The observation of seismic resistivity plays an important role in earthquake monitoring and prediction. Due to the acceleration of urbanization, the observation environment of surface resistivity stations is seriously disturbed. In order to suppress environmental interference, geoelectric scientists have carried out underground geo-resistivity observation and research since the 1980s. In this paper, the research on the development of underground geo-resistivity observation in China is reviewed. The suppression ability of stray current and metal pipelines, the relationship between annual variation of underground geo-resistivity caused by seasonal variation and observation device, and the seismic reflection efficiency are evaluated and analyzed. The advantages of underground geo-resistivity observation are described: it can suppress the interferences caused by abnormal bodies and seasonal changes, weaken the influence of surface stray current obviously, reduce the annual variation range of resistivity effectively, and solve the problem of increasingly serious surface environmental interferences. With the development of seismic monitoring and prediction from empirical prediction to physical prediction, more and more attention will be paid to the establishment and application of underground geo-resistivity observation system.

The Sanhetun gold deposit in Heilongjiang Province is located at the southwest end of the Nenjiang-Heihe tectonic melangite gold metallogenic belt. Due to the thick Quaternary overburden and insufficient deep geophysical work, the breakthrough of the deep prospecting and the research of metallogenic model are restricted. In this study, the two-dimensional electrical structure of the study area was obtained by the two-dimensional data inversion of the audio geomagnetic long profile (about 8.5 km) across the deposit using the nonlinear conjugate gradient method. The results show that the 100 m shallow layer of the Sanhetun gold deposit has the characteristics of low resistivity. It reflects the shallow Cretaceous sand-mudstone and Quaternary weathering in this area. The continuous distribution of low resistance layers and the underlying high resistance anomalies in the northwest side of the section indicates the Cretaceous volcanic rocks and Carboniferous intrusive rocks. The high and low resistance transition zones under the section reveal the deep distribution characteristics of ductile shear zones and faults. These are important ore guiding and storage structures. In this paper, the metallogenic model of the Sanhetun gold deposit is established based on the regional geological data. In the Early-Middle Jurassic tectonic extensional period, the ore-forming fluid migrated upward along the fault and ductile shear zone, and then leached the gold elements from the Late Carboniferous intrusive rocks，which contributed to the first phase of mineralization in the study area. In the Early Cretaceous, the study area was again in an extensional and pull-apart setting, and the gold elements carried by the deep magmatic eruptions were transported along the newly formed and reactivated ductile shear zones and basin margin fractures toward the edge of the Sanhetun volcanic basin with the magmatic hydrothermal fluids,and gradually precipitated and  superimposed on the top of the earlier mineralization phase with the temperature decrease in the later period.

 

 Due to the influence of equipment and environmental factors, the signals collected by ground-penetrating radar (GPR) are vulnerable to varying degrees of noise interference. Traditional variational mode decomposition (VMD) suppresses noise by searching for the optimal solution of variational modes to separate the components with different center frequencies. However, the selection of optimal mode number is challenging and subjective, resulting in the reconstructed signals being affected by different degrees of oscillation. To solve these problems, we proposed a combined denoising method based on the adaptive VMD and singular spectrum analysis (SSA). Firstly, the energy loss ratio is defined to facilitate the adaptive selection of the optimal mode number, and the Pearson correlation coefficient method is employed to extract the valid signal. Secondly, to solve the problem of the low-frequency oscillation phenomenon in VMD, SSA is further used to perform secondary filtering to improve the signal-to-noise ratio (RSN). The effectiveness of the proposed method is verified by the synthetic wavelet experiment, numerical simulation experiment, and field experiment. In the synthetic wavelet experiment, the SNR of VMD-SSA processing is improved maximum by 13.587 8 dB over the ensemble empirical mode decomposition (EEMD) and the traditional VMD methods; in the numerical simulation experiment, the SNR of the processed B-scan using the VMD-SSA method is improved by 3.765 9 dB and 2.655 7 dB respectively compared with the EEMD and traditional VMD methods; in addition, the background noise and the random noise are also properly suppressed in the field data processing. The proposed method not only solves the oscillation problem but also highlights the features of the abnormal signals more effectively.

