanxi Province. Jiaohe olivine gem deposit in Jilin is the main source of olivine gem in China. The calc-magnesium-olivine deposit in Shangluo Mountain area at the border of Henan Province and Shaanxi Province has reserves of about 500 million tons with a grade of 44%. [Conclusions] The known resources of peridotite in China are not very rich, but the ore quality is good. As of 2022, China''s Ministry of Natural Resources statistics, the national reserves of 16008 million tons, the total amount of peridotite ores for fertilizer in the country is 2,492,200 tons, and the total amount of peridotite ores for refractory in the country is 17,766,100 tons. The olivine gem deposit in Jilin Jiaohe and Wanquan County of Hebei Province is an important olivine gem deposit because the olivine gem mine in Hebei Province has been closed. At the same time, the partial melting of peridotite is closely related to the enrichment of chromium, and the liquid phase immiscibility of the melt formed by partial melting of the depleted mantle leads to the formation of silicate magma and chromium-rich pulp. The study of peridotite is of great significance not only for the exploration of peridotite deposits, but also for the deposits with peridotite as the surrounding rock.
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Feng Yongtai, Wei Yi, Yang Bing, Zhang Xinzhi, Lei Xiaoting, Ma Yanting, Huang Zhuo, Wang Tao, Tan Ning
DOI: 10.12029/gc20230827001
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[Methods]Plant fossils are the best materials to record terrestrial climate change in geological history, especially to the change of the paleo-CO2 concentration. Phoenicopsis (Windwardia) cf. rudinervis was identified due to the study of the morphology of the fossils collected from the Jurassic Yan ''an Formation in well Ningdong 2, Yanchi area, Ordos Basin. [Objective]In order to reconstruct the paleo‐atmospheric CO2 concentration, paleo‐temperature and water use efficiency of plants during the Middle Jurassic, leaf fossils of Phoenicopsis (Windwardia) cf. rudinervis were selected from horizon for calculating the the epidermal stomatal parameters and their isotope carbon composition of leaf cuticles. [Results]The results show that the average stomatal index (SI) of Phoenicopsis (Windwardia) cf. rudinervis is 4.25%, The paleo‐atmospheric CO2 concentration obtained by the stomatal ratio method is 1599 ppm. The paleo‐average temperature of Yanchi is about 1.2℃~31.4℃. The average value of the stable carbon isotope δ13C of plant fossils is -23.6‰, and its water use efficiency (WUE) is calculated to be 348.2 mmol/mol. [Conclusions] In general, the Middle Jurassic of Yanchi area in Ordos Basin belongs to a warm temperate - subtropical humid climate which reflected by the high CO2 concentration. Compared with previous data, we speculate that the paleo-CO2 concentration of the Middle Jurassic in northern China was significantly higher than that of the Early Jurassic, which may be related to the large-scale volcanic activities of the Yanshan Movement.
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In-situ stress characteristics and fault stability analysis of hot dry rock GR2 well in Gonghe Basin
chendongfang, yang yuihui, niu zhaoxuan, wang hongwei, jin xianpeng, li zhenyu, WU Haidong, LIU Donglin
DOI: 10.12029/gc20230901003
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[Objectives]The magnitude and direction of in-situ stress are important parameters for well placement, fracturing design and reservoir evaluation in hot dry rock development. It is of great significance to study reservoir stress state for hot dry rock development. [Methods] In this paper, the characteristics of current stress field in Gonghe Basin are analyzed based on regional geological structure evolution, focal mechanism solution and inversion results, statistics of joints and fissures, and in-situ stress measured data. Combined with the reservoir structure and stratigraphic lithofacies characteristics of Gonghe GR2 well, a three-dimensional model is established, and the three-dimensional in-situ stress data of well GR2 in Gonghe Basin is obtained through numerical simulation by using orthogonal anisotropic elastic constitutive relation. The regional tectonic stress field and occurrence conditions of dry hot rock resources are discussed. [Results] The results show that: ① The simulated stress distribution is consistent with the theoretical value, which meets the requirements of initial displacement accuracy, and finally predicts the distribution characteristics of in-situ stress field in the well. ② In the depth range of 500~4500 m, the relationship of three principal stresses is principal stress is σv> σH >σh, indicating that the stress structure in this region is favorable to normal fault activity. ③ The maximum horizontal principal stress direction of Gonghe Basin in Qinghai province is mainly NE direction compression deformation, which is conducive to low fluid permeability and low heat transfer of granite. ④Under the action of a unified regional stress field, the faults may be come instability near the injecting well, when the continuous injection pressure on the ground reaches or exceeds about 19.9 MPa during the water injection development of 3900~4500 m depth in the study area, leading to the occurrence of medium and small earthquakes, which should be prevented in the development and utilization of the hot dry rock. [Conclusions]This study have certain reference value for geodynamics research and the safe development and utilization of dry hot rock in Gonghe Basin.
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LIU Weipeng, JIA Xiaofeng, ZHANG Zichun, ZHANG Qiuxia, YANG Li, LI Shengtao
DOI: 10.12029/gc20230708001
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Abstract: The paper is the result of geothermal geology survey engineering. [Objective]The mountainous areas surrounding the capital city belong to the ecological conservation area of Beijing-Tianjin-Hebei, including the contiguous areas of extreme poverty, and are rich in hot spring resources, but the degree of exploration and development is low. It is of certain guiding significance to carry out research on the distribution pattern and development characteristics of hot springs for the exploration and development of geothermal resources in mountainous areas. [Methods]In this paper, based on the collection of information on hot springs and deep tectonics in the mountainous areas of Beijing, Tianjin and Hebei, superimposed analysis reveals the connection between hot spring distribution and deep tectonic thermal background, and explores in depth the hot spring heat source and its formation. Combined with supplementary surveys, sample collection and comprehensive research, the development characteristics of hot springs were summarized, and prospects for hot spring development and utilization in the study area were proposed according to local conditions. [Results]The results show that hot springs are mainly distributed along NE and EW deep major fractures in the form of bands or beads, 90% of the hot springs are distributed within the deep structural variation zone of the Moho surface in the study area. The temperature of hot springs has a certain negative correlation with the depth of dwelling, the depth of dwelling in the high hot spring area in the northern Yanshan being about 20km, the depth of dwelling in the relatively high hot spring area in the Yanshan-Taihang Mountains junction zone being about 22～24 km and the depth of dwelling in the low hot spring area in the southeast Yanshan being 22～26 km; the heat source of hot springs mainly comes from the mantle heat or "low-velocity-high-conductivity layer", and the upper mantle diapirs and deep large faults provide good channels for the upwelling of deep heat sources; On the regional scale, there is no direct correspondence between the hot spring outcrop temperature and the depth of circulation, and the thermal reservoir temperature of sedimentary rock reservoirs in the intermountain basin is low, with a large flow rate of hot springs, up to about 120 m3/h. The thermal reservoir temperature of metamorphic rocks is generally greater than 100℃, with a smaller flow rate. The hot spring water in the study area generally has medical development and utilization value, among which, the northern Yanshan and intermountain basins, have a better potential for space heating, and areas such as Qijia-Maojingba can be further developed in the direction of thermol-electric integration. [Conclusions]The distribution and development characteristics of hot springs in the mountains area around the capital city are influenced by the deep tectonic and regional geological structure. The northern Yanshan Mountains and intermountain basins have good development and utilization prospects.
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ZHOU Mo, ZHANG Ming, TANG Zhimin, ZONG Leli, WANG Shangxiao, TIAN Fujin, ZHANG Xiaodong, ZHANG Jie, NIU Xiaonan, HUANG Dingling
DOI: 10.12029/gc20230620001
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Abstract:This paper is the result of land quality geochemical survey engineering. [Objective] Metal elements mainly enter the human body through the food chain, thus affecting health. Research on the geochemical characterization of heavy metal elements in the soil-rice system is significant for the scientific management of arable land, the guarantee of food security and the implementation of the strategy of a healthy China.[Methods] A total of 129 sets of rice seeds and root soil samples were systematically collected, analyzed by chemical analysis to obtain geochemical data such as As, Cd, Hg, Pb, Cr, pH, and soil Cd morphology, thus using the human health risk model to assess the health risk in the study area. [Results] (1) The average soil Cd content in the study area was 0.49 mg/kg, which was significantly higher than the background value of Jiangxi surface soil.There were 80 soil samplesCd content higher than the risk screening value, accounting for 62%.There were 57 rice seeds with excessive Cd content, the rate of exceeding the standard was 44%.(2) The results of the pollution evaluation of soil Cd and safety evaluation of rice seeds Cd in the study area were poorly correlated.Soil pH was the major influencing factor, with soil alkalinity increasing, soil Cd content increased by 2.3 times, but rice seeds Cd content decreased by 4.5 times.(3) The three fugitive forms of water-soluble, exchangeable and residual Cd in the soil had a significant effect on the Cd content of rice seeds, and the bio-efficacy of Cd was enhanced in a strongly acidic soil environment.(4) Children in the study area have greater health risks than adults, with non-carcinogenic and carcinogenic risk factors dominated by the heavy metal Cd.[Conclusions] The correlation between soil Cd and rice seeds Cd content in the study area is relatively poor, and there are some limitations of misjudgment and omission according to the current norms; the health risk evaluation results revealed that there is a human health risk caused by rice Cd intake in the study area.
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Yang Zhihua, WU Ruian, GUO Changbao, SHAO Weiwei, Wu Yuming, YU Pengfei
DOI: 10.12029/gc20230630002
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[Objective] The slope deformation is common in the mountainous areas, which significantly promotes landslide development and increases landslide risk. So, it is the important factor for the regional landslide assessment. [Methods] By reviewing literatures, the research status of regional landslide assessment integrating slope deformation characteristics were summarized. [Results] The relevant theoretical models and technical methods are not mature and are still in the stage of preliminary research. The temporal resolution of regional slope deformation should be further improved, and key characteristics of the long time series slope deformation should be captured, and the spatio-temporal distribution of regional slope deformation should be deeply analyzed. A preliminary regional landslide assessment system integrating slope deformation was constructed, including process steps, technical methods and factor indicators. The main technical methods include the qualitative judgment based on expert experience, weighted layer overlay based on expert experience and correction matrix, slope deformation as a factor index of regional landslide assessment, slope deformation as a landslide sample of regional landslide assessment. The slope deformation factor can be further divided into slope deformation type, intensity, distribution position and time change. [Conclusions] It is necessary to combine new technologies such as machine learning and artificial intelligence to propose or optimize the new quantitative regional landslide assessment models that integrate the slope deformation characteristics to improve regional landslide assessment accuracy. It is expected to promote the study on regional landslide assessment integrating slope deformation, and support the early landslide prevention in the complex mountainous areas.
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XU Qingyang, Dai Liangliang, PENG Zhigang, ZHANG Jun, XIAO Kaiqi, GONG Hao, WU Huanhuan
DOI: 10.12029/gc20230703001
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Abstract: This paper is the result of geological survey engineering. [Objective] A total of 775 soil samples were collected in Longshan County for the purpose of analyzing the content characteristics of soil heavy metals, including As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn. Additionally, an evaluation of the health risks caused by soil heavy metals was conducted. [Methods] To assess the level of soil heavy metal pollution, the geo-accumulation index was utilized. The source of soil heavy metals was identified through correlation analysis and principal component analysis. Furthermore, a health risk model was employed to assess the potential risks imposed by soil heavy metals on human health. [Results]The results of the analysis revealed that the average concentration of Cd in the soil of Longshan County was significantly higher than the background value observed in the soil of Hunan Province. This suggests that there is a certain degree of Cd enrichment in the soils of Longshan County. Moreover, the coefficients of variation for Hg, As, and Cd were greater than 0.5, and the coefficient of variation for Hg exceeded 1, indicating that these heavy metals may be influenced by human activities. The presence of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn contamination was observed in the soils of Longshan County. Notably, Cd pollution was widespread, and some areas exhibited severe levels of Hg contamination. The sources of soil heavy metals in Longshan County can be categorized into three groups: Cr, Cu, and Ni primarily originate from the soil parent materials, while As, Cd, Pb, and Zn are predominantly influenced by lead-zinc mining and smelting activities. The source of Cd also has some association with the soil parent materials. Furthermore, Hg is mainly derived from the combustion of fossil fuels. The health risks caused by soil heavy metals were found to be higher for children compared to adults. Additionally, special attention should be given to the health risks caused by soil heavy metals in Liye Town, Miaoertan Town, and Luota Town of Longshan County. Furthermore, non-carcinogenic risks are primarily attributed to As and Cr, whereas carcinogenic risks are primarily linked to Cr and Ni. Oral ingestion was identified as the main exposure route contributing to health risks. [Conclusions] There was a variable degree of heavy metal pollution in the soil of Longshan County, and As, Cr, Ni were the main contributing factors to health risks.
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shenjie, xuhao, denghucheng, hejianhua, liguofeng, liuyan, songweiguo, dengnaier
DOI: 10.12029/gc20230421004
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[Objective] Dingbei area is rich in tight gas resources of Upper Paleozoic and has great exploration potential. However, faults are widely developed in this area, and the characteristics of geostress field near the fault zone are unknown, which seriously restricts oil and gas exploration and development in this area. [Methods] Therefore, this paper conducts a detailed analysis of the characteristics of the Upper Paleozoic geostress field in the study area based on differential strain experiment, acoustic emission experiment, logging interpretation of geostress size, wave velocity anisotropy experiment, paleomagnetism experiment, imaging logging and dipole acoustic logging data interpretation of geostress direction, numerical simulation and other methods, in order to find out the distribution characteristics and disturbance mechanism of the geostress field in Dingbei area. [Results] The research shows that the three-dimensional stress of Upper Paleozoic in Dingbei area has the characteristics of vertical principal stress > maximum principal stress > minimum principal stress, and the regional geostress field is mainly controlled by the fault zone, and the stress disturbance degree is related to the fault location, fault scale, fault genesis and other factors, among which the three-dimensional stress in the karst fault zone is relatively lowest. The direction of regional principal stress field is N35°E ~ N45°E. The direction of reservoir geostress is mainly controlled by the direction of regional principal stress field and fault zone, and the range and degree of geostress disturbance caused by different types of fault zones are different, among which the range of geostress disturbance is mainly affected by fault strike and fault length. [Conclusions] Based on the research on the characteristics of geostress field, this paper clarifies the distribution characteristics and disturbance law of geostress size and direction in Dingbei area, discusses the disturbance mechanism of different genetic fault zones on geostress size, and establishes a prediction model for the disturbance width of geostress direction in the research area, which has important reference value for subsequent well pattern deployment and fracturing reconstruction.
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LIU Xuehao, Zou Jin, Yi Chenyun, Wang Ping, Wang Lei, Li Jiangshan, Long Sijie, Huang Changsheng
DOI: 10.12029/gc20230209001
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[Objective] The leakage of leachate from a landfill can cause severe groundwater contaminations. Characterization the spatial distribution of the landfill-derived contamination plume is crucial for site remediation and pollution investigation. [Methods] In this paper, a typical case of groundwater pollution investigation at a landfill in Hubei is combined with the implementation of a six-layer groundwater multilevel sampling well (-6 m、-8 m、-10 m、-12 m、-16 m、-20 m), and 14 sets of groundwater chemical samples as well as other hydrogeological survey data to reveal the hydrogeochemical spatial distribution of the contaminated groundwater. [Results] The results indicate that the concentrations of most ions in groundwater such as TDS, COD (Mn), Mg2+, HCO3- and Cl- decrease linearly with increasing vertical depth, thus indicating that surface rainfall infiltration and anthropogenic pollution are the controlling influences on the shallow groundwater. The concentration of NH4+, NO3-, NO2-, Mn, Ni and other ions increases linearly with increasing vertical depth, reflecting groundwater chemical field under the control of natural geological condition and water-rock interaction. In addition, the correlation coefficient matrix analysis characterises the stratified distribution of groundwater chemical components, the correlation coefficient between the groundwater sample from the U-tube groundwater multilevel sampling well and other conventional shallow boreholes decreases from 0.984 to 0.566.[Conclusions]The conclusion indicates that the novel groundwater multilevel sampling technology has the ability, to characterize the hydrogeochemical spatial distribution of groundwater along the vertical depth of the geological layers, to differentiate and reveal the impacts of natural geological factors and human-made pollution, thus to identify the spatial distribution of groundwater plumes. In a word, the groundwater multilevel sampling technology could provide quantities’ data and accurate guidance for site-scale groundwater pollution remediation and risk management.
