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Genesis and Geological Significance of Late Archean Syeno-monzogranite in Western Shandong Province YANG Fan, CHEN Yuelong, YU Yang Geoscience    2022, 36 (04): 1155-1172.   DOI: 10.19657/j.geoscience.1000-8527.2022.04.18 Abstract （864）   HTML （14）    PDF（pc） （10063KB）（145）       Knowledge map    Save The Western Shandong is located in the east of North China Craton, which is an important area to study the Archean evolution.Petrology, geochemistry and zircon U-Pb dating and Hf isotopic composition were studied on the syeno-monzogranite in the southwest of Western Shandong Province.The syeno-monzogranite is characterized by calc-alkaline and peraluminous affinities.Zircon U-Pb dating shows that the syeno-monzogra-nite emplaced at~2 540 Ma to~2 530 Ma.Zircon Hf isotopic compositions show that they were primarily molten by TTG rocks of~2.70 Ga, and there is recycled ancient crustal component. The mixing calculation results under constraints of isotopic and trace element compositions confirm that the primary magma of syeno-monzogranite is composed of the mixing of 97% of the juvenile TTG crustal material after partial melting and 3% of metamorphic supracrustal rocks after partial melting.Combined with previous studies, we propose that the syeno-monzogranite was formed in an extensional tectonic environment.The late Neoarchean magmatism in Western Shandong was related to slab rollback.The upwelling of asthenosphere caused by the rollback provided heat source for the formation of this group of rocks. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Deformation Characteristics and Evolution of the Eastern Xiangfan-Guangji Fault Zone ZHU Qingbo, CHENG Wanqiang, ZHOU Quan Geoscience    2022, 36 (03): 755-769.   DOI: 10.19657/j.geoscience.1000-8527.2021.142 Abstract （581）   HTML （124）    PDF（pc） （12716KB）（254）       Knowledge map    Save The Xiangfan-Guangji fault zone(XGF) is a boundary fault separating the Dabie orogen and the foreland fold-thrust belt on the northern Yangtze cratonic margin. Its geometry, kinematics and structural evolution characteristics have recorded the collision, assembly and interaction between two tectonic units in the north and south. Based on field investigation, structural and geochronological analyses, and combined with published regional geological and geophysical data, we considered that the eastern XGF is characterized by a “crocodile mouth” offset structure of deep south-directed thrust and shallow north-directed thrust, which differs significantly from the structural deformation style and sequence of the western XGF. The eastern part of the middle Yang-tze block is controlled by the N-S-directed tectonic system. Subduction of the northern Yangtze cratonic margin beneath Dabie oregen may have extruded the orogen from north to south. The nappe structure may have affected the Ruichang area, and the shallow thrust nappe from south to north may have affected the vicinity of Meichuan. The two structures are likely connected in the Qichun-Wuxue-Xishui area in the eastern XGF. The XGF has undergone various structural deformation stages, including the N-S-directed thrust nappe ductile shearing (end T2), Early-Middle Yanshanian shallow bipolar offset detachment (J1-3), Late Yanshanian normal faulting (K1-2), and minor early Xishanian thrusting (E1) from north to south. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Characteristics, Genesis and Evolution of Daigu Landform in Yimengshan UNESCO Global Geopark CAI Yinlu, WU Fadong, HAN Jinfang, HUANG Zhen, ZHOU Ying, LIU Baoyin, CHEN Yangyang Geoscience    2023, 37 (04): 1065-1074.   DOI: 10.19657/j.geoscience.1000-8527.2023.085 Abstract （556）   HTML （8）    PDF（pc） （12188KB）（220）       Knowledge map    Save The Yimengshan UNESCO Global Geopark (UGGp) is the origin of the “Daigu Landform”. Through field investigation of the characteristics of Gu landform, based on the measurement of river valley stratigraphy and profiles, and using the OSL dating of the river terrace to calculate the cutting rate, the formation time of Daigu Landform has been determined. The results show that the geomorphological features of the Daigu Landform are related to the strata lithology of the Gu body. Daigu Landform is a type of mesa structure, with a flat top, steep margin and gentle slope. Gu body is mainly composed of two strata with different lithologies: The top comprises Cambrian limestone with strong weathering resistance but develops many joints, while the Gu body with weak erosion resistance is dominated by mudstone and siltstone. We estimated that the formation time is about 1.77 Ma by using the erosion rate, based on the dating results of the river terrace. The Daigu Landform formation and evolution can be divided into four main stages: (1) the material was formed in the Early Cambrian; (2) tectonic uplift, and the strata gradually exhumed and the shaping stage began; (3) long-term weathering and denudation of various external forces, such as surface water that gradually created the mature Daigu Landform; (4) the landform ended its development when the upper limestone collapsed. The systematic study of the Daigu Landform has great importance in understanding the Daigu Landform and its scientific value, which also contributes to the spreading of geoscience knowledge of UGGps. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Characteristics and Scientific Values of “Canyon and Danxia” Landform in Hualong County, Qinghai Province LIU Xinlan, ZHANG Xujiao, LI Junlei, WANG Yifan, ZHANG Xiangge, YUAN Xiaoning, WANG Kaiya, WANG Chongge, LIU Jiang, HOU Engang Geoscience    2023, 37 (01): 233-244.   DOI: 10.19657/j.geoscience.1000-8527.2023.031 Abstract （507）   HTML （35）    PDF（pc） （12319KB）（201）       Knowledge map    Save “Canyon and Danxia” is a composite landscape formed by both internal and external geological processes, and has great landscape and scientific value. The Lamu river in Hualong county (Qinghai Province) is a primary tributary of the Yellow River, where typical angular unconformity and Danxia landform are developed. This makes Hualong a suitable area for studying the Qinghai-Tibetan Plateau uplift and the Yellow River evolution. Aiming at elucidating its morphology, genesis, and chronology, this field study focuses on the rock formation, strata and tectonic setting of “Canyon and Danxia” landform. We systematically concluded the driving force and formation processes of the landscape in the Lamu canyon, and discussed its implications to the Qinghai-Tibetan Plateau uplift and the Yellow River evolution. The Lamu canyon is composed of the Neoproterozoic Hualong Complex gneiss (~900 Ma) and Paleogene Xining Group red glutenite (~54 Ma) with an angular unconformity. The Danxia landform in the canyon was developed when the Qinghai-Tibetan Plateau started uplifting at 8 Ma. After the Hualong Basin was cut by the Yellow River at 1.1 Ma, the canyon developed “Canyon and Danxia” landform via continuous river incision and gravitational collapse. The canyon is precipitous and the Danxia landform is lifelike, which are typical, unique and rare national-class geoheritage. It has important research value on the uplift of the Qinghai-Tibetan Plateau, the evolution of the Yellow River, and the Cenozoic climate and environment. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Distribution,Sources and Ecological Effects of Selenium in Topsoil of Cultivated Land in Jiande City, Zhejiang Province LIU Jian, WANG Yifan, LIN Zhongyang, PAN Shaojun Geoscience    2022, 36 (03): 953-962.   DOI: 10.19657/j.geoscience.1000-8527.2022.03.15 Abstract （498）   HTML （7）    PDF（pc） （6146KB）（142）       Knowledge map    Save Selenium is one of the important life elements, which is of great significance to animal and human health. In this paper, we systematically summarized the geochemical characteristics of selenium in topsoil of cultivated land, and analyzed the distribution law of selenium in soil and the genetic relationship between selenium and black rock series. We also discussed the selenium enrichment mechanism in black rock series, and studied the selenium enrichment law in rice plants. We hope that these studies are helpful to reveal the source and ecological effect of selenium in soil of Jiande City. Our results show that the selenium content in topsoil of cultivated land in Jiande City ranges from 0.06 to 11.5 mg/kg, with an average of 0.35 mg/kg. The difference of selenium content in soil is very significant in different geological background, soil parent materials and soil types. In our study aera, 2,647 hectare of clean selenium-rich soils were delineated according to the content of selenium and heavy metals in the soil. Selenium-rich soils are mainly distributed in Cambrian limestone, carbonaceous shale, calcareous mudstone, indicating that the enrichment of selenium in the soil is closely related to the Cambrian “black rock series”. Paleosedimentology research shows that the black rock series were formed in the sedimentary environment of anoxic stagnant water. The organic-rich submarine sediments adsorbed a large amount of selenium from the mantle. After the consolidation and diagenesis, the black rock series which are rich in selenium and other elements were formed. The morphological characteristics of selenium in rice root soil in this study area show that the proportion of acetic acid soluble selenium is relatively small, while the proportion of residual selenium is relatively large, indicating that the availability of selenium in rice root soil is low. The selenium contents in rice, lotus seed and strawberry show that rice has the highest selenium enrichment coefficient, and the selenium content in rice plants was characterized by root > leaf > stem ≈ seed. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Sulfur and Lead Isotopic Compositions of Zebuxia Pb-Zn Deposit in Tibet:Implications for the Sources of Ore-forming Material DU Baofeng, ZHANG Rongzhen, YANG Changqing, LI Shanpo, TAN Heyong, ZHU Hongyun Geoscience    2022, 36 (04): 1138-1145.   