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Journal of Jilin University(Earth Science Edition)
ISSN 1671-5888
CN 22-1343/P
主 任:蒋 函
编 辑:邱殿明 王晓丽
    刘 莉
电 话:0431-88502374
E-mail:xuebao1956@jlu.edu.cn
地 址:长春市西民主大街938号
    (130026)
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27 January 2022, Volume 52 Issue 1
Metamorphism of Pelitic Gneiss from Sidaolazihe Formation of Longgang Groupi n Southern Jilin Province#br#
ZhengChangqing1, 2, WangBo1, 2, WangLinlin1, 2, LiMeihui1, 2
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  1. 
Abstract ( 71 )   PDF (16223KB) ( 43 )  

Neoarchean pelitic gneisses crop out in the Sidaolazihe formation of the Longgang Group, southern Jilin Province. Through systematical study on petrography, mineral chemistry and LA-ICP-MS zircon U-Pb chronology of these gneisses, this paper has discussed the metamorphic age, evolution, and its tectonic significance. Our results indicate that three distinct metamorphic stages are recorded in these rocks: 1) the prograde stage (M1) with mineral assemblage of garnet + biotite + plagioclase + quartz + muscovite; 2) the peak granulite facies stage (M2) with mineral assemblage of garnet + sillimanite + K-feldspar + biotite + plagioclase + quartz; and 3) the retrograde stage (M3) with assemblage of kyanite + garnet + biotite + plagioclase + quartz + muscovite, which is characterized by the transformation from sillimanite into kyanite. Conventional geothermobarometries are used to estimate the metamorphic T and p conditions. The metamorphic conditions for Mstage are 468~515 ℃ and (3.8~4.3)×10kPa, 703~760 ℃ and (6.6~7.1)×10kPa for the Mstage, 552~591℃ and (5.5~6.0)×10kPa for the Mstage, which constitute a typical isobaric cooling (IBC)-type p-T-t path, suggesting that the metamorphism likely formed from underplating of the mantle-derived magmas under the interaction between mantle plume and lithosphere. Zircon U-Pb dating shows the granulite facies metamorphism occurred at 2 495 ~2 442 Ma, which likely represents the Neoarchean metamorphic thermal event.

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Characteristics of Kalagang Formation Source Rock and Its Significance of Tight Oil Reservoir in Madong Area of Santanghu Basin,NW China#br#
YinYue1, 2, JiaPengfei3, HuangZhilong2, WuHongzhu4, JinXi4, LiuGuojie4
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  26. 
Abstract ( 38 )   PDF (11919KB) ( 23 )  

Tight tuff oil reservoirs, as a special lean oil type, have drawn great attention.The quality of source rocks plays a vital role in the formation of tight oil reservoir. In order to study the oil and gas accumulation law of the Carboniferous volcanic rock reservoir in the Malang Sag in the Santanghu basin in Xinjiang autonomous region,the authors described and evaluated the characteristics of source rock with various lithologies in the Kalagang Formation in Madong area throughthe experiments including rock pyrolysis, kerogen carbon isotope, and GC-MS analysis of saturated hydrocarbon. The results showed that both the tuffaceous mudstone and the dolomitic mudstone have certain hydrocarbon generation potential. The tuffaceous mudstone has greater hydrocarbon generation potential, which is characterized by high abundance of organic matter with TOC greater than 2%, mainly type II kerogen. The source rock is shallowly buried, and the vitrinite reflectance is mainly  0.5%-0.8%, which is in the low-mature stage. Longitudinally, source rocks of different lithologies are alternately superimposed, which is conducive to the formation of self-generated and self-stored reservoirs, and it is of great significance to the formation of tight tuff reservoirs in the Kalagang Formation.