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DOI: 10.12029/gc20230601001
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This paper is the result of hydrogeological survey engineering. [Objective] Meteoric water in the mountain areas infiltrates deep underground and circulates to the surface. It involves deep structural and hydrogeochemical processes, and it is one of the fluid source of forming rich geothermal and mineral resources. Predecessors focused on the groundwater source, circulation depth and flow system using methods of hydrochemistry isotope and numerical simulation, and further evaluated the distribution of regional geothermal and mineral resources. [Methods] Based on the data of DEM, fault structure, and lithology of the Yangbajing-Ningzhong basin, we establish 3D geometry finite element model. The standard saturated groundwater flow equation is solved using groundwater simulation software, and we analyse the circulation system of the typical hot springs and regional groundwater migration. [Results] The simulation results show that the maximum circulation depths of groundwater are respectively 5~7 km, 3.5~4 km, and 3~3.6 km at Yangbajing, Laduogang, and Qucai springs, and the corresponding groundwater circulation times are 23~80, 5~6 and 4~8 years. The groundwater of Nyainqentanglha Mountain seeps down to 10 km depth, where the time spans million years. [Conclusions] In general, the circulation depth and the recharge time of hot springs are different due to their different supply sources and circulation paths. Notably, there is no hydraulic connection between the hot springs at Yangbajing, Laduogang, and Qucai, although they are located in the same rift valley. It results in differences in material composition among these springs.
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Ding JIanhua, ZHANG Yong, LI Li-xing, YE Huishou, LI Houmin, FU Xue-rui
DOI: 10.12029/gc20230526003
Abstract:
This paper is the result of mineral exploration engineering. [Objective] Vanadium is widely used in multiple fields due to its unique physical and chemical properties, playing an increasingly important role in economic development, and its demand is increasing. China is one of the countries with the largest amount of vanadium ore resources, ranking first in the world in terms of total resources, mineral product production, and consumption. It is of theoretical and practical significance to summarize the metallogenic regularity and assess the potential of vanadium. [Methods] we evaluated the potential of vanadium resources in China based on systematically summarizing the metallogenic regularity and mineralization patterns of vanadium deposits. [Results] The sedimentary vanadium deposits related to the black rock series are the type of vanadium deposits with the highest proportion of identified resources in China. This type of deposits mainly distribute in the northern edges and southeastern part of the Yangtze block, the Qinling-Dabie orogenic belt, and the northern edge of the Tarim block. The black strata deposited under the influence of marine invasion, biological organic matter, and hot water are the most important elements for searching for this type of deposit. The next important deposit type is vanadium titanium magnetite type related to basic ultrabasic rocks. The mineralization mainly related to deep and large faults that cut the crust. The banded structure igneous rock belt is the most important element for searching for this type of deposit. We delineated 213 prediction areas, including 32 in class A, 85 in class B and 96 in class C. [Conclusions] The characteristics of vanadium resources in China are abundant resources, low grade, abundant co associated minerals, and complex mineral composition. The low level of mineral processing and smelting technology leads to a low level of comprehensive utilization of vanadium resources and significant waste of resources. In order to consolidate and cultivate the advantages of vanadium resources in China, we suggest as fellow: (1) Increase the investment in the exploration of magmatic- type V-deposits to ensure the production capacity demand of the existing V-industrial base. (2) Strengthen the research and development of sedimentary-type V ore processing and metallurgical technology, strengthen the scientific and technological research and development of high-grade vanadium products. Improve the efficient and high-end development and utilization of vanadium resources.
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XING Zuochang, JIA Licheng, WANG Xiujie, LUO Min, ZHANG Hang, ZHANG Yunlong, LIN Xiaobin
DOI: 10.12029/gc20230412001
Abstract:
Abstract: This paper is the result of mineral exploration engineering. [Objective] The study of uranium metallogenic conditions of Sifangtai Formation in the hinterland of Songliao basin is relatively weak. [Methods] Through comprehensive analysis of core, logging, seismic, trace and other data, the tectonics, stratigraphy and transformation of Sifangtai Formation in Qian’an area has been sorted and it is the first time to systematically summarize the uranium metallogenic elements of sandstone-type uranium deposits in the the hinterland of Songliao Basin. [Results]It shows that Sifangtai Formation in Qian''an area has favorable metallogenic conditions such as structural window, deep and large faults, braided river delta channel sand belts, good uranium source conditions and epigenetic transformation. It is considered that Sifangtai formation has both infiltration and exudative uranium metallogenic conditions, and exudative metallogeny is dominant. Based on these facts, the exudation-infiltration coupling Uranium metallogenic model of Sifangtai Formation in Qian''an area, Centrel Songliao Basin, has been constructed. Finally，it is proposed that the braided river to braided river plain channel sand in Rangzhi-Chaganhua Town has great uranium metallogenic potential, which as been predicted to be the most favorable object for further exploration. [Conclusions]This study is the first to introduce exudative metallogeny into the systematic evaluation of uranium mineralization conditions in Sifangtai Formations of the Songliao Basin, changing the previous single approach of evaluating the target layer from the perspective of infiltration metallogeny. It can effectively expand the exploration thinking of the red variegated formations in the hinterland of the basin, thereby greatly expanding the prospecting range in the Songliao Basin.
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WANG Qiushu, LI Wen, Chen Qishen, Chen Xiufa, ZHANG Yanfei, Li Yujie
DOI: 10.12029/gc20221130001
Abstract:
Abstract: This paper is the result of mineral exploration engineering. [Objective]Under the background ofthe global carbon neutral and the green energy transition, lithium has become a global consensus as a key mineral. The exploration and development of Lithium resources in Africa have put on the agenda. The paper’spurpose is to analyze the metallogenic characteristics and exploration and development potential of Lithium deposits in Africa, and to provide reference for international cooperation of Lithium industry in Africa. [Methods]The paper summarizes the metallogenic characteristics of Lithium resources, and analyzes the development prospects of Lithium industry by tracking the exploration and development trends of lithium resources in Africa. [Results]Africa''s proven resources are mainly LCT pegmatite deposits, distributed in the lithium rich pegmatite belt of Congo (DRC), Mali, Zimbabwe, Ghana and Namibia, which are characterized by large resources, high grade and favorable development conditions, so that it is attracting the investment of mining companies from Australia, China and the UK..[Conclusions] The paper considers that Africa has a late start in lithium exploration and slow development progress, but has good resource endowment. The current high-quality resources have been locked in advance, and it is expected to become a new growth point of global lithium resource supply in the future.
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Gao Jinggang, liangting, Fengyonggang, Tanxijuan, Lyanrong, Liyong, Zhaoruyi, Zhoubin
DOI: 10.12029/gc20230314001
Abstract:
Abstract: This paper is the result of mineral exploration engineering. [Objective] The aim of this paper is to investigate the relationship of Li-Be-rare metal mineralization and Indosinian magmatism in the eastern part of the West Kunlun Orogenic Belt through a comprehensive study of Indosinian magmatic activities, granite chronology, and geochemical characterization. Furthermore, the corresponding metallogenic regularity is summarized, and the exploration prospecting of rare metal pegmatite deposits is given. [Methods] Based on the our recent research, the geological details in the eastern part of the West Kunlun Orogenic Belt, including ages, mineral assemblages, geochemical characteristics, isotopic characteristics (Hf, Nd and Li, etc.) of the Indosinian magmas, are summarized and fully compared for the first time. The genetic link between the pegmatite-hosted Li-Be-rare metal mineralization and Indosinian magmatism is investigated. [Results] The large composite granite pluton formed in Indosinian period in the eastern part of the West Kunlun Orogenic Belt is mainly composed of quartz diorite, biotite monzogranite and two-mica monzogranite (including garnet tourmaline two-mica monzogranite), which was formed due to partial melting of the crust in a post-collision regime. The reliable chronological data show that there is no age difference between the composite granite (216.7~208.8Ma) and the granitic pegmatites (211.9~208.1Ma), suggesting that they were formed at the same time. The characteristics of minerals (garnet, tourmaline) and Li isotopes indicate that the two-mica monzogranite (garnet tourmaline two-mica monzogranite), garnet-bearing tourmaline muscovite granite pegmatite and spodumene-albite pegmatite were likely derived from the same magma source. [Conclusions] Results show that two-mica monzogranite and in particular garnet, tourmaline-bearing two-mica monzogranite exhibit close relationship with the pegmatite-type rare metal deposits. The peripheries of Aktas and the 509 Daoban-Quanshuigou area are favorable section for prospecting lithium-rich pegmatite.
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Lin Ruiqin, Wang Yisong, Shi Fulun, Liu Dadong, Zhang Daquan, Feng Xia, Zhou Zhe, Chen Yi, Zhao Fuping, Zhang Ziya, Du Wei
DOI: 10.12029/gc20230317002
Abstract:
[Objective] By analyzing the organic geochemistry, physical properties, and pore characteristics of the Wufeng-Longmaxi Formation in well RX1, the basic geological conditions of the Fuyan yansynclinal shale gas accumulation are clarified, and the exploration and development potential of ultra-shallow shale gas in the complex structural area outside the basin is discussed. [Methods] This study utilizes the core of Well RX1 in northern Guizhou to conduct comprehensive experimental analysis such as on-site desorption, geochemical testing, on-site fracturing effect, and reservoir characteristics. In combination with exploration data from neighboring areas, it explores the impact of burial depth and the structural preservation environment on the enrichment of ultra-shallow shale gas in northern Guizhou. [Results] The results show that the thickness of the high-quality hydrocarbon source rock section in the Wufeng-Longmaxi Formation of the RX1 well is 14.78m, the average content of total organic carbon is 4.43%, the maturity of organic matter is between 2.36% and 2.78%, and the kerogen type is II1, which has a good hydrocarbon generation basis; the average porosity of high-quality shale is 3.30%; and the content of brittle minerals is high, with an average brittleness index of 69, which provides a good reservoir space for shale gas. [Conclusions] The successful exploration practice of well RX1 confirms that shale gas can be enriched in the synclinal structural unit with a depth less than 1000m in the target layer of the complex structure area outside the Sichuan basin, which has good potential for construction and production and can be used as a favorable exploration target in the next step. Based on the analysis of regional geological data, it is believed that the compression-torsional structural system formed by the superposition and transformation of Cenozoic structures is an important place for shale gas accumulation in complex structural areas outside the basin. The reservoir-controlling effect of the compression-torsional structural system should be the focus of the next round of exploration and research.
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LIU Jinlong, Li Zhumin, ZHOU Yongheng, Dong Cunjie, Chen Liangxi
DOI: 10.12029/gc20230215001
Abstract:
[Objective] The eastern section of China, Mongolia and Russia has a complex geological evolution history and strong mineralization. Strengthening the study of cross-border regional mineralization, especially the summary of region-wide mineralization regularity, is of great significance for improving the level of regional basic geological research and prospecting and exploration. [Methods] By collecting various geological datas, the metallogenic geological characteristics, resource endowment, temporal and spatial distribution of deposits, metallogenic background and so on are sorted out. [Results] In the study area, 10 super-large deposits, 33 large deposits, 55 medium deposits and numerous small deposits (and occurrences) have been proved or discovered. Generally, they can be divided into the deposits related to the Precambrian tectonic system, the deposits related to the Paleo-Asian Ocean tectonic system, the deposits related to the Mongolia-Okhotsk tectonic system, and the deposits related to the superposition Mongolia-Okhotsk tectonic system and the Paleo-Pacific tectonic system. [Conclusions] The spatial and temporal rules of regional deposits are obvious. The most important deposits formed in various historical periods include: Archean Fe deposits distribute in the West Aldan -Sutam area; The Paleoproterozoic Cu, Fe, Ti deposits distribute in the Udokan-DyosLeglier area and the Neoproterozoic Pb, Zn deposits distribute in the Baikal–Muya tectonic zone; The Cambrian-Silurian Fe, Zn, Ti deposits distribute in the Yenisey-Transbaikalian tectonic belt; The Carboniferous Au deposits distribute in the Baikal-Patom tectonic zone; The Triassic Cu and Mo deposits in the Orhon-Selenge region and the Late Permian-Early Triassic Fe deposits in the Angara-Ilim region; The Middle Jurassic to Cretaceous Au, Pb, Zn, W, Mo deposits distribute in the Mongolia-Okhotsk tectonic belt and its surrounding areas.
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YU Yang, WANG Denghong, WANG Wei, YU Feng, GAO Juanqin, LIU Shanbao, WANG Chenghui, QIN Yan
DOI: 10.12029/gc20230316002
Abstract:
Abstract: [Objective] The new pattern of harmonious coexistence between humans and nature is influencing the research concept of geological ecological organic systems. Understanding and mastering the distribution characteristics of lithium in different geological environments can help improve the utilization efficiency of lithium resources and promote green transformation of development methods. [Methods] Focusing on the needs of geological work, this study analyzed the distribution characteristics, ecological, environmental, and biological health effects of lithium in different geological environments through extensive surveys, field sampling, physical and chemical property testing analysis using interdisciplinary research methods.[Results] The regional and multi-field coupling distribution characteristics of lithium in various spheres (hydrosphere: ocean floor, groundwater, rivers, lakes, glacier meltwater, snow water and rain; lithosphere: continental crusts, rocks and soil; atmosphere and biosphere ) were clarified. The spatial-temporal distribution characteristics and regional differences of lithium were analyzed. The influencing factors for complex biological, geological, geochemical processes as well as spatial-temporal patterns for each layer''s large amount but complicated elements were preliminarily summarized. The distribution features for key layers with respect to land biosphere was enriched while a comprehensive evaluation index system was improved for large-scale lithium resource bases. A systematic quantitative evaluation model was established to assess changes in lithium concentration on surface water, groundwater, and soil caused under human activities (mining), revealing unique ecological and environmental effects associated with "key layers" along with both lack or excess health effects from lithium. [Conclusions] Research on the distribution characteristics and ecological and environmental effects of lithium in different geological environments shows that pegmatite-type lithium resource development has overall safety control over its impact on ecology and environment while there are still some critical issues that need to be resolved regarding clean efficient development and utilization for clay-type and brine-type Lithium resources. With further deepening research into theoretical problems related to lithogenic mechanisms coupled with interdisciplinary basic research applications and simulation technology will make breakthrough progress possible towards understanding migration and transformation mechanisms associated with Lithium elements. While physiological amounts are beneficial to health excessive levels within organisms can cause certain side-effects even toxic reactions so it is necessary to continue conducting systematic studies on eco-environmental and biological health effects across different types and sources of Lithium resources providing theoretical basis support towards safe rational development strategies concerning strategic emerging minerals along with promoting eco-civilization construction efforts within China.
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liujingyu, heyingfeng, gengjianyang, huhongli, DUGUER Weiwei, zhangyi, chenzhichao
DOI: 10.12029/gc20230417001
Abstract:
【Objective】To accurately analyze the migration enrichment pattern of soil fluoride in the arid oasis area and the risks to human health. 【Methods】Combining statistical theory and spatial analysis tools to analyze the factors influencing soil fluoride transport enrichment and carry out soil fluoride health risk assessment.【Results】The results show that: (1) The mean fluoride content of the surface soil in the study area is 543 mg?kg-1, which is 1.28 times the background fluoride value for soils in the oasis zone and 1.14 times the national background fluoride value for soils in layer A. (2) The vertical variation of soil fluoride content in the study area is influenced by soil texture, organic carbon content, and other soil physicochemical properties; the horizontal distribution of soil fluoride content is influenced by soil pH, strong evaporation climate, etc., and shows a clear "Surface Riches". At the same time, the fluoride content of the soils in the area was significantly and positively correlated with Fe2O3 and MgO, with Al2O3, K2O, and CaO, and negatively correlated with SiO2 and Na2O, the ''signature'' indicators of the landscape environment. (3) The sensitivity analysis showed that body weight contributed -49.5% and -50.9% to the non-cancer risk in adults and child, respectively, indicating that the lower the body weight, the higher the non-cancer risk, which was more pronounced in children.【Conclusions】The main source of soil fluorine in the study area is the soil-forming parent material, and the "sand source" of the Tarim Basin is the main source of fluorine. At the same time, exogenous inputs such as anthropogenic factors also influence the spatial distribution pattern of soil fluorine. The spatial distribution pattern of soil The main route of exposure to soil fluorine in the study area is oral ingestion, which is more pronounced in children, but the overall risk is low.
