27 September 2023, Volume 46 Issue 3

    

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  Metallogenic epoch of sandstone type uranium deposits in the Ordos Basin and the temporal and spatial regularity of uranium enrichment

  WEN Sibo, ZHU Qiang, CHENG Yinhang

  North China Geology. 2023, 46(3): 1-11. https://doi.org/10.19948/j.12-1471/P.2023.03.01

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  Uranium mineralization age is a hot and difficult point in the study of sandstone type uranium deposits. In order to deeply understand the temporal and spatial distribution of sandstone type uranium deposits in Ordos Basin, the applicability and limitation of whole rock U-Pb dating, electron probe method EMPA, LA-ICP-MS, fs-LA-ICP-MS, SIMS and other methods are summarized and compared, and counts and compares the mineralization age and ore bearing horizon information of more than 20 sandstone type uranium deposits in the basin. Taking the typical deposits in the northeast of Ordos Basin as an example, the metallogenic process of sandstone type uranium deposits is systematically analyzed. The results show that the ore bearing horizons of sandstone type uranium deposits in Ordos Basin are mainly Middle Jurassic Zhiluo Formation, Lower Cretaceous Luohe Formation, followed by Lower Cretaceous Madongshan Formation and Luohandong Formation. The uranium mineralization time is mostly concentrated in Miocene, which is well coupled with Cenozoic tectonic events. From east to west in the northeast of the basin, the elevation of the ore bodies in the Dongsheng - Nalinggou - Tarangaole - Daying - Bayinqinggeli deposit is roughly the same, while the relative position of the ore bodies in the ore bearing horizon is gradually rising. It reflects that the formation of each ore body is controlled by the near contemporaneous metallogenic events. The mineralization time of sandstone type uranium deposits in Ordos Basin is mainly concentrated in the Mesozoic Cenozoic era and has a good coupling with the Cenozoic tectonic events. In typical deposits of the northeastern Ordos Basin, the uranium ore bodies are produced in different parts of the same target layer, indicating that uranium mineralization may be closely related to the Cenozoic tectonic activities.
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  Analysis on the metallogenic conditions and prospecting direction of sandstone-type uranium deposits in Yuejin area northwestern margin of Qaidam Basin

  ZHAO Lijun, LIU Xiaoxue, ZHANG Chao, FENG Ping, SI Dan

  North China Geology. 2023, 46(3): 12-20. https://doi.org/10.19948/j.12-1471/P.2023.03.02

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  The Mesozoic and Cenozoic depression in the northern margin of the Qaidam Basin is a favorable area for sandstone-type uranium deposits. To identify the occurrence of uranium deposits in the basin, we studied  the screening of radioactive anomalies in the oil and gas fields of the Qaidam Basin, we found that most of the oil and gas fields have radioactive anomalies and have multiple abnormal horizons, mainly in Quaternary, Neo-Paleogene, Jurassic, buried depth of 45～1 000 m, and drilling to verify the discovery in the sandstone layers of the Quaternary Qigequan Formation and upper Youshashan Formation Industrial ore bodies in Yuejin area provide new prospecting clues for finding sandstone-type uranium deposits in the basin.
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  Analysis of coal formation environment in the south of Huoxi Coalfield based on coal quality characteristics

  CHEN Yan

  North China Geology. 2023, 46(3): 21-27. https://doi.org/10.19948/j.12-1471/P.2023.03.03

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  The Huoxi coalfield is an important coking coal producing area in China. In order to fully identify its coal quality characteristics and coal-forming environment, this paper chooses No.2 and 9 (9+10) coal seams which are representative in southern coalfield to research. By analyzing the data of coal rock, sulfur content, ash content and ash composition of coal samples, the coal quality characteristics were evaluated and the coal forming environment was inferred. The results show that the higher the mirror laziness ratio of coal seam is, the deeper the sedimentary environment is covered by water. The higher the sulfur content is, the more affected by sea water; The higher the ash content is, the stronger the hydrodynamic force is. The larger the grey component index K is, the stronger the reduction is. The higher the CaO/MgO value is, the wetter the coal-forming climate is. The m value reflects whether the sedimentary environment is fresh or salt water. According to the characteristics of No. 2 and No. 9 (9+10) coal ash with low to medium and low ash composition index and 1 < m < 10, it is inferred that their formation process was influenced by river transport, and they were depositional environments with strong hydrodynamics, reduced form and brackish water. By analyzing other coal quality characteristics of the two coal layers, it is found that there are differences in the coal-forming environment between the two coal layers, as follows: No. 2 coal has the characteristics of low vitreous inert ratio (V/I), low sulfur content and high CaO/MgO value, indicating that the coal-forming environment is a deltaic plain peat swamp environment with low overlying water and humid paleoclimate environment. No. 9 (9+10) coal has the characteristics of moderately high mirror inert ratio (V/I), high sulfur content and high CaO/MgO value, indicating that the coal formation environment is a lagoon peat swamp environment with strong water cover, seawater influence and extremely humid paleoclimate environment.
Regional Geology
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  The northwestern boundary location on Langshan area of North China Craton and its tectonic significance