 With the increasing requirements for large-depth and fine-structure detection of geological targets, the research on further improving the relative resolution of the controllable source electromagnetic method has gradually become a research hotspot. In order to improve the high-frequency signal-to-noise ratio, suppress human interference, increase the depth of exploration, we proposed high frequency power supply technology based on capacitor compensation, data acquisition and processing technology based on frequency optimization and digital filtering to suppress power frequency interference, and interpretation technology based on direct inversion of observed electromagnetic field. First, the capacitor network unit is connected to the power supply circuit, and by calculating distribution circuit inductance and selecting compensation branch，the closest resonant capacitance is combined to the theoretical value, so as to increase the sending current of sending signals at different frequencies by putting capacitors with different capacitance values in series for different frequencies of 1 000-10 000 Hz. Then, by optimizing the sampling rate and sampling length, and by digital filtering, the influence of 50 Hz power frequency and its harmonics on the observed data can be corrected. Finally, through extending the frequency of conventional CSAMT low frequency observations from 0.100 Hz to 0.025 Hz, the exploration depth can be improved by direct treating and inversing the observed electromagnetic field components. On this basis, the theoretical model of numerical simulation was established. The deep exploration tests of known geothermal fields were carried out in the disturbed area. The results show that the depth of CSEM can reach 3 000-5 000 m, which effectively enhances the exploration depth of the artificial source electromagnetic method.

Controlled-source electromagnetic method (CSEM) signals are often contaminated by strong human noise, and the resolution of CSEM exploration is greatly affected. In order to improve the quality of CSEM data, in this paper, a new intelligent data processing method is proposed based on support vector machine (SVM) algorithm. Firstly, the baseline-drift noise is removed by complementary ensemble empirical mode decomposition (CEEMD) algorithm, and then the data is classified by SVM to select high-quality signals. In order to validate the proposed method, a targeted experiment was conducted using simulated noise and measured high-quality data, and then the method was applied to the measured data by the wide-field electromagnetic method (WFEM). The results show that the recognition accuracy of SVM is greater than 92.00%. After the treatment of the proposed method, the apparent resistivity changes from jumping shape to continuous and smooth.

The seismoelectric effect is an important representation of the seismoelectric transformation phenomenon in underground porous media. It can be used to detect underground oil, gas, and other pore fluids. In the numerical simulation of seismoelectric effect, traditionally the quasi-static approximation is adopted for the theoretical simulation of electromagnetic response. However, the quasi-static approximation ignores the influence of seismic shear waves, leading to significant errors in the simulation of electromagnetic field, and may not satisfy the premise of applying quasi-static in some cases. In order to accurately reveal the mechanism of seismoelectric effect, a finite difference method in frequency domain based on Maxwell’s full equation is proposed to simulate the frequency electromagnetic response of seismoelectric  effects, and the seismoelectric characteristics of the layered and anomalous conductivity models in an elastic homogeneous medium are analyzed and discussed. The results show that the reflection and transmission of electromagnetic wave field can be characterized by the Maxwell’s full equation numerical simulation more accurately at the interface of different media, and the abnormal position can be more accurately identified. This provides a new idea for improving the resolution of deep underground oil and gas detection.

Transient electromagnetic method(TEM) is a type of time-domain electromagnetic detection method, which is widely used in mineral resource exploration, coal mine, water and mud inrush investigation, karst investigation, and other issues. In conventional TEM data inversion，smoke-ring fast imaging and linear iterative inversion methods are used, which have the disadvantages of low accuracy, easy to fall into local minimum, and large calculation amount of sensitivity matrix. In this paper, a nonlinear optimization algorithm is proposed for transient electromagnetic data inversion, and the particle swarm optimization (PSO) algorithm and firefly algorithm are used for comparative analysis.  Typical three-layer and four-layer geoelectric models are established, and the convergence and anti-noise characteristics of the two methods are analyzed. The research results show that the PSO algorithm has high computational efficiency, however the data processing accuracy is low and the anti-noise ability is poor. The firefly algorithm has great advantages over the PSO algorithm in terms of noise resistance and data processing accuracy. We processed the measured data by using the two methods and compared the results, the above conclusions are verified.

The topography of geophysical exploration areas is often undulating and complex, and the traditional long-offset transient electromagnetic method (LOTEM) 3D forward modeling generally does not consider the influence of topography. However, the topographic factors seriously affect the reasonable interpretation of LOTEM data. The 3D forward modeling of LOTEM under real topography by the unstructured edge finite element method is developed in this study. Firstly, the 3D modeling software Blender is used to accurately build a complex geoelectric model, and the unstructured tetrahedral mesh is used to finely describe the real topography. Secondly, the dipole discrete field source processing technique is used to separate the long conductor source into several electric dipoles, and the second-order backward-Euler scheme is used to complete the time discretization. In this way, fast and high precision 3D forward modeling of LOTEM can be realized. The transient electromagnetic field response characteristics of the complex geological model under real topography conditions are simulated on the premise of guaranteed computational accuracy. The results demonstrate that due to the influence of topography, the LOTEM electromagnetic field response is severely “distorted”, which can weaken or even completely “cover up” the transient electromagnetic field response of underground targets, and it seriously affects the effective detection of underground targets.