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CUI Xiaodan, REN Jinghua, FAN Jian, XU Hongting, ZHOU Qiang, WANG Ziyi, ZHU Baiwan
DOI: 10.12029/gc20211125001
Abstract:
【Objective】In order to prove the health risk from the Cd pollution in typical cultivated soils in Jiangsu province, and understand the main geochemical factors to control rice seeds uptake of Cd in soil, and provide scientific evidences to cure Cd pollution. 【Method】1330 sets of rice-soil samples were systematically collected in the studied areas, and Cd, Pb, Hg, As, Cr, Cu, Zn, Se, Sb, TOC(Total Organic Carbon), pH, and CEC (Cation Exchange Capacity) in soil and Cd in rice seeds were determined by advanced testing methods such as ICP-MS, etc, the available Cd in soil was determined by calcium chloride extraction, and mastering the actual distribution data related to rice seeds Cd contents and elemental concentrations in soil. By the means of calculating their geochemical parameters and comparing its difference, developing correlation analysis and R-type cluster analysis, etc., and exploring main geochemical controlling factors to impact rice seeds uptake of Cd in soil, evaluating healthy risk in the local Cd polluted farmland.【Results】The available Cd concentrations are 0.0018~1.44mg.kg-1, their mean value is 0.265mg.kg-1, and the Cd concentrations are 0.13~30.0mg.kg-1 with an average amount of 2.11 mg.kg-1 in soil, and the rice seeds Cd contents are 0.0053~2.58mg.kg-1 with the mean amount of 0.478 mg.kg-1 in the studied areas. The available Cd in soil is the most important factor to control the rice seeds uptake of Cd, and the local Cd pollutants have spread to the food chain and human hairs in the farmland.【Conclusion】1) there are significant positive correlations between rice seeds Cd contents and the available Cd in soil, and its correlated coefficient (named r)is 0.54 without deleting anyone in the 1330 sets samples , if pH values being from 6.5 to 7.5 in soil, the positive correlated relationship between rice seeds Cd contents and the available Cd in soil is best with correlated coefficient maximum value of r=0.86. In addition to the available Cd, the following geochemical factors as to Cd, TOC, CEC, and pH of soil are also important to control rice seeds uptake of Cd, and there exist some significant or more significant positive correlation between rice seeds Cd contents and Cd concentrations too, and similar significant or more significant negative correlation between rice seeds Cd contents and pH, TOC and CEC in soil. In general, the factors order to impact rice seeds Cd absorption is the available Cd﹥Cd﹥pH﹥TOC≈CEC in soil; 2) as to pollution-free Cd farmland, the Cd carcinogenic health risk index (simplified CR value) increased by more than 85 times, the average amount of Cd concentration in the human hair samples increased by 1.09 times because of eating rice seeds with Cd over standard, and the Cd concentration of the soil solution was significantly increased higher in the farmland distributive area contaminated by Cd. Meanwhile, the rice seeds Cd contents and its relative health risk evaluation are more dependent on the soil effective Cd in those areas contaminated by Cd, it means that there are higher health risks or ecological security risks in those local farmland Cd pollution areas; 3) there are too significant correlation or obvious antagonism in soil between the available Cd and other geochemical factors such as Cd, pH, TOC, CEC and Se, and so on, which comprehensively regulate the Cd absorption of rice seeds , but the available Cd in soil is the most main one; 4）the Cd pollution is generally slight, and its healthy risk level is mainly mild from the cultivated land in Jiangsu province, if we can take appropriate restoration and treatment measures (for example deep tillage, etc.) in order to reduce the Cd, especially effective Cd content in soil, reasonably increase soil organic matter, improve soil pH, etc., block the migration of soil Cd to food chain and human bodies, the Cd polluted risk will completely be controlled, and produce qualified rice seeds to meet the social needs at last.
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ZHANG Xiaofei, ZHANG Xuebin, ZHANG Yongyi, Niu Shuyin, Sun Aiqun, WANG Yongli, FAN Hangyu, LI Mingchen, HAN Rongwen
DOI: 10.12029/gc20221207001
Abstract:
Abstract: This paper is the result of maring geological survey engineering. [Objective] The northwest of Bohai Bay is an area where the depositional environment changes frequently in North China Plain and is also the main depressed area of the neotectonics. Strengthening the stratigraphic research since Late Pleistocene in Northwestern Bohai Bay and analyzing the evolution process of the depositional environment is of great significance to the study of sea-level change and subsidence of coastal areas.[Method]Based on the three full coring boreholes QLT03, QEJ01 and NHG14 in the northwest coast of Bohai Bay, and by integrating the lithostratigraphic and biostratigraphic methods, AMS14C and optical stimulated luminescence dating are used to compare and analyze the collection boreholes in the adjacent area, discussing the depositional environment and its indications to transgression and tectogenesissince late Quaternary in the study area.[Result]The results show that early Late Pleistocene of the study area is the development period of delta plain and fluvio-lacustrine facies, the middle is the development period of floodplain-lacustrine facies and delta plain, the late is the development period of meandering stream- floodplain facies, and Holocene is the development period of delta plain- flood plain. The study area develops three phases of transgressive strata from bottom to top, namely, the third transgressive layer in early Late Pleistocene, the second transgressive layer in late Late Pleistocene and the first transgressive layer in Holocene. The scale of transgression has gradually strengthened from the ancient to the present. The transgressive layers in each phase are more consistent with the global sea level change and have good correspondence with the high sea level in MIS5, MIS3 and MIS1 phases from bottom to top. There has been differential subsidence movement in the study area since Late Pleistocene, and the differential movement has slowed down in Holocene.[Conclusion] Under the background of continuous tectonic subsidence, large-scale marine transgressions in the coastal area of Bohai Bay have all occurred since Late Pleistocene. These transgressions are related to the long-term subsidence process in the southeastern area of Tianjin along the coast of Bohai Bay, and the subsidence center moved from Bamencheng Town of Baodi District to Chadian Town of Hangu District. After entering Holocene, the tectonic activity weakened and the differential subsidence movement was not obvious. The late Quaternary stratigraphic development and depositional environment evolution in the coastal areas of Bohai Bay are controlled by sea level changes.
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Distribution of Quaternary sedimentary thickness in South China Sea and its main controlling factors
LI Xuejie, SUN Meijing, CHEN Jiale, GAO Hongfang, PENG Xuechao
DOI: 10.12029/gc20220930001
Abstract:
Abstract：This paper is the result of 1:1,000,000 marine geological survey engineering. [Objective] Quaternary sedimentary thickness can not only reflect the provenance and sedimentary characteristics, but also reflect the tectonic activity characteristics to a certain extent. [Methods] Based on a large number of single channel and multi-channel seismic data and verified by drilling holes, the Quaternary thickness map of the SCS was compiled. [Results] The thickness of quaternary sediments in the South China Sea (SCS) varies a lot, with the maximum thickness over 2000m and the minimum one close to 0. [Conclusions]Sedimentary and subsidence centers were formed in the western margin of SCS, including Yinggehai, Zhongjiannan and Wan''an sea area, which indicates that the fault zone in the western margin is still active in Quaternary period and controls the development of these subsidence centers. The development of NE trending sedimentary centers on the northwest continental slope of the South China Sea may indicate that the northwestern SCS is still dominated by extension in quaternary. The thickness of quaternary in Dongsha sea area is near 0, indicating that the area has been continuously uplifted and washed by strong current since quaternary. Therefore, the northern South China Sea shows a pattern of subsidence in thewest and uplift in the east. The relatively thicker Quaternary in the Manila Trench in the eastern margin of the SCS is mainly a result of tectonic compression resulting in sedimentary layers thicker and abundant provenance from Taiwan and the Philippines.
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fuxiugen, chenminghao, wangjian, weihengye, zengshengqiang, wangzhongwei, shenlijun, zhougang
DOI: 10.12029/gc20230307001
Abstract:
This paper is the result of petroleum geological survey engineering. [Objective] Effect and significance of various tectonic history on the development characteristics and spatial distribution of source rocks in the Qiangtang Basin during the Triassic-Jurassic. [Methods] In the present study, we discuss the sedimentary records of the Late Triassic tectonic inversion. [Results] The Middle Triassic sequence has typically shallowing-upward changes and a marine regression related regional uplift. However, the Early Jurassic sequence displays typically deeping-upward changes due to the tectonic subsidence and transgression. We also identify paleogeographic inversion during the Late Triassic in the Qiangtang Basin. In the northern Qiangtang depression, the pre-existing (Middle-early Late Triassic) marine depositional areas turned into terrestrial units during the Norian. In contrast, the previously (Middle Triassic) terrestrial part of the sourthern Qiangtang depression became marine units. [Conclusions] Our study suggests that the distribution of source rocks in the Qiangtang Basin was mainly controlled by the sedimentary change and paleogeographic inversion during the Late Triassic. The Late Triassic source rocks were probably related to the foreland basin and developed in the deep water area of the northern Qiangtang depression, while the coal-bearing source rocks were developed around the basin. The Early Jurassic source rocks are probably related to the passive continental margin basin and developed in the deep-water area of southern Qiangtang depression. Oil shale-bearing source rocks are well developed in the lagoon in the northern part of Southern Qiangtang depression.
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XU Lei, ZHAO Mengsheng, CHEN Weizhi, BA Yong, ZHANG Ya, HOU Qingye, LU Fangfang, QIAN Kun
DOI: 10.12029/gc20230216002
Abstract:
Abstract: This paper is the result of agricultural geological survey engineering. [Objective] A land quality geochemical survey carried out in Chuxiong area of central Yunnan Province had found a large area of zinc and copper-rich soil. The purpose of this study is to study the migration and transformation mechanism of Zn, Cu and other beneficial elements in the soil-crop system in the farming area of zinc and copper-rich red bed mountain basin in southwest China. [Methods] In this paper, the typical farming area of Yao''an in central Yunnan is selected as the research area. Based on the geochemical data of surface soil and crop seed-root soil, the main control factors affecting the absorption and enrichment of Zn and Cu in rice and corn are discussed by analyzing the content characteristics of Zn and Cu in surface soil, crop seed and root soil, and the prediction model of crop Zn and Cu bioconcentration coefficient is established. [Results] The results showed that the average Zn and Cu contents in the surface soil of Yao ''an alluvial basin are 105.40 mg/kg and 42.67 mg/kg, the proportion of zinc-rich and copper-rich land (first-class) area are 84.86% and 90.59%, the average Zn and Cu contents in rice seeds are 19.28 mg/kg and 2.92 mg/kg, the enrichment rates are 100% and 70%, and the bioconcentration coefficients are 0.20 and 0.07, the average Zn and Cu contents in corn seeds are 21.42 mg/kg and 2.06 mg/kg, the enrichment rates are 80.00% and 6.70%, and the bioconcentration coefficients are 0.20 and 0.07. [Conclusions] There are differences in factors affecting Zn and Cu enrichment in rice and corn seeds. The main factors controlling Zn bioconcentration coefficients in rice are Soil-Zn, N, TFe2O3, and the main factors controlling Cu bioconcentration coefficients in rice are Soil-Cu, OM and S. The main factors controlling Zn bioconcentration coefficients in corn are Soil-Zn, SiO2/Al2O3 and TFe2O3. The multi-linear regression equation of Zn and Cu bioconcentration coefficients of rice and corn seeds in the typical farming area of the red layer mountain basin in Yunnan was established, and the optimal model decision coefficient was greater than 0.495, the prediction effect of rice is better than corn, and the prediction effect of Zn is better than Cu. The optimal model predicted that the planting area of Zn-rich rice, copper-rich rice and zn-rich corn in Yao''an County are 72.87 km2, 70.47 km2 and 69.71 km2. Therefore, the planting structure planning of rice and corn in the study area can be optimized to serve the development of plateau characteristic agriculture and the implementation of rural revitalization strategy.
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Li Xin, Dong Haogang, Xie Xiang, Luo Minxuan, Wu Feng, Yang Tao, Huang Jinyan
DOI: 10.12029/gc20220918002
Abstract:
Abstract: This paper is the result of ecological geological survey. [Objective]Formation is the carrier of the geological environment. Studying the correlation between formation and ecological characteristics is helpful to correctly understand the causes of ecological problems and serve the precise restoration of the ecological environment. [Method] In this paper, Luoshan County, which has both low mountains, hills and plains, is selected as the research area. On the basis of combing the geological background and tectonic evolution characteristics of Luoshan County, 13 geological formation types are divided; Based on profile survey, data statistics, hydrological parameter test and other means, the geological characteristics of four typical geological formations were analyzed from the four aspects of rock, soil, hydrogeology and terrain slope, and the correlation between ecological characteristics and geological formations was discussed. Taking soil erosion as an example, the spatial distribution, cause analysis and restoration suggestions are carried out based on geological formation. [Results] The results show that, from the Cretaceous acid magmatic rock formation in the low mountain and hilly area to the Cretaceous continental pyroclastic rock-volcanic formation in the hilly area, the thickness of the parent material layer and soil layer has been increasing, and the content of gravel and sand has increased. Gradually less, the particle size of the soil becomes smaller, so the soil texture gradually changes from gravel soil (sandy loam), sandy loam, silty loam, and loam; the vegetation transitions from natural secondary forest to artificially planted economic forest, and the vegetation type changes from diversity It tends to be single, but the tree height and diameter at breast height are increasing; the correlation between geological formation and ecological characteristics is strong. The genetic analysis based on geological formations shows that soil erosion develops differently in different formations, among which the Cretaceous acidic magmatic rock formation is the most serious. The problem of soil erosion has a strong correlation with the terrain slope, mineral composition and grain size of rocks in different formations. [Conclusions] Using formation as a unit to analyze ecological characteristics has better pertinence and application prospects, and can more reflect the constraints of geology on ecology. The research results can provide a geological basis for accurate restoration of ecological protection and soil erosion in Luoshan County.
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DOI: 10.12029/gc20220724001
Abstract:
【Objectives】In order to identify nitrate sources and health risks in groundwater of Cenozoic basaltic rock in Hebei province.【Methods】The basalt distribution region in Zhangbei county is selected as a typical study area. Based on hydrochemistry and isotopes data of 45 groups groundwater samples, the distribution characteristics and origin of nitrate in basalt groundwater were studied, the health risk of nitrate in groundwater was evaluated using the health risk assessment model .【Results】The results showed that the average concentration of nitrate in the groundwater of the study area was 86.08 mg?L-1, The nitrate concentration of 26.6% of the sampling sites exceeded the limit value of the III grade groundwater quality in GB/T 14848-2017《The Quality standard of Underground Water》 (20 mg?L-1);The nitrate pollution of different land use types varied greatly, and the content of nitrate in urban areas was the highest, followed by irrigated land,with forests、grasslands or dry land not exceeding the standard.The sources of nitrate in groundwater was mainly manure and domestic sewage, and the next was chemical fertilizer leaching;The health risks of nitrate exposure through skin contact among the population in the study area were at acceptable levels, while the health risk of nitrate intake from drinking water was higher, and the contribution rate of nitrate intake from drinking water accounted for 99.23% of the total risk, which was much higher than that from skin contact route.The health risks of drinking water intake and skin contact in children were significantly higher than those of adults.The health risks of groundwater nitrates to children in 75.55% of the sampling sites exceeded acceptable levels.【Conclusions】From the perspective of water supply safety, it is recommended to increase water purification equipment in high-risk areas to reduce human health risks
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Feng Weiming, Lin Jiashan, Li Rong, Zhao Zhan, PENG jun, Yu Qian, Yang Ping, Cao Junfeng, ZHAI Kun, Liu Wei, YE DIngnan
DOI: 10.12029/gc20221228001
Abstract:
This paper is the result of Shale gas geological survey engineering. [Objective] Dark shales in Lower Carboniferous upper are widely distributed in the Yadu-Ziyun-Luodian aulacogen, the upper Yangtze Platform, and its thickness varies greatly. In particular, the development characteristics and hydrocarbon generation center distribution of the dark shale of the Jiusi Fr in the northwest section of the rift aulacogen are not clear. [Methods] The strata, sedimentary facies, dark shale distribution and organic geochemical characteristics of Jiusi dark shale in well GWD-2 are studied in detail by the logging, core observation, rock thin-section identification, kerogen type microscopic identification, TOC, vitrinite reflectance measurement and other experimental test data. And the following research results were obtained. [Results] First, the drilling thickness of Jiusi Fr in the well GWD-2 is 1148.67m, according to the characteristics of rock combinations, the Lower Carboniferous Jiusi Fr can be divided into two members and five sub members, Second, the dark shales are mainly distributed in the first member of Jiusi Fr, which are mainly composed of tidal flat by delta and shallow shelf facies deposits, the cumulative thickness of shale is 525m, the cumulative thickness of shale with TOC value greater than 1% is 425m. Third, The TOC value of Jiusi shale of the well is concentrated in the range of 1% ~ 2%, the type of organic matter is mainly type II2 kerogen and III kerogen, the organic matters are in the early stage of over maturity. The last, it is predicted that the subsidence center of Jiusi Fr is distributed in a long strip with NW-SE direction, and the distribution of hydrocarbon generation center is consistent with the subsidence center. The thickness of argillaceous source rock with TOC value greater than 1% can reach more than 300m. The hydrocarbon generation center has the hydrocarbon generation conditions of argillaceous source rock with huge thickness, good organic matter type and high degree of thermal evolution. [Conclusions] It is concluded that the shale of Lower Carboniferous Jiusi Fr in the hydrocarbon generation center of the northwest section of Yadu-Ziyun-Luodian aulacogen has considerable hydrocarbon generation intensity and total hydrocarbon generation, and has good natural gas exploration potential.
