The timing of the final closure of the Paleo-Asian Ocean is one of the controversial issues in the field of geoscience.The central Jilin Province, which was controlled by the evolution of the Paleo-Asian tectonic regime during the Paleozoic, is an ideal place to resolve the above issue.The authors conducted systematic zircon U-Pb geochronological and geochemical studies on lithic sandstones and silty slates from Yangjiagou Formation in the Dakouqin area, central Jilin Province, and determined the deposition time and provenance characteristics of Yangjiagou Formation.The maximum depositional age of the formation can be constrained by the youngest weighted average age of detrital zircons, and therefore the lower depositional ages of the two lithic sandstones samples (PM001-38-TW1 and PM001-135-TW1) from Yangjiagou Formation were determined to be (255 ± 5) Ma and (251 ±2) Ma, which are consistent to the Permian and Triassic boundary (251.902 ±0.024) Ma.Combined with the ages of zircons that captured from the surrounding Late Triassic monzogranite dated (235-227) Ma, and the timing of the monzogranite aged (232 ±2) Ma which intruded in, the Yangjiagou Formation in the study area would deposit during the Late Permian.Whole rock major and trace element geochemical data of the lithic sandstones and silty slates from Yangjiagou Formation indicate that w (SiO2) ranges from 65.13% to 70.73%, w (Al2O3) form 14.75% to 17.29%, w (K2O) form 2.43% to 3.87%, w (Na2O) form 1.59% to 3.26%, and the ratio of K2O/ Na2O is from 0.75 to 2.34.The light rare earth elements are relatively enriched, while the heavy rare earth elements are depleted, with LREE/ HREE and Eu/ Eu∗ ratios of 6.98-9.09 and 0.56-0.70, respectively.Based on the CIA-ICV diagram, the source composition discrimination diagram and the tectonic setting discrimination diagram, the sedimentary provenance of Yangjiagou Formation has experienced a relatively moderate weathering with a high maturity.The Yangjiagou Formation whose source rocks are mainly felsic, were deposited in active continental margin or continental island arc.Detrital zircon age distributions of Yangjiagou Formation can be divided into five groups: Paleoproterozoic (1 819- 1 785 Ma), Meso-Neoproterozoic (1 491-561 Ma), Cambrian-Carboniferous (522-301 Ma), Early and Middle Permian (295-259 Ma), and Late Permian to Middle Triassic (258-238 Ma).Based on previous studies of regional magmatism, Yangjiagou Formation has bidirectional provenance characteristics (North China Plate and Xing􀆳an-Mongolian Orogenic Belt).The provenance attribute and paleontological evidence of Yangjiagou Formation show a tectonic transition from collisional orogeny to a stable tectonic environment.Combined with the characteristics of magmatism in the study area, the final closure of the Paleo-Asian Ocean in central Jilin Province is considered to happen in the Late Permian-Middle Triassic.