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Salt-Bearing Characteristics and Distribution of Cretaceous Reservoirs of the Dabei and Keshen Areas in the Kuqa Depression#br#
FengJiarui1, 2, GaoZhiyong1, 2, ZhangYuhang1, 2, LiXiaohong1, 2, ZhouPeng3, ShangJiangwei4, LiChenchen5
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  38. 
Abstract ( 43 )   PDF (40009KB) ( 23 )  
The deep subsalt reservoir is an important field for natural gas exploration in Kuqa depression. The salt is widely developed in the Cretaceous reservoirs, and the detailed characterization and evaluation of salt-bearing characteristics of the reservoirs is of great significance to the optimization of exploration zones in this area. By taking 72 core samples in the Cretaceous sandstone reservoirs as the research object, based on thethin section identification, scanning electron microscope, spectrum and QEMSCAN analysis, the microscopic characteristics, distribution, diagenetic conditions, and provenance of salt in the Cretaceous reservoirs were studied. The results show that the halite crystals in the Cretaceous sandstone reservoirs occurred between clastic particles, on the surface of clastic particles, and in the dissolution pores and cracks, and they existmainly in three forms: Skeleton crystal, grain-shaped, and block-shaped. Different types of halite crystals have different atomic percentages of elements such as Na and Cl. In the whole Dabei and Keshen area, the distribution of halite content is higher in the west and lower in the east, and the closer the vertical distance is to the overlying gypsum layer, the higher the salt content. The aggregate form of the halite crystals is affected by many factors, such as salt source supply conditions, reservoir burial depth, sandstone particle size and sorting, etc. The salt source is mainly the dissolution seepage of the Paleogene paste salt sediments, and it may also be related to the lateral infiltration of saline fluids along tectonic faults. 
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Geological Characteristics of Tuff Reservoir of Yingcheng Formation in Dehui Fault Depression,Songliao Basi#br#
ChiHuanzhao1, ZhaoYuting2, LiuCai3, WangTong4, HuJia4, YangSongshan4
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  55. 
Abstract ( 48 )   PDF (26475KB) ( 13 )  
Through the tuff core description, well logging, seismic data, X-ray diffraction, scanning electron microscopy, physical properties, and other test data of Yingcheng Formation in Dehui fault depression of Songliao basin, combined with the structural background analysis, the authorsstudied the geological characteristics of tuff reservoirs. The results show that the mineral components of the tuff in Yingcheng formation are mainly quartz, feldspar, and clay minerals. Tuff is widely distributed in the region, and composed of several superimposed units in vertical direction that underwent weathering and alteration. The logging curve has three peaks and two valleys. According to the tuff scale and gas-bearing characteristics, the volcanic edifice can be classified into three categories: small tuff volcanic edifice, large tuff volcanic edifice, and super large tuff volcanic edifice. The tuff reservoir has middle porosity and low permeability. There are two factors of low yield: the first one is higher content of clay minerals(especially the imam mixed layer), and the second one is compaction. The porosity of tuff reservoir layer accounts for more than 80%.The main reservoir space types are dissolved pores and dissolved fractures, andthe dissolved pores are mainly feldspar dissolved pores and matrix dissolved pores. The fracture development is a key factor in the formation of  tuff reservoir, and there is a  high possibility to find high-yield gas reservoirs in the shallow and middle areas(especially in the high part of the structure). Using logging curve(neutron and density) can predict tuff reservoir effectively. 
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Influencing Factors of Irreducible Water Saturation in Tight Sandstone Reservoirs:A Case Study of Linxing Area in Ordos Basin#br#
WuMeng1, 2, QinYong2, ShenJian2, SongDangyu3, WangXiaoqing3, ZhangGuchun1, LiGuozhang2, ZhuShifei1
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  68. 
Abstract ( 35 )   PDF (9040KB) ( 20 )  

With the tight sandstone gas exploration and development, to study the influencing factors of tight sandstone irreducible water saturationbecomesimportant, as it can effectively guide reservoir description, evaluation, and productivity prediction. As an example of the tight sandstone reservoir in Linxing area in Ordos basin, the influencing factors of irreducible water saturation in tight sandstone were analyzed by casting thin section, X-ray diffraction, nuclear magnetic resonance, high pressure mercury injection, gas-water phase permeability, and scanning electron microscope experiments.The results show that the irreducible water saturation of tight sandstone in the study area is 34.77% - 83.78%, withanaverage of 63.86%, and the T2cutoff is 3.86 - 65.60 ms withan average of 20.96 ms.The irreducible water saturation of tight sandstone is affected by physical properties, wettability, sensitivity, clay mineral type, mass fraction, and particle size in reservoirs. The smaller the tight sandstone size is, the higher the clay minerals content, and the stronger the rock hydrophilicity; The greaterthe specific surface area and water film thickness of the rock, the higher the capillary and membrane irreducible water. Water sensitivity and salt sensitivity are the main factors causing the damage of permeability. Residual intergranular pores, dissolution intergranular pores, dissolution within grains, intercrystalline pores and micro-fractures are developed in the research area. The types and forms of clay minerals filled in the pores are different, resulting in the complex pore structure of tight sandstone, strong micro-heterogeneity, and largeirregular changes in water saturation.

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Origin of Dolomitic Tuff in Permian Fengcheng Formation in WuXia Area of Junggar Basin
Liu Yinghui
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  80. 
Abstract ( 33 )   PDF (29967KB) ( 10 )  
 The dolomitic rocks are developed in the Fengcheng Formation in WuXia area, Junggar basin and are considered to be the important reservoirs for further petroleum exploration and exploitation. Based on the core observation of 13 wells as well as the core sample tests, the dolomitic rocks petrological and geochemical characteristics were systematically analyzed, and the origin of dolomitic rocks with different occurrences were discussed. In this study, five types of rock textures were distinguished according to their macroscopic occurrence, including rippled, diffuse, flocculent ,random bedded, and massive dolomitic rocks. They are characterized by high δ13CPDB values (average 4.0‰) and high paleosalinity values (average 13.0%). Their geochemical characteristics and deepwater originated sedimentary structures together with evaporation indicate a lowenergy, reduction in deepwater, dryhot climate and high salinity deposition environment. The formation of rippled dolomitic rocks is considered to be of the brine delamination in salted lakes. In contrast, the single crystals of random bedded, massive, flocculent, and diffuse dolomitic rocks have fogged center and clear margin, which may be resulted from the metasomatism after burial. This study provides a scientific basis for further oil and gas exploration in the Fengcheng Formation of WuXia area and other dolomiterich areas.