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Liu Yuegao, Zhang Jiangwei, Feng Zhixing, Yang ShunLong, Wang Yizhong, Li Jiqing, Zhao Zhiyi, Wang Zhian, Li Shulei, Wang Houfang
DOI: 10.12029/gc20230128003
Abstract:
[Objective] To improve the supply security of Cu-Ni-Co resources in China, it is necessary to sort out the mineralization regularity and prospecting indicators of the magmatic copper-nickel-cobalt sulfide deposit in the Phanerozoic in the Eastern Kunlun orogenic belt on the northern margin of the Qinghai-Tibet Plateau. [Methods]The geological, geochronology, geochemistry, and geophysical characteristics of five stages mafic?ultramafic complexes including the Late Ordovician?Early Silurian, the Middle Silurian?Middle Devonian, the Early Carboniferous, the Middle Permian?Early Triassic, and the Middle?Late Triassic are summarized. [Results] Based on the above work, the source area properties of magmatic copper?nickel deposits and their relationship with the highpressure?ultrahighpressure eclogite and the evolution of Proto?Paleo Tethys were discussed. The influence of crustal sulfur contamination and crystal differentiation on sulfide saturation was analyzed. The rules of the optimal location of copper-nickel ore bodies were summarized. The typical differences between the ore-forming mafic-ultramafic complexes and the no-ore mafic-ultramafic complexes were described. [Conclusions] At last, a comprehensive information exploration model was established.
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DOI: 10.12029/gc20220805004
Abstract:
[Objective]Gannan area in the upper reaches of Dongjiang River Basin is a typical water shortage area in China. The distribution of acid groundwater intensifies the lack of regional domestic water. [Methods]In this paper, Xunwu area in the upper reaches of the Dongjiang River basin is selected as the study area. Shallow groundwater is systematically collected, and the pH value, spatial distribution, hydrochemical types and action characteristics of acidic groundwater are analyzed by using hydrochemistry and mathematical statistics methods. From the point of view of material basis, circulation conditions and external factors, the causes of control of water rock action, aeration zone medium, acid rain, human action and other factors on acidic groundwater are discussed.[Results]The pH value of groundwater in the area is concentrated between 5.0 and 7.0; The spatial distribution has obvious correlation with geomorphic characteristics and circulation conditions: middle and low mountains
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SU Dong, GONG Xulong, YANG Lei, XU Shugang, ZHANG Yan, LYU Hang, BU Jianwei, GONG Yabing, GU Chunsheng
DOI: 10.12029/gc20221019001
Abstract:
Abstract：This paper is the result of hydrogeological survey engineering. [Object] Changzhou is a typical industrialized city in the Yangtze River Delta. The regional groundwater there had experienced a periodic historical process of overdrafts and prohibitions of mining, resulting in a greatly change in the groundwater dynamic field. Thus, it is necessary to conduct a further study on the renewable capacity of the groundwater of Changzhou. [Methods] Based on the analysis of the existing hydrogeology conditions, the recharge, runoff and discharge conditions of groundwater and the characteristics of groundwater ages are systematically analyzed to evaluate the renewable capacity of groundwater using isotope technology. [Results] The results showed that, 18O and D of the shallow groundwater are more abundant than the deep groundwater due to the evaporation to a certain extent. The recharge time of the deep groundwater with relatively closed storage environment is earlier than that in the shallow groundwater. The shallow groundwater, basically affected by infiltration recharge of modern water, has an active circulation zone of modern water reached to a depth of 40m. As for the ages of the deep groundwater, it varies from less than 2000 to 25000 years, indicating that it is mainly composed of ancient water. [Conclusion] The renewal rate of the shallow groundwater is generally higher than 0.1%/a, and controlled by the storage conditions, surface water recharge and human activities, etc. Weakly, the renewal rate of the deep groundwater is generally less than 0.05%/a, and controlled by the distribution of river ancient channel, exploitation and utilization of human beings, etc. These results can provide scientific basis for protection and utilization the groundwater in Changzhou and other areas in the Yangtze River Delta.
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JIANG Haiyang, CAO Yanling, LIU Lian, KANG Fengxin, CUI Su, GUO Liangliang, SUN Zhe
DOI: 10.12029/gc20221104002
Abstract:
[Objective] To assess deep granite type geothermal resource potential of Wendeng area in Shandong peninsula, [Methods] we established discrete fracture network model of hydraulic fracturing based on the geological data, the deep well temperature data, core physical and mechanical test results. The potential created heat reservoirs were simulated for target reservoir. According to the fracturing results, a coupled numerical model of seepage and heat transfer in fractured heat reservoir is established using TOUGH2-EOS1-MINC code. The influence of fracture spacing, well pattern and injection rate on productivity is studied. [Results] The results show that natural fractured reservoirs with stress shielding should be selected as the target reservoirs in deep geothermal exploitation. Large well spacing should be maintained, and reservoirs with overdeveloped natural fractures should not be selected. For the same heat reservoir, the variation of each performance index of five-well mode and three-well mode is similar, but their dynamic variation of productivity is different. The pressure index is more sensitive to the well pattern than the temperature index. The power generation of five-well mode is slightly higher than that of three-well mode for the same reservoir. [Conclusions] When selecting the target reservoir, the high temperature reservoir with moderate natural fractures and high stress shielding should be preferred. Meanwhile, a large amount of fracturing fluid should be injected to drive the reservoir to extend as far horizontally as possible. For the ideal large-scale heat reservoir, the five-well mode should be preferred, but its overall economic benefits should be considered.
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wanggaofeng, ligang, sunxiangdong, lihao, tianyuntao, donghanchuan, gaoyoulong, xuyouning, wanghongde, liruidong
DOI: 10.12029/gc20230220001
Abstract:
Abstract: This paper is the result of mineral exploration engineering. [Objective] Gansu Province is one of the areas with high incidence of geological disasters in China. The scientific construction of a "point-surface dual control" model of geological disaster risks is the key to disaster prevention and mitigation. [Method] Taking Longlin Town as an example, on the basis of on-site refined survey and mapping, multi-phase remote sensing data modelling, indoor test and numerical simulation analysis, the paper expounds the typical urban geological disaster risk management and control technical process with six steps, including geological disaster risk identification, disaster mode research, risk analysis, vulnerability assessment, risk assessment and risk prevention and control countermeasures, and introduces the semi-quantitative risk assessment process of urban risk slope, the quantitative risk assessment method of single geological hazard based on dynamic process and the "point-surface dual control" mode of geological hazard risk have been formed. [Results] (1) The main types of geological hazards in the study area are landslide and debris flow, with a total of 71 hidden danger points of geological hazards developed, 15 of which directly threaten the safety of people''s lives and property. The three types of landslide hazard models are summarized and the geological early identification signs are established; (2) Based on the geological hazard risk zoning of different precipitation frequencies (5%, 2%, 1%), 75.23% of the regions always maintain low risk under different precipitation frequencies, 24.38% of the regional risk level increases with the reduction of precipitation frequency, and 0.39% of the regions always maintain high risk; (3) Based on the results of risk assessment, a comprehensive risk dual control proposal for disaster reduction in towns and specific disaster sites is proposed. [Conclusions] Relevant research can provide technical support for disaster prevention and mitigation, land space planning and control and use control of complex mountain towns.
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danyong, yanjianfei, zhangqingyu, malong, nieguoquan, jishoacong
DOI: 10.12029/gc20220717001
Abstract:
Abstract: This paper is the result of shale gas geological survey engineering. [Object] In 2020, shale gas shows were first discovered in the Lower Cambrian Wuxun Formation on the southwestern margin of the Xuefeng uplift, but its accumulation conditions and exploration potential are unknown. [Methods] Based on field geological survey and drilling data, combined with organic geochemical analysis, a comprehensive study of the Lower Cambrian Wuxun Formation in the southwestern margin of Xuefeng was carried out. [Results] The results show that: (1) The shale of the Wuxun Formation was deposited in the carbonate outer ramp facies, which is different from the Longwangmiao Formation in central Sichuan at the same time. (2) The organic-rich shale is developed in the middle and lower parts of the Wuxun Formation, and the rock combination is calcareous carbonaceous shale intercalated with thin limestone, with a thickness of 30–80 m, and a long and narrow distribution in the northeast-southwest. (3) The average TOC content of shale organic matter is 1%, the organic matter type is I type sapropelic type, the average Ro is 2.02%, and the degree of thermal evolution is moderate.(4) The content of brittle minerals in shale ranges from 43% to 69%, with an average value of 59.2%, and the content of clay minerals ranges from 16% to 37%, with an average value of 28.2%.Therefore, shale has high siliceous content and high brittleness, which is easy for reservoir stimulation. (5) Shale is a low-porosity and low-permeability reservoir. Organic pores, intercrystalline pores, interlayer pores, and carbonate mineral dissolved pores provide storage space for shale gas enrichment, but at least four stages of structural fractures and The shale cleavage domain caused by tectonic action greatly improves the shale storage capacity. [Conclusion] Comprehensive evaluation indicators such as geochemistry, reservoir physical properties and preservation conditions suggest that the eastern flank of the Xingren syncline in the southwestern margin of Xuefeng can be a favorable area for shale gas exploration.
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LiTong, YuReng’an, RONG Hui, YangTongxu, ZhuQiang, PengShenglong, TangYongxiang, SiQinghong, QuanXiaoqin
DOI: 10.12029/gc20220718001
Abstract:
Abstract: This paper is the result of mineral exploration engineering. [Objective] In recent years, the exploration of sandstone uranium ore in the north has progressed rapidly, and Baiyanhua uranium ore is a newly discovered medium-sized sandstone uranium ore source in the Chuanjing Depression of the Erlian Basin. The systematic study of sandstone uranium ore in Baiyanhua area is intended to provide some valuable references for the prediction of sandstone uranium ore search and the study of mineralization pattern in Chuanjing Depression of Erlian Basin. [Methods] Based on drilling data compilation, map compilation study, systematic sampling, microscopic analysis, and geochemical data compilation, the author elaborates the geological conditions of ore formation, ore body distribution, ore characteristics, and the tectonics, sedimentary filling, and fluid action of Chuanjing Depression in the mining area, and discusses the sandstone type uranium ore formation pattern in this area. [Results]The main ore-bearing level in the study area is the upper section of the Lower Cretaceous Saihan Formation, and the ore bodies are relatively gently spreading in the east and high west. The uranium minerals are mainly uraninite, mainly in gray and dark gray-black sand conglomerates. In the region, the braided river-delta system is mainly developed, the sand bodies are widely distributed and well connected, and the redox zone is developed in the center of the river, which provides favorable conditions for regional mineralization by mineralizing fluids and reducing gas transport and uranium source material transport. [Conclusion] The mineralization pattern of uranium ore in Baiyanhua area is that the uranium-rich fluids from the Baiyanhua Bulge occurred at the end of sedimentary interruption in the upper part of the Lower Cretaceous Saihantala Formation, and the uranium ore bodies were formed by diving and infiltration of uranium-rich fluids from the Baiyanhua Bulge, and the Baiyanhua Bulge was covered by sediments after the deposition of the Erlian Formation, and interstratified oxidation mineralization occurred in due course.
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liupengfei, zhangguanghui, cuishangjin, niezhenlong, caole, cuihaohao, wangqian
DOI: 10.12029/gc20220401007
Abstract:
Abstract：【Obiective】The object of the study is focusing on the characteristics and dynamic mechanism of the same variation of surface soil water and its salt in different seasons in groundwater level depth area of the northwest inland basin.【Methods】Based on data obtained from the in situ multi-factor high frequency monitoring system in groundwater regulation field site, changing processes of topsoil moisture content, pore water electronic conductivity (ECp), groundwater level depth and so on without the direct influence of precipitation and irrigation infiltration were comprehensively analyzed and studied.【Results】20 cm (shallow part)and 40 cm (deep part) depth soil moisture content in later spring，summer and early autumn were all arranged in descending order. However, the shallow and deep part soil ECp were all arranged in increasing order. The shallow part soil electronic conductivity of saturated leach solution (ECe) was arranged in descending order and the deep part soil ECe was arranged in increasing order. In later spring day variation trends of soil moisture content, ECp and ECe were the same in shallow part , which were different in the deep part soil. In summer day variation trends of shallow part soil moisture content and ECe were the same and that of soil ECp was different from them. However, day variation trends of deep part soil ECp and ECe were the same and that of soil moisture content was different from them. In early autumn day variation trends of soil moisture content, ECp and ECe were all different in shallow and deep part. 【Conclusions】Irrigation is the leading factor of influencing differences of surface soil moisture content and salt among seasons. Evapotranspiration is the major factor of resulting in changes of surface soil moisture content and salt in each season. Moreover, the higher the temperature, the more obvious the effect of the evapotranspiration. Groundwater level depth is an important and regulatory factor of affecting topsoil moisture content and salt. In summer when the groundwater level depth becomes bigger, topsoil salt content obviously decreases. In the study area the critical groundwater level depth of prevention and control of farmland salinization is between 1.6 m and 1.9 m in summer.
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liuhan, sun xianfeng, guo jing, zhang shizhen, gou zhengbin, zhang yujie, li jun, wang baodi
DOI: 10.12029/gc20220825004
Abstract:
Abstract: This paper is the result of basic geological survey engineering. [Objective] Jilong Valley will be an important area for major engineering projects across the Himalayas in Tibet in the future for a long time. However, we still lack a systematic understanding of the basic geological characteristics, especially the N-S-trending structure, which may induce unexpected engineering construction risks. [Methods] Field geological survey, joint statistics, geothermal investigation, audio frequency magnetotelluric sounding and calcite U-series dating were conducted to reveal the characteristics of the N-S-trending faults and joints in Jilong Valley, and through this to explore the main engineering geological risks related to the N-S-trending structures. [Results] The N-S-trending faults in Jilong Valley are generally small in scale, partially cutting through the high Himalayan belt, and also the basin controlling faults of Jilong Basin. The formation and sedimentary evolution of Jilong Basin were controlled by the four N-S-trending normal faluts in its east boundary and interior. The seismic rocks near the east boundary faults and syn-sedimentary faults in the basin indicate that the Jilong basin has intermittent activity characteristics. The regional permeable distribution is displayed by the N-S-trending joints, which were formed in a simialr stress field controlled by the N-S-trending rift. [Conclusions] The N-S-trending structure in Jilong Valley are potential engineering geological risk sources, according to its Holocene activity and its control over regional geothermal, and collapse, landslide, debris flow geological disasters. We propose that the North-South structure will be one of the important directions of geological safety risk assessment for the planning and construction of Jilong Valley major engineering project.
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LIU Tianhang, GAO Yongbao, LIU Jiajun, WEI Liyong, TANG Weidong, LI Zonghui, HE Jiale, LI Jiawei
DOI: 10.12029/gc20220816002
Abstract:
Abstract: This paper is the result of mineral exploration engineering. [Objective] The Dongqiyishan fluorite deposit is a super-large fluorite deposit, which is related to alkali feldspar granite in the eastern part of the Beishan metallogenic belt. The orebodies are hosted in alkali feldspar granite, griotte and andesite, which are controlled by the rupture and fracture zones near SN or NE dipping. [Methods] On the basis of studying the geological characteristics of Dongqiyishan fluorite deposit, carry out the studies of rare earth and trace elements geochemistry of fluorite and wall rocks in the fluorite deposit. [Results] The results show that the trace elements curves in fluorites are consistent, and obviously enriched in high-temperature elements such as Bi, Cd and Mo relative to the crust values, indicating that these fluorite samples have the characteristics of high temperature mineralization and homology. Fluorites and alkali feldspar granites have similar geochemical characteristics of rare earth. The Y/Ho ratios of 10 fluorite samples are ranging from 21.02 to 28.52, the La/Ho ratios ranging from 3.58 to 15.23. The samples all falling into the hydrothermal region of Tb/La-Tb/Ca diagram, except one close to the sedimentary. The Sm/Nd ratios of fluorites ranging from 0.26 to 0.42, and the Sm/Nd ratios of alkali feldspar granites ranging from 0.26 to 0.42. The δEu vaule ranging from 0.6 to 0.64, and the δCe vaule ranging from 0.89 to 0.94. [Conclusions] Combined with the geological characteristics of the deposit, It is considered the genetic type of the deposit is medium-high temperature magmatic hydrothermal filled type, which belongs to the tungsten-tin-rare -fluorite metallogenic system related to alkali feldspar granite in the area. The ore-forming fluid of Dongqiyishan fluorite deposit is mainly magmatic hydrothermal. The ore-forming material F mainly comes from the deep alkali feldspar granite body, and the Ca mainly comes from the marble strata.