In order to constrain the tectonic evolution of the eastern part of the Jiao-Liao-Ji Orogenic Belt,the authors carried out a study on the petrogenesis and diagenetic tectonic background of the metamorphic gabbrocarbonatite complex in the Daxing iron mining area by using petrology, petrochemistry, petrogeochemistry and zircon U-Pb dating.The results show that the metamorphic gabbro-carbonatite complex in the Daxing iron mining area has the rock types of meta-gabbro, carbonatite and magnet ore body, and the mata-gabbro is the main rock type.Petrochemical study of the meta-gabbro showed that the w (SiO2) is from 44.23% to 48.80%, w (Na2O) is from 0.94% to 2.86%, w (K2O) is from 0.51% to 1.90%, w (TiO2) is from 0.42% to 0.93%, w (CaO) is from 8.73% to 14.78%, and the Na2O/ K2O ratio ranges from 1.12 to 2.27, MgO/ (FeO+MgO) ratio ranges from 0.54 to 0.60, (Mg2++Ni2+) / (Fe2++Fe3++Mn2+) ratio ranges from 1.44 to 2.02, Mg/ (Mg+Fe2+)ratio ranges from 0.60 to 0.68, and the differentiation index (DI) ranges from 11.76 to 31.79.The meta-gabbro rocks are basic-ultrabasic magma which is rich in iron and sodium, poor in potassium and titanium, and weak in differentiation.Geochemical studies show that the rocks are rich in large ion lithophile elements such as Rb, Ba [w (Rb) (4.80×10-6-74.82×10-6), w (Ba) (83.09×10-6-430.10×10-6)], and relatively rich in high field strength elements such as Hf, Th, Ta [w (Hf) (1.41×10-6-6.20×10-6), w (Th) (0.51×10-6-28.91×10-6),w (Ta) (0.47×10-6-9.91×10-6)], and ΣREE=(29.56×10-6-812.59×10-6 ); while, Nb is obviously depleted [ w (Nb) (2.94× 10-6-36.01× 10-6 ) ].The (Na2O+K2O) / TiO2 ratio is 0.10-5.54, Zr/ Y ratio is 1.93-5.67, La/ Nb ratio is 0.54-1.73, La/ Ta ratio is 5.53-11.13, Nb/ U ratio is 1.51-14.23.The geochemical characteristics are similar to continental tholeiitic basalts, and having the properties of intra-plate alkaline basalts.The carbonatite and meta-gabbro are interbedded.The average CaO/ (CaO+MgO+Fe2O3+FeO+MnO) ratio is 0.98, mean w (MgO) is 0.62, and mean w (FeO+Fe2O3+MnO) is 0.41.It is calcareous metamagnesic carbonatite which obviously rich in Sr [w (Sr) (1 727×10-6-1 794×10-6)].The complex magma may come from the partial melting of the asthenosphere enriched mantle, formed in the tectonic background of the stretching of the deep fault zone in the continental plate, and assimilated and mixed with crustal materials in a certain extent during the ascent.Most of the meta-gabbro zircons have the core-rim structure, the color of the core is mostly black.It is difficult to observe its internal structure, a few of the core can be seen wide oscillating bands.The Th/ U ratio is 0.23-4.19, which shows the characteristics of basic magmatic zircon.The weighted average age of 207Pb/ 206 Pb of the core is (2 098 ± 11) Ma (MSWD=1.2, n=18), which represents the condensation crystallization age of the gabbro.The color at the rims of the zircons is relatively light and uniform, without zonation,and the Th/ U ratio is 0.03-3.22, indicating metamorphic origin.The weighted average age of 207Pb/ 206Pb of the rims is (1 892 ±23) Ma (MSWD=2.2, n=14), which represents the metamorphic age of gabbro.Combined with regional geological data, it is considered that the eastern part of the Jiao-Liao-Ji Orogenic Belt was in a extensional tectonic environment in the Middle Paleoproterozoic, the formation of metamorphic gabbro-carbonatite complex in the Daxing iron mining area may be related to the extension during the tectonic evolution of the Songjiang-Chongshan fault zone.

Rational development and utilization of cultivated land reserve resources are essential for ensuring China’s food security, while suitability evaluation is the prerequisite and foundation.By scientifically assessing the development suitability of these resources, it provides a scientific basis for rational allocation and sustainable utilization of regional land resources.The authors take Da’an City of Jilin Province as the study area and develop a comprehensive suitability evaluation system from natural, social, and ecological perspectives.Using methods such as AHP (analytic hierarchy process), landscape pattern indices, and composite indices, the authors conduct a systematic analysis to reveal quantity, quality, and spatial distribution characteristics of development suitability levels of cultivated land reserve resources in Da’an, and propose corresponding development and utilization strategies.The research results indicate that: the development suitability of cultivated land reserve resources in Da’an City can be categorized into four levels: highly suitable, moderately suitable, marginally suitable, and unsuitable, accounting for 26.64%, 38.83%, 25.08%, and 9.44% of total area of cultivated land reserve resources, respectively.Development suitability levels gradually decrease from central part of Da’an City toward northeast and southwest.Highly suitable and moderately suitable development areas are mainly concentrated in Xinping’an Town and Haituo Township, while unsuitable development areas are mainly concentrated in Longzhao Town in southwestern part of the city.Land use types are primarily saline-alkali land and other grasslands, accounting for 99.67% of total area of cultivated land reserve resources in city.The highly suitable development areas for saline-alkali land are distributed in northwest and southeast, while the highly suitable development areas for other grasslands are concentrated in the central and western parts.Spatial distribution of development suitability levels for cultivated land reserve resources in Da’an City shows significant variation, with moderately suitable development areas being the most prevalent.Development and utilization strategies for cultivated land reserve resources should be tailored to local conditions.Saline-alkali land development should focus on water resource management and soil salinization amelioration measures, while development of other grasslands should carefully control development intensity to maintain regional ecological balance.