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Metallogenic Geological Conditions and Prospecting Direction of Jiadi Gold Deposit in Panxian County, Guizhou Province
Zhang Bingqiang, Zhao Fuyuan, Yang Qinghao, Huang Yi, Li Junhai, Liu Song
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  94. 
Abstract ( 51 )   PDF (12788KB) ( 17 )  
Jiadi gold deposit is located in the southeastern wing of Lianhuashan anticline, 3 km away from the anticline core. It’s the first large primary gold deposit closely related to Emeishan basalt found in China in recent years. Similar to other gold deposits in southwest Guizhou, Jiadi gold deposit belongs to fine grained disseminated gold deposit, and the source of oreforming fluid is characterized by magmatic water. Basalt is the main orebearing stratum in the mining area, and black tortoise volcanic breccia is the main orehosting rock. Through the analysis of mineralization trend, the superimposed area of Lianhuashan anticline (marginal fold) and the near EW anticlinorium is the favorable oreforming position, which controls the distribution and occurrence characteristics of the orebodies in the deposit, and the near EW anticlinorium directly controls the characteristics of the near EW distribution of the orebody: the closer to the core of Lianhuashan, the higher the ore grade and the thicker the orebody. Based on the analysis of the primary halo geochemistry, there may still be gold orebodies bound by faulted or strata on the top of the ore body. It is considered that the goldbearing hydrothermal solution came from the deep, rose to a certain position along the deep fault, and migrated from east to west along the interlayer fracture zone, experiencing at least two major metallogenic stages. The comprehensive study shows that the whole Lianhuashan area has a better prospecting prospect, and the gold deposits in this area may be distributed in an isometric or unequal interval pattern in the SN direction, and the favorable oreforming area controlled by superimposed folds are estimated to be more than  5 km away from the core of Lianhuashan anticline. Except for Emeishan basalt, the strata bound or faultcontrolled gold orebodies may be formed in the Upper Permian Longtan Formation and Triassic strata in favorable structure and suitable lithology.

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LA-ICP-MS Zircon U-Pb Age of Shanglang Metamafic Rocks in Longsheng, Northern Guangxi and Its Geological Significance
Qin Ya, Feng Zuohai, Wan Lei, Wu Jiang, Wu Jie, Xing Quanli, Xue Yunfeng
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  109. 
Abstract ( 31 )   PDF (42863KB) ( 16 )  
 The chronology of  Shanglang metamafic rocks in Longsheng area of northern Guangxi was researched by LAICPMS zircon UPb dating. The age information of two chronological samples  are nearly consistent, concentrated in eight intervals (114.8±1.6), (152.0±5.0), (213.9±3.5), (274.6±9.4), (442.5±6.7), (553.5±9.2), (774.2±5.9), and (822.0±10.0) Ma. The genetic types of zircons show that the zircon of (774.2±5.9) Ma is the youngest magmatic zircon, representing the emplacement age of  Shanglang metamafic rocks. The zircon of (822.0±10.0) Ma is the captured zircon, representing the age of the captured materials during the magma emplacement. The hydrothermal zircon ages are (114.8±1.6), (152.0±5.0), (213.9±3.5), (274.6±9.4), (442.5±6.7), and (553.5±9.2) Ma, representing the time limits of the later tectonic thermal events of metamafic rocks. Among the hydrothermal zircon ages, (442.5±6.7) Ma represents the ductile deformation age of ShouchengSanmen fault, which is consistent with the ductile deformation age of regional NNE faults, and the hydrothermal zircon age of less than (442.5±6.7) Ma is the tectonic thermal events after ductile deformation. The existence of (553.5±9.2) Ma PanAfrican hydrothermal zircon indicates that the South China continent was influenced by PanAfrican tectonic thermal events and should be  related to Gondwana continent. 