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LIU Haiqing, JIN Pengbo, Liu jingdong, Liu Hua, ZOU Juan, Chen lei
DOI: 10.12029/gc20220910001
Abstract:
[Objective] The superimposed development of multistage faults is very important to the difference of hydrocarbon migration and accumulation in faulted basins. [Methods] Taking Laoyemiao structural belt in Nanpu Depression, Bohai Bay Basin as an example, the fault assemblage style and its origin, the relationship between fault system and oil and gas reservoir formation were studied based on geological analysis and physical simulation experiment. [Results] The results show that Laoyemiao structural belt developed fault combinations of "ladder" type, "domino" type, compound "y" type, compound anti "y" type. The formation of fault combinations is closely related to the boundary of the fault activity, in which "ladder" type and "domino" type fault combinations formed by the northwest - southeast and nearly north – south direction stress fields in Paleogene, while compound "y" type and anti "y" type fault combinations formed because of late superposition of fracture in Minghuazhen period. The discrete element numerical simulation results show that the existence of large plastic mudstone layers in Dongying Formation is the key material factor leading to the difference of deep and shallow deformation and vertical superposition. [Conclusions] Multistage fault superimposition plays an important role in controlling hydrocarbon accumulation: early faults control depressions and structural belts, late faults control traps and hydrocarbon accumulation, and fault assemblages affect hydrocarbon enrichment strata.
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ZHEN Shi-jun, ZHAO Jia-yi, ZHANG Cui-yun, YIN Mi-ying, ZHANG Sheng
DOI: 10.12029/gc20220830002
Abstract:
[Objective] Understanding the diversity of methanogenic communities in the deep environment is the basis for exploring the origin of early life, extreme environmental life and regulating methane production. However, the diversity of methanogenic communities in the deep carbonate karst-fracture geothermal water is still unclear. [Methods] The deep geothermal water samples were collected for methanogenic marker gene mcrA-based high-throughput sequencing by the pumping tests performed in the geothermal scientific drilling holes located in the Jizhong geothermal area, China to explore the diversity of methanogenic communities in the deep carbonate rock karst-fracture geothermal water. [Results] Results showed that 3 classes, 4 orders and 8 genera of methanogenic communities were detected in the deep geothermal water, of which Methanothermobacter, belonging to Euryarchaeota, Methanobacteria and Methanobacteriales, was dominant methanogens, accounting for 99.85% of the total sequences. The dominant species based on mcrA was closely affiliated with Methanothermobacter wolfeii (similarity 99%, accounting for 71%). The metabolic pathway of methanogens was mainly the pathway of CO2 reduction. The compositions of methanogenic communities in different samples were different, but Methanothermobacter was a dominant genus in all of the samples, accounting for more than 99.77%. [Conclusions] This study reveals that the deep geothermal water from the carbonate rock karst-fracture geothermal reservoirs contains relatively abundant but extremely uneven compositions of methanogenic communities and expands the habitat type of Methanothermobacter, which provides scientific basis for further studying the function of methanogens in the earth ecosystem.
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Wu Shanshan, Yao Weijun, Zhou Juan, Jia Zhijie, Wang Dan, Zhu Peng, Yang Binbin
DOI: 10.12029/gc20220706002
Abstract:
This paper is the result of geothermal geothermal geological survey engineering. [Objective]Dafeng District，located in the northern part of Yancheng City，Jiangsu Province，is an area with abundant geothermal resources. It is of great practical significance to systematically study the characteristics of geothermal resources for the potential of coal and emissions reduction in the development and proper utilization of local geothermal resources. This is to strive for the strategic goal of achieving peak carbon dioxide emissions as soon as possible. [Methods]By comparing and analyzing the "heat source， channel， reservoir，and cap" of geothermal geological conditions for three typical geothermal wells in Hengbei Village，Holland Flower Sea Geothermal Well，and Milu Town Geothermal Well in Dafeng District，the characteristics of geothermal resources in Dafeng District were studied and summarized. [Results]Through the evaluation of water quality and theoretical calculations of mineable and reserve amounts of geothermal wells in this area，we surmised that the geothermal well development and utilization in this area is mainly towards physical therapy，bathing，and heating. The theoretical total coal-saving amount that can be achieved through the exploitation of the geothermal resources in the three wells is 8，884 tons per year， and the corresponding CO2 emissions reduction is 21，197 tons per year. The theoretical total coal-saving amount that can be achieved through the storage of geothermal water in the resources reserved area of the three geothermal wells in Hengbei Village，Holland Flower Sea Geothermal Well，and Milu Town is 18，885，886 tons，corresponding to a CO2 emissions reduction of 45，061，725 tons. [Conclusions]The results of this study provide basic evidence or references for the exploration and development of geothermal resources and the analysis of carbon emissions reduction potential in the Dafeng District.
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DOI: 10.12029/gc20221025004
Abstract:
[Objective] Through studying the content and spatial distribution characteristics of heavy metals in the surface soil of Yuanzhou District, Guyuan City, Ningxia, the ecological risk of this area was evaluated, and the accumulation of heavy metals in the surface soil of Yuanzhou District was clarified. [Methods] A total of 12,988 soil samples were collected and tested for the concentration of eight heavy metals, namely As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn. The single-factor index, Nemerow comprehensive pollution index, and potential ecological hazard index methods were employed to estimate the ecological risks associated with heavy metal contamination in soils. [Results] Compared to the background values of Ningxia Autonomous Region, the average enrichment coefficients of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were 1.01, 1.42, 1.04, 0.99, 1.03, 0.81, 1.01, and 1.07, respectively. We observed similar distributions of the eight heavy metals, with high concentration values primarily found in areas with frequent human activities, such as the east and west sides of Liupan Mountain, Guyuan City, Zhangyi Town, and Huangduobao Town. In contrast, low concentration values were observed in Tanshan Township and Zhaike Township in the northeast Quaternary areas with loess-covered soil. The single-factor index evaluation revealed that the soil was "clean" in the Yuanzhou area. The Nemerow comprehensive pollution index evaluation indicated that the soil pollution index of all heavy metals was less than 0.7, which is considered "clean." While the single-element potential hazard index of Cd and Hg reached moderate risk levels, the comprehensive potential ecological hazard index of heavy metals was at a slight risk level.[Conclusion] Overall, the soil quality in Yuanzhou District, Guyuan City is in good condition, but heavy metals were slightly enriched in the topsoil due to human activities in some areas.
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CHEN Binghan, LI Peng, LIU Jiannan
DOI: 10.12029/gc20220321002
Abstract:
[Objective] In the national dynamic evaluation project of potential mineral resources, the features, type and spatiotemporal distribution of caesium resource in China are studied, the metallogenic regularities of caesium deposits in China is summarized. [Methods] This paper introduces the resource characteristics of cesium deposits in China; Cesium deposit types are divided, and the mineralization age and spatial distribution of cesium ore are counted. [Results] Caesium deposits in China are divided into seven types, namely the granite type, granite pegmatite type, magmatic hydrothermal type, salt lake type, brine type, geyserite type, granite weathering crust type, the spatiotemporal distribution feature of each type of caesium deposits is preliminarily summarized. Based on the statistics, the metallogenic period of caesium deposits in China is divided into Paleozoic, Mesozoic and Cenozoic. 10 caesium metallogenic belts are divided. 31 caesium-related metallogenic series are determined and the metallogenic pedigree of caesium deposits in China is established. [Conclusions] China''s Cesium deposits are mainly Mesozoic and Cenozoic granite pegmatite type, granite type and salt lake type cesium deposits in north Altay and North China continental block, salt lake type in Qinghai Tibet Plateau, granite pegmatite, granite Cesium deposit and magmatic hydrothermal Cesium deposit in the middle and lower reaches of the Yangtze River. The exploration work in Xinjiang, the middle and lower reaches of the Yangtze River, the Qinghai-Tibet Plateau and the Qianjiang basin should be strengthened.
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ZhangHaizu, XuTong, XieYani, ZhangHuifang, Fanshan, Chenchangchao, ZhuChuanqing
DOI: 10.12029/gc20210830002
Abstract:
The distribution relationship between oil and water in Ahe Formation of Jurassic in the eastern Kuqa Depression, Tarim Basin is complicated, and the characteristics of formation water and its relationship with oil and gas reservoirs are lack of systematic study. In order to clarify the chemical characteristics of formation water and its relationship with reservoirs, based on the selection of formation water samples, the formation water test data of Ahe Formation in eastern Kuqa Depression are analyzed to study the distribution characteristics of water type, TDS and ionic ratio coefficients of formation water and its significance to reservoirs. The results show that the formation water of J1a is mainly NaHCO3 type,followed by CaCl2 type and MgCl2 type, and has relatively low salinity. The TDS and ionic ratio coefficients of formation water are controlled by the structure characteristics: In the open area of the structure and the pinch-out area of the formation, the formation water is mainly NaHCO3 type with low salinity, the sodium chloride coefficient and desulfurization coefficient are high and the deterioration coefficient is negative. Nevertheless, the formation water in the closed formation has the opposite chemistry feature. There is a good coupling relationship between the chemical characteristics of formation water and the plane distribution characteristics of oil and water, with Dibei oilfield as an example, although YN4 and YS4 wells had experienced oil and gas filling, but the formed oil and gas escaped along the fault, and the chemical characteristics of the formation water and the kaolinite content reveal that the formation was affected by the meteoric water that entered along the fault. On the contrary, the chemical characteristics of formation water and kaolinite content in well YN2 indicate that the formation is well sealed and less affected by meteoric water, which corresponds to the distribution of oil layers. The relationship between the chemical characteristics of formation water and the distribution of oil and gas reservoirs provides a basis for subsequent exploration, development and evaluation of tight oil and gas reservoirs.
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Li ZhiZhong, Luo TengYue, ZhangYi, Xia Peng, Mu Huayi, Sun Pingping, Wang Jianhua, Wang Xin
DOI: 10.12029/gc20221009002
Abstract:
[Objective] Ordos Basin is an important energy base in China, with rich oil, natural gas and coal resources, bauxite, uranium and other mineral resources. Bauxite is abundant around the basin, but there is little research on deep bauxite in the basin. Oil and gas drilling shows that the basin is rich in bauxite resources, with a buried depth of one hundred to four kilometers. If the exploration and mining of deep bauxite can be realized, the situation of insufficient bauxite resources in China will be greatly alleviated. [Methods] The geological characteristics and petrophysical characteristics of bauxite in Tongchuan area, Ordos basin are studied in this paper. [Results] First, the deep bauxite in the basin has obvious electrical characteristics, which is characterized by "four high and two low". With reference to oil and gas logging interpretation methods, bauxite identification standards and bauxite logging interpretation models can be established to obtain diaspore content and complete the evaluation of bauxite; Second, the distribution of bauxite in the basin is controlled by the palaeogeomorphology of the Paleozoic Majiagou Formation, and the ore bed is stably distributed, with considerable resources and great exploration potential; Third, bauxite belongs to sedimentary rock, which has certain porosity and permeability, and presents sandwich structure. The bauxite ore bed with high permeability is often surrounded by clay rock with low permeability, meeting the geological conditions of in-situ solution mining; Fourthly, according to stress sensitivity analysis, bauxite is compressible, and new pores or cracks will appear under certain stress, which can further improve the permeability of the ore bed and increase the possibility of in-situ leaching mining of bauxite. [Conclusions] Logging technology can be used to evaluate the deep bauxite resources in Ordos Basin. In combination with the petrophysical characteristics of bauxite, in-situ leaching mining can be considered for bauxite.
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Wang Zhenli, Zhang Lian, Luo Jianlin, Li Fuping, Lei Tianci, Huang chang sheng, yu dong sheng, Deng Tongde
DOI: 10.12029/gc20220826001
Abstract:
This paper is the result of eco-geological survey engineering. [Objective]The purpose of this paper is to study the relationship between the quality of taro and the eco-geological environment, explore the eco-geological mechanism that the eco-geological environment to create the special flavor of taro, provide a scientific basis for the selection or improvement of the eco-geological environment for taro planting, and provide a reference for the research of related disciplines. [Methods] Study was carried outfrom the aspects of geological construction control, soil parent material traceability, soil physics, soil geochemistry, biogeochemistry, etc.Systematic sampling of rocks, soil, waterand plants was donein the core area and the control area of the taro. Themineral elements, organic nutrients and main indexes of physical properties of farmland soilwere detected. The test data were analyzed and processed by a variety of methods and studied comprehensively. [Results] The results show that:① The main indexes reflecting the unique flavor of taro were higher than those in the control area, such as protein, energy, carbohydrate, vitamin B, starch, amino acid, etc. ② The essential elements K, P, Zn and S played a major role in the formation and improvement of taro flavor substances, followed by Fe, Mg, Cl, Ni, Mn, Ca, Cu and SOM. ③ The average soil particle size is small, the soil bulk density and soil compactness is low, the soil burning reduction and pH value is moderate, and the soil moisture and soil Eh value is higher, the soil is well cultivable. [Conclusions] The unique flavor of Jibu taro is the product of the superposition effect of excellent soil physical, soil geochemical and biogeochemical characteristics caused by a unique eco-geological environment.
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JIN Wenzheng, BAI Wankui, YE Zhixu
DOI: 10.12029/gc20220306001
Abstract:
Abstract: This paper is the result of geological survey engineering. [Objective] In order to discuss the relationship between the vertical tectonic uplift and the lateral tectonic expansion happened in Meso-Cenozoic in the Longmenshan thrust belt, this paper carries out low-temperature thermal chronology testing and analysis. [Methods] Through the determination and analysis of apatite and zircon fission track age, the characteristics of tectonic evolution are studied. [Results] The study shows that the lengths of apatite fission tracks are within the range of 11.4±2.6~12.2±2.2μm, which can effectively reflect the local tectonic uplift history; the results of thermal history simulation show that the apatite samples have experienced three critical stages, including the rapid tectonic uplift, the stable tectonic stage and the rapid tectonic uplift. Besides, the uplifting events happened in the northern area were earlier than those in the southern area. The cooling rate of each rock sample is within the range of 1.211~6.053℃/Myr. The tectonic uplift rate gradually increases from southeast to northwest, and the time of uplifting gradually becomes late in the same direction. [Conclusions] The tectonic deformation of Longmenshan thrust belt has had the characteristics of piggyback propagation from northwest to southeast since Meso-Cenozoic (150Ma), and it has showed these characteristics again from late Cretaceous to Eocene (70~50Ma), even Oligocene (about 20Ma). The central and western regions of the Longmenshan thrust belt are characterized by multi-stage tectonic uplift and superposition.
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SONG Teng, LIN Tuo, LI Fei, LI Haohan, WU Hai, DUAN Ke
DOI: 10.12029/gc20210602004
Abstract:
Objective: Marine black manganese-bearing carbonaceous shale of Datangpo Formation was generally developed in the mid-Neoproterozoic Nanhua period in the Middle-Upper Yangtze Region，South China, which has been widely concerned as a manganese deposit for a long time, but with little attention to its petroleum geological characteristics. This paper expounds the lithofacies paleogeography of the Datangpo Formation and its indication of oil and gas accumulation, so as to guide the oil and gas investigation in the Suthern China. Methods: Through field investigation and data collection on the Datangpo Formation, the oil and gas geological conditions, the source rock characteristics and hydrocarbon accumulation assemblage, especially lithofacies and paleogeography, were systematically analyzed by methods of single well analysis, continuous well comparison, lithofacies paleogeographic map compilation, etc., combined with source rock characteristic analysis, reservoir analysis and other experimental testing methods. Results: The Datangpo Formation was formed during the interglacial period, and the depositional process was controlled by the extensional rifting process. Its sedimentary facies can be divided into two types, seven subtypes and several microfacies. The entire depositional period constitutes a complete transgressive-Highstand-Regressive sedimentary cycle; the most potential facies belts for oil and gas resources in the Datangpo Formation are limited shelf subfacies and lagoon subfacies, mainly distributed in the first member, with good organic geochemical index characteristics, and are high-quality source rocks. Conclusions: The first member of the Datangpo Formation has good hydrocarbon generation and shale gas development potential. Songtao, Huayuan, Xiushan, Xiangtan, Hefeng and other areas at the junction of Hunan, Chongqing and Guizhou Province have favorable conditions for shale gas development and are potential shale gas development areas. With the Datangpo Formation as the source rock, a variety of potential reservoir-forming assemblages can be formed. The Xiushan, Songtao and Huayuan areas at the junction of Chongqing, Guizhou and Hunan Province have good source-reservoir configuration conditions and are potential conventional oil and gas development areas.