  GUO Shuo, LIU Yang, TENG Xuejian, TIAN Jian, TENG Fei, WANG Wenlong, HE Peng, ZHANG Guozhen

  North China Geology. 2023, 46(3): 26-34. https://doi.org/10.19948/j.12-1471/P.2023.03.04

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  There are two views on the boundary location of the northwest margin of the North China Craton (Langshan Area): the Narenbaolige-Huogeqi-Saiwusu fault or the Chaganmaodao-Ganqimaodao fault. In order to determine the boundary location, we compared the Meso-Neoproterozoic depositional age, depositional environment and Hf isotopes of intrusive rocks on both sides of the Narenbaolige-Huogeqi-Saiwusu fault, combined with geophysical characteristics, and determined that the Chaganmaodao - Ganqimaodao fault should be the northwestern boundary of North China Craton. The Narenbaolige-Huogeqi-Saiusu fault was formed in the late Paleozoic, which has the significance of dividing the geological characteristics and evolutionary history of the Paleozoic on both sides. This boundary has guiding significance for the division of tectonic units and the summary of metallogenic law in this area. At the same time, we proposed whether the Bayan Obo - Huade - Duolun - Chifeng fault is suitable for the northern boundary of North China Craton.
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  Geochemical characteristics and tectonic environment of Late Ordovician intrusive rocks in Suanjingzi, Beishan area, Inner Mongolia

  XU Cui, ZHANG Zhengping, CAI Xiaoyu, ZHANG Yong, ZHAO Qiyu

  North China Geology. 2023, 46(3): 35-42. https://doi.org/10.19948/j.12-1471/P.2023.03.05

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  In this paper, LA-ICP-MS zircon U-Pb age and whole rock geochemistry of Suanjingzi late Ordovician granite in Beishan orogenic belt are reported to discuss its formation age, petrogenesis and tectonic setting. LA-ICP-MS zircon U-Pb data from the monzogranite show that it was formed at 456.3±3.5Ma. The tonalite have low SiO₂, ALK, K2O/Na₂O and A/CNK, ranging from 61.99% to 66.62%, 4.66% to 5.16%, 0.52 to 0.64, and 0.89 to 1.05, respectively, while the monzogranite have higher SiO₂ (71.93%～73.20%), ALK (6.44%～6.89%), K₂O (K₂O/Na₂O 1.32～1.94) and A/CNK (1.04～1.05). These rocks are enriched in LREEs and LILE（e.g., Rb, Th and K), while depleted in HREEs and HFSEs (e.g., Nb, Ta and Ti), with weak negative Eu anomaly. These above characteristics show that the rocks belong to metaluminium- weak peraluminous calc-alkaline high differentiation I- type granite, and their primary magma is dominated by crust-derived materials with a small amount of mantle-derived materials, formed under the tectonic setting of island arc in late Ordovician. Combining with regional geologic background, we propose that the Beishan Ocean have began to subduct northward before 456.3 ± 3.5 Ma.
Hydrogeology and Envieronmental Geological Survey
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  Significance evaluation on available properties of soil mass in underground space in Xiongan New Area based on rough set theory

  HAN Bo, ZHANG Xi, DU Yanan, XIA Yubo, MA Zhen, GUO Xu, LIU Hongwei, MIAO Jinjie, BAI Yaonan, LI Zhuang

  North China Geology. 2023, 46(3): 43-48. https://doi.org/10.19948/j.12-1471/P.2023.03.06