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Geochronology, Geochemical Characteristics and Tectonic Environment of Granite in Songnan Low Uplift, Qiongdongnan Basin
Zhong Jia, Wang Yanquan,
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  134. 
Abstract ( 36 )   PDF (18153KB) ( 10 )  
 In this paper, the lithofacies, zircon chronology and geochemistry are studied to discuss the petrogenesis and tectonic environment of the Songnan low uplift granite in Qiongdongnan basin, northern of the South China Sea. The results show that the buried hill lithology is mainly granodiorite and monzonitic granite. The zircon UPb dating results of LAICPMS are 228.6 and 243.7 Ma, the age of Triassic magmatic activity. The rock mass belongs to highk calcium alkaline series, with high content of SiO2(54.94%79.71%), moderate alkali (3.53%6.43%), Al2O3 ( 9.82%18.23%), CaO(1.24%9.55%), and MgO(0.37%2.28%). The A/CNK values range from 1.09 to 2.13, which are both aluminum and peraluminous granites. The rocks are generally rich in large ion lithophile elements such as K, Rb and Th, depleted of high field strength elements such as Ta, Nb, Ti, with moderate to weak negative Eu anomalies (δEu= 0.50~0.85). The petrological and geochemical characteristics show that the granodiorite is aluminum Itype granite, and the monzogranite is peraluminous Stype granite, which were formed by partial melting of sediments in the crust. The comprehensive analysis suggests that the granite has the characteristics of postcollisional granite, formed in extensional tectonic environment, and is related to the reverse extension after collision of South China and Indosinian blocks.

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Characteristics and Formation Mechanism of Geohazards in Hunhe Fault Zone
Zhang Tiantian, Yang Weimin, Wan Feipeng,
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  149. 
Abstract ( 50 )   PDF (58291KB) ( 23 )  
Hunhe fault is the most important active fault in Fushun City, Liaoning Province. In order to deeply investigate the development of geological disasters along Hunhe fault, understand the relationship between disaster formation and the preexisting faults, and provide scientific basis for the prevention and early warning of geohazards. In this paper, we adopted the field investigation method and the ground deformation monitoring data to study. The disaster types and characteristics of Hunhe fault zone are clarified, and the formation mechanism of the fault zone disaster is analyzed. The results show that the ground fissures distributed along the hidden fault area, and extended 3002 400 m; The mining activities in the south of Fushun City induced the local tension and opening of the preexisting weak fault surface, which then extended and penetrated to the surface to form ground fissures. In the bedrock area where the fault extends, small landslides distributed along the fracture and the affected zones of the fault, and the main sliding direction is perpendicular to the fault strike or inclined at a large angle. These landslide formation mechanisms are related to the structural plane inside the rock mass. Especially, the structural planes along the slope  were coupled with the slope to form a sliding structure. Under the action of longterm rainfall, the structural planes soften, penetrate, and accelerate the creep deformation of rock and soil mass, and finally forms a landslide.

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Study on Unsteady Flow of Slope SelfStarting Drainage Method
Lei Yi, Shuai Feixiang, Sun Hongyue, Zhang Zekun, Xiong Chao
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  162. 
Abstract ( 31 )   PDF (2818KB) ( 24 )  
The selfstarting drainage method is a new type of intermittent wave drainage method. In this paper, a selfstarting drainage model for analytical study is established innovatively, and Diracδ function is introduced to describe the mathematical characteristics of the point sink of the selfstarting drainage model and to derive the twodimensional flow motion equation of the diving profile and the boundary conditions of the diving surface from this model. The twodimensional Fourier transform is used to solve the problem of the model, and the analytical solution of the seepage field after selfstarting drainage is obtained. Under the two setting conditions, the slope phreatic line curves obtained from the numerical simulation results and the theoretical solutions by the selfstarting negative pressure drainage method are calculated and compared. The results show that in the three groups of working conditions with different drain hole positions, the deeper the drain hole position, the greater the error of the theoretical solution, and the error between the theoretical solution and the numerical simulation results is the largest near the drain hole area when the drain hole position is (24,10); In the three groups of working conditions with fixed drainage hole position but different initial head heights, the higher the left and right heads, the greater the error of the theoretical solution, and the error between the theoretical solution and the numerical simulation results is the largest when the left head is 28 m and the right head is 8 m. The theoretical solution of saturation line of the analytical solution of the self starting negative pressure drainage seepage field is in good agreement with the numerical simulation results under simplified conditions.

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Optimization of Area Replacement Ratio of Stone Column Based on Robustness Principle
Li Qingfang, Wang Zhu, Yu Yang
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  171. 
Abstract ( 41 )   PDF (9330KB) ( 5 )  
 Determination of the specific area replacement ratio is crucial in construction, considering the uncertainty of mechanical parameters of soft soil itself and the balance between postconstruction settlement satisfaction and cost. Based on the robust geotechnical design principle, the pile and soil constrained modulus is regarded as noise factors with uncertainty, and by using the MonteCarlo simulation method the value of several possible noise factors is determined; Further, the standard deviation of postconstruction settlement is calculated by the oneway layerwise summation method as the measure of robustness; Finally, the area replacement ratio of gravel pile could be optimized with considering safety, cost and robustness simultaneously. In this study, a robust design framework of stone column was proposed and its application was illustrated through an engineering example. Based on this example, the influence rules of settlement limit, coefficient of variation of compression modulus, and parameter distribution mode on the optimization were discussed. The results show that the optimal replacement rate is 29%; The improvement of settlement limit increases the engineering cost; The compressive modulus of soil has a greater influence on the final optimization than that of gravel pile; When using normal instead of lognormal distribution to simulate the noise factor distribution, the results of this calculation are more uncertain.