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MA Jian-fei, LI Xiangquan, ZHANG Chunchao, FU Changchang, XIE Xiaoguo, WANG Xiaogang, LI Xinze, ZHANG Dengfei, BAI Zhanxue, WANG Zhenxing
DOI: 10.12029/gc20220416004
Abstract:
Abstract:【Objective】 There are many tectonic karst areas in the east of Qinghai-Xizang Plateau, with complex karst hydrogeological structure, diverse recharge sources and abundant groundwater. Conducting the analysis and research of recharge sources and summarize the plateau tectonic karst cycle law is of great significance for guiding the development and utilization of karst water resources, ecological protection and disaster prevention and reduction.【Methods】 Based on field investigation, flow measurement, hydrochemistry and stable isotope analysis, this paper analyzes the groundwater recharge sources in typical karst areas in the east of Qinghai-Xizang Plateau, the influencing factors of recharge sources and recharge progress were discussed, and suggestions of development and utilization were put forward. 【Results】 The results show that the main recharge source of the main karst springs in the eastern Qinghai-Xizang Plateau is atmospheric precipitation. Four recharge modes are established, including direct recharge through fissure in high-level, continuous recharge by high-level lake, continuous seepage recharge in catchment depression, river seepage recharge. 【Conclusion】 The reason for the difference of recharge modes is that the eastern Qinghai Xizang Plateau has experienced internal and external dynamic coupling for a long time, in which the internal dynamic control factors are karst formation and evolution history, geological structure and lithologic combination; The external dynamic control factors mainly include meteorology, landform and glacier movement. According to the characteristics of water quality and quantity of karst spring, three development and utilization modes are put forward: the first is karst spring with water quality of class I ~ III, which can directly expand the degree of development and utilization, the second is brackish water, which can be properly developed and utilized after mixing with other water, and the third is salt water, which can be properly transformed and used for tourism development.
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Li Juan, Wang Shengjian, Tian Yukun, Zhou Hui, Liu Ce, Xue Zongan
DOI: 10.12029/gc20210407003
Abstract:
【Objective】 The brittleness of shale reservoir is one of the parameters reflecting the fracturing quality of shale gas reservoir, which has an important influence on the degree of difficulty of fracturing and the shape of fracture network. 【Methods】 In order to accurately evaluate the brittleness characteristics of Niutitang Formation shale reservoir in Western Hubei, systematic sampling, whole rock mineral and clay content test, main and trace element content test, acoustic mechanics joint test and other analytical tests were carried out on five wells in the south wing of Huangling anticline in Western Hubei. The quantitative evaluation of shale brittleness was carried out by cluster analysis and principal component analysis. 【Results】The results show that tThere is a close relationship between minerals and rock brittleness, and the cluster analysis method can quantitatively characterize the effective brittle mineral composition and non-effective brittle mineral composition in shale; The comprehensive quantitative evaluation formula of brittleness index based on rock mechanics, mineral composition and element composition is established by using principal component analysis method, which overcomes the limitation of single method and forms the brittleness index profile of Niutitang Formation shale section in Western Hubei. 【Conclusions】The results of microseismic monitoring and fracturing show that the newly established brittle index profile can accurately indicate the high brittle layer of shale, and the fracturing effect is good. 【Key words】Key words: shale brittleness; mineral composition; mechanical parameters; elements; statistical analysis; geological survey project 【Highlights】Overcoming the limitation of a single method, a brittleness index model is established by using a variety of geological factor mathematical models; The shale brittleness is quantitatively evaluated and tested in practice.
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li fenqi, Zhang shizheng, li jun, liu han, gou zhengbin, qin yadong
DOI: 10.12029/gc20201214001
Abstract:
This paper reports depositional characteristics of deep?water debris flow of Lagongtang Formation in Nagqu area, Tibet, and points out that it is significant for its controlling factors, depositional process analyzed and depositional model proposed to improve marine theories of gravity flow, to assess petroliferous basins. The debris flow deposit consists of gravel debrites in its lower and sandy one alternating with muddy one in its upper, and soft depositional deformation structures with varying types, scales are developed in it like soft depositional deformation folds, boudinages and soft dual structures. And many slumps and slides are identified in the gravel? and sandy debites. The research shows that along with Mugagangri Group gradually being exposed and denuded in Middle Jurassic, a delta was developed at the tectonic transition from Bangong Co?Nujiang suture zone to Lhasa blok after closure of Bangong Co?Nujiang ocean, forthurmore, it laid a material foundation for the formation of gravity flow deposits of Lagongtang Formation. Futhurmore, the main delta river turned into a canon channel, along with the junction zone thrusting southwards and delta lifting continuously on it. Loose deposits resulted from unconsolidated sediments of the delta collapsed in the channel steep bank flows towards basin along the channel under self?gravity. The debrites diversion took place under the influence of several factors such as terrain when it passed by the mizoguchi, and 2 sub-debrites formed and deposited frozenly at last.
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Kong Jiahao, Zhang Guanlong, Xu Shumei, Wangjinduo, Zeng Zhiping, Wang Qianjun, Ren Xinchen, Wu Xiangfeng, Shu Pengcheng, Ma Huilei, Cui Huiqi
DOI: 10.12029/gc20220322001
Abstract:
Che-Mo Synsedimentary paleouplift in Junggar basin is an important geomorphic unit that affects the structural style and reservoir distribution characteristics of Jurassic. At present, the geometry, distribution range, evolution stage and formation mechanism of Che-Mo paleouplift have been deeply studied. Based on the logging data and seismic data of 41 wells in the abdomen of the basin, this paper makes a detailed analysis and isochronous comparison of Jurassic sand body and stratigraphic structure, and focuses on the synergistic evolution between the phased development of Che-Mo paleouplift and the orogenic belt around Junggar basin, especially Bogda mountain, and its influence on the basin boundary and sedimentary pattern. The formation and evolution of Che-Mo paleouplift in Jurassic not only affected the sedimentary landform of the basin, but also significantly changed the basin boundary and provenance pattern, and led to significant changes in sedimentary system, stratigraphic structure style and distribution law. These changes will have an important impact on sand body distribution and reservoir distribution. The evolution of Che-Mo paleouplift can be divided into three stages: initial development stage, rapid uplift stage and post uplift denudation stage. The initial development stage of Early Jurassic Che-Mo paleouplift has no or little influence on the distribution and structural style of Badaowan Formation and Sangonghe formation. The study area is supplied by Zhayier mountain in the northwest and Kelameili mountain in the northeast, mainly forming braided river delta sedimentary system; The Middle Jurassic was the rapid uplift stage of Che-Mo paleouplift. In addition to the source supply of Zhayier mountain in the northwest and Kelameili mountain in the northeast, Bogda mountain also rose out of the water at the same time and began to supply the source, resulting in significant changes in basin boundary, stratigraphic distribution and structural style, resulting in large-area overlap of the first and second members of Xishanyao Formation, loss or denudation of the third members of Xishanyao Formation, The sedimentary system combination of Braided River Delta and beach bar is formed; The uplift of Che-Mo paleouplift in late Middle Jurassic and late Jurassic resulted in the denudation loss of Toutunhe Formation and Qigu formation, forming a regional unconformity with Cretaceous.
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Jiang Gaolei, Wang Naiang, LI Zhuolun, Li Meng, Su Xianbao, Ning Kai
DOI: 10.12029/gc20220304004
Abstract:
[Objective] It is of great significance to understand the distribution pattern of saline mineral deposits in lake basin for the reconstruction of palaeoenvironment and palaeohydrology. However, the studies on mineral distribution for groundwater recharged lake sediments are few, which hinders the climate-environmental reconstruction in arid area. [Methods]The Badain Jaran Desert, located in western Inner Mongolia in a hyper-arid area of China, is characterized by the coexistence of more than 110 perennial lakes and thousands of mega-dunes. More than 90% of the recharge of lakes between mega-dunes is from groundwater. In this study, we analyzed the mineral assemblage and distribution characteristics of the surface sediments of eight lakes with different salinity in the Badain Jaran Desert. [Results]The results show that: 1) For individual lakes, the distribution pattern of saline mineral deposits is similar to those of lakes with runoff recharge, that is, there are more detrital mineral deposits at the edge of the lake, and the saline mineral deposits gradually increase towards the lake interior, and the mineral types gradually change from carbonate to sulfate and chloride. 2) The mineral composition of the sediments near the lake edge is more easily affected by the variation of lake water level and area, while the sediments near the lake center may be affected by the water depth and the groundwater recharge. 3）The shallow lakes are well mixed and are not easily affected by the stratification of lake salinity and water temperature, and the replenishment of fresh water at the bottom. Moreover, the total content of salt minerals has a good linear relationship with the salinity of lake water. [Conclusion] The changes of saline mineral assemblage and its content in the lakes recharged by groundwater can well reflect the changes of lake salinity and can be used as a proxy of climate-environmental reconstruction in desert areas. This study will provide an important basis for the reconstruction of palaeohydrological information using lake saline deposits in arid areas of China.
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gongwenqiang, Su Kui, zhangzhen, gaowei, weiliyong, zhaochao, wangate, hejiale
DOI: 10.12029/gc20210412001
Abstract:
There are many disputes about the the age and prowenance of Dacaotan Formation, With clastic rocks of the Upper Devonian Dacaotan Formation at Qiagai area in the West Qinling Orogenic belt as the study object, the authors used LA-ICP-MS zircon U-Pb isotope geochronological method to explore the age and prowenance of Dacaotan Formation. The results show that the detrital zircon ages can be divided into 4 groups: (1)The Archen-Paleoproterzoic(2232-3258Ma); (2)The Mesoproterzoic(1018-1791Ma); (3) The Neoproterzoic(544-999Ma); (4)The Early Paleozoic(417-519Ma). Among which, the Early Paleozoic(417-519Ma) ages data possess the largest proportion, accounting for about 39.6% of the total data. The lesser is the Neoproterzoic(544-999Ma) ages, about 37.3%. The other two groups ages possess a smaller proportion. Preliminary analysis show that, the provenance source of Dacaotan Formation were much more complicated and characterized by obvious diversity and periods, derived from northern margin of western Qinling orogenic belt, the eastern part of the Qilian orogenic belt and the basement of North China plate. The predominant part among them was the active magmatic arc produced by collision orogen, which come from the northern margin of western Qinling orogenic belt and Qilian orogenic belt during the Caledonian period.
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FU Changchang, LI Xiangquan, ZHANG Wenjing, CHENG Xu, BAI Zhanxue, LI Jinqiu
DOI: 10.12029/gc20220426002
Abstract:
Abstract: This paper is the result of hydrogeologic survey engineering. [Objective]Budongquan spring is in the region of Hoh Xil on the northern Qinghai–Tibet Plateau. It is a typical sub-surface spring with discharge that ascends to the surface through taliks in the permafrost. It is an important water supply for the Qinghai–Tibet railway and the construction of small towns along the railway. Therefore, it is very important to understand its formation and water characteristics. [Methods] In this paper, we evaluated spring water quality using the single index evaluation method. We analyzed water storage, circulation, and sources of main chemical components by examining the local geology, environmental isotopes, and hydrochemistry. [Results] Results show that Budongquan spring water quality is in class V throughout the year. It is in class V in terms of total hardness, SO42?, and Cl?, and in class I–II in terms of toxicological and heavy metal indices. Nearby glacier meltwater and river water are in class I–II. The spring is mainly recharged by glacial meltwater from the southern slope of Kunlun Mountains, atmospheric precipitation, and surface river water. Average cycle length is less than 5–10 years. Groundwater flow follows the talik zone along the northeast-trending active normal faults. Budongquan spring is formed by the surfacing of groundwater that is blocked by the west-northwest-trending active reverse faults. Its chemical composition is mainly determined by evaporation, and presence of and interaction with magnesium salts and carbonate rocks. [Conclusions] To meet standards for drinking water, we recommend mixing spring water with river water at a ratio of 1:2.
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Fang Jing, Wang Fu, SHANG Zhiwen, YAN Xia, KANG Qinwei, QU Yinghui, WANG Tianjiao, LIU Yufei
DOI: 10.12029/gc20210725002
Abstract:
【Objective】In order to study the diatoms indication significance to the sea level and the maximum transgression range, 【Methods】this paper analyzes the diatoms and AMS 14C dating data from three 30m deep drilling cores collected near Chenier V of northern Cangzhou, Bohai Bay. 【Results】The results show that diatoms are rare in these drilling cores, and there is only one diatom rich layer in each core, which is composed of peat and humus gray clay. The thickness of the layer is 10 cm to 60 cm, and thinner from seaward to landward. 7473 cal BP, site of DC01 changed from a sea water influenced swamp environment to a fresh water swamp environment, indicating a relative sea level lower than -6.37m; 7513 cal BP，site of QX02 was transformed from saltmarsh environment (zone I) to sea water influenced shallow swamp, then to salt marsh environment (zone III), The elevation of the boundary between zone I and zone II indicating a relative sea level of -6.68m. 7836 cal BP, site of QX01 was transformed from a freshwater swamp (zone I) to a salt marsh environment (zone II). The boundary between zone I and zone II indicating a relative sea level of -7.68m.【Conclusions】Relative sea level raised ~1m during these ~350 years, and the sea water affected the area to the west of the Chenier V. The salt marshes and freshwater swamps were the main environmental types near the transgression maximum in the Early-Mid Holocene. Under the background of modern sea level rise, marshification is a major environmental problem that modern coastal areas must face.
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Chen Xiaohong, Tian Wei, Li Xubing, Li Hai, Zhang Baoming, Zhang Guotao
DOI: 10.12029/gc20210816001
Abstract:
On the basis of natural gas exploration in Xiangzhong Depression, the Yangjiashan anticline with active shallow natural gas was selected to carry out shale gas investigation. The results show that the shale in the lower part of Lower Carboniferous Tianeping Formation has large thickness and high gas content, which is of great significance for shale gas exploration. Based on the systematic study on the genesis of organic-rich shale and the physical properties of shale gas reservoirs in Tianeping Formation, combined with the thermal evolution simulation of medium-high maturity shale gas reservoirs in semi-open environment, the following understandings are obtained: (1) The organic-rich shale of Lower Carboniferous Tianeping Formation is the sedimentary product of seawater stratification and seabed anoxia caused by the violent climatic fluctuations in the Early Carboniferous in Lianyuan area, and has the characteristics of wide distribution and large thickness. (2) The extensive and intense Mesozoic magmatic events in central Hunan led to the obvious increase of shale maturity near the rock mass, which has changed the deep thermal evolution model of shale organic matter maturity increasing with burial depth, and have important influence on the evolution process of hydrocarbon generation and shale gas reservoir of the Lower Carboniferous organic-rich shale in Lianyuan area. (3) The experimental results of thermal evolution simulation of medium and higher maturity shale reservoir under semi-open system show that the crude oil generated by thermal decomposition of organic-rich shale will fill various pores of shale reservoir, resulting in the deterioration of physical properties of the reservoir. However, after entering the gas generation stage, the bedding fractures and organic pores of shale become wider and increase with the increase of maturity, which makes the physical properties of the reservoir significantly improved.(4)The organic-rich shales of the Lower Carboniferous Tianeping Formation in the Lianyuan Sag experienced the early Carboniferous to middle Triassic plutonic thermal evolution stage, the late Triassic to Cretaceous magmatic thermal evolution stage, and the oil and gas adjustment and reconstruction caused by two regional folds and uplifts in the Indosinian and early Yanshanian. Shale gas enrichment in Tianeping Formation is the result of favorable facies zones controlling reservoir and tectonic-magmatic activity controllingSaccumulation. The low concealed structures of the foot wall of the thrust nappe fault developed in Yanshanian period may be the most favorable exploration areas. S
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CHEN Shuwang, SUN Shouliang, ZHANG Tao, Barry P. Kohn, Andrew Gleadow, LIU Yan, Ling Chung, LI Yongfei, DING Qiuhong
DOI: 10.12029/gc20210407001
Abstract:
【Objective】The tectono-thermal history of the Cretaceous fault basins in the Songliao peripheral area had not been well explored. The Xiushui basin is a new exploration area with high hydrocarbon potential in the southern part of the Songliao peripheral area. The reconstruction of the burial and thermal history of the Xiushui basin has become an important issue for hydrocarbon exploration in this area. 【Methods】Based on five samples from the well LFD1 in the Xiushui Basin, burial and thermal history as well as hydrocarbon source rock evolution history of the Xiushui basin were studied using apatite fission track methods. 【Results】The results show that the Xiushui basin reached its maximum burial depth in the late Early Cretaceous, and then uplift continued and denudated about 2000m. The terrestrial heat flow value increased linearly with time during the initial subsidence period, reaching the maximum value of about 100.5 mW/m2 at about 120Ma, and then experienced a three-stage cooling process, i.e., rapid cooling, then slow cooling, and finally rapid cooling. The heat flow pattern is similar to and comparable with the adjacent Zhangqiang Depression and the Songliao Basin. 【Conclusions】The reconstruction results of the burial and thermal history of the well LFD1 indicate that the hydrocarbon source rocks of the third member of the Yixian Formation entered the oil generation window around 90 Ma, and thereafter, due to the uplift and cooling of the formation, the thermal evolution of the source rock ceased, thus remain unchanged to date. 【Key words：】Burial history; Thermal history; Apatite Fission Track; Xiushui basin; southern Songliao Basin; oil-gas geological survey enginnering 【Highlights：】 1. Burial and thermal history as well as hydrocarbon source rock evolution history of the Xiushui basin were studied using apatite fission track methods for the first time, which lays a foundation for further oil and gas exploration. 2. The regional paleothermal flow shows a trend which the Songliao basin is the highest and gradually decreases to the south, and the reasons for this trend are discussed.