DOI: 10.19657/j.geoscience.1000-8527.2022.04.16 Abstract （458）   HTML （11）    PDF（pc） （4804KB）（103）       Knowledge map    Save Zebuxia Pb-Zn deposit in Tibet is located in the western part of the north Gangdean metallogenic belt,and it occurs in the Dianzhong Formation of Paleogene. Based on analysis of the metallogenic geological conditions,this paper studies systematically the composition characteristics of sulfur and lead isotope in the ore minerals and discusses the sources of the ore-forming materials. The results have shown that the composition of sulfur isotope in ore sulfides has a narrow variation range from -0.6‰ to 2.7‰ and a tower distribution features,which indicates relatively concentrate and presents a characteristic of sulfur from magmatic origin,and may be related to the lots of granite porphyry or concealed granite. The lead isotopic composition of ore sulfides is stable and should belong to ordinary lead. According to the μ values range from 9.61 to 10.0 and the tectonic evolution diagram of lead isotopic,it can be concluded that the ore lead mainly derived from upper crust. Combined with regional diagenesis-metallogenic event and geological characteristics of Zebuxia Pb-Zn deposit,the ore-forming materials probably came from the magma formed by partial melting of the upper crust in the period of main collisional setting in Tibetan orogenic belt. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Application of GF-5 Satellite Hyperspectral Data to Uranium Ore Geological Prospecting in Longshoushan Area in Gansu Province FENG Bo, DUAN Peixin, CHENG Xu, LU Huixiong, LI Ruiwei, ZHANG En, WANG Bing Geoscience    2022, 36 (06): 1594-1604.   DOI: 10.19657/j.geoscience.1000-8527.2022.06.14 Abstract （457）   HTML （14）    PDF（pc） （16126KB）（193）       Knowledge map    Save Hyperspectral remote sensing technology is widely used in geological prospecting. Gaofen-5 (GF-5 for short) is China’s first hyperspectral comprehensive observation satellite, which has hyperspectral resolution remote sensing data of 330 spectral segments. To improve our understanding, it is necessary to explore the application effect and potential of GF-5 space hyperspectral remote sensing technology to unveil the relevant processes in uranium geological prospecting. This study used hyperspectral data in Longshoushan metallogenic belt, Gansu Province, to carry on hyperspectral data processing and alteration information extraction study. GF-5 hyperspectral band repair was innovatively realized. By constructing standard spectral library and diagnostic spectrum, MNF algorithm, PPI algorithm and SAM spectral angle mapping technology were used to complete alteration mineral end-member extraction and spectral matching. We finally achieved the extraction of albite, calcite, quartz, chlorite, hematite and kaolin alteration minerals in our study area. Comprehensive regional uranium ore-forming geological background, by conducting ground spectrum measurement and field investigation, on the basis of accuracy verification alteration, we analyzed the space hyperspectral alteration information and metallogenic regularities, built the regional prospecting orientation model, at the same time three prospecting prediction areas were delineated, and good prospecting results were achieved. This paper provides reference for the application of GF-5 hyperspectral remote sensing in geological prospecting. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Division and Geological Evolution of Pre-Nanhua Tectonic Units in Qaidam Basin and Its Northern and Southern Margins ZHANG Jinming, WANG Bingzhang, FU Yanwen, TIAN Chengxiu Geoscience    2022, 36 (05): 1193-1205.   DOI: 10.19657/j.geoscience.1000-8527.2022.040 Abstract （454）   HTML （22）    PDF（pc） （4673KB）（234）       Knowledge map    Save Based on the comprehensive research and regional survey in recent years, we have studied the material composition, metamorphism and deformation of the Pre-Nanhua period in the Qaidam Basin and its northern and southern margins. Tectonic units in the Qaidam basin and its northern and southern margins are divided into five ancient land mass (i.e., Mesoproterozoic Huangyuan continental block, Neoarchean-Paleoproterozoic Quanji continental block, Paleoproterozoic Dakendaban continental block, Paleoproterozoic Jinshuikou continental block, and Mesoproterozoic Ningtuo continental block) and eight secondary structural units. The geological characteristics of each tectonic unit are discussed, and the geological process and evolution of the Qaidam Basin and its northern and southern margins in the pre-Nanhua geological stage are reconstructed. Compiling the key geological events in the region, tectonic evolution of the Qaidam basin and its northern and southern margin includes Neoarchean continental nuclei formation, Paleoproterozoic early rifting, the Late Paleoproterozoic-Mesoproterozoic ancient land mass formation, Early Neoproterozoic mid-stage intracontinental rifting, the Early Neoproterozoic continental convergence. Six Neoproterozoic continental riftings were in response to the global Kenorland, Columbia and Rodinia supercontinental cycle events. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Zircon U-Pb Age and Geochemical Characteristics of Granites from the Qianchuiliu Gold Mine in the Jiaodong Peninsula and Its Geological Significance GUO Yuncheng, DUAN Liuan, HAN Xiaomeng, WANG Jiantian, WANG Lipeng, ZHAO Pengfei Geoscience    2022, 36 (03): 876-897.   DOI: 10.19657/j.geoscience.1000-8527.2021.128 Abstract （451）   HTML （19）    PDF（pc） （15038KB）（148）       Knowledge map    Save The Qianchuiliu gold deposit was located in northeastern margin of Jiaolai Basin, Jiaodong Peninsula. Concealed gold orebodies with 13.5 tons of inferred gold reserve were discovered in the major ore-controlling structure-alteration belt in 2020. Two different granites were found adjoining to the major ore-controlling structure-alteration belt based on drilling. The hanging-wall comprises monzogranite of the Muniushan pluton and the Jingshan Group, whereas the footwall comprises mylonitized monzogranite of the Queshan pluton. The Muniu-shan pluton was conventionally considered as a part of the Queshan pluton, but we observed some differences in terms of metamorphic/deformation degree and mineral assemblages. Therefore, both kinds of granites were systematically analyzed by zircon U-Pb geochronology, lithogeochemistry, and zircon Hf isotope geochemistry to identify the differences and any gold metallogenic link. Zircon U-Pb age of the Muniushan monzogranite is 1,844.1±4.4 Ma, indicating a Paleoproterozoic (Orosirian) magmatic product. The monzogranite is characterized by relatively high SiO2 but low MgO contents. The monzogranite has low Sr content and Sr/Y ratio, high Y and Yb content, and obvious negative Eu anomaly (δEu=0.30-0.48). The Muniushan monzogranite is calc-alkaline and strongly peraluminous. The monzogranite has zircon εHf(t) values range from -9.5 to 3.0, most of them are negative with two positive values (0.2 and 3.0). The two-stage Hf model ages range from 2,492 to 3,083 Ma, indicating that they were mainly originated from partial melting of the Archaean lower crust. The Queshan mylonitized monzogranite yielded Late Jurassic zircon U-Pb age of 154.6±1.5 Ma, coeval with the well-known Linglong and Kunyushan granitic complexes in the region. The mylonitized monzogranite has high content of SiO2 and low content of MgO. Trace elements are characterized with high Sr and Sr/Y ratio, low Y and Yb content and significant positive Eu anomaly (δEu=1.61-2.20). The rocks are high-K calc-alkaline and peraluminous, showing adakite-like affinity. The mylonitized monzogranite has zircon εHf(t) values of -26.6 to -14.1. The two-stage Hf model ages range from 2,681 to 3,860 Ma, concentrated around 2,820 Ma, indicating that the granite was formed by melting of the Archaean thickened lower crust. All the above studies show the Muniushan monzogranite and the Queshan mylonitized monzogranite granite are two different granites with different zircon U-Pb ages, lithogeochemistry and tectonic setting. Both granites show close spatial link with the gold mineralization, but no temporal or direct genetic connection. Drill-cores of Qianchuiliu gold mine could be divided into three layers. This three-layer structure is geologically similar to the Queshan metamorphic core complex. The newly-discovered Qianchuiliu gold deposit implies great potential of gold prospecting in this area, especially the ductile shear zones and low-angle major detachment faults around the Queshanpluton. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Gemological and Chemical Composition Characteristics of Basalt-Hosted Rubies from Thailand LI Enqi, ZHANG Yufei, XU Bo Geoscience    2023, 37 (02): 486-499.   DOI: 10.19657/j.geoscience.1000-8527.2021.143 Abstract （420）   HTML （7）    PDF（pc） （7129KB）（146）       Knowledge map    Save We analyze the basalt-hosted ruby from Thailand to explore the gemological, chemical and spectral characteristics of ruby, by using gemological conventional instruments, EPMA, LA-ICP-MS, UV-Vis spectrophotometer, FTIR, Raman spectrometer and other testing methods. We then compare our data with the ruby from Myanmar and Mozambique, and identify the characteristics of different deposit origins. The results show that the Thai rubies have dark color, and they are mostly of medium-weak red fluorescence under UV-long wave and inert under UV-short wave. Internal inclusions are plentiful, with various forms of solid and fluid inclusions and twin-crystals. The rubies contain mainly Al2O3, with trace elements including Cr, Fe, Ti, Mg, V, Ga, Si, and Ni, and are characterized by high Fe, high Mg and low Ga contents. The UV-Vis absorption spectral data show Cr and Fe, and the Cr-related fluorescence peak is weak. The infrared spectral test result shows ruby. There are six vibration peaks in Raman spectrum, which display high coincidence with the standard corundum Raman spectrum. The ruby origin can be identified by the ruby appearance, fluorescence, solid inclusions, and fluid inclusions. Contents of Cr, Fe, Mg, Ga, V, and Ti have obvious origin inheritance. The UV-Vis spectra of rubies from different origins have slightly different absorption peaks. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Formation Age and Magma Source of the Shazhangtu Diorite Porphyry, Inner Mongolia: Constraints of Petrogeochemistry, Zircon U-Pb Geochronology and Hf Isotopes LÜ Yunhe, DONG Guochen, ZHAO Liwei, SU Lin, YIN Guodong, TANG Jiahui Geoscience    2022, 36 (03): 836-847.   DOI: 10.19657/j.geoscience.1000-8527.2021.147 Abstract （417）   HTML （19）    PDF（pc） （7729KB）（139）       Knowledge map    Save Diorite porphyry has been widely studied due to its genesis and ore-bearing characteristics. Many diorite porphyry intrusions were found in the north of Abagaqi (Inner Mongolia), accompanied by high-background geochemical anomalies. Studies on petrology, zircon U-Pb geochronology, geochemistry and Lu-Hf isotopes have been conducted for the formation age and magma source of diorite porphyry samples from the Shazhangtu mining area in Inner Mongolia. The diorite porphyry was emplaced at (311.1±1.7) Ma, and is the product of the middle Hercynian (Late Carboniferous) tectonomagmatic activities. The rocks have SiO2=56.19%-60.45%, Na2O+K2O=4.81%-5.87%, and aluminum saturation index (A/CNK)=1.00-1.43. It belongs to high potassium calc-alkaline and peraluminous rocks. The LREE LILE (K, Rb) and HFSE (Zr,Th and U) are enriched, and the HFSE (Nb, Ta, P, Hf and Ti) are depleted, indicating that the geochemical characteristics of island are magmatic rocks in subduction zone. The total REE contents ranges from 139.62×10-6 to 150.67 ×10-6, showing a right-inclined pattern of light rare earth enrichment and heavy rare earth depletion with weak negtive Eu anomaly. The Hf isotopic data of zircons show that the single-stage and two-stage model ages range from 637 to 905 Ma and from 827 to 1,259 Ma, respectively, and the εHf(t) value of zircons varies from 1.10 to 7.80, indicating the characteristics of mantle-derived magma. It is probably the partial melting magma in the mantle wedge due to the dewatering of the subduction plate that underplated under the bottom of the lithosphere and the molten body rises to cause under-invasion, heated and induced the partial melting of the new formed juvenile basic lower crust, forming the crust-mantle sources mixed magma. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Geochemical Characteristics and Source Analysis of Heavy Metals in Soils of Eastern Yinan, Shandong Province LIU Tong, LIU Chuanpeng, KANG Pengyu, ZHAO Xiufang, DENG Jun, WANG Kaikai Geoscience    2022, 36 (04): 1173-1182.   DOI: 10.19657/j.geoscience.1000-8527.2022.04.19 Abstract （416）   HTML （17）    PDF（pc） （5528KB）（193）       Knowledge map    Save In order to present the status of soil heavy metal pollution in Yinan County, Shandong Province, 4,779 surface soil samples were collected systematically in this area, and the concentration of Cd, Hg, Pb, As, Cr, Ni, Cu, Zn and pH value were analyzed. The geochemical characteristics of heavy metals and possible sources have been discussed by geostatistics, multivariate statistics, spatial analysis and other analysis methods. The results show that the Hg mean value in soil is slightly higher than the background value of surface soil in Linyi city, and the respective mean values of the other seven elements are equivalent to that of Linyi. Compared with the screening value of GB 15618—2018 (soil environmental quality risk control standard for soil contamination of agricultural land), the concentration over-standard rate of eight heavy metal elements in the research area is low. But the exceeding standard multiple of the maximum value is large, that shows local point and small pieces are seriously polluted. The concentration of 8 kinds of elements in the research area shows a three-step decline from west to east. The high concentration of Cd, Pb, Zn and As in the soil are mainly controlled by natu-ral source, parent rocks, superimposed different degrees of industrial and mining transportation and agricultural activities. Cr and Ni are almost completely controlled by parent rocks. Hg and Cu are controlled mainly by the mining and smelting activities of Yinan Jinchang and Tongjing gold mine, followed by industrial and traffic emissions, agricultural manure and pesticide application. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Development of the Chinese Continental Scientific Deep Drilling: Perspectives and Suggestions ZOU Changchun, WANG Chengshan, PENG Cheng, WU Caowei, GAO Yuan Geoscience    2023, 37 (01): 1-14.   DOI: 10.19657/j.geoscience.1000-8527.2022.101 Abstract （416）   HTML （43）    PDF（pc） （2533KB）（313）       Knowledge map    Save As the most direct and important method to detect the Earth’s deep interior, scientific drilling plays a key role in solving the strategic technological issue of deep Earth exploration. This study briefly reviews the development and current situation of domestic and international continental scientific drilling and deep drilling, and analyzes the characteristics and trends of continental scientific drilling development. We summarized the Chinese Continental Scientific Drilling, its key scientific and technological issues, as well as challenges and opportunities. Accordingly, we proposed the development goals, priorities and approaches of the Chinese Continental Scientific Drilling. Continental scientific deep drilling can provide a unique pathway for investigating global concerns in Earth sciences, such as geodynamic processes, geohazards, mineral and energy resources, and environmental changes. However, its implementation depth is constrained by ultra-high temperature and ultra-high pressure in harsh borehole environments. Modern scientific advances have promoted the development of various technologies in continental scientific drilling, which provide important support for ultra-deep and extra-deep drilling. The Chinese Continental Scientific Drilling should aim for 9,000-15,000 m extra-deep boreholes, focusing on scientific issues in the fields of ultra-deep, deep-time and deep-observation. Priority development directions can include deep Earth tectonics, deep-life, deep-climate, and deep-resources. The priority detection technologies can include those for drilling, logging, and long-term observation in ultra-high temperature-pressure environments. Priority should also be given to the experimental technique development for ultra-deep matter, dynamics processes, and petrophysics. This would promote a breakthrough in the capacity and level of Earth interior detection in China. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Dangjiasi Granite Complex and Late Triassic Dykes in Qinghai Nanshan Tectonic Zone, and Its Constraints on the Early Mesozoic Tectonic Environment YANG Yanwei, LU Xinxiang, WANG Liwei, YANG Yi, YANG Chongke, HUANG Fan Geoscience    2022, 36 (03): 796-811.   DOI: 10.19657/j.geoscience.1000-8527.2022.016 Abstract （384）   HTML （16）    PDF（pc） （8913KB）（95）       Knowledge map    Save The Dangjiasi granite complex is a larger pluton in the central-eastern part of the Indosinian Nanshan granite belt(Qinghai Province). The complex was emplaced in the Early Triassic (243.5±2.9 Ma,247.2±1.7 Ma)-Middle Triassic (240.1±2.1 Ma,241.0±2.6 Ma). There are many intermediate felsic dykes in the intrusion, comprising mainly diorite porphyry, quartz diorite porphyry, and granite porphyry, LA-MC-ICP-MS zircon U-Pb dating on the diorite porphyry dyke yielded early Late Triassic age (235.6±2.4 Ma), slightly younger than the minimum emplacement age limit of the Dangjiasi granite complex. As a shallow intrusive body, the dykes are similar to the Dangjiasi intrusion in structural setting, and their mineral and geochemical compositions have similar characteristics, indicating that the two rock types have similar genesis and tectonic background, and may have had the same crust-mantle mixed magma source region. Litho-geochemistry shows that the intermediate dykes have low SiO2(54.68%-64.75%), whilst the felsic dykes have high SiO2(66.00%-77.13%), and both have high Al2O3(12.24%-17.11%). The rocks are high-kcalc-alkaline metaluminous-weakly peraluminous (A/CNK=0.85-1.04), with typical island arc granite and collision granite affinities. The rocks are enriched in LREE, Rb, Th and K, but depleted in HREE, Nb, Ta, P, Ti and Ba with (La/Yb)N=5.05-17.61 and medium negative Eu anomaly. Comprehensive analysis suggests that the dykes were formed in the Late Triassic Gonghe rift-closure related collisional orogeny. The tectonic setting changed from compression to intraplate stability-extension, suggesting that the Gonghe Basin(and surroundings) had entered post-collision intracontinental environment in the early Late Triassic. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Geochemical Characteristics and Influencing Factors of Selenium-enriched Soils in Cultivated Land Around Typical Stone Coal Mines in Western Zhejiang WANG Meihua Geoscience    2022, 36 (03): 941-952.   