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  The development and utilization of underground space is the only way to realize the sustainable and coordinated development of urban economy, society, resources and environment in the new era. In order to objectively evaluate the importance of soil mass in Xiongan New Area, according to the engineering geological characteristics of shallow soil mass 50 meters underground space in Xiongan New Area, the common engineering types and the factors affecting the availability of soil mass in different depths (0～15 m, 15～30 m and 30～50 m) are discussed. Based on the rough set theory, the importance of the factors affecting soil exploitability was evaluated, and the importance and weight of the factors affecting soil exploitability were obtained. The results showed that: (1) The engineering geological properties of foundation soil in Xiongan New Area are generally good and suitable for large-scale construction. However, attention should be paid to artificial filling soil (miscellaneous fill soil and plain fill soil), soft soil (silty clay and soft plastic silty clay), liquefied soil (silty soil and fine sand), groundwater, pit-ponds and other undesirable engineering geological characteristics. (2) The importance order of available soil properties is obtained: 0～15 m is the bearing capacity of foundation, the thickness of mixed fill, the thickness of silt soil layer, the thickness of sand soil layer, the distribution of pit, and the groundwater level, 15～30 m is the thickness of silt layer, the groundwater level, the thickness of silt soil layer, the thickness of sand soil layer, and the uniformity of foundation soil, and 30～50 m is the groundwater level, the thickness of sand soil layer, and the thickness of silt soil layer. (3) Rough set theory can be used for objectively evaluating the availability of soil mass in the underground space in Xiongan New Area, excluding the influence of subjective factors. The internal laws of influencing factors are explored from the knowledge expression system, which provides an evaluation basis for the development and utilization of soil in the underground space in Xiongan New Area.
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  Review on the application of H, O, Sr, Ca, Li and B isotopes in the research of high-fluoride groundwater

  ZHANG Zhuo, LIU Futian, CHEN Sheming

  North China Geology. 2023, 46(3): 49-56. https://doi.org/10.19948/j.12-1471/P.2023.03.07

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  This article aims to explore the use of stable isotopic techniques in elucidating the origin, cycling and evolution processes of high fluoride groundwater. By collecting and synthesizing relevant research findings, a comprehensive review is conducted concerning the utilization of hydrogen and oxygen isotopes, strontium-calcium isotopes, and lithium-boron isotopes in the investigation of high F- groundwater within subterranean environments. The research reveals that δ²H and δ¹⁸O values in groundwater can be utilized to identify the sources and mixing processes of water, thereby identifying potential sources of high fluoride groundwater. Of particular interest in the investigation of high fluoride groundwater is the use of strontium-calcium isotopes. By determining the ⁸⁷Sr/⁸⁶Sr ratio and δ⁴⁴/⁴⁰Ca in groundwater, hydrogeochemical processes such as mineral weathering dissolution, cation exchange, and secondary mineral precipitation can be elucidated, crucial for understanding the formation and evolution mechanisms of high fluoride groundwater. Additionally, lithium-boron isotopes serve as important tools in the study of high fluoride groundwater. Measurements of δ⁷Li and δ¹¹B allow for the assessment of the influence of geothermal fluids on deep-seated high fluoride groundwater. In conclusion, stable isotopes hold immense potential in high fluoride groundwater research. By measuring deuterium-oxygen isotopes, strontium-calcium isotopes, and lithium-boron isotopes, we can gain profound insights into the origin, cycling, and evolution processes of high fluoride groundwater, thus providing a scientific basis for its management and water resource conservation. This research also offers crucial support for the development of appropriate prevention and control measures, ultimately safeguarding human health.
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  Health risk assessment in the groundwater of a certain mine in Hunan

  MAO Kuanzhen, LI Haiming, MING Qiang, LIU Huan, ZHAO Hang, LU Baisong, HAO Wenjie

  North China Geology. 2023, 46(3): 57-66. https://doi.org/10.19948/j.12-1471/P.2023.03.08