The Online First column displays articles that have been accepted by Geology in China through peer review. These articles are currently in the redaction process and have not yet determined the volume and page number. And the final printed version of the article may be slightly different in individual formatting or text expression, but the overall content of the article is completely consistent. The copyright of its contents is protected by relevant laws and regulations.
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Exposure risk and genesis of groundwater fluoride contamination from Huaihe River Plain, China
XU Naizheng, LIU Lin, WANG Hesheng, LI liang, GONG Jianshi, TAO Xiaohu, TAN Mengjiao
Abstract:
[Objective] Fluoride (F-) is ubiquitous in groundwater and it is listed as Class III specific carcinogen by International Agency for Research on Cancer. Presently, Huaihe River Basin is identified as a region with F- rich groundwater in China. In order to comprehensively evaluate groundwater F- exposure risk in this basin, this study is to assess its risk magnitude of investigating wells and to predict its risk probability in at unmonitored points based on the recently obtained high-density hydrochemical data. [Methods] This study is to assess the risk magnitude and likelihood for F- rich groundwater in Huaihe River Plain, China using Risk Magnitude and Indicator Kriging methods, and discusses how it formed additionally. [Results] The results show F- concentrations from 5575 investigating wells are in the range of 0.01~5.45 mg/L, with a median of 1.02 mg/L and a mean of 1.97 mg/L, respectively. F concentrations in plain areas are significantly higher than those in hilly areas. There are 548 (9.83%) wells with High Risk Magnitude, and 576 (10.33%) wells with Very High Risk Magnitude, which are predominant positioned in inland plain. Compared with deep groundwater, shallow groundwater exhibits higher F- levels and spatial variability. Based on the prediction of shallow and deep Risk Probability maps, the potential high F- hazard areas over shallow groundwater encompass more than 5137 km2, while the counterpart over deep groundwater is 864 km2; where 3.14 million people are estimated to be potentially exposed to F- contamination. The Risk Probability map of shallow groundwater shows a similar spatial pattern with that of deep groundwater, and both Risk Probability peaks are located in inland plain areas. [Conclusions] It is the main route for inhabitants exposed to F- through drinking groundwater. The spatial coincidence of high F- Risk Probability and high incidence rate of fluorosis observed in inland plain, which might suggest that groundwater F- level is related to the fluorosis cluster. F- rich groundwater is of in-situ origin, and F- is manly derived and released on fluorite dissolution. Besides, alkaline desorption and evaporation concentration affect the formation of high F- groundwater. This paper carried out research on exposure risk of F- rich groundwater from Huaihe River Plain, China, which results can provide scientific basis for the rational utilization and management of regional groundwater.
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Chenyang LI, Xinchun WANG, Chunzhen HE, Xuan WU, Zhaoyu KONG, Xiaolei LI
2019,46(S1):1-10, DOI: 10.12029/gc2019Z101
Abstract:
As the only one of its kind, China National Digital Geological Map (Public Version at 1:200000 scale) Spatial Database (CNDGM-PVSD) is based on China's former nationwide measured results of regional geological survey at 1:200 000 scale, and is also one of the nationwide basic geosciences spatial databases jointly accomplished by multiple organizations of China. Spatially, it embraces 1163 geological map-sheets (at scale 1:200 000) in both formats of MapGIS and ArcGIS, covering 72% of China's whole territory with a total data volume of 90 GB. Its main sources is from 1:200 000 regional geological survey reports, geological maps, and mineral resources maps with an original time span from mid-1950s to early 1990s. Approved by the State's related agencies, it meets all the related technical qualification requirements and standards issued by China Geological Survey in data integrity, logic consistency, location accuracy, attribution fineness, and collation precision, and is hence of excellent and reliable quality. The CNDGM-PVSD is an important component of China's national spatial database categories, serving as a spatial digital platform for the information construction of the State's national economy, and providing information backbones to the national and provincial economic planning, geohazard monitoring, geological survey, mineral resources exploration as well as macro decision-making.
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MAO Jing-wen, ZHOU Zhen-hua, FENG Cheng-you, WANG Yi-tian, ZHANG Chang-qing, PENG Hui-juan, YU Miao
2012,39(6):1437-1471, DOI:
Abstract:
Abstract：Triassic tectonic evolution in China is characterized by high intensity and wide influence. However, the metallogenic study related to the major Triassic tectonic events has obviously been lagging behind. This paper preliminarily and systematically discusses the space-time distribution and basic characteristics of the large scale Triassic mineralization in China based on the latest research achievements. Triassic deposits in China are distributed mainly in the two main Triassic orogenic belts of the Kunlun-Qinling orogenic belt and the Red River - Ailaoshan orogen belt and their adjacent regions; Besides, there are a series of polymetallic deposits developed in the three intraplates of southern China, northeastern China and Xinjiang area. Major types of Triassic deposits mainly include： ① Cu-Ni sulfide deposits related to basic-ultrabasic rock; ② porphyry Cu-Au, Cu-Mo, Mo deposits, skarn Cu-Pb-Zn, Cu-Fe, Sn, W deposits and vein-type Au deposits related to intermediate-acid rocks and acidic plutons; ③ pegmatite-type rare metal deposits related to high temperature gas-fluids; ④ orogenic Au deposits related to tectonic-hydrothermal activities in the orogenic process; ⑤ MVT Pb-Zn deposits related to basinal fluids in the orogenic process; ⑥ carbonated vein-type Mo deposits related to mantle fluids. Most of the Triassic deposits in the Kunlun-Qinling orogen belt were mainly formed in collisional stage, or in the post-collision setting. In East Qinling area, the Triassic deposits are dominated by Mo, Au, with the formation ages mainly concentrated in 233-221Ma. In contrast, Au deposits and Pb-Zn deposits of Triassic are widely distributed in West Qinling area, Au deposits are distributed along the NW-trending brittle-ductile shear zones, and Pb-Zn deposits are largely concentrated in the two targe basins of Xicheng and Fengtai, whose metallogenic epochs are mainly in the Late Triassic (232-214Ma). In East Kunlun area, newly discovered Cu-Mo-Fe polymetallic deposits were formed in 240-210 Ma. Influenced by Neo-Tethys evolution, Triassic metal mineral resources are scattered in the Red River - Ailaoshan orogen belt, mainly distributed in Zhongdian ancient island arc, Yunnan-Guizhou-Sichuan border area in the east of the orogenic belt and Dulong area of southeast Yunnan. In Zhongdian area, the metallogenic ages are concentrated in 228-201Ma and their distribution shows the characteristics of porphyry-skarn Cu deposits in the middle part and porphyry-epithermal Cu-Pb-Zn deposits and Au deposits on both north and south sides. The dating results obtained in recent years indicate that Pb-Zn deposits in Yunnan-Guizhou-Sichuan border area were mainly formed in Triassic. Moreover, a series of Triassic W-Sn deposits have been discovered recently in Dulong area of southeast Yunnan, whose peak age is 214-209Ma. In addition to the two main collision belts, rare metal and W-Sn deposits in South China, rare metal and Mo deposits in Xinjiang, porphyry Mo deposits, Cu-Ni sulfide deposits and vein type Au deposits in Northeast China and its adjacent areas were also formed in Triassic, and all of these deposits were closely related to the collision regime, most Triassic deposits in South China were related to EW-extending tectonic-magmatic systems and derived from the emplacement of aluminum granite resulting from the remelting of thickened crust. The mineralization of Triassic deposits in Northeast China and its adjacent areas, Xinjiang, and some neighboring areas of Mongolia and Russian Altay as well as Siberia were probably related to mantle plume activities.
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LI Xu-bing , ZHAO Can, LIU An, WEI Kai, LI Jitao
2013,40(5):1493-1504, DOI:
Abstract:
Abstract：This paper divided and depicted in detail two second-order sequences and seven third-order sequences which are regionally well correlatable according to the Ediacaran system, by employing the research method of sequence stratigraphy “from lithofacies to meter-scale cycle,from depositional facies to sequence classification”. With the reservoir as the center, the authors mainly studied the temporal and spatial distribution of source rocks and reservoirs based on sequence framework, and comprehensively considered the matching relationship of source rocks and cover rock affecting reservoir formation. The source-reservoir-cap rock combinations in carbonate rock of the Ediacaran system were divided into 3 types, i.e., boundary type, transgression type and high water type. The findings indicate that the source-reservoir-cap rock combinations associated with sequence boundary in the study area have the most superior initial geological condition, the high water type is usually combined with the karst or boundary type, thus serving as another source-reservoir-cap rock combination with obvious effectiveness.
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QU Cui-xia1, YANG Xing-ke1, HE Hu-jun1, GAO Ping2, SONG Hong-ye3
2013,40(5):1409-1420, DOI:
Abstract:
Abstract：This paper deals with petrologic and geochemical features and zircon U-Pb isotope ages of the intrusive rocks from Yantan belt in Beishan area，which are mainly composed of quartz diorite, granodiorite, monzonitic granite, K-feldspar granite, granite and granite-porphyry, belonging to high-K calc-alkaline and calc-alkaline series; All the rocks are characterized by enrichment of LREE，depletion of HREE and strong Eu negative anomalies. The trace elements are enriched in LILE(Rb, Th), and depleted in Sr, Nb, Ta evidently. The zircon SHRIMP U-Pb ages of the quartz diorite and granite are (296±4.1) Ma and (294±3.7) Ma respectively，both of the data are consistent within test errors, suggesting that the rocks were formed at the beginning of the early Permian period. An analysis suggests that these intrusive rocks are I-type granite which are indicative of the underplating of the mantle material into the lower crust and the formation of these rocks in the post-collision tectonic environment after the closure of Beishan rift. The result shows that the Beishan rift was closed in the early Permian in the study area.
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GAO Lin-zhi1, LU Ji-pu2, DING Xiao-zhong1, WANG Han-rong2, LIU Yan-xue1, LI Jiang2
2013,40(5):1443-1452, DOI:
Abstract:
Abstract：In the zircon study of bentonite from the Danzhou Group and overlying strata of the Nanhua System, the authors accurately determined the age of (801±3) Ma for zircon from the Hedong Formation and (778±6) Ma for zircon from the Gongdong Formation. (778±5) Ma is the age of zircon from the Chang’an Formation, which is the bottom of the Nanhuan System, and (661±7) Ma is the age of zircon from Datangpo Formation of the intraglacial period. Some zircon ages of tuff bedding were reported for the first time from the Sibao and Xiajia Groups in Guangxi and Guizhou. In combination of the SHRIMP U-Pb age of the granite (834±4 Ma) which intruded into the Sibao Group (842±13 Ma) and the SHRIMP U-Pb age of (837±7) Ma of Bendong granite, the authors hold that the Sibao Group is Late Neoproterozoic strata below the strata of 820 Ma. These isotopic data are very important for us to redefine the age of the Sibao Group and to conduct regional correlation of strata of the corresponding period as well as to study tectonic evolution. There is an angle unconformity between the Sibao Group and overlying Danzhou Group and a nonconformity between the Danzhou Group and the Nanhuan System, suggesting the existence of three levels of tectonic factor. The revised age column will influence the whole metamorphosed basement in the Jiangnan Orogen and the constraints on the relationship of the cover strata in South China.
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ZHU Xiao-qing1, WANG Gan-lu2, LU Huan-zhang3, WU Xue-yi1, CHEN Wen-yi4
2006,33(5):1092-1099, DOI:
Abstract:
Abstract：Gold deposits in southeastern Guizhou are quartz vein type gold deposits hosted in the Neoproterozoic low-grade metamorphic series. The protoliths of the metamorphic rocks are represented by a volcanic-sedimentary sequence composed of tuff, tuffaceous sandstone and siltstone with a distinct rhythmic ribbon texture, reflecting an environment of turbidite sedimentation. The occurrence of quartz veins is controlled by anticlines and shear faults. Two types of vein may be distinguished: conformable interlayer veins and filling veins in fracture zones. The mineral composition of quartz veins is rather simple, and in addition to quartz, the veins mainly contain sulfide minerals and some minerals captured from wall rocks. Rb-Sr and isochron dating of inclusions in quartz from five gold deposits indicates that their age is Caledonian, which is consistent with the age of gold deposits of the same types of gold deposit in western Hunan adjacent to Guizhou. A Caledonian Hunan-Guizhou gold belt of gold has been delineated according to the lithology of host strata, geological evolution and structural environment, which will be of great reference value for mineral prospecting.
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DU Xiao-dong1, 2, ZOU He-ping1, 2, SU Zhang-xin1, LAO Miao-ji1, CHEN Shi-ai1, DING Ru-xing1, 2
2013,40(4):1112-1128, DOI:
Abstract:
Abstract：The Daoyaoshan-Damingshan area is located in the southwestern section of the Qinzhou-Hangzhou juncture between the Yangtze Block and the Cathayian Block．The study of the early Paleaozoic sedimentary environment and tectonic setting of this area is a key to understanding the geotectonic problems in South China. Major and trace elements of 27 pieces of samples from Cambrian sandstones and mudstones in this area were analyzed and discussed. The samples generally have high ratios of Al2O3/TiO2 ( in the range of 11.95~36.26,20.81 on average) and lower ratios of Rb/Cs（in the range of 13.02~68.27, 32.21 on average） and Cr/Zr（ranging 0.14～1.15,averagely 0.59）. Geochemical characteristics, such as the plots of Ni-TiO2,Th/Sc-La/Sc and La/Th-Hf , indicate that the Cambrian sediments in the Daoyaoshan-Damingshan area were mainly sourced from the upper crustal felsic quartz rocks,with the addition of a small amount of igneous sources and ancient recirculation sediments．The distribution of trace and rare-earth elements and the data of La-Th-Sc,K2O/Na2O-SiO2, δCe,δEu,Tb/Yb,La/Sc,La/Th,Th/U as well as the comparison with different tectonic settings show that the study area belonged to a passive continent-marginal setting. In addition, such evidence as the marks of shallow-sea deposits,the data of sedimentary palaeogeography,regional geology and geochemistry suggests that during the Early Paleozoic there existed no geochemical evidence for the so called “ancient ocean in South China”．
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CHEN Gang1, LI Shu-heng2, ZHANG Hui-ruo2, DING Chao1, YANG Fu1, LEI Pan-pan1
2013,40(5):1453-1465, DOI:
Abstract:
Abstract：Geochronology of oil-gas accumulation (OGA) is a key research frontier for petroleum reservoir-forming dynamics in the multi-cycle superimposed basin. The OGA timing and stages of the Permian reservoirs in northeastern Ordos Basin (OB) are constrained in this paper by K-Ar dating of authigenic illite (AI) and indirect dating of fluid inclusions (FI) from oil-gas-bearing sandstone core samples of the Lower-Upper Permian period. AI dating results of the Permian samples show a wide time span of 178～108 Ma and a spatial decreasing trend from 178～122 Ma in the south to 160-108 Ma in the north. The distribution of the AI ages generally reveals 2-stage primary OGA of the Permian reservoirs, which were mainly developed in the time spans of 175～155 Ma and 145～115 Ma respectively with 2-peak ages of 165 Ma and 130 Ma. Additionally, the FI temperature peaks of the samples and their projected ages on AFT thermal path of the FI-host rocks not only statistically present two groups with a low and a high peak temperatures in ranges of 90～78 °C and 125～118 °C, respectively corresponding to 2-stage primary OGA processes of 162～153 Ma and 140～128 Ma in the Permian reservoirs; nevertheless, there is also a medium temperature group with the peak of 98 °C in agreement with a secondary OGA process of ca. 30 Ma in the Upper Permian reservoirs. An integrated analysis of the AI and FI ages with the regional tectonic thermal evolution reveals that the Permian reservoirs in the northeast OB mainly experienced 2-stage primary OGA processes of 165～153 Ma and 140～128 Ma during the Mid-Early Mesozoic multi-cycle burial heating processes, and then the Upper Permian reservoirs further experienced 1-stage secondary OGA of ca. 30 Ma in accordance with a critical tectonic conversion from the slow to rapid uplift-cooling process during the Late Cretaceous-Neocene period.