Because of the advantages of surface nuclear magnetic resonance, such as direct, quantitative and unique inversion, it is widely used in hydrological environment investigation, early warning of disaster water source, and other fields. However, in practical applications, the nanovolt level SNMR signals is often submerged in the environmental noise and difficult to break down, which makes the result inaccurate. In this paper, a method for extracting SNMR signal envelopes based on local mean decomposition (LMD) is proposed. First, the real and imaginary envelopes of the noisy SNMR signal are decomposed sequentially from high frequency to low frequency. Then the noise interferences in the signal are removed, and the required signal components are extracted. Finally, the effective real and imaginary components are synthesized to obtain the target SNMR signal envelope. The results indicate that the fitting error of the initial amplitude of the SNMR signal envelope extracted by LMD  is within ±4.17%, and the error of the average transverse relaxation time is within±5.63%. The signal-to-noise ratio is improved by 30.3-37.2 dB.

Magnetic resonance sounding (MRS) is a geophysical method for directly detecting groundwater. It is widely used in water resources investigation and other fields, as it is quantitative, accurate, and efficient. The quality of MRS signal strongly affects the interpretation of magnetic resonance data. In this paper, the random noise suppression of MRS signal under strong environmental interference is studied. Based on the framework of convolutional neural networks (CNN), the nonlinear mapping relationship between the time spectrum of noise signal and the time spectrum of original noiseless signal is obtained by using the training method of supervised learning, so as to suppress the noise of magnetic resonance signal. The simulation results show that the signal-to-noise ratio of noisy MRS signal can be improved by more than 15 dB. The noise suppression effect of CNN is analyzed and compared with that of the time-frequency peak filtering (TFPF) method. The effectiveness and superiority of this method is proved by the noise suppression of the measured field data. 

For the exploration of deep earth resources in China, the authors developed a high-power borehole induced polarization system ( referred to as borehole IP system) for mineral resources exploration within 3 000 m. Compared with  ground induced polarization method,  borehole IP system conducts exploration through drilling and its transceiver is closer to the target body, which has more advantages in the exploration of deep concealed minerals and oil and gas resources. The acquisition control and data processing of  borehole IP system is the center of the whole system. In the work, it is necessary to solve the technical problems such as data acquisition, long-distance remote communication, high-speed data transmission, and transceiver synchronization under the condition of high temperature and high pressure. Based on the high expansibility of the logging ACME (acquisition control management expert), the authors developed a set of acquisition control and processing software matched with  borehole IP system. The acquisition control software of borehole IP system is connected to  ACME  through a dynamic library to realize the functions of data acquisition, real-time data transmission, display, monitoring, storage, processing and mapping, and has been successfully applied to the borehole detection experiment of copper iron metal mine in Daye City. The data processing results are highly consistent with the known data and meet expectations.

In order to clarify the strata and sedimentary filling characteristics of the Lower Jurassic Lianggaoshan Formation in eastern Sichuan basin, for effectively guiding the hydrocarbon exploration, this study comprehensively utilizes the research tools of outcrop survey, core observation and analysis of sedimentary petrology and petroleum geology. On the basis of systematically sorting out the stratigraphic structure and sedimentary facies in the study area, we further discuss the synergistic reservoir-forming rule between shale oil and gas and tight oil and gas under the constraints of sedimentary sequence. The results show that typical dichotomy sequence stratigraphic structure is developed in the study area. In the early lake transgression stage, the Lower Lianggaoshan Formation formed a landward stepping parasequence set, which was composed of delta front, prodelta, semi-deep lake and deep lake. In the late lake regression stage, a seaward stepping parasequence set is developed in the Upper Lianggaoshan Formation, which can be subdivided into three parasequences or subsections, showing the evolution from semi-deep lake to delta front, shore and shallow lake. The mudstones and shales of semi-deep lake, deep lake and prodelta facies are vertically superimposed with the sandstone bodies of underwater distributary channel in the delta front subfacies, forming various source-reservoir contact relationships, such as “self-generation and self-storage, lower generation and upper storage, side generation and side storage”. This provides a geological basis for the coordinated accumulation of shale oil and gas in the Lower Lianggaoshan Formation and tight oil and gas in the Upper Lianggaoshan Formation.