DOI: 10.19657/j.geoscience.1000-8527.2021.03.14 Abstract （377）   HTML （9）    PDF（pc） （5064KB）（112）       Knowledge map    Save To better understand the geochemical characteristics and influencing factors of the selenium-enriched soils of the arable land around the stone coal mine,144 topsoil samples were collected from the cultivated land around Huibu stone coal mine in Changshan County, Zhejiang Province, and 20 sugarcane samples, 6 soil vertical profile samples, 5 rock samples, 3 surface water samples were collected at the same time. The contents of Se, organic matter, As, Cd, Cu, Pb, Zn, Ni, Hg and Cr were determined to explore the geochemical characteristics of Se rich soil. The results showed that Se content mainly concentrated in the range of 0.47-1.34 mg/kg in surface soil, with an average content of 0.87 mg/kg, which was much higher than that average value of Zhejiang Province, and the high value area of Se content was consistent with the strike of stone coal mine in Huibu. Se content decreased with the increasing depth along the vertical profile of soil. 89.58% of the soil samples and 65% of the sugarcane samples reached the Se enrichment standard, but there was an ecological risk that the contents of Cd and other major heavy metals in soil and agricultural products exceeded the state standard. The average content of Se was the highest (1.31 mg/kg) in the $\epsilon$1h of soil stratum, and the lowest (0.64 mg/kg) in the O1-2. The average selenium content in dry field was slightly higher than that in paddy field without significant difference(p>0.05). The highest average selenium content was that of coarse bone soil, followed by that of limestone soil and paddy soil, and that of red soil was the lowest. The selenium content in soil had been affected by geological background, soil type and organic matter. The main factors for the formation of selenium rich soil had been regarded as the stone coal bed, black rock series and carbonate rocks, and a small part was related to human activities such as mining. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Natural Gas Exploration Prospect of the Platform Marginal Zone of the Fourth Member of Sinian Dengying Formation in Southeastern Sichuan Basin SUN Ziming, BIAN Changrong, ZHANG Rongqiang, SUN Wei, WU Chongyang, LIN Juanhua Geoscience    2022, 36 (04): 979-987.   DOI: 10.19657/j.geoscience.1000-8527.2022.194 Abstract （376）   HTML （21）    PDF（pc） （7357KB）（135）       Knowledge map    Save The platform marginal zone of the Sinian Dengying Formation on both sides of Mianyang-Changning extensional trough is an important exploration target for natural gas in Sichuan Basin. Since Anyue natural gas field, located in the platform marginal zone of Dengying Formation on the eastern side of the extensional trough, was discovered at the core of central Sichuan paleo-uplift, more and more attention has been paid to the deep to ultra-deep platform marginal zone of Dengying Formation on the south and north side of the paleo-uplift. However, it is unclear about its distribution, geometrical features and hydrocarbon accumulation conditions of the platform marginal zone of Dengying Formation and exploration potential, especially in southeastern Sichuan Basin. Therefore, the platform marginal zone of the fourth member of Dengying Formation in the southern slope of central Sichuan paleo-uplift and its adjacent depression was systematically studied by using the latest seismic and drilling data in southeastern Sichuan Basin. It was shown that the distribution direction of the platform marginal zone of the fourth member of the Dengying Formation extends from NE to NNW from south to north, and shows the characteristics of gentle slope platform marginal zone, which is significantly different from those in the central Sichuan paleo-uplift and its northern slope to depression. There exist three sets of source rocks developed in the Sinian Doushantuo Formation, the third member of Dengying Formation and the Cambrian Qiongzhusi Formation, which laid the sound resource basis for large and medium-sized oil and gas fields. Reservoir has a good quality. The traps are mainly lithologic traps, developed in large numbers, and have good self-sealing characteristics in the updip direction. There are three kinds of accumulation assemblages of “lower generation and upper reservoir, side generation and side reservoir, and upper generation and lower reservoir”. Two sets of regional cap rocks, Qiongzhusi Formation shale and Middle-Lower Cambrian gypsum rock, provide a good preservation condition for hydrocarbon accumulations. All of the above mentioned indicate that there are good exploration prospect and great potential for natural gas in the platform marginal zone of the fourth member of the Dengying Formation in southeastern Sichuan Basin. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Study on Organic Petrology Characteristics of the Wufeng-Longmaxi Formation Black Shale, Sichuan Basin LIU Siyi, GAO Ping, XIAO Xianming, LIU Ruobing, QIN Jing, YUAN Tao, WANG Xu Geoscience    2022, 36 (05): 1281-1291.   DOI: 10.19657/j.geoscience.1000-8527.2022.046 Abstract （372）   HTML （8）    PDF（pc） （7415KB）（239）       Knowledge map    Save At present, there is no unified classification and definition of organic macerals in the Wufeng-Longmaxi Formation black shale, which made it difficult for regional shale gas exploration and evaluation. In this study, organic macerals in the Wufeng-Longmaxi Formation black shale from the Sichuan Basin were identified and summarized via optical microscopic observation of polished blocks and organic geochemistry (TOC, δ13Corg), and their origins and organic matter types were determined. Our results show that organic macerals are mainly composed of the marine vitrinite, sapropelinite, organic zooclast and secondary groups. Among them, marine vitrinite group consists of round-/rod-shaped structureless vitrinite, and displays strong light reflection, but it is only locally distributed. The sapropelinite group is mainly composed of structureless sapropelinite, and is widely developed in organic-rich shale, which is the product of algal materials that underwent geological processes of thermal degradation. The organic zooclast group includes graptolite epidermis, chitinozoans and radiolarians. Meanwhile, the secondary group is composed of secondary bituminites, which is widely developed in matrix porosity of shales and is amorphous. The sapropelinite and secondary groups are the major types of organic macerals in the shales of Wufeng-Longmaxi Formation, whereas organic zooclast and marine vitrinite groups are less common. The organic matter type of studied shales is predominately type Ⅰ-Ⅱ1 kerogen. Moreover, the relative contents of sapropelinite and secondary groups increase, and organic matter type tends to oil-prone, contributing to their greater potentials of hydrocarbon generation. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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In-situ Stress Distribution and Its Influence on Coalbed Methane Development in Tielieke Mining Area, Kubai Coalfield, Xinjiang WEI Yongheng, GE Yanyan, WANG Gang, WANG Wenfeng, TIAN Jijun, LI Xin, WU Bin, ZHANG Xiao Geoscience    2022, 36 (05): 1324-1332.   DOI: 10.19657/j.geoscience.1000-8527.2022.021 Abstract （372）   HTML （7）    PDF（pc） （5136KB）（110）       Knowledge map    Save In-situ stress, coal reservoir permeability and coal reservoir pressure are the important factors on coalbed methane development.Based on the analysis of injection/fall-off well analysis and in-situ stress measurement data, and combined with the analysis of daily gas production of coalbed methane wells in the Tielieke mining area (Kubai coalfield, Xinjiang), we study the characteristics of in-situ stress distribution at Tielieke and its influence on CBM development.The results show that: (1) the in-situ stress state changes vertically, with σH>σv>σh, σH≈σv>σh and σv>σH>σh at 550-650 m, 650-850 m and 850-1,200 m reservoir depth, respectively; (2) 850 m depth is not only the conversion point of the vertical principal stress and the maximum horizontal principal stress, but also the transition point of permeability trend. This demonstrates the in-situ stress the control on permeability; (3) the in-situ stress correlates negatively with permeability, but positively with coal reservoir pressure; (4) for the in-situ stress, its negative effect of on productivity is greater than its positive effect on productivity, and hence the typical daily gas production decrease with increasing in-situ stress; (5) the central coal reservoirs in Tiexi and Tiedong mining areas have relatively developed granular coal, large adsorption pore volume and gas content, which are favorable intervals for CBM development.Our results provide theoretical guidance for further CBM development in the Kubai coalfield. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Geochronology and Petrogenesis of the Highly-Fractionated Early Cretaceous Narenwula Granite, Inner Mongolia, China LI Zhu, ZHANG Dehui, ZHANG Rongzhen, SHEN Cunli, JIAO Shihao, LI Lin, ZHU Penglong Geoscience    2022, 36 (03): 848-861.   DOI: 10.19657/j.geoscience.1000-8527.2021.064 Abstract （369）   HTML （8）    PDF（pc） （10778KB）（300）       Knowledge map    Save A number of rare metal deposits have been discovered in Narenwula area of Inner Mongolia, with high metallogenic potential. However, there are still many controversies about the chronology and genesis of Narenwula granite. LA-ICP-MS zircon U-Pb dating and geochemical analysis have been carried out to determine the age and genetic type of the Narenwula granite. The U-Pb dating results show that the medium-coarse biotite monzogranite and porphyritic monzogranite were emplaced in the Early Cretaceous, at (142.1±1.0)Ma and(142.3±1.2)Ma, respectively. Its diagenetic age is basically consistent with the ages of the extensive regional granite emlacement in the Late Jurassic-Early Cretaceous period. Whole-rock geochemistry shows that the granite is characterized by high silica(SiO2=73.69%-76.67%)and alkali(Na2O+K2O=8.40%-8.80%), but low P2O5, MgO, FeOT, CaO, and REE. The rocks have high LREE/HREE ratios(LREE/HREE=6.23-14.28) and marked negative Eu anomalies (δEu=0.20-0.36). They are obviously enriched in Zr, Hf, Rb, and Th, but strongly depleted in Ba, Sr, P, and Ti, and slightly depleted in Nb. The granite is high-K calc-alkaline and weakly peraluminous. Based on the characteristics of mineralogy, petrology and geochemistry, we concluded that the granite belongs to highly-fractionated I-type. Considering the structural features and regional geological background, we inferred that the Narenwula granite in the northern margin of the North China Plate was formed in the Early Cretaceous within-plate extensional setting. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Site Selection Strategy for An Annual Million-Ton Scale CO2 Geological Storage in China WANG Zijian, TANG Xuan, JING Tieya, YOU Mingxin, ZHANG Jinchuan, LI Zhen, ZHOU Juan Geoscience    2022, 36 (05): 1414-1431.   