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ZHANG Wan-Yi1, 2, NIE Feng-Jun3, LIU Shu-wen2, ZUO Li-Yan2, SHAN Liang2, YAO Xiao-Feng2
2013,40(5):1583-1599, DOI:
Abstract:
Abstract：Located in Chagan Obo－Aououte－Chaobuleng area along the southern edge of the Siberian plate, the study area on the western slope of the southern section of the Da Hinggan Mountains metallogenic belt (northern Dong Ujimqin Banner of Inner Mongolia ) is controlled by multiple subduction, collision and connection of North China platform, and characterized by widely exposed Paleozoic volcanic-sedimentary rocks, complex structures, all kinds of intense magmatic activities, and widespread ore deposits and ore spots. The study area has special favorable geological structure and setting for mineralization. On the basis of geological survey, the authors studied geological features of ore deposits and genesis of typical deposits, and summarized metallogenic regularities of this area. The results show that there are many kinds of ore deposits such as iron, silver, copper, lead, zinc, gold, and molybdenum. The δ34S values of typical deposits vary from +1‰ to +8.6‰. The sulfur isotope compositions show different sources. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of different samples vary in ranges of 17.949～18.529, 15.370～15.691 and 37.653～38.460, respectively. The lead isotope compositions indicate that the sources of lead were wall rocks and granites. The main types of ore deposits were skarn deposits and medium-low temperature hydrothermal deposits, which were significantly affected by formation, structure and magma. In general, the wall rocks of metal deposits were Ordovician, Devonian and Carboniferous volcanic- sedimentary rocks. Skarn deposits were formed near the contact zone between the carbonate and granite, while medium-low temperature hydrothermal deposits were formed in argillite and sandstone without carbonate. NE- and NW-trending faults were important ore channels or places for ore storage. The regional ore deposits in the study area were formed in three periods, i.e. Hercynian, Indosinian and Yanshanian. They were closely related to granite intrusions in temporal and spatial distribution.
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SUN Zhong-shi1, LIU Si-chuan1, 2, ZHENG Chang-qing1, TAN Lian2, SUN Li1, LI Juan1, SHI Lu1, CUI Fang-hua1, FAN Si-qi3
2013,40(2):529-537, DOI:
Abstract:
Abstract：Ore-controlling structure is always one of the difficulties in the study of hydrothermal deposits. With Chaihezhen-Moguqi region of the Da Hinggan Mountains as the study object, this paper puts forward some conclusions on the basis of the 1:250000 geological investigation of. Chaihezhen-Moguqi region. 1. The main ore-controlling structures are Daheishan-Taipingling-Jiguanshan fracture zone and Zalantun City-Haduo River fracture zone, and the formation ages are mainly Hercynian and Yanshanian. 2. Ore-controlling structures mainly show compression, tensile and shear properties, and between the three properties, there existed the conversion between shear and tensile and between shear and torsion, with the principal compressive stress field changing in the directions of E-W, SE-NW to SSE-NNW in succession. 3. The regularities of the main ore-controlling structures, the branching ore-control structures, and the parallel and inclined ore-controlling structures are summarized in this paper. These regularities, the structures as passageways for ore fluids and the ore source were closely related to deep subduction which produced molten magma. These new ideas are of great significance for the detailed study of geological foundation, metallogenic theory and prospecting work in this region.
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WANG Lei, LONG Wen-guo, ZHOU Dai
2013,40(4):1016-1029, DOI:
Abstract:
Abstract：LA-ICP-MS U-Pb dating was conducted for zircons from four gneissic granites in Yunkai area, which were assigned to Precambrian basement rocks or Neoproterozoic intrusion in 1∶250000 geological survey. The dating yielded 206Pb/238U weighted mean of 443.3±2.6 Ma (sample 1009, Lutou Reservoir in Luchuan City), 445.7 ±2.3Ma (sample 1010, Yuedong in Luchuan city), 441.1±2.0Ma (sample 1012, Xieji in Gaozhou city) and 443.7±1.7Ma (sample 1018, Zhusha in Xinyi city), suggesting that these rocks are Caledonian products rather than Precambrian basement or Neoproterozoic intrusive rocks. In combination with previous studies, the authors hold that these granites probably resulted from partial melting of the Proterozoic materials due to the Caledonian orogeny in South China. These results and recently published data (Caledonian) for the so-called Precambrian basement rocks, such as the crystallization age or metamorphic age of gneissic granite and gneiss, indicate that Yunkai area has undergone extensive reformation by the Caledonian orogeny. Actually, the Precambrian basement of Yunkai area mainly consists of gneissic rocks and meta-sedimentary rocks, which serve as the representative of the Gaozhou complex and the Yunkai Group, respectively. The Gaozhou complex was formed during the Meso- to Neo-proterozoic and the Yunkai Group might have been formed in the Neoproterozoic. The Paleo- to Meso-Proterozoic crystallized basement does exist in Cathaysia Block, however，which is not so widely distributed as previously thought.
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2013,40(2):430-438, DOI:
Abstract:
Abstract：Using samples from typical sections, drilling data and geochemical information from the Devonian black shale in Guizhong depression of central Guangxi, the authors analyzed the accumulation condition of shale gas reservoirs. The results demonstrate that there exist two suites of excellent marine source rocks in the middle and lower Devonian strata of Guizhong depression, which are characterized by large thickness and extensive distribution, high abundance of organic matter and moderate buried depth, thus possessing basic conditions for the formation of shale gas reservoirs. However, the preservative condition of shale gas is very poor because of the subsequent multistage severe tectonic movements as well as the development of faults and magmatic activities in some areas. Therefore, the central and western areas of Guizhong depression with integrated strata, underdeveloped faults and magmatic activities seem to be the favorable places for shale gas exploration. It is suggested that the preservation condition is very important in exploring shale gas resources under the conditions of high organic thermal evolution extent and subsequent multistage severe tectonic movements. The preservation condition is one of the key factors for shale gas exploration in China.
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ZHOU Jie1, 2, JIANG Yao-hui1, ZENG Yong2, GE Wei-ya2
2013,40(5):1379-1391, DOI:
Abstract:
Abstract：Jingde pluton is one of the Mesozoic plutons in eastern Jiangnan orogen of northeast Yangzte Block. New LA-ICPMS zircon U-Pb dating for one granodiorite yielded an emplacement age of (141.0±1.0) Ma. The pluton is composed of monzogranite and granodiorite. New petrographical and petrochemical data show that the pluton is intermediate-somewhat acid (SiO2=66.01%~70.87%), and has high content of Al2O3 (Al2O3=14.91%~16.24%) and rich alkali (K2O+Na2O = 6.64%~8.01% ), with K2O/Na2O value ranging from 0.78 to 1.04. The pluton has relatively low content of MgO, TFe2O3 and P2O5 (MgO = 0.68%~1.06%, TFe2O3=2.0%~3.34%, P2O5 = 0.10%~0.14% ). As for trace elements, the pluton is enriched in Sr (189×10-6~452×10-6) with high Sr/Y ratios (23~66) and also enriched in light rare earth elements (LREE) ((La/Yb)N = 13 ~ 58) , but somewhat depleted in Nb, Ta, P, Ti, Y, Yb, with slightly negligible to positive Eu anomalies (δEu=0.81~1.18), similar to the geochemical characteristics of Mesozoic adakitoid in eastern China. Jingde pluton has relatively high Nd isotopes (εNd(t)=-6.28~-7.32), high εHf (t) values (-6.5~-1.1) and younger tDM2 model ages (1.4~1.5Ga), with mafic microgranular enclaves (MMEs), suggesting the importance of mantle material in the magma source. The mafic magmas ascended and heated the lower crust, triggering the partial melting of the lower crust to form the Jingde pluton, with the input of mantle-derived materials.
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LIN Jin1, 2, LI Yun1, 2, HE Jian1
2013,40(5):1542-1551, DOI:
Abstract:
Abstract：By investigating data extracted from well cores, field outcrop samples, thin sections, cathodoluminescence images and the laboratory tests, the authors conducted a comprehensive study of the Carboniferous Benxi Formation in Yanchang area of Ordos Basin and then deduced its source directions from the angles of the mineral composition, genetic type, paleocurrent features, and enrichment regularities of rare earth elements. On such a basis, the authors analyzed the sedimentary facies distribution and evolution. It is revealed that from north to south in the study area, the sandstone grains decrease in size and increase in psephicity; the quartz cluster cathodoluminescence images are mainly fuscous, light-dark brown in color, indicating metamorphic genesis. The debris component is chiefly metamorphic debris, which is up to 85.1%. The paleocurrent of field outcrop moved northward, from northwest southward and southeastward. the distribution of the rare earth elements is quite similar to the Daqingshan old land at the northeast edge of the basin. It is thus concluded that the Benxi Formation primarily originated from Yinshan-Alxa in the north. The second stage of Benxi Formation in late Carboniferous epoch constituted a major turning point in the Upper Palaeozoic evolutionary history of Ordos. Due to the invasion of the slowly-subsiding sea water from the east, the study area formed a system composed of shallow argillaceous shelf, barrier island-lagoon and lagoon. The first stage was similar to the second stage in general features, but had larger argillaceous shelf and lagoon because of the intense water invasion, which had a good performance in the sand body continuity in parallel with the coastline.
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WANG Yong-lei1, CHEN Yu-chuan2, WANG Deng-hong1, XU Jue1, CHEN Zheng-hui1, LIANG Ting3
2013,40(5):1366-1378, DOI:
Abstract:
Abstract：Antimony is one of the dominant minerals in China, which was listed as the first global shortage minerals by British Geological Survey in 2011. In this paper, based on the mineral resource potential assessment project, in combination with data available and grade III metallogenic belt research, the authors summarized the characteristics of antimony resources in China and preliminarily assigned antimony deposits in China to 13 large ore concentration areas, with a brief description of their geological characteristics. Meanwhile, based on the existing data and new advances in the exploration of antimony deposits in recent years, this paper makes a comment on the metallogenic characteristics of the six most important antimony ore concentration areas with an analysis of their resource potentials. The authors hold that there are still some blank areas for working as well as some potential prospecting areas around the known mines. The new prospecting direction is also pointed out.
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SHAN Liang1, 2, XU Rong-ke3, ZHENG You-ye1, 3, ZHANG Yu-lian4, CAO Liang5, PANG Ying-chun5
2013,40(5):1600-1611, DOI:
Abstract:
Abstract：Beishan area is an important metallogenic belt, and the Baishantang Cu polymetallic deposit is one of the representative porphyry copper deposits. Two kinds of magmatic rocks along ore belt I in the Baishantang ore district were dated by the zircon LA-ICP-MS U-Pb method, which yielded a porphyry granite diagenetic age of （275.0±3.0）Ma (MSWD =1.17) , indicating early Permian. Two groups of ages were obtained for rhyolite porphyry: a magma zircon group of the rhyolite porphyry has an age of （371.1±2.8）Ma (MSWD=1.7) , suggesting late Devonian. The other inheritance zircon group of inheritance zircon with remarkable rounded shape or enveloped in the former group has ages of （2627±35）Ma, （2598±35）Ma, （705±44）Ma, （1722±48）Ma, （1642±51）Ma, （1213±54）Ma, which can be assigned roughly to 2.6 billion years, 1.7 billion years and 1.2 billion years, indicating that the rhyolite porphyry was related to the remelting of the upper-middle crust in late Devonian, as also shown by the geochemical characteristics.
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CHEN Guo-chao1, 4, PEI Xian-zhi1, LI Rui-bao1, LI Zuo-chen1, PEI Lei2, LIU Zhan-qing3, CHEN You-xin1, LIU Cheng-jun1
2013,40(4):1044-1065, DOI:
Abstract:
Abstract：In the East Kunlun orogenic belt (EKOB), mafic microgranular enclaves (MME) occur frequently in Late Permian-Triassic granitic rocks. In this paper, the authors took Helegang Xilikete granodiorites in the eastern part of the EKOB as an example to study their host rocks and MME in detail. Characteristics of the host rocks and the MME, such as field occurrence, morphology, texture and structure and mineralogy, together with the geochemistry, show that they were cooled and crystallized in a short time immediately after the intrusion of basaltic magma into intermediate-acidic magma and thus have similar distribution patterns to the host rocks in the REE diagram and trace element spider diagram, such as the enrichment of the LREE and LILE and the depletion of the HREE and HFSE, reflecting a typical feature of magma mixing. The result of LA-ICP-MS zircon geochronology implies that the crystallization age of the MME is about 224.9±4.1 Ma, very close to that of the host rock (225±5 Ma), suggesting a crust-mantle magma mixing event at the stage of post-collision in the EKOB in Late Triassic.
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LI Bing1, 2, CHAO Dai-chao3, WEI Ming-jun2, 4, LI Yong-feng2, 5, LUO Zheng-zhuan2, 5, SHANG Jian-ge1
2013,40(5):1644-1654, DOI:
Abstract:
The application of electromagnetic sounding method to deep iron ore exploration：A case study of the Wuyang iron mining area of Henan
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YAN Jian-she1, NIU Shu-yin2, FENG Jian-zhi3, SUN Wei-zhi3, SUN Ai-qun2, WANG Xing-cun3, CUI Xie-xiang3, CHEN Chao2
2013,40(2):538-548, DOI:
Abstract:
Abstract：The Xiaoqinling gold ore concentration area is known for its great uplift amplitude, high denudation extent, intense tectonic movement, clear structural features and concentrated distribution of ore deposits. The study area experienced four periods of folding, comprising from early to late plastic flow folding→regional EW-trending main folding →NS-trending crossing superimposed folds→transverse folding of vertical uplift, and was subjected to four periods of shearing, in order of plastic flowing →brittle ductile transpression→ductile brittle tenso-shearing →brittle forward detachment caused by uplift. The main stage brittle-ductile shearing was developed in the main limb of the weak tectonic belt. The third phase ductile-brittle shearing process of Yanshanian period provided favorable ore-hosting conditions for the large-scale injection of ore-forming fluids and mineralization. Researches show that the ore-forming fluids were mainly derived from the depth and, through the multistage evolution of mantle plume, injected into the ductile shear zone to form ore deposits via accumulation. In the ore district, there often exist one or two main ore veins which control more than 50% of metallic reserves.
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NIU Xiao-lu1, YANG Jing-sui1, CHEN Song-yong1, LIU Fei1, XIONG Fa-hui1, LIU Zhao1, GUO Guo-lin2
2013,40(3):756-766, DOI:
Abstract:
Abstract：Located in the western part of the Yarlung Zangbo suture zone, the Dongbo ultramafic rock massif is comparable with the Luobusa ultramafic rock massif which holds the largest chromite deposit in China in terms of their petrology and mineralogy. In this paper, the authors attempted to characterize its origin by examining the geochemistry of platinum group elements (PGE), major elements and rare earth elements (REE) of the harzburgites which are the main rocks of the rock mass. The harzburgites are characterized by high abundances of Os (3.52×10-9~4.36×10-9), depleted major element compositions and low REE content (0.89×10-6~1.37×10-6) which is lower than that of the primary mantle, indicating that the Dongbo ultramafic rocks belonged to depleted residual mantle rocks after a significant degree of partial melting and melt extraction. They also have high PGE content (23.97×10-9~31.98×10-9) which is higher than that of primary mantle, and display IPGE-depleted, PPGE-enriched chondrite- and primary mantle- normalized PGE patterns with Pd/Ir being 1.49~2.65. Their chondrite- and primary mantle-normalized REE patterns are all U- or V-shaped with (La/Sm)m being 1.05~3.37 and (Gd/Yb)m 0.28~0.64 (primary mantle-normalized values). These features are consistent with the opinion that the Dongbo ultramafic rocks were formed by the interaction of depleted residual mantle rocks with melts/fluids which were enriched with incompatible elements and PGE, especially IPGE relative to PPGE. In addition, the low Cu/Pd ratios (1226~3448) argue that the melts/fluids should also have high content of sulfides. The authors infer that the melts/fluids that reacted with the residual mantle rocks probably originated from the magmas produced in a subduction-related tectonic setting.