The basin edge slope area of Changling fault depression in Songliao basin is mainly composed of intermediate-basic volcanic rocks. At present，there is a lack of in-depth understanding of the lithology, lithofacies distribution pattern， and high-quality reservoir stratum development law of the intermediate volcanic rocks in the basin edge slope area. By taking Longfengshan area in Changling fault depression as an example, the spatial distribution characteristics of volcanic edifice and volcanic facies were described by making a comprehensive use of well drilling, well logging, and seismic data,the volcanic facies model and eruption model were established, and the development law of the high-quality reservoir stratum was discussed. The research results indicate that the volcanic eruption center is located in the basin edge slope zone near the high place of the basin edge and distributed along the fault. The proximal facies belt of the volcanic edifice is featured with interlayers of effusive facies and explosive facies. The central facies belt of the volcanic edifice is mainly composed of pyroclastic flow of thick explosive facies. The pyroclastic flow is further advanced to the sub-concave center of the basin and then transformed into volcanic deposit facies. The volcanic facies is jointly controlled by  multi-stage Plinian eruptions, the transport and placement of volcanic eruptions, and other factors. High-quality volcanic rock reservoirs are dominated by volcanic tuff and vesicular andesite with strong dissolution, which are located in the medial facies belt of the volcanic edifice on the basin edge slope. The proximal facies belts with lava flow developed are the favorable development parts of the volcanic reservoir stratum in the area. The research has certain directive significance in the oil-gas exploration of intermediate-basic volcanic rocks in the slope belt of the basin margin of a fault depression basin.

Aiming at clarifying the strongly heterogeneous Archean metamorphic rock buried hill reservoir in    Jinzhou   south,   the main controlling factors of the buried hill reservoirs are studied, and the development model of the buried hill reservoir in this area was established. Based on the data of drilling, coring, thin section, logging, and seismic, the characteristics of metamorphic buried hill reservoir are defined, the key factors controlling the reservoir development are discussed and the reservoir development model is established. The results show that: 1) Plagioclase gneiss, monzonite gneiss, cataclastic rock and diabase are developed in the study area, among which gneiss and cataclastic rock are the main lithology for reservoir development; Tectonic fractures, fractured intergranular pores and dissolution pores constitute a variety of reservoir spaces, among them tectonic fractures are the dominant. 2) Tectonic movement, lithology and weathering have an important control action on the high quality reservoirs distribution: reservoirs development degree of granite gneiss with high brittleness mineral content is superior to the basic intrusion; the reservoir thickness is large in the multi-stage fault superposition position; high position of the Paleo-geomorphology suffered strong weathering to further enhance the quality of the reservoir. Based on the above analysis, a reservoir development model considering tectonic position was established. Stably distributed reservoirs are developed in the platform area, thicker reservoirs are developed in the high slope area, the reservoir thickness changes fastest in the uplift area, the reservoir development in the low slope is relatively thinner, and the reservoir development in the depression area is the worst.

Modern geochemical analysis and biomarker analysis methods, the characteristics of Chang 7 Member and Chang 9 Member source rocks in Zaoyuan exploration area of Ordos basin were studied, and oil source correlation of Chang 4+5 Member Chang 61 Member and Chang 8 Member crude oil samples were carried out. The results show that the organic matter abundance of the source rocks of Chang 7 Member in the study area is higher, the type of organic matter is Ⅱ1-Ⅱ2, and the configuration of regular sterane C27-C28-C29 is V-shaped or partially V-shaped, which is the characteristic of sapropel; The organic matter abundance of Chang 9 Member source rocks is lower, the type of organic matter is Ⅱ2, and the configuration of regular sterane C27-C28-C29 is L-shaped, which is the characteristic of close mixing with terrestrial higher plants. The results show that the crude oil Pr/Ph ratios of Chang 4+5 Member, Chang 61 Member and Chang 8 Member are between 0.78 and 0.85, which indicate that their sedimentary environment belongs to a freshwater reducing environment; The crude oil of Chang 4+5 Member, Chang 61 Member and Chang 8 Member come from the same set of continental freshwater lake source rocks similar to Chang 61 Member, belonging to medium low mature crude oil. The crude oil of Chang 8 Member is more mature than that of Chang 4+5 Member and Chang 61 Member. The crude oil of Chang 4+5 Member, Chang 6 Member and Chang 8 Member in Zaoyuan exploration area is mainly from the dark mudstones, the main contributor is the Zhangjiatan shale of Chang 7 Member, and the dark mudstone of Chang 9 Member also makes a small contribution. 