This study is the first to analyze the geothermal resource occurrence conditions and the formation evolution mechanisms in the southern part of Taiyuan City, Shanxi Province, from both geothermal geophysical and geothermal water isotope geochemical perspectives. Based on geophysical exploration data and geothermal water isotope chemical analysis, and combined with regional geological data, a comprehensive study of the geothermal field in southern Taiyuan is conducted. The geophysical methods primarily include gravity, magnetic, and electrical surveys, which are used to analyze the structural characteristics and reservoir distribution of the geothermal field. The geochemical methods mainly include hydrochemical and isotopic analyses, aimed at revealing the origin, evolution, and water-rock interaction processes of thermal groundwater. The geophysical exploration results indicate that the Taiyuan Basin as a whole exhibits a low gravity field and negative magnetic anomalies, reflecting a deeply buried basement and strong tectonic activity, which provide favorable heat sources and reservoir spaces for the formation of geothermal fields. The southern geothermal field of Taiyuan is located at the southeastern margin of the basin, where the gravity field shows a distinct gradient zone, and the magnetic anomalies are characterized by negative values, suggesting the presence of concealed fault structures that serve as channels for deep thermal flow upwelling. Moreover, an apparent arcuate low-resistivity zone exists within the geothermal field, inferred to represent the geothermal reservoir, further demonstrating the favorable conditions for geothermal resource accumulation in this area. Geothermal water isotope geochemical analysis reveals that the thermal groundwater in the southern Taiyuan geothermal field originates from meteoric water, undergoing processes of infiltration, leaching, and transformation into sedimentary (semi-confined) water. During this process, water interacts with surrounding rocks through leaching, dissolution, and cation exchange. Stable components accumulate in the groundwater, while unstable components precipitate, thus forming the hydrogeochemical characteristics of modern geothermal water. The formation of the geothermal field in southern Taiyuan is mainly controlled by the favorable regional geological structure, the development of concealed faults, and the good storage capacity and permeability of the geothermal reservoir.

 Recent significant breakthroughs in natural gas exploration have been achieved in the tight sandstone reservoirs of the Bashijiqike Formation (Member 1) within the Cretaceous system of the Luntai S3 block, Tarim Basin, which has emerged as a crucial exploration target with substantial hydrocarbon resource potential. However, the reservoir characteristics and main controlling factors of these potential intervals remain insufficiently understood, constraining zone evaluation and target optimization in this area. Based on physical data including mud logging, well logging, core samples, and cuttings from existing wells, this study systematically investigated the petrological characteristics, reservoir space types, and physical properties of the tight sandstone reservoirs through thin-section analysis, cast thin-section observation, X-ray diffraction, mercury injection, and scanning electron microscopy. The results revealed that: (1) The reservoirs predominantly consist of lithic arkose and feldspathic litharenite with low compositional maturity (quartz is 59. 7%, feldspar is 23. 0%, lithic fragments is 17. 3%) and moderate tex tural maturity. The interstitial material (predominantly calcite) accounts for an average of 7. 1%. The reservoir space is dominated by residual primary intergranular pores (plane porosity is 2%) and intergranular dissolution pores (average pore diameter is 109. 65 μm), exhibiting bimodal pore-throat radius distribution (main peak at 1 μm). The average displacement pressure measures 0. 27 MPa, with porosity ranging from 8. 6% to 11. 9% and permeability between 0. 64 ×10-3 and 6. 10 ×10-3 μm2, collectively indicating low porosity and low permeability characteristics. (2) Reservoir heterogeneity was controlled by depositional environment, with medium-coarse sand stones in subaqueous distributary channels of braided river delta fronts (sandbody thickness proportion 42%-91%) being identified as effective reservoir development zones, where high-energy environments promoted better sorting and lower clay volume fractions. (3) Reservoir evolution was dominated by diagenesis: early calcite cementation (volume fraction 7. 1% to 11. 3%) inhibited compaction and preserved residual intergranular pores (porosity reduced to 5%-8%), while late dissolution created intergranular/ intragranular dissolution pores (maximum plane porosity is 15%), though local re-cementation intensified heterogeneity. (4) Structural uplift (Late Cretaceous strata exposure) enhanced epigenetic dissolution, with differential uplift causing spatial variations in dissolution intensity. The study concluded that effective reservoir development in Member 1 was jointly controlled by sedimentology diagenesis-tectonics coupling, with the subaqueous distributary channel sand bodies in the eastern 3-4 sand groups being prioritized exploration targets, particularly focusing on calcite cement dissolution zones and fault-modified areas.