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Groundwater Origin and Hydrochemical Characteristics in Cenozoic Basaltic Aquifer in North China:A Case Study of Zhangbei County,Hebei Province
He Jin, Zheng Yidi, Deng Qijun, He Xueqin
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  171. 
Abstract ( 28 )   PDF (7680KB) ( 21 )  
 In order to study the chemical characteristics and formation of groundwater in Cenozoic basalt in North China,the groundwater  of the basaltic aquifer of Zhangbei County was taken as the research object. Based on the field collection of groundwater samples and the determination of groundwater chemistry and isotopic composition, the hydrochemical formation mechanism of basalt groundwater in the study area was analyzed by means of statistical analysis, ion proportion coefficient, hydrogen and oxygen isotopes, and inverse geochemical simulation. The results show that along the direction of groundwater flow, most of the ions in basalt groundwater are increasing. The chemical types of groundwater in the recharge area are mainly HCO3Ca·Mg, with the average TDS less than 500 mg/L, while the anions in groundwater in the discharge area are mainly Cl-, cations are mainly Na+, and the average TDS is more than 1 400 mg/L; The groundwater recharge in the study area is the local atmospheric precipitation and the weathering and dissolution of aluminosilicate, and rock salt and sulfate are the main sources of ions in groundwater; The effects of human activities such as dissolution and filtration, cation alternate adsorption, and agricultural fertilization are the main factors controlling the hydrochemistry of groundwater.

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CO2 Solubility Model of OilWater System Based on KRR Optimization Algorithm
Long Zhenyu, Wang Changquan, Shi Lihong, Ye Wanli, Liu Yang, Li Yifan
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  194. 
Abstract ( 27 )   PDF (5782KB) ( 18 )  
 In the process of CO2 injection, a threephase dynamic equilibrium of CO2, crude oil, and formation water is formed. The solubility of CO2 in oilwater system will directly affect the displacement effect and storage potential of CO2. In order to study the solubility of CO2 in oilwater system, by taking the oilwater system of Jilin oilfield as an example, the solubility experiment of CO2 in oilwater system with different volume proportion was carried out by using PVT analyzer, and the solubility rule of CO2 in oilwater system was clarified. In the experiment, the solubility of CO2 in oilwater system increased with the increase of saturation pressure and oilwater volume ratio. Based on the experimental data, the parameters of kernel ridge regression(KRR) were optimized by Grid search method (GS) and Bayesian optimization algorithm (BOA), respectively, and the CO2 solubility prediction model of CO2 in oilwater system was established. The average relative errors of GSKRR model and BOAKRR model in the optimization model based on KRR algorithm are 6.758% and 1.998% respectively. It shows that by this BOAKRR model , the solubility of CO2 in oilwater system can be predicted and plotted with higher precision. By using BOAKRR model, the solubility chart of CO2 in oilwater system under different temperature and oilwater ratio provides support for the application of CCUS(carbon capture, utilization and storage) technology.

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Application of Fusion Distributed Scatterer TimeSeries InSAR Technique in Deformation Survey of Mining Area
Jia Huihui, Zhang Haiqing, Li Keda, Zhang Xiaopeng
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  202. 
Abstract ( 29 )   PDF (19249KB) ( 7 )  
In order to investigate and monitor the deformation of the iron mining areas in Zhoutaizi Village, Zhangbaiwan Town, Luanping County and eliminate potential safety hazards, 48 Sentinel1 images from the mining areas is analyzed by using the DSCSInSAR (distribute scatterercoherent scatterer InSAR) technique that developed based on the time series CSInSAR (coherent scatterer InSAR) technique. Firstly, AD test is used to identify the statistically homogeneous pixels, and then the optimal phase is estimated based on the eigenvalue decomposition algorithm of the covariance matrix; Finally, the surface deformation results of the iron mining areas are obtained through the calculation of timeseries deformation. The results show that: The annual mean deformation rates in the study area range from -34.50 to 24.50 mm/a; Most of the mining areas have different degrees of subsidence, among them, Zhoutaizi Village and the mining area near the roadside have the largest deformation values and Yaolinggou mining area has a significant uplift; The maximum settlement and maximum uplift reached 34.00 mm and 24.03 mm respectively. These results are in good agreeement with those of the four local GPS monitoring points. Compared with CSInSAR, this technique greatly improves the density of the point targets and the quality of the interferograms.