DOI: 10.19657/j.geoscience.1000-8527.2022.044 Abstract （358）   HTML （18）    PDF（pc） （4500KB）（337）       Knowledge map    Save CO2 geological storage are very important technology for the sustainable development for the industries with difficulties in reducing CO2 emissions. Compared with some countries that have succeeded in large CO2 geological storage projects with storage capacity of over a million tons per year, China’s CO2 geological storage projects are still in early stage, most projects in the size of 100,000 tons per year. China still lacks experience in CO2 storage site selection, injection and monitoring of large(>1 m tons CO2/year) CO2 geological storage projects. We classify the storage space into two types in term of their geological type, e.g. structural traps (anticline, fault and fracture) and lithologic traps (sandstone and carbonate reef). Based on the study of 15 large CO2 geological storage projects around the world, four classes of indices for site determination were summarized, storage size, injecting capacity, safety and economic evaluation. The site selection principle and parameters for CO2 geological storage sites with an annual storage capacity of one million tons are defined. In terms of basin types and geological characteristics of China, different CO2 storage strategies need to be adopted. For instance, for large cratonic basins, such as the Ordos and Songliao basins, which contain wide distribution of sandbodies, and large-scale anticline and lithologic traps, they provid the potential for large-scale deep saline aquifers or depleted petroleum reservoir storage site. For the fault-bound basins such as the Bohai Bay and China offshore basins, well-developed faults or fault-related traps provide only small storage capacity and they are easily influenced by sealing effectiveness. It is thus necessary to adopt the strategy of comprehensive evaluation of trap groups with dynamic evaluation of fault activity; as for the superimposed basin in western China, the structural thrust belts on the basin margin have generally intensive tectonic stress, and great difficulty in CO2 injection. This brings high risk for CO2 injection and storage. Instead, the paleouplifts and slopes in the basin center may represent effective storage sites. Therefore, the evaluation strategy for basins in western China would need to consider zoning and stratification. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Comparison of Washing Oil Experiment of Core Samples from Shale Oil Reservoir WANG Zhihao, ZHAO Jianhua, PU Xiugang, LIU Keyu, LI Junqian, CHENG Bin Geoscience    2022, 36 (05): 1304-1312.   DOI: 10.19657/j.geoscience.1000-8527.2022.049 Abstract （346）   HTML （8）    PDF（pc） （2694KB）（192）       Knowledge map    Save Fractures and micro-/nano-scale pores in shale reservoirs are the main occurrence space of shale oil. Efficient and non-destructive washing oil of core samples is the key to the characterization of shale pore structure and shale oil occurrence, yet there is no unified scheme currently. In this study, we investigated and summarized the common “washing oil” schemes, and selected Soxhlet extraction, rapid extraction and gas flooding + Soxhlet extraction to compare their effects on shale block samples (1 cm×1 cm×1 cm) from the Kongdian Formation (Ek2, 2nd member) in the Cangdong depression. Rock-eval pyrolysis instrument and gas chromatograph were used to compare the experimental results and the pros and cons of the three methods, by analyzing the samples before and after washing oil and the extracted soluble organic matter. The results show that the heavy hydrocarbon components in the extract increase gradually with time. It is difficult for low-porosity/-permeability shale cores to achieve ideal washing oil effect under room temperature and pressure. Heating and pressurization can improve experimental efficiency, but heavy hydrocarbons and adsorbed components would partially break down into light hydrocarbons due to prolonged high temperatures, and the S1 value would rise when the rate of decomposition is higher than that of extraction. Appropriate pressure conditions can effectively promote the washing oil rate, but the samples or its pore structures may be destroyed under the unstable pressure. We suggested to use lower pressure, room temperature or slightly higher temperature in washing oil to speed up the process, which would produce better results when combining the displacement and extraction methods. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Fission Track Dating of Mesozoic-Cenozoic Tectonic Evolution in Ningwu Basin HUANG Zhigang, ZHENG Qingrong, REN Zhanli, SUN Erhu, GOU Chaoyang Geoscience    2022, 36 (04): 1043-1051.   DOI: 10.19657/j.geoscience.1000-8527.2022.198 Abstract （342）   HTML （2）    PDF（pc） （6393KB）（95）       Knowledge map    Save To study the Mesozoic-Cenozoic tectonic evolution of the Ningwu Basin and occurrence conditions of coalbed methane resources, samples were collected from the basin for fission track dating. The obtained fission track ages are of 156~139 Ma (zircon) and 97~47 Ma (apatite). Mesozoic-Cenozoic tectonic evolution of the basin is divided into three stages accordingly: Late Jurassic (156 Ma): granites on both sides of Ningwu basin began to uplift slowly, and the core depression was deposited; late Early Cretaceous (100 Ma): the paleo-temperature of the basin reached its peak, and the source rocks also reached the gas-generation peak; Late Cretaceous-Paleocene (79~59 Ma): rapid uplift erosion occurred. Although there was a short burial later, the region remained uplifted. Since the Late Oligocene (40~30 Ma), the region has been rapidly uplifted to the present position. Uplift erosion of the basin was spatially uneven: uplifting in the northeast was earlier than in the south, and the intrusion uplift and denudation rate on both sides was higher than that in the core. In the Mesozoic, the regional tectonics formed a series of en-echelon complex anticlines and synclines. In the Cenozoic, Indian Ocean plate compression on Eurasia may have formed the Ningwu Basin via strong uplift and thrusting of mountain ranges on both sides, which responded to the regional tectonic events in the North China Craton. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Gas Accumulation Model of Mesozoic Buried Hill in Qiongdongnan Basin GAN Jun, JI Hongquan, LIANG Gang, HE Xiaohu, XIONG Xiaofeng, LI Xing Geoscience    2022, 36 (05): 1242-1253.   DOI: 10.19657/j.geoscience.1000-8527.2022.050 Abstract （340）   HTML （13）    PDF（pc） （10407KB）（141）       Knowledge map    Save The exploration of basement buried hill in Qiongdongnan basin is facing many problems, such as unclear geological age, strong reservoir heterogeneity and complex accumulation forming conditions. Through regional tectonic evolution, basement zircon dating, buried hill reservoir description and accumulation forming dynamic analysis, the development area and favorable accumulation area of buried hill reservoir are identified. The study shows that under the superimposed control of Indosinian, Yanshanian and Himalayan orogenic movements, Indosinian granite buried hill reservoirs are widely developed in Songnan low uplift and Lingnan low uplift. In plane view, three groups of faults and fractures in NW, NE and near EW directions are cut into a network, forming a double-layer structure with a total thickness of more than 300 m in weathering fracture zone vertically. It is clear that brittle minerals and bidirectional fluid transformation are the key factors for the development of fractured reservoirs. Based on the Early Oligocene paleogeomorphology and source rock sedimentary study, the accuracy of TOC distribution prediction of terrigenous marine source rocks in Yacheng Formation is improved, and the distribution law of high-quality hydrocarbon source in central depression is clarified. By comprehensive analysis of the relationship between the distribution of Paleogene burial hill reservoir and space-time configuration with Yacheng Formation hydrocarbon source stove, two natural gas accumulation models are established, which are “long-distance lateral migration and high buried hill limited-accumulation outside the source” and “short-distance migration and low buried hill efficient-accumulation alongside the source”.So L26-B is the the potential prospect. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Lithospheric Electrical Structure of Eastern Segment of Central Asian Orogenic Belt and Its Tectonic Implications LI Bo, JIN Sheng, YE Gaofeng, WEI Wenbo Geoscience    2023, 37 (01): 15-30.   DOI: 10.19657/j.geoscience.1000-8527.2022.069 Abstract （340）   HTML （28）    PDF（pc） （22398KB）（147）       Knowledge map    Save The eastern segment of the Central Asian Orogenic Belt (CAOB) in central Inner Mongolia has always been a hot research field in the Earth’s internal dynamics and global change. Tectonic study in this region is of great significance given its important role in understanding the CAOB formation. A 364 km-long magnetotelluric sounding (MT) profile in the eastern CAOB is collected in this study. The profile starts from the northwest near the national border in Dongwuqi of Inner Mongolia, and extends to the southeast through the Northern Orogenic Belt (NOB), Solonker Suture Zone (SSZ) and Southern Orogenic Belt (SOB), and terminates about 30 km west of Wengniuteqi of Inner Mongolia. Based on the data analysis results, 2D inversions were conducted on the dataset. Resulting model shows that the electrical structure of the lithosphere along the profile is characterized by NS-trending transverse blocking. The NOB is generally characterized by low resistivity; The SSZ is the transition zone of the electrical characteristics of the whole section from low to high resistivity; The SOB is mainly characterized by high resistivity. The low resistivity characteristics of NOB indicate that the region is unstable, which may be caused by the residual oceanic crust or asthenospheric upwelling after the Paleo-Asian Ocean closure. The SSZ electrical structure indicates that a new tectonic event may have occurred after the suturing. The high resistivity characteristics of the SOB indicate that the basement is stable and “cold”, and the fluid content is very low, with the geometric characteristics of the electrical structure reflecting the thickened lithosphere. The regional electrical structure characteristics along the profile indicate that new tectonic events, such as asthenospheric fluid ascent and lithospheric thickening, may have occurred after the collision between the Siberian and North China Cratons. In addition, the regional electrical structure is consistent with the suture zone characteristics, which provides new deep geophysical evidence for the continuous accretion model of tectonic evolution in the eastern CAOB. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Diagenesis and Diagenetic Facies of Upper Wuerhe Formation in the Shawan Sag YU Jingwei, LUO Gang, LI Bin, PAN Tuo, YU Haitao, KUANG Hao, CHU Xu, ZHANG Xiaotong Geoscience    2022, 36 (04): 1095-1104.   DOI: 10.19657/j.geoscience.1000-8527.2022.206 Abstract （334）   HTML （4）    PDF（pc） （8666KB）（137）       Knowledge map    Save The Permian Upper Wuerhe Formation is a key exploration target zone in the Shawan Sag, which is a typical lithologic reservoir. Fewer studies were dedicated to the diagenesis of Upper Wuerhe Formation, which hinders deeper exploration. The data of slice, physical property, SEM and electromagnetic spectrum, combined with lithologic analysis and reservoir reserve characters, were applied to analyze the diagenetic types and facies. The results show that the diagenetic types comprise compaction, cementation and resolution. According to the diagenetic phenomena and characters, we concluded that the diagenetic evolution of Upper Wuerhe Formation has already been in the middle diagenetic stage B. Based on the intensity and typical phenomenon diagenesis, the diagenetic facies could be divided into five types, including the strong compaction tight, strong compaction-medium resolution, medium-strong compaction-calcite cementation-weak resolution, medium-strong compaction-mixed-layer illite cementation-weak resolution, and the medium-strong compaction-zeolite cementation-weak resolution digenetic facies. Combined with the Fisher typical discriminant, the diagenetic facies were built on discriminant functions to analyze the diagenetic facies distribution patterns, which would provide a foundation for deeper exploration. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Geological Conditions and Resource Potential of Coalbed Methane Reservoirs in Laochang Mining Area, Yunnan Province LI Jinlong, LI Qian, CAI Yidong, CHEN Wei, CHEN Zhizhu, WANG Jian, XUE Xiaohui Geoscience    2022, 36 (05): 1351-1359.   DOI: 10.19657/j.geoscience.1000-8527.2022.056 Abstract （333）   HTML （8）    PDF（pc） （3962KB）（137）       Knowledge map    Save The Laochang mining area in Yunnan is rich in coalbed methane resource, and is a hot spot for coalbed methane resource exploration and development in China in recent years. Here, the basic reservoir parameter characteristics, such as coal seam thickness, reservoir physical properties and gas content are analyzed, and the potential of regional coalbed methane resources is discussed. Our results show that the coal seams in Laochang mining area are thick and multi-layered, the coal seam roof and floor are mainly mudstone and siltstone, respectively, and the configuration of source-reservoir-cap is good. The target coal seam has relatively high porosity and well-developed fractures, which can provide favorable conditions for the enrichment and output of coalbed methane. The main coal seam pressure belongs to the normal pressure reservoir as a whole, and the desorption rate of coal seam is high. Meanwhile, most of the coal reservoirs are under-saturated, and it took long time to drain and depressurize during their development. The coalbed methane resource with buried depth below 1,000 m in the Yuwang block are 27.093 billion m3, and the resource abundance is 320 million m3/km2. In general, the local coalbed methane exploration and development conditions are good, and there is great resource potential for exploration and development. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Geochemical Characteristics and Prospecting on Stream Sediment Survey in Qianhongquan Area of Beishan in Gansu Province, China CHEN Shiming, YANG Zhenxi, LEI Ziqiang, KANG Weiliang, ZHANG Jing, ZHAO Qinghu Geoscience    2022, 36 (06): 1513-1524.   DOI: 10.19657/j.geoscience.1000-8527.2022.06.07 Abstract （319）   HTML （6）    PDF（pc） （10807KB）（192）       Knowledge map    Save After the regional geochemical survey and natural heavy mineral survey with the scale of 1∶200 000, a detailed geochemical survey with the scale of 1∶50 000 was implemented in Qianhongquan area of Beishan in Gansu Province, China. The sampling media in this detailed survey is stream sediments sieved between 4 and 20 meshes and 17 elements (W, Sn, Mo, Bi,Cu,Pb,Zn, Cd,Au,Ag, As, Sb, Hg, Co,Ni,Cr, Nb) were analyzed. The geochemical characteristics such as the statistical parameters of elemental concentrations, elemental assemblages based on correlation analysis and R-type cluster analysis were reported and the geochemical anomalies were determined and assessed. Based on these results of geochemical survey, four metallic prospecting areas are recognized which are Wansuishan Au metallic prospecting area controlled by the fracture zone, Heishantou Au-polymetallic prospecting area controlled by the ductile shear zone, Zhangfangshan Cu-Co-Ni polymetallic prospecting area controlled by the basic rocks, and Hongliugeda W metallic prospecting area controlled by tectonic fractures formed in acidic intrusive rocks. Furthermore, four detailed metallic targets are delineated in these prospecting areas for the future exploration works. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Method for Calculating Short-term Non-interference Nominal Heat Rate of Deep Coaxial Heat Exchangers TANG Changfu, LUO Wanjing, HUANG Junwei Geoscience    2022, 36 (05): 1440-1446.   DOI: 10.19657/j.geoscience.1000-8527.2022.053 Abstract （316）   HTML （6）    PDF（pc） （2013KB）（62）       Knowledge map    Save Based on basic underground heat transfer mechanism, an analytical solution of the mean inlet and outlet fluid temperature, accounting for the geothermal gradient effect is formulated for deep coaxial heat exchanger. An approximate solution is also derived. Furthermore, a method for calculating short-term non-interference nominal heat rate of deep coaxial heat exchangers is developed and validated by comparison with published results. It is revealed that the nominal heat rate is a linear function of geothermal gradient. The analytical method proposed here is very practical and requires less computation cost, which enables rapid evaluation of short-term thermal capacity of deep coaxial heat exchangers. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Effect of Methane from Natural Gas Hydrate Decomposition on Marine Life GUO Zihao, LI Canping, CHEN Fengying, GOU Limin, WANG Hongtao, ZENG Xianjun, LIU Yilin, TIAN Xinyu Geoscience    2023, 37 (01): 138-152.   DOI: 10.19657/j.geoscience.1000-8527.2022.034 Abstract （312）   HTML （23）    PDF（pc） （8487KB）（170）       Knowledge map    Save With changing seabed environment and the intensification of global warming, more natural gas hydrates have decomposed and released large amount of methane into the oceans. Some of the methane would ascend through the seawater and enter the atmosphere, which would increase the atmospheric greenhouse gas concentration, and thereby exacerbate global warming. From the perspective of methane release and migration pathways, the direct/indirect effects of methane on marine life are elucidated and summarized: (1) hydrates decompose to release methane, which is an indispensable compound in lifeform formation. This provides energy and material for autotrophic microorganisms, and supplies the food base of cold-spring biota. This maintains cold-spring biota based on a food chain of chemoautotrophic bacteria, which multiply in the cold-spring ecosystem; (2) some of the methane gas would diffuse and dissolve in the seawater, which causes seawater acidification. Seawater acidification would both affect the biosynthesis of calcium carbonate shells (calcification) and accelerate the shell dissolution; (3) as a strong greenhouse gas, the released methane in the atmosphere would exacerbate global warming. In addition, the melting of the polar permafrost would also release large amount of methane into the atmosphere, which generates an adverse cycle. The warming of seawater would affect the survival, metabolism, reproduction, development and immune response of marine life and other biological activities. Our findings provide important reference for future research on the impact of methane on marine ecosystem. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Geochemical Characteristic and Ore-forming Material Sources of Daping-Jinling Barite Deposit in Northern of Daba Mountain CAO Linjie, ZHANG Yunzhou, LI Silong, WANG Zhihong, ZHANG Yao, ZHANG Han Geoscience    2022, 36 (06): 1497-1502.   DOI: 10.19657/j.geoscience.1000-8527.2022.06.05 Abstract （311）   HTML （4）    PDF（pc） （3241KB）（121）       Knowledge map    Save The Daping-Jinling barite deposit is located in southern wing of the Qinling compound anticline in the southern Qinling Mountain, on the southern and western edge of the Pingli dome of Daba Mountain. The geochemical characteristic and ore-forming material sources of Daping-Jinling barite deposit in northern Daba Mountain were studied on geological background, deposit geological characteristics, carbon and oxygen isotopic and rare earth elements. The oxygen isotope compositions showed that the δ18OV-SMOW ranged from 1.44‰ to 2.20‰, indicating that the ore-forming temperature was low-or-medium temperature(60.72-122.87 ℃). The ore and surrounding rock had similar rare earth element characteristics to reveal that the material sources of barite and surrounding rock may be the same, with high ratio of HREE/LREE, anomaly negative europium, anomaly negative cerium. The analysis of petrogenesis and tectonic environment indicates that the horizon of barite deposit is hosted the Cambrian Liujiaping Formation. The sedimentary environment is the slope facies of continental margin and provides superior conditions for the formation of $SO_{4}^{2-}$. The Sinian Dengying Formation in the underlying strata contained high abundance of Ba, which may be the main source of barium in the barite deposit. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Spatial Prediction of Surface Soil Ore-forming Elements Based on Machine Learning: Taking Rare Metal Rubidium as An Example DAI Liangliang, NIE Xiaoli, GUO Jun, GONG Hao, WU Huanhuan, ZHANG Tao, TANG Yuanyuan, MAO Cong, PENG Zhigang, HE Can Geoscience    2022, 36 (03): 972-978.   DOI: 10.19657/j.geoscience.1000-8527.2022.03.17 Abstract （309）   HTML （11）    PDF（pc） （4325KB）（223）       Knowledge map    Save Mass geochemical data of surface soil have been obtained in recent years with the development of geochemical surveys of land quality. However, there is an obvious defect in the dataset of 1∶50 000 large-scale surface samples, i.e., the lack of ore-forming elements. In view of the important role of ore-forming elements in the prospecting of mineral resources, this article attempts to provide a supplementary plan based on existing data. Taking the rare metal rubidium as an example, 2,548 groups of 1∶250 000 small-scale surface soil data in the same area were divided into two groups randomly using the random forest algorithm according to the ratio of 8∶2, with 80% of the data for model training and 20% of the data for model verifying. The combination of variable importance metric ranking and learning curve construction was used to select 8 elements (K, B, Ni, V, Zn, As, Co, Cu) as predictors. The goodness of fitness(R2)of the model to the training data and test data reached 0.983 2 and 0.895 6, respectively, indicating that the optimal method of predictor variables is effective. Subsequently, the above-mentioned predictive variable data of 1∶50 000 surface soil was imported into the model as input variables, and the predicted Rb element content was obtained. The predicted results were in line with the actual characteristics. This study indicating that it is feasible to introduce the big data machine learning random forest algorithm into the spatial quantitative prediction of surface soil geochemical element content, and the service application dimension of land quality geochemical data can be further expanded. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Geochemical Characteristics of Selenium in Surface Soil of Qingzhou, Shandong LIU Yang, JIANG Bing, ZHANG Hairui, SUN Zengbing, WANG Songtao Geoscience    2022, 36 (03): 933-940.   DOI: 10.19657/j.geoscience.1000-8527.2022.03.13 Abstract （306）   HTML （6）    PDF（pc） （3735KB）（105）       Knowledge map    Save In order to study the geochemical characteristics of selenium in surface soil of Qingzhou in Shandong Province, 8,132 surface soil samples were collected with the average density of 5.2 pieces/km2 in Qingzhou and the selenium content, organic matter, pH and other indicators were analyzed. The results showed that the selenium content in surface soil ranged from 0.02 to 2.77 mg/kg and the background value was 0.21 mg/kg (n=7,462). The area of selenium-abundant soil in the study area is 140.56 km2, accounting for 9.00% of the study area. The area of selenium-sufficient soil is 1,248.39 km2, accounting for 79.93% of the study area; the area of potential selenium-deficiency soil is 148.45 km2, accounting for 9.50% of the study area; the area of selenium-deficient soil is 24.52 km2, accounting for 1.57% of the study area. Selenium in surface soil has different characteristics in different geological units, soil types, landform types and land-use types. Selenium is relatively accumulated in the surface soil with Cambrian-Ordovician parent material, clay soil type, dissolution or moderate-cutting landform type, grassland and woodland land-use type. Correlation analysis showed that there was no correlation between pH and selenium content in surface soil of the study area, but there was a significant positive correlation between organic matter and selenium content. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Study on the Intrusive Ages of the Granites and Metallogenic Age from Zhongteng Copper Deposit, Pinghe, Fujian Province REN Chenghao, SHE Hongquan, KE Changhui, SUN Yandong, ZHOU Qunmao, JIAO Tianlong, LI Baoliang Geoscience    2022, 36 (06): 1447-1464.   DOI: 10.19657/j.geoscience.1000-8527.2022.06.01 Abstract （304）   HTML （23）    PDF（pc） （8509KB）（227）       Knowledge map    Save Zhongteng Cu deposit, located in the Shanghang-Yunxiao tectonic magmatic metallogenic belt on the southeast margin of Cathaysian Plate, is a magmatic hydrothermal deposit. Geochemistry of the three types of granitic intrusive rocks from the ore deposit indicates that they belong to high potassium calc-alkaline series, characterized by high K2O, low Si and low TiO2; some rocks belong to peraluminous. Analysis on REE and trace elements has shown the granites are enriched in light rare earth elements, have weak negative europium anomaly, enriched in large ion lithophile elements (K, Rb, Th, etc.), and depleted in high field strength elements (Nb, Ta, Ti, etc.). Zircon LA-ICP-MS dating of the granites gives (103.5±0.4) Ma, (102.2±0.4) Ma, (103±0.4) Ma,respectively. Zircon εHf(t) values of granites is between -2.9 and 2.0,the two-stage model ages (TDM2) are 1.04-1.35 Ga. Re-Os isotopic dating on the molybdenite samples from the ore body obtained an isochronic age of (105±2.5) Ma, indicating that the formation of Zhongteng copper deposit is mainly related to intrusive rocks formed at late stage of Yanshan period. Based on this study and newly other study results, it is reasonably to considered the granites at Zhongteng copper deposit belong to I-type, its formation and related mineralization were related to subduction of the Paleo-Pacific Plate occurred at southeast coastal area during late Early Cretaceous Period (110-90 Ma). Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Geochronology, Geochemistry,and Tectonic Significance of Carboniferous Andesite in the Zhongguai Uplift, Northwestern Margin of the Junggar Basin SHAO Longfei, YU Fusheng, WANG Dandan, LI Chao Geoscience    2022, 36 (03): 812-823.   DOI: 10.19657/j.geoscience.1000-8527.2022.024 Abstract （303）   HTML （12）    PDF（pc） （7026KB）（106）       Knowledge map    Save To deepen our understanding in the Carboniferous tectonic background in the western Central Asian Orogenic Belt, drill-core samples of andesite in Jinlong 10 well area of Zhongguai uplift (northwestern margin of Junggar basin) were studied via petrography, chronology and geochemistry. The results show that our andesite samples are low-K to medium-K calc-alkaline, with slightly right-inclining REE diagram and weakly negative Eu anomaly. In the primitive mantle-normalized spider diagram, the rocks have Pb and LILE (Rb, Ba) enrichments and HFSE (Nb, Ta, Zr) depletions, resembling those of typical subduction-related arc volcanic rocks. The Th/La, Th/Ce and Lu/Yb ratios of andesite are below those of the average continental crust, but similar to those of typical mantle-derived magmas. The andesite samples belong to the normal island arc volcanic rocks, which are derived from the water-rich mantle wedge and by partial melting of the fluid-metasomatized mantle wedge (produced by subducting-slab dehydration). LA-ICP-MS zircon U-Pb dating of the andesite yielded Middle Carboniferous age of (322.4±1.1) Ma. Combined with regional geological background and compared with coeval magmatism, we considered that the andesite in the Zhongguai uplift was formed in a continental arc setting, and was the subduction product of residual oceanic basin in West Junggar, which was not completely closed at (322.4±1.1) Ma. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Microscopic Pore Structure and Fractal Characteristics From the Carboniferous Xiangbai Formation Shale in Northwestern Guizhou JIANG Bingren, DENG Ende, HAN Minghui, MA Zijie Geoscience    2022, 36 (04): 1065-1073.   DOI: 10.19657/j.geoscience.1000-8527.2022.201 Abstract （303）   HTML （3）    PDF（pc） （7238KB）（92）       Knowledge map    Save To study the microscopic pore characteristics of shale in marine coal-bearing strata, we studied the Carboniferous Xiangbai Formation shale in northwestern Guizhou, and used SEM and N2 adsorption analyses and fractal theory to study its fractal characteristics. We then explore the influencing factors of microscopic pore structure. The results show that four types of pores can be identified (intragranular, intergranular, organic matter and micro-fracture pores), a large number of microfractures and organic matter pores are developed, which have strong hydrocarbon generating ability and good reservoir performance. The adsorption isotherms of N2 show an inverse S-type, indicating that the adsorption isotherms were mainly mesopores. The hysteresis loops formed by adsorption isotherms and desorption isotherms were mainly H2-type thin-necked wide-body ink bottle pores. The specific surface area is large (average 13.20 m2/g), and the total pore volume is large (average 0.015 5 cm3/g). The average pore size is 6.22 nm and the massive development of nano-scale micropores would provide rich reservoir space for hydrocarbon gases. The fractal dimension D of microscopic pore structure of shale samples is larger (average 2.723 2), reflecting strong heterogeneity of pore structure. BET specific surface area shows negative correlation with TOC and quartz content, and positive correlation with fractal dimension. The average pore size has good positive correlation with the quartz content, strong negative correlation with fractal dimension, and moderate negative correlation with clay mineral content. Larger BET specific surface area and smaller average pore size correspond to larger fractal dimension and more complex pore structure. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Three-dimensional Magnetic Structure and Geological Structural Characteristics of Shuangjianzishan in Southeastern Inner Mongolia JIA Zhengyuan, WANG Fenggang, SUO Kui, GUO Lei, GUAN Ye Geoscience    2023, 37 (01): 48-57.   DOI: 10.19657/j.geoscience.1000-8527.2022.072 Abstract （302）   HTML （11）    PDF（pc） （10978KB）（111）       Knowledge map    Save The Shuangjianzishan Ag-Pb-Zn deposit, located in the middle-southern section of the Great Xing'an Range, is the largest silver-polymetallic deposit discovered in the region in recent years. It is a hydrothermal deposit that has undergone multistage mineralization. Magnetic anomaly has a strong correlation with mineralization, and the magnetic structure can well reflect the ore-controlling structures. In this study, building on various existing information, a three-dimensional inversion of high-precision magnetic data of about 1200 square kilometers in the study area is carried out, and the local three-dimensional magnetic structure within 5 km is obtained. The main conclusions are: (1) The high magnetic intrusion is mainly distributed in the middle and northwest, and shows a NE-SW-elongated distribution; (2) The study area comprises four major structural units and six sub-structural units; (3) The overall local fault structure shows as a NE-SW trend, and the southern fault structure changes to NW-SE trending; (4) There are various concealed magmatic rock units in the central and southeastern parts of the study area, which are mainly intermediate-felsic igneous rocks. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Stable Isotope Characteristics of Geothermal Water and Calculation of Geothermal Reservoir Temperature in the Erdaoqiao Area of Kangding in Sichuan Province JIANG Zhe, ZHOU Xun, CHEN Binghua, TAO Guangbin, LI Zhuang, CAO Ruwen, SUI Liai Geoscience    2022, 36 (04): 1183-1192.   DOI: 10.19657/j.geoscience.1000-8527.2022.04.20 Abstract （298）   HTML （6）    PDF（pc） （4925KB）（225）       Knowledge map    Save In order to study the stable isotope characteristics of geothermal water and geothermal reservoir temperature in the Erdaoqiao area near Kangding in Sichuan, five hot springs including the Erdaoqiao hot springs (SC107 and SC107-2), Kangbarenjia hot spring (SC107-3), the flowing hot water well (SC107-4) and spouting hot water well (SC107-5) are investigated. The Yalagou fault and the Yala river valley control the occurrence of the hot springs in the study area. The water temperature of the hot springs in the study area ranges from 33.2 ℃ to 46 ℃, and pH value, from 6 to 6.5. The hot springs are of medium-low temperature. The stable isotope compositions of hydrogen and oxygen of the hot springs indicate that the hot water in the study area is of meteoric origin. Based on the altitude effect and temperature effect, the elevations of the recharge areas of the hot springs are estimated to be about 3 000-4 500 m, and the temperature of the recharge areas range from -3.5 ℃ to -0.3 ℃, indicating that the hot springs may be recharged partly by snow-melting water. The Na-K-Mg triangular diagram shows that the hot water in the study area is the unmature water, so it is impossible to calculate the temperature of geothermal reservoirs with the cation geothermometry. The temperature of the geothermal reservoir in the study area ranges from 65 ℃ to 75 ℃ by using the SiO2 geothermometry, multi-mineral saturation index method and Fix-Al method. The hot springs in the study area are recharged by precipitation and snow-melting water at the eastern part of the Paoma mountain and the western part of the Nongge mountain. The groundwater flows along the Daxue mountain-Nongge mountain fault and the Paoma mountain fault and undergoes a deep circulation. After heated by heat flow, the thermal groundwater rises and emerges as hot springs in the Yala River valley and near the Yalagou fault. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Thermal and Paleoenvironment Evolution of the Fengcheng Formation of Permian in Mahu Depression, Junggar Basin JIANG Zhongfa, JIANG Mengya, CHEN Hailong, LIU Longsong, WANG Xueyong, BIAN Baoli, LI Na Geoscience    2022, 36 (04): 1118-1130.   DOI: 10.19657/j.geoscience.1000-8527.2021.182 Abstract （297）   HTML （6）    PDF（pc） （10738KB）（104）       Knowledge map    Save Several exploration wells were recently drilled into the thick hydrocarbon source rock of Fengcheng Formation in the southern slope of Mahu Depression in the Junggar Basin, which brings an opportunity to reveal the source rocks there. This study collected data from five key exploration wells in the southern and northern Mahu Depression, and obtained the following findings: (1) the Fengcheng Formation source rocks are widely distributed in Mahu Depression, and the northern and southern Mahu Depression geochemical parameters show that the source rocks are of II-type and high-quality; (2) based on current geothermal, pyrolysis, biomarkers and group compositions, the Fengcheng Formation source rocks around the Mahu Depression entered mature and highly-mature stage at below 4,350 m and 4,800 m, respectively, and have entered the oil generation peak widely; (3) integrating multiple biomarker parameters, the Fengcheng Formation source rocks in northern Mahu Depression were deposited in a saline and reducing environment, and the source rocks of the Fengcheng Formation (2nd member) in southern Mahu Depression were deposited in a saline and semi-reducing environment, whilst the 3rd member (also in southern Mahu Depression) were deposited in a brackish and semi-reducing environment, and adsorbed more terrigenous organic matter. Paleoenvironment of the local Fengcheng Formation is featured by salinization (early) and desalinization (end), and the degree of salinity and reduction in the north is higher than that in the south. This study provides a theoretical basis for the subsequent exploration and deployment of tight oil and shale oil for the Fengcheng Formation in Mahu Depression. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Geochemical Characteristics and Influencing Factors of Germanium in Surface Soil of Lishui District, Nanjing City ZHOU Mo, LIANG Xiaohong, ZHANG Ming, WEN Bangyong, TANG Zhimin, ZHAN Long Geoscience    2023, 37 (01): 217-226.   DOI: 10.19657/j.geoscience.1000-8527.2023.01.23 Abstract （295）   HTML （15）    PDF（pc） （5884KB）（208）       Knowledge map    Save Germanium (Ge) is an essential trace element for life and has extensive health care effects on the human body. It is valuable to develop Ge-rich soil, whereas the research on soil Ge is still insufficient in China.Based on the results of land quality geochemical survey in Lishui district, Nanjing, the content and spatial distribution characteristics of Ge in surface soil and the influence of geological background on soil Ge were studied in this paper.The results revealed that the average Ge content in surface soil of Lishui district was 1.40 mg/kg, which was mainly controlled by geological background and its spatial distribution was highly consistent with geological background.The high value area of Ge content is mainly the outlying area of J3d1-2, and the lithology is mainly trachyandensite and andesite, while the Quaternary sediment distribution area has relatively low Ge content.There was no significant relationship between Ge and pH value in the soil, there was a certain negative correlation with organic matter content, and an obvious positive correlation with Cr, Co, Ni and As. The Ge-rich soil area in the study area is 84.18 km2, accounting for 10.84% of the total area of the whole region, and there is basically no Ge deficient area in the whole region.In this paper, the content, spatial distribution and influencing factors of Ge in surface soil of Lishui district, Nanjing were discussed, which can provide basic data for the ecological geochemical study of Ge in soil in China, and have guiding significance for the scientific development and utilization of Ge-rich soil resources. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Re-Os Isotopic Characteristics and Geological Significance of Mafic Rocks from the Xigaze Ophiolite,Tibet LI Wenxia, ZHAO Zhidan, WANG Xiaoli, YAN Rong, LU Yuanfa Geoscience    2022, 36 (06): 1503-1512.   DOI: 10.19657/j.geoscience.1000-8527.2022.06.06 Abstract （289）   HTML （12）    PDF（pc） （6815KB）（166）       Knowledge map    Save Petrology and elemental geochemistry of mafic rocks from the Xigaze ophiolite are studied so as to investigate the petrogenesis and source characteristics of the ophiolite. At the same time, Re-Os isotope geochemical constraints in formation mechanisms of the Yarlung Zangpo ophiolite is also explored. The result shows that the primitive mantle-normalized multi-element pattern of the mafic rocks is similar to the normal Mid-Ocean Ridge Basalt (N-MORB) with the characteristics of island arc. Combined with the characteristics of the trace elements and isotope, all of these are shown that the petrogenesis is related to subduction. The Xigaze ophiolite was formed in the SSZ environment far away from the continental crust, so it’s not contaminated by the continent crust during its development, also the alteration in Re-Os isotope systematics was not obvious. The reason of Re-Os isotopic characteristics with low Re, low Os and high ratios of 187Os/188Os for the mafic rocks is manifested by the source characteristics and the subduction. The multi-stage Tethyan subduction resulted in the mantle heterogeneity. During the subduction of Neo-Tethys, the mafic magma from the above-mentioned heterogeneous mantle went through the peridotite channel influenced by the early melts, leading to the Re-Os fractionation and amplifying the Os-isotope mismatch between the melt and residual mantle, that’s the petrogenesis of the Xigaze ophiolite. Table and Figures | Reference | Related Articles | Metrics | Comments（0）