The Erdaokan Ag-Pb-Zn deposit is a large Triassic Ag-Pb-Zn deposit newly discovered in the Duobaoshan metallogenic belt, Heilongjiang Province. Till now, little research has been conducted on  its formation mechanism, and its genesis is not clear yet. We selected the hydrothermal rhodochrosite as the research object, and systematically studied its mineralogical properties and geochemical characteristics by using optical microscope and LA-ICP-MS dating. The results show that the rhodochrosite is characterized by strong negative Eu anomaly and positive Ce anomaly, enrichment of light rare earth elements, and depletion of heavy rare Earth elements. In addition, the fractionation degree of light rare Earth elements  is significantly higher than that of the heavy rare earth elements, showing an overall right REE  distribution curve. On this basis，it is considered that the rhodochrosite in the Erdaokan Ag-Pb-Zn deposit was formed in a reducing environment, and the ore-forming materials  came from mixed sources. The deep ore-forming materials from the mantle, the carbonaceous shale and limestone near the ore all have important contributions to the formation of rhodochrosite.

Sulfur plays an important role in the formation of magmatic sulfide deposits. Based on the drill core data of the Voisey’s Bay nickel-copper sulfide deposit in Labrador, Canada, the correlation between nickel and copper mass fraction and sulfur mass fraction was analyzed by support vector machine (support vector machine, SVM) and kernel function based on radial basis function (radial basis function, RBF), and the prediction model of sulfur was established based on     sulfur mass fraction. In the prediction model, nickel and copper mass fractions are used as independent variables, sulfur mass fraction is used as the dependent variable, the predicted value of sulfur mass fraction is calculated by SVM to fit the original value. According to the calculation results of the fitting curve, the sulfur evolution can be divided into three stages: In the sulfur saturation stage, the mass fraction of sulfur element is 3.12×10-6-20.80×10-6, the variance is less than 1.44×10-7, the fractal dimension is 0.35, λ>0, and the stage is chaotic; In the mineralization stage, the mass fraction of sulfur element is 6.60×10-7-17.80×10-7, the variance is less than 1.37×10-9, the fractal dimension is 0.60, λ>0, and the stage is chaotic; In the sulfur loss stage, the sulfur mass fraction is 2.00×10-8-38.0.×10-8, the variance is less than 1.56×10-10, the fractal dimension is 0.94, λ=0, and the stage is stable. The results show that the mass fraction of nickel, copper and sulfur in the immiscible sulfur-saturated magma is not linearly or simply nonlinearly correlated, but staged nonlinearly.

The large-scale gold mineralization in Jiaodong Peninsula occurred in 125-110 Ma. Coincided with the mineralization period, the Early Cretaceous the Dazeshan and Tianzhushan plutons  are distributed in the eastern margin of the North China craton. Based on the studies of the petrography, geochemistry, zircon LA-ICP-MS U-Pb dating, and Lu-Hf isotopic constitution, in this paper, the petrologic classification, forming age, magmatic source, petrogenesis and tectonic dynamic background are discussed. The Dazeshan and Tianzhushan plutons are characterized by w(Na₂O) >3.68, 1.0δEu=0.49-0.64). They are a set of weakly peraluminous high potassium calc-alkaline rocks, showing the characteristics of I-type granites. The LA-ICP-MS zircon U-Pb ages of the Dazeshan and Tianzhushan plutons are (120±1) and (112±2) Ma, respectively. They are the late Early Cretaceous magmatic rocks of the Mesozoic in Jiaodong, and the products of different evolution stages of the same period. Their zircon εHf(t) values are －15.3-－10.7 and －21.8-－14.1, respectively, and the two-stage Hf model ages (TDM2) vary in the range of 2.15-1.86 Ga and 2.55-2.07 Ga, respectively. According to their petrology, geochemistry and Lu-Hf isotopic constitution, combined with the results of previous studies, the authors believe that the Dazeshan and Tianzhushan granites are the products of lithospheric thinning and intracontinental extension, and the diagenetic materials are mainly derived from the partial melting of the ancient crustal materials with the addition of some mantle materials. In the early stage, the Dazeshan pluton was formed at the same time as a large number of dark dykes in the Jiaodong area, and more mantle materials were added, which led to the decrease of the two-stage Hf model ages of the Dazeshan pluton.