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  The text describes an analysis conducted on hydrogeochemical survey data in a typical mining area in Hunan Province, China. By utilizing the Health Risk Assessment (HRA) mechanism, the study evaluated the health risks for males and females associated with different exposure pathways. The main assessment indicators included the carcinogenic substance arsenic (As), as well as non-carcinogenic chemically toxic substances cobalt (Co), manganese (Mn), molybdenum (Mo), selenium (Se), and barium (Ba), with antimony (Sb) identified as a potential carcinogenic substance. The research findings indicated that heavy metal content in the groundwater of the mining area poses certain health risks to the human body. Notably, the health risks for females were found to be greater than those for males. The maximum and minimum values of health risk for females were 1.69 and 6.37E-03, respectively, while for males, they were 4.36E-2 and 1.75E-03, respectively. Among the studied elements, antimony (Sb) posed the highest non-carcinogenic health risk to humans, while cobalt (Co) posed the lowest. The average carcinogenic risk for both males and females caused by arsenic (As) was 1.73E-02 and 1.80E-02, respectively, exceeding the acceptable range by 10 times. Moreover, only six water samples for both males and females were within the maximum acceptable lifetime risk level. In conclusion, the hydrogeochemical indicators in the research area pose a significantly high health risk to humans, with antimony and arsenic being the most severe pollutants.
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  Study on the factors influencing high water temperature geothermal resources in Chengning uplift area

  LIU Wei, LI Dongliang, WANG Xuepeng, ZHAO Shuxing, QIN Xuequan

  North China Geology. 2023, 46(3): 67-75.

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  Chengning uplift area is a typical layered heat reservoir, and the geothermal wellhead water tempera‐ture is usually less than 60℃, but the deep karst heat reservoir, represented by Xiangya Town, Ningjin County, Shandong Province, has a high water temperature of 78-82℃ , and there are obvious high water temperature anomalies. On the basis of collecting previous research results, this paper uses special geothermal geological sur‐vey, geophysical exploration, rock and mineral testing and other work methods to preliminologically identify fault structure as the main factor causing the high water temperature of deep karst thermal reservoir in the area, and identify the related factors of heat source, water source, cap layer, channel and thermal reservoir, so as to es‐tablish a conceptual model of thermal reservoir. It provides guiding significance for the rational development of geothermal resources in deep karst thermal reservoir.
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  Study on soil water and salt movement and its effect on wheat production under saline water irrigation in North China Plain

  WANG Zhe , WANG Lijuan , LI Mengxing

  North China Geology. 2023, 46(3): 76-80.

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  In order to explore a scientific and rational utilization way of the saline groundwater resources in North China, the effects of saline groundwater irrigation on soil water-salt movement and wheat production was studied by the field experiments of saline water irrigation for winter wheat, with both saline water and fresh water irrigation. The results showed that the water movement depth of fresh water irrigation side was deeper than that of salt water irrigation side, and the soil water content of fresh water irrigation side was higher than that of salt water irrigation side at the same depth. It can be inferred that salt water irrigation affects soil infiltration and soil water holding capacity to a certain extent. With the continuous irrigation, salt accumulated in the surface layer（0~0.2 m）and the deep layer (0.6 m~1.2 m) of the saline water irrigation side. The salt content accumulated differently at different depth of the soil profile in the whole growth period, and it reached a peak value of 1.6 g/kg at the depth 0.4 m. The effect of fresh water irrigation on salt accumulation was relatively weak, but it would leach salt from surface to deep layer. When the salinity of irrigation water reached 8.69 g/l, the yield of winter wheat reduced by 37.65%. Therefore, when saline water irrigation is carried out, the mineralization degree of irrigation water should be reasonably controlled.
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  The application of remote sensing technology in the monitoring of mining：a case study of Shanxi province

  LIU Xiaoxue, CHEN Donglei, HUANG Xuhong, ZHANG Yun, YANG Junquan

  North China Geology. 2023, 46(3): 82-88.

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  Shanxi Province is rich in mineral resources, and its dominant minerals are coal mines, bauxite mines and iron mines. With the development of social economy, the demand for mineral resources is increasing, and the development speed of mineral resources is also accelerating. At the same time, mine development has caused great damage to the ecological environment, and the contradiction between mining development and environmental protection has gradually intensified. Using remote sensing images combined with ArGIS to monitor mining and utilization can not only provide reliable data for relevant law enforcement departments, but also be of great significance for standardizing regional mine development order and protecting ecological environment. Combining with the interpretation of remote sensing data of mining in Shanxi Province, this paper establishes mine interpretation signs, and puts forward the existing problems in mining, which provides reference for related mine administration and management.