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Short-Term Prediction of PM2.5 in Beijing Based on VMDLSTM Method
Qin Xiwen, Wang Qiangjin, Wang Xinmin, Guo Jiajing, Chu Xiao
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  214. 
Abstract ( 63 )   PDF (6085KB) ( 9 )  
 Haze is a hot issue closely related to social development. In order to predict PM2.5 concentration and provide basis for its effective prevention and control,  the PM2.5 prediction model VMDLSTM is proposed based on the combination of the improved VMD (variational modal decomposition) and LSTM (long and shortterm memory) neural network. Firstly, the threshold method is used to determine the decomposition number of VMD method, then the historical data is decomposed into different sequences, further each sequence is predicted, and the final prediction result is obtained by summing the prediction results of each sequence. The VMDLSTM model is applied to the shortterm prediction of PM2.5 series in Beijing, and its result is compared with nine models such as ARIMA (autoregressive integrated moving average), RFR (random forest regression),LSSVR(least squares support vector regression), LSTM and so on,  by using seven evaluation indexes. The comparison results show that among the five error evaluation indexes, the VMDLSTM model performs best,  with only one error index ranking second. In the protocol index evaluation, the VMDLSTM model is closest to 1 and has the highest accuracy; The mean square error of VMDLSTM model is 41.10, the root mean square error is 6.42, the mean absolute error is 5.79, and the protocol index is 0.97. The mean square error range of RFR,VMDLSSVR,ARIMA,SVR,and LSTM models is from 60.72 to 1 058.07, the root mean square error range is from 7.79 to 32.53, the mean absolute error range is from 7.45 to 26.14, and the protocol index range is from 0.39 to 0.95. The VMDLSTM model proposed in this paper has the highest accuracy.

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Removal of Microcystins from Water by UV/Chlorine Process
Wang Hongqiao, Bai Yu,
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  222. 
Abstract ( 23 )   PDF (4616KB) ( 10 )  
Eutrophication leads to the outbreak of algae and the release of algal toxins into water. Microcystins (MCLR), the most common algal toxin, shows high potential toxicity to human health. In this study, the combination of ultraviolet and chlorine was applied to investigate the degradation ability of MCLR. The results show that a synergetic effect between UV and chlorine is produced, and  MCLR can be completely removed in 30 min. The produce of active radicals such as ·Cl and ·OH during the UV/chlorine process is the main reason for the synergetic effect. In the test, the MCLR removal efficiency increased with the increase of chlorine dosage. While pH had negligible effect on MCLR removal during UV/chlorine process under neural and acid conditions.  However, an effect was observed that the remove efficiency decreased significantly with pH increase in alkaline conditions, the remove efficiency was only 41.3% at pH 9. The water matrix can significantly affect  MCLR degradation: the degradation percentage of pure water, filtrated water, and water treatment plant influent was 99.5%, 40.2%, and 63.3%, respectively. The degradation efficiency of MCLR decreased with the increase of humic acid concentration: the removal of MCLR without humic acid was as high as 99.5% within 60 minutes; while the removal of MCLR was only 45.3% with 10 mg/L humic acid. 

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Adaptive Weight Density Inversion Method for Gravity Anomaly and Mesozoic Division of Diaobei Sag in East China Sea
Li Jian, He Xinjian, Huang Jun
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  229. 
Abstract ( 26 )   PDF (14246KB) ( 11 )  
 Gravity density inversion is to divide underground into multiple grids and calculate the density of each grid. The resolution of the current methods is low. To make an improvement,an adaptive weight function of the density inversion method was proposed. Because the upper space height anomalies highlight different buried depth of geological bodies, the corresponding space abnormal weight function iteration inversion was established to effectively improve the results of convergence and resolution. The model test shows that by using this adaptive anomaly weight density method more accurate and convergent results can be obtained compared with the conventional method, and the method has a good noise suppressing effect. Based on this inversion technique, the spatial density structure of the eastern depression was reconstructed, and the residual characteristics of Mesozoic in the eastern depression were analyzed. The results show that the distribution of Mesozoic group in the eastern depression belt is clearly different from that in the north and south. The Mesozoic group in the south (Diaobei sag) is widely distributed with large thickness(about 4 km), which overturns the previous understanding that the Mesozoic in the Xihu sag in the northern part of the basin is relatively thin, and that the Mesozoic characteristics of the two sags are the same. Diaobei sag of the Mesozoic is an epicontinental depression basin, which is limited to the central and southern part of the basin.

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Fast Constructing Full Tensor Maps of Global Disturbing Gravity Gradient Using Heterogeneous Parallel Algorithm
Tan Xuli, Wang Qingbin, Feng Jinkai, Huang Yan, Huang Ziyan
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  238. 
Abstract ( 36 )   PDF (5662KB) ( 14 )  
Disturbing gravity gradient is the second derivative of disturbing potential, containing more highfrequency information of the changing and irregular earth gravity field with respect to other sort of gravity data. Using highorder spherical harmonic coefficient model to obtain largescale and highresolution disturbing gravity gradient data is timeconsuming and inefficient caused by repetitive computation. To solve this problem, a simplified method was proposed which computed and saved some intermediate variables that can be converted into global and local parameters separately. Based on this method, a fast heterogeneous parallel algorithm for calculating disturbing gravity gradient tensors was proposed. The parallel calculation of gradient tensor on GPU was realized by CUDA (compute unified device architecture),and by using this algorithm, a full tensor map of the global disturbing gravity gradient with 5′×5′ resolution was quickly constructed based on the 2 190order EIGEN6C4 model, which shows the numerical characteristics of the disturbing gravity gradient on a global scale and its correlation with changes in topography and Earth’s mass distribution. The reliability of this algorithm was validated by checking whether the calculated Txx, Tyy  and Tzz met the Laplace constrain, and the computational efficiency was compared with the traditional serial algorithm. The experimental result shows that using this algorithm can reduce time consumption by 90% and increase computational efficiency by 60 times.