Geological hazard risk evaluation plays a significant guiding role in disaster prevention and mitigation.Focusing on the issues of frequent and severe geological hazards in Lüchun County, this study conducts a geological hazard risk evaluation to provide scientific support for disaster prevention planning and risk management in Lüchun County.Taking Lüchun County in Yunnan Province as the study area, grid unit is selected as the evaluation unit, and nine evaluation factors are chosen: elevation, slope, aspect, distance to faults, distance to rivers,engineering geological rock groups, geomorphological types, curvature, and land use types.Utilizing the spatial analysis function of geographic information system, the weighted information value model, which combines the information value model and the analytic hierarchy process, is applied to evaluate the susceptibility of collapse and landslide geological hazards in Lüchun County.The monthly average rainfall in Lüchun County is selected as the triggering factor for geological hazard evaluation of landslides and collapses in the study area.Three disaster bearing factors: population density, the number of threatened people, and land use types, are selected to complete the vulnerability evaluation.The hazard index and vulnerability index are multiplied then to produce the risk evaluation of collapse and landslide geological hazards.The results show that Lüchun County can be divided into four risk levels:low, medium, high and extremely high, which accounted for 12.84%, 46.01%, 38.28% and 2.87% of the county area, respectively.The low risk areas are mainly located in the middle of Banpo Township, the north of Qimaba Township, the north of Daxing Town and the south of Gekui Township.The middle risk areas are mainly distributed in the north of Daheishan Town, the west of Dashuigou Township, the middle and south of Qimaba Township, the middle of Gekui Township and the southwest of Pinghe Town.High and extremely high risk areas are mainly distributed around Lüchun County and Daxing Town, Niukong Town, Sanmeng Township, Pinghe Town,and the middle of Dashuigou Township.The results of geological hazards risk evaluation obtained in this paper are in good agreement with the actual investigation.

Songliao Basin is one of the main basins for unconventional oil and gas exploration and development in China.The 1st and the lower part of the 2nd members of the Upper Cretaceous Qingshankou Formation are key focus layers for shale oil exploration.The research on the unclear sedimentary facies division and distribution issues of these layers in Changling Sag is beneficial for providing geological basis for shale oil exploration and selection in study area.Based on the drilling core, logging, and geochemical data of the 1st and the lower part of the 2nd members of the Qingshankou Formation in the Changling Sag of the Songliao Basin, and combining with the research results of the previous researchers, this paper conducts a detailed study of the sedimentary facies of the target layers in the study area from the aspects of lithofacies, sedimentary structure, and logging.The target strata in study area are divided into two sedimentary facies, the lake and delta facies, and four sedimentary subfacies including delta front, front delta subfacies, semi-deep lake and deep-lake subfacies.Among them, the front delta and semi-deep lake subfacies are advantageous sedimentary facies for shale oil exploration and development.The transgressive systems tract mainly develops delta front and front delta subfacies.Vertically, the two subfacies gradually slow down from bottom to top.Horizontally, the two subfacies gradually decrease towards the edge of the basin.The high water level systems tract mainly develops semi-deep lakes and deep-lake subfacies.Vertically, the two subfacies have a large thickness.Horizontally, the two subfacies extend to the center of the basin.The regressive systems tract mainly develops delta front, front delta, and semi-deep lake subfacies.Vertically, the semi-deep lake subfacies gradually slow down from bottom to top, while the thickness of the delta front and front delta subfacies gradually expands.Horizontally, the semi-deep lake subfacies decrease towards the center of the basin, while the delta front and front delta subfacies gradually extend towards the center of the basin.The dominant sedimentary facies zones mainly develop in late transgressive system tract and early regressive system tract.