Quartz porphyry veins and granite porphyry veins are developed in the Dubi area of Zhengxiangbai Banner, Inner Mongolia, and are structurally located in the Bainaimiao island arc belt on the northern margin of the North China craton. Through LA-ICP-MS zircon U-Pb dating, the diagenetic ages of the quartz porphyry and granite porphyry are (127.8±2.1) and (128.8±0.7) Ma, respectively, and both are products of the Early Cretaceous magmatism. Petro-geochemically, the quartz porphyry is rich in silica (w(SiO₂) 76.06%-77.20%) and potassium (w(K₂O) 4.66%-6.48%), high TFeO/MgO ratio (10.42-12.55), higher 10000Ga/Al ratio (2.71-3.27), low w(CaO)(0.58%-0.70%). w(Al₂O₃) is 11.63%-12.67%, and the aluminum saturation index(A/CNK) is 1.08-1.15. The granite porphyry is rich in silica (w(SiO₂) 70.67%-71.88%) and potassium (w(K₂O) 5.83%-6.45%), high TFeO/MgO ratio (10.91-12.10), higher 10000Ga/Al ratio (2.64-3.03), and low w(CaO) (0.33%-0.44%). w(Al₂O₃) is 14.47%-15.14%, and the aluminum saturation index is 1.14-1.16. Their REE distribution curves show “seagull” right-leaning  pattern with obvious negative Eu anomalies. They are relatively rich in Rb, Th, K, Zr, Hf etc., and depleted in Sr, Ba, Ti, P, etc., indicating the characteristics of aluminous A-type granite. The zircon εHf(t) values of quartz porphyry and granite porphyry are －1.56-1.85 and －0.87-2.14, respectively, and the two-stage model ages(TDM2) are 1 281-1 067 Ma and 1 240-1 046 Ma, respectively, indicating that the two rocks are the products of  mixed materials from the crust and mantle. Combined with the regional tectonic evolution, it is considered that the quartz porphyry and granite porphyry were formed in the intraplate extensional environment during the thinning of the Early Cretaceous lithosphere on the northern margin of the North China craton.

The Erdene granite in Southern Mongolia is located on the western margin of the massive Cretaceous magmatic granite in the whole Northeast Asia. The zircon U-Pb geochronology, rock geochemistry and zircon Hf isotopes in the Erdene region were studied to determine the formation age, petrogenesis, and tectonic setting.The main rock type is biotite granite. The zircon LA-ICP-MS U-Pb dating yields  a weighted mean age of (123.4±1.4) Ma, indicating that it formed in the Early Cretaceous. The granite has high silicon(w(SiO₂）=71.01%-72.66%), high alkali(w(Na₂O+K₂O)=8.52%-8.90%), poor phosphorus(w(P₂O₅)=0.06%-0.11%), low magnesium and calcium（w(MgO)=0.27%-0.39%, w(CaO)=1.10%-1.27%)，and A/CNK=(1.05-1.07），indicating that it belongs to the metaluminous-peraluminous rock. It is characterized by enrichment of LILE(such as Rb, U,Th), depletion of HFSE(such as Ta, Zr, Hf) and depletion of Nb,Sr,Ba elements, with obvious negative Eu anomalies(δEu=0.11-0.15).The average magmatic temperature is 816  ℃. It belongs to A1 type granite. The εHf(t) of the rocks ranges from 2.54-7.92, and the TDM2 varies from 1 016-673 Ma, indicating that a little young materials might have been  added in the source region. Based on the regional extensional tectonics, it is believed that the large Erdene granite formed in an extensional thinning environment, which is related  to the decompression and melting of the middle and lower crust.

The 3D geological modeling for super long tunnel site faces problems such as large human-computer interaction, long time-consumption, and deviation of modeling results from expectations. To deal with these problems, the authors proposed a set of efficient modeling schemes that conform to the geological characteristics of the tunnel site based on some super long tunnel projects in southwest China. According to factors such as the types of lithology and the geometric features of the geological surface, the processing method and naming rules for the initial modeling data were formulated, and the mapping system of “data name-geological surface modeling scheme” was established. Besides, the corresponding modeling schemes of different types of geological surface and the intersection relationship between geological surfaces were clarified, and based on discrete smooth interpolation and multi-condition constraint method, the rapid and accurate modeling scheme of geological structure model was realized. Taking Daliangshan No.1 and No.2 tunnels and Siguxi tunnel under construction as examples, the proposed modeling scheme was used to construct the 3D geological model of these tunnel sites. The results show that the modeling scheme proposed in this study can realize the automatic construction of various complex geological surfaces on the premise of ensuring the precision of the model. Therefore, the modeling efficiency is greatly improved, and the geometric shape and topological characteristics of the generated geological surface also meet the expectations of the modeler.