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Analysis of Influence Characteristics of Topography on GroundedSource ShortOffset Transient Electromagnetic Responses
Qi Yanfu, Li Xiu, Sun Naiquan, Qi Zhipeng, Zhou Jianmei, Zhang Mingjing, Xing Tao
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  247. 
Abstract ( 29 )   PDF (14790KB) ( 4 )  
 The shortoffset transient electromagnetic method (SOTEM) is an effective tool for mineral resource exploration in mountainous areas. However, the topography has a serious effect on the survey, which brings great difficulties to the fine interpretation of transient electromagnetic data.  We analyzed the influence characteristics of terrain on SOTEM data based on the 3D unstructured timedomain finiteelement method. By using unstructured mesh to match the rugged  terrain, the SOTEM responses  on a complex geological model  were quickly simulated by combining the edge finiteelement method and backwardEuler scheme,and the spatial distribution characteristics of the 3D topographic responses were obtained based on the simulation of a large number of typical terrain models such as hills and valleys. The results show that topography has serious influence on SOTEM response, and the law is very complex. On this basis, we further analyzed the influence of complex topography on the detection of underground targets. It is found that the coupling of complex topography and underground anomaly   makes it impossble to effectively distinguish underground targets, which brings great difficulties to the accurate detection of underground targets.

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Difference and Combination of Artificial Boundary Conditions in Seismic Acoustic Numerical Simulation
Han Fuxing, Wang Ruowen, Sun Zhangqing, Gao Zhenghui
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  261. 
Abstract ( 39 )   PDF (10534KB) ( 11 )  
In seismic numerical simulation, the boundary reflection generated by the finite calculation area will interfere with the results of normal wave field simulation. In this paper, the artificial boundary condition is introduced to reduce the influence of boundary reflection. For the decoupled and uncoupled differential forms of PML (perfectly matched layer) boundary conditions, different spatial difference orders are used for seismic wave field numerical simulation. When the order of spatial difference is increased, the nondecoupled PML differential form has more advantages in computational efficiency and implementation mode than those of the decoupled. Aiming at the problems of CE (ClaytonEngquist) boundary condition limited by the incident angle of incident wave, low accuracy at the boundary, and poor absorption effect, the secondorder CE boundary condition and PML boundary condition are combined into a new combined boundary condition, which can reduce the thickness of attenuation band while ensuring the absorption effect, so as to improve the calculation efficiency. The effectiveness of this algorithm is verified by the numerical simulation results.


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Seismic Tomography of the Crustal Structure in Northeast China
Li Hongli, Liu Cai, Tian You, Fan Hao
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  270. 
Abstract ( 40 )   PDF (20877KB) ( 20 )  
Since the Late Paleozoic,Northeast China has experienced the combined effect of PaleoAsian Ocean, MongoliaOkhotsk Sea, and Pacific tectonic domain, resulting in the extremely complex crustmantle structure. In this study, we collected 100 980 Pwave arrival times and 91 030 Swave arrival times compiled by the National Earthquake Network, and the 3D P and Swave velocity structures in Northeast China were determined by using seismic tomography method. The Poisson’s ratio structure of the study region was also obtained to explore its complex crustal structure. The tomographic results show that the crustal velocity structure in Northeast China exhibits strong lateral heterogeneities with various degrees of heterogeneity between and within different tectonic units. The Songliao basin is a typical rift basin. The shallow crust shows low Pwave and significantly low Swave anomalies as a whole, with some low resolution regions. Largescale highvelocity anomalies exist in the middle and lower crust, which may be related to the subduction and retreat of the Pacific plate beneath the Eurasian continent, resulting in the lithospheric delamination and upwelling of hot and wet asthenosphere material. The northern part of the Great Xing’an Range gravity lineament and the Changbai Mountain show lowvelocity anomalies, which may indicate largescale magmatism. The widespread magmatism may provide heat or material sources for the formation of solid mineral resources. The crust beneath Changbai Mountain and Wudalianchi volcanic areas shows significant low velocity and high Poisson’s ratio anomalies, which may indicate the possibility of volcanic activities.