To explore the geodynamic mechanisms of the large-scale magmatic activity during Early Cretaceous in Da Hinggan Ling (Mts.), the authors focused on diabase in Huoluotai area in northern segment of Erguna Block,Da Hinggan Ling (Mts.), through the study of petrogeochemical characteristics and zircon U-Pb dating of diabase in Huoluotai area, aimed to determine its formation age, petrogenesis, and tectonic setting.Zircon LA -ICP -MS U –Pb dating results show that the weighted average age of diabase in Huoluotai area is (135.1 ±3.6) Ma, indicating that the crystallization age of diabase is Early Cretaceous.Whole rock geochemical data reveal that diabase in Huoluotai area is characterized by low w (SiO2) (48.84%-52.11%), high w (MgO) (5.13%-6.85%) and w (Fe2O3) (7.45%-8.60%).The Eu anomaly of diabase is insignificant or exhibits a weak negative anomaly (δEu =0.83-1.06).The diabase is enriched in large ion lithophile elements (such as Ba, Sr, and K), and depleted in high field strength elements (such as Zr, Ta, Nb, and Th).Diabase in Huoluotai area is only minimally influenced by fractional crystallization, crustal contamination, and accumulation processes.The Nb/ Yb -Th/ Yb diagram shows that diabase in Huoluotai area falls within the area of primitive mafic melts derived from subduction-modified lithospheric mantle.The Th/ Nb-Ba/ Th and Th/ Yb-Ba/ La diagrams indicate that the magma source of diabase in Huoluotai area was modified by fluids derived from subducted slabs.The La/ Nb-La/ Ba diagram reveals that the magma source of diabase in Huoluotai area is from the lithospheric mantle.The above geochemical characteristics indicate that diabase in Huoluotai area originated from a lithospheric mantle source metasomatized by fluids derived from subducted slabs.Combined with previous research, it is concluded that the formation of diabase in Huoluotai area in northern segment of Erguna Block, Da Hinggan Ling (Mts.) is closely related to the rollback process of the Paleo-Pacific Plate.

To study imaging optimizing algorithms for low signal-noise rate (SNR) seismic data in irregular topography, an effective coherence constraint noise suppression method is established according to the obvious difference in coherence characteristics between noise and effective reflected signals, which can provide theoretical and technical support for practical applications of the imaging in irregular topography.In order to solve the problem of conventional imaging of low signal-to-noise ratio seismic data in irregular topography, a coherence constraint Gaussian beam migration method for irregular topography is proposed in this paper.The elevational correction of
time-shift eliminates the inaccuracy of beam decomposition caused by irregular topography.Horizontal projection equivalent discrete interval (HPEDI) for beam center and receiver location is designed to solve the drawback of unbalance of imaging amplitude.About the coherence constraint, a new stable complex domain weighted coherence spectrum computing method is proposed, and the threshold extraction and exponential strengthening methods for effective reflection signal are designed to achieve the effective suppression of random noise and incoherent false imaging.Numerical experiments of 2 synthetic data examples and 2 measured data examples are applied to validate the effectiveness of the proposed methods in noise and false image suppression.The proposed HPEDI method can achieve significant image optimization in amplitude equalization and arc false image suppression for the synthesized data in irregular topography.The coherence spectrum of real measured data verifies that the weighted coherence spectrum is smoother and more stable than the conventional coherence spectrum.Most of the arc false images of the synthesized data in a layered model are suppressed by using the threshold of coherence spectrum.The irregular real measured low signal-to-noise ratio data prove that the proposed coherence constraint method suppresses random noise obviously.The proposed coherence constraint migration imaging method can effectively suppress the noise and false imaging without coherence characteristics in the imaging process, and can significantly improve the imaging effect. 