Physical model test is an effective means to study the deformation and fracture characteristics, dynamic process, and genetic mechanism of geological disasters. Limited by the size of model box, the boundary effect is significant in the test process, so how to reduce the influence of boundary effect has always been the focus of researchers. In this study, the physical model test of the rupture propagation of buried ground fissures was taken as the research object， and the boundary effect of physical model box was systematically analyzed by means of phenomenal analysis of the physical model tests and numerical simulation verification. The results show that the main controlling factor of the boundary effect of the model box is the ratio of sidewall damping to box size. The sidewall damping is positively correlated with the amplitude of the boundary effect. When the sidewall friction angle is smaller than the internal friction angle of the soil, the cohesion is the main factor affecting the boundary effect. When the friction angle of the sidewall is larger than the friction angle of the soil, the friction is the main factor affecting the boundary effect. The box size ratio affects the amplitude of boundary effect, and the aspect ratio is positively correlated with the amplitude of boundary effect. The box boundary effect has a significant influence on the results of the physical model test on the fracture propagation of buried ground fissures. The optimal size ratio of the experimental model box is determined to be 5∶3∶2.2.

Shuangyang Qijia water source in Changchun City is close to the oil field, and the original division of one-level water source protection zone is not enough to reconcile the increasingly prominent contradiction between oilfield exploitation and water quality safety of water sources. In order to protect the groundwater drinking water source from the influence of oilfield development activities, a new division is needed to help the oilfield development layout in the area where the drinking water source is located. Firstly, the hydrogeological conditions in the study area were analyzed, the groundwater flow models and solute transport models of the water sources were established by using the MODFLOW and MT3DMS modules in the numerical software GMS (groundwater model system) on the basis of the original primary water source protection area. Then the secondary protected area division study was carried out in Shuangyang Qijia water source area in Changchun City to determine the degree and scope of pollution caused by the oilfield development activities. The simulation results show that after 1 000 d transportation in groundwater, the pollutants are 400-800 m away from the pollution source. On this basis, a total of 33.5 km2 of the secondary protected area is designated, and the oil wells originally planned in and around the designated area should be cancelled or properly relocated.

In order to deeply understand the water cycle mechanism of Ziquejie Terrace in Hunan Province, a comparative study between the Ziquejie region and the surrounding areas was carried out to reveal the superior precipitation condition behind the terraces with the help of the concentration degree (DC) and rainfall standard index (ISP) methods, based on the precipitation data of 11 meteorological stations in the Ziquejie region and the surrounding areas from 1986 to 2015. The results show that the annual average rainfall in the Ziquejie region is 1 638.7 mm, which is 177.4 mm higher than that of the eight outer stations. The average rainfall in summer (from June to August) is 675.1 mm, which is 122.4 mm higher than the eight outer stations. The average DC of ten-day rainfall sequence of the three stations in Ziquejie is 0.373, which is significantly higher than the average value of 0.354 of the eight outside stations. Summer is the main predominant period of rainfall for the Ziquejie Terrace region. The average rainfall peak period in the Ziquejie Terrace region is in mid-June, later than the eight outside stations in early June or late May. The drought frequency of the three-month time scale shows the characteristics of “small first and then large”  from May to August in the Ziquejie region： The values of drought frequency in May and June are markedly less than the average value of the whole region, while the values in July and August are just the opposite. The main irrigation period of rice in the Ziquejie region lasts from mid-June to mid-August. The seasonal distributions of rainfall and drought frequency form a good match with the rice growth-period in the Ziquejie Terrace region, which is one of the important supporting conditions of the artesian irrigation system.

Kast pools often lead to a trailing of breakthrough curve (BTC) in karst conduits. It is of great significance to study the influence of the pool on its breakthrough curve for predicting and controlling groundwater pollution. Different sizes and number of pools were designed and the indoor tracer experiments were performed to investigate the influence of the pool volume on its breakthrough curve. The experimental results showed that as the pool volume (pool size or pool number) increased, the BTC tailing increased and the peak mass concentration decreased; As the flow rate increased, the BTC trailing decreased and the peak mass concentration of both symmetrical and asymmetric pools increased first and then decreased. The penetration time of main solute plume in the symmetrical pool was basically constant with the increase of pool size, and increased exponentially with the number of pools. The other time characteristic parameters basically increased linearly with the pool volume, and the adjusted peak mass concentration showed a power function relationship with the pool volume. When the pool volume was the same, the time variance, the penetration time of the descending solute plume, and the tracer duration time for different pool sizes were larger than for different number of pools, while the mean migration time was basically the same for the two pool distributions. The penetration time of the main solute plume and the adjusted peak mass concentration in the asymmetric pool were basically the same for the two pool distributions. The mean migration time basically increased linearly with the pool volume in the symmetric and asymmetric pools, the penetration time of the main solute plume and the adjusted peak mass concentration respectively showed a good linear and power function relationship with the volume of the asymmetric pool. It is indicative to predict the volume of pools in karst conduits by using these three characteristic parameters of the breakthrough curve in the field.