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Seismic Responses Simulation of InterSalt Shale Oil Rhythm Formation and Prediction of Layer Thickness of Thin Shale Reservoirs
Zhang Tao, Guo Zhiqi, Liu Cai, Liu Xiwu, Liu Yuwei,
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  281. 
Abstract ( 37 )   PDF (10340KB) ( 11 )  
 The geological structure of shale oil reservoir of the Qianjiang Formation in the Qianjiang sag of the Jianghan basin is thinlayer shale under the background of rhythmic layers. It is difficult to accurately describe the spatial distribution of the thin intersalt shale oil reservoir thickness by the conventional seismic exploration methods due to the limitation of seismic resolution. This study is based on the existing seismic data to explore the method of thinlayer seismic prediction suitable for shale thin layers in rhythmic structure. In this paper, the seismic propagation matrix method is used to calculate and analyze the seismic response characteristics of the target rhythmic layer in the study area and the dynamic characteristics of seismic reflection when the thickness and velocity of the target shale thin layer change in the nonuniform thin interbedded structure. It is found that the amplitude and phase of seismic reflection waveform change obviously with the velocity and thickness of the nonuniform shale thin layer. On this basis, combined with logging analysis, a rhythmic geological and geophysical model is constructed, with 99 combinations of shale thin layer velocity and thickness being considered in the model space. Through finding the best match between the actual seismic reflection waveform of the target layer and the seismic waveform in the constructed model space, a seismic prediction method of the thin shale reservoir thickness is established, and by which, the thickness of the thin shale reservoir in the study area is predicted: The thickness varies from 520 m, showing an increasing trend from southwest to northeast. There is a high consistency between the thickness of the predicted shale thin layer and that of the logging interpretation, which verifies the effectiveness of this seismic prediction method and provides important information for the identification and evaluation of shale oil reservoirs.

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Land Expansion of Urban Construction in the Three Provinces of Northeast China Based on Google Earth Engine
Wang Mingchang, , Liu Peng, Chen Xueye, Wang Fengyan, Song Yulian, Liu Hanyuan
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  292. 
Abstract ( 35 )   PDF (7770KB) ( 7 )  
Combined with social economy and population changes, the rapid extraction of urban construction land from medium and high resolution remote sensing images based on cloud platform can be used to effectively and accurately monitor the dynamic changes of urban construction land expansion in a large range and a long time series, thereby providing reference for urban management and planning. Based on Google Earth Engine (GEE) cloud platform, the urban area was extracted by NPP/VIIRS (suomi national polar-orbiting partnership/visible infrared imaging radiometer suite) annual average night light data and threshold segmentation. We obtained 3 142 Landsat images covering the cities of the three provinces of Northeast China. On the basis of the original spectral band, we constructed exponential features, texture features, and terrain features, and used SEaTH algorithm for these features optimization. Based on the JM distance, the number of features was reduced from 20 to 12. Within the urban area, combined the optimal features with random forest (RF) algorithm, the Landsat monthly composite images were reclassified, and more accurate extraction of construction land was obtained. The experimental results show that the average overall accuracy and Kappa coefficient of urban construction land expansion in the three provinces are 96.19% and 0.92, the method is more efficient and reliable. The urban construction land of the three provinces had expanded by 49.07% from 1989 to 2019. Among the provincial capitals, the expansion rate of Shenyang is the fastest, followed by Changchun, and Harbin is the slowest. Population and economy are the main factors that promote the expansion of urban construction land.
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Space Requirements and Routes Optimization of Earthquake-Proof Evacuation on University Campus in Earthquake-Prone Zones
Zhang Jiayu, Zhao Xiaoyong, Bai Linbo, Wang Yong, Zheng Fang
Journal of Jilin University(Earth Science Edition). 2022, 52 (1):  305. 
Abstract ( 24 )   PDF (6577KB) ( 10 )  
here is a serious threat of earthquake disaster in earthquakeprone areas. Campus is an important place for talent training and population gathering. In earthquakeprone areas, earthquake prevention and disaster reduction are particularly urgent and necessary through earthquake evacuation planning and design. In order to improve the efficiency of earthquake evacuation and reduce the evacuation injury, we analyzed the evacuation demand based on the spatial layout and population aggregation on the campus, and studied the optimization from the two aspects of evacuation space demand and evacuation route by using GIS spatial analysis technology by taking Ningxia University as the research area. The open space such as square, grass, and playground can be determined as earthquake emergency shelters. Under the constraints of shelter’s capacity, the optimized LA (location allocation) model can be used to allocate the campus evacuees to the shelters. According to the spatial distribution of earthquake shelters, the seismic routes were established by avoiding dangerous areas and people moving disorderly. The imbalance of the spatial distribution of shelters will lead to evacuation failure. We suggest that the emergency signs should be more visible in the campus to improve the identification of evacuation passages, and the open space near the shelter demand points (such as dormitory buildings) should be increased such as grasslands or squares with their landscape functions, so that people can quickly move to the shelter in an event of disaster. 

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