Thallium is highly toxic to mammals. Tl(Ⅰ) is a common stable and migratory form in water, and hard to remove. In this study, Fe-Mn binary oxide composite active aluminosilicate mineral (FMAAM) was prepared via coprecipitation method by loading Fe and Mn oxides on active aluminosilicate mineral (AAM) and applied to Tl(Ⅰ) removal in water. The effects of the initial pH, ionic strength and FMAAM dosage as well as the removal mechanism of Tl(Ⅰ) were studied. The results showed that the adsorption of Tl(Ⅰ) by FMAAM reached its equilibrium at 120 min, and the removal rate was more than 89.0% at the solution pH range of 3-9. The adsorption process of Tl(Ⅰ) by FMAAM was more consistent with Langmuir model. The maximum adsorption capacity of Tl(Ⅰ) by FMAAM was 61.50 mg/g at 293 K (pH=7, a dosage of 1.00 g/L). The specific surface area (SBET), average pore size and total pore volume of FMAAM were tested, which showed that the SBET of FMAAM (36.830 m²/g) was significantly higher than that of AMM(0.165 m²/g), with a difference of more than 200 times. According to the analyses of energy-dispersive X-ray spectroscope (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the adsorption mechanism of Tl(Ⅰ) by FMAAM is related to ion exchange, complexation reaction, and oxidation precipitation.

At present, the monitoring methods of personnel motion trajectory mainly rely on camera networks and thermal imaging and radar systems. However, these methods have limited monitoring range and are easily affected by light, heat sources, obstructions and distance. In response to the above problems, we have developed a new method of using distributed acoustic sensing（DAS）to recognize human vibration signals to monitor personnel motion  trajectory, which can be undisturbed and unaffected by environmental changes such as light, heat sources, and obstructions over long distances. First, the DAS signals are automatically picked up by the long-to-short time window ratio (STA/LTA) method, and then the picked-up signals are analyzed and can be divided into three types: personnel motion, hammer, and noise. Further, a convolutional neural network (CNN) architecture is constructed, and the three types of signals are input into the network as a CNN database for learning and training. Finally, the results of the three types of signal classification results are obtained through the actual data test. The accuracy reaches more than 80.00%. The recognized signal by CNN classification result can be used to determine the person's fiber channel to track the position of the person, the personnel motion trajectory can be monitored by input the updated DAS signal continuously to identify the personnel motion signal, and the motion speed can be calculated by the number of personnel movement  channels  identified per unit time.

 Aiming at the characteristics of diversity of land use requirements, various types of land cover and multiple functions in the agro-pastoral ecotone, this article introduces the land classification system to scientifically and reasonably simplify and summarize the land types, in order to achieve the sustainable economic growth of the ecologically fragile land in the agro-pastoral ecotone. Based on the interpretation data of land utilization from 1990 to 2020, and on the basis of land use classification system of production-living-ecological space （PLES）and function scores, the  agriculture and pasture interlaced area in western Jilin  Province is selected as the demonstration area, and the characteristics of spatial-temporal differentiation of PLES in the research area and its coupling and coordination changes for nearly 31 years are discussed by using the coupling and coordination model. The results show that: 1) From 1990 to 2020, the production and living space began to expand, while the ecological space showed a decreasing trend. 2) The distribution pattern and change of PLES in western Jilin Province are obviously different, the expansion of production space is mainly located on the western edge of the Songnen plain, the distribution of living space is relatively scattered with the most expansion in the core area of prefecture-level cities, and the reduced scope of ecological space basically coincides with the expanded scope of living space. 3) The overall development process of coupling and coordination in western Jilin Province is in a running-in and moderate state, and it is increasing year by year. For different levels of development in different counties, it shows the characteristics of “high in the east and low in the west”. The seriously imbalanced areas are Tongyu County and Da’an City, with poor coordination. According to the research results, it is suggested that the distribution pattern and evolution of PLES should be the basis to formulate the relevant policies and regulations, so as to support and promote the construction of ecological civilization and the coordinated development of regional economy and ecological protection.