Dachebeigou--Fu􀆳erling area is an important gold deposit distribution area, which located in the north of Jiapigou gold deposit mining area in Jilin Province, and several gold and antimony minerals such as Xingfu and Datudingzi have been discovered, indicating a certain prospecting potential. Based on the detailed study of metallogenic geological background and typical deposit characteristics of gold deposits in Dachebeigou -- Fu􀆳erling area of Jilin Province, the authors systematically summarized the prediction factors of regional gold deposits, established a regional prediction model for gold deposits, and delineated the minimum prediction areas with prospecting potential to provide a basis for the further deployment of exploration work. The evidence weight method was used to carry out the prediction of gold ore by “ mineral resources evaluation system” ( MRAS) software, and on the basis of the contour map and color block map, the delineation of the minimum prediction area was carried out according to the principle of minimum area has maximum minerality and minimum ore leakage rate, and the predicted gold resources were estimated by using the geological volume parameter method. In this work, a total of 13 minimum prediction areas of gold deposit were delineated, including 5, 6 and 2 minimum prediction areas of class A, B and C, respectively, and the estimated predicted resources of gold deposit were 36 295. 24 kg, of which the predicted resources of gold deposit within 500 m were 21 604. 31 kg and the predicted resources of 500 m to 1 000 m were 14 690. 93 kg. It is recommended to deploy investigation and evaluation work in the minimum prediction areas of class A, such as Zhilin, Datudingzi, Erdaodianzi, Beishan, Sidaogou and Xingfutun through the comprehensive evaluation of geological condition, geophysical and geochemical anomalies, resource potential and prospecting prospects, in order to explore new mineral areas and achieve new breakthroughs in gold prospecting.

Aming to the unique temperate forest vegetation within the Northeast Tiger and Leopard National Park, a study on multi-source remote sensing image coverage classification has been conducted, which aims to utilize modern remote sensing techniques and advanced machine learning methods to perform fine classification of complex vegetation types, thereby better understanding the ecological conditions of the region and providing scientific basis for the conservation efforts in the Northeast Tiger and Leopard National Park. Firstly, the authors employed multi-scale image segmentation technology to decompose the original remote sensing images into a series of small regions with similar texture and color features, which helps reduce data redundancy and highlight different characteristics of vegetation. Subsequently, these segmented images have been optimized by extracting feature parameters that effectively distinguish different types of vegetation. Then, the authors input these optimized feature parameters into three different machine learning classifiers for training and testing, including support vector machine ( SVM) , C5. 0 decision tree and random forest. The experimental results show that, in terms of classification accuracy, random forest achieving the highest accuracy of 91. 33% , and C5. 0 decision tree reaching 89. 59% , with the Kappa coefficients of 0. 90 and 0. 88, respectively. In comparison, the classification accuracy of support vector machine was lower, at only 58. 96% , and the Kappa coefficient is 0. 54. These results indicate that, for distinguishing vegetation cover types and identifying other land features, the random forest algorithm has significant advantages. It not only accurately distinguishes different vegetation types in complex backgrounds, but also effectively identifies other features such as roads and buildings. 

In order to study the importance of the spatial and temporal distribution characteristics of sea ice in the marine disaster warning, resource development and global climate change research, the authors use multi-tem- poral remote sensing data to extract and analyze the spatial distribution range and sea ice thickness information in Liaodong Bay of Bohai Sea during winter months based on the remote sensing inversion modeling of sea ice thickness. First, the sensitive wavebands that have a significant response to differences in sea ice thickness were screened based on the variance analysis method, and a sea ice thickness-sensitive band reflectance statistical correlation model was constructed based on the regression analysis method. The multi-temporal remote sensing data were used further to reflect the sea ice thickness in Bohai Sea and to analyze the spatial and temporal distribution characteristics of sea ice. Experimental results show that the red-light band data of Landsat satellites have high sensitivity in retrieving sea ice thickness, and the regression statistical model established on the red-light data has a linear fitting regression sum of squares as high as 0. 975 1, which indicates that the model has high accuracy and reliability. The result of Landsat red-light band data used for retrieval on the sea ice thickness and spatiotemporal distribution of sea ice in Liaodong Bay of Bohai Sea indicates that the sea ice begins in late December every year at Panjin and Yingkou in Bohai Sea, and reaches the thickest and largest distribution area by January. As the temperature gradually rises, sea ice gradually recedes in early February, and completely disappears by early March. In addition, the proportion of thin ice is generally high in each winter month, while that of thick ice is relatively low. The sea ice in Bohai Sea freezes earlier and thicker in higher latitude areas or closer to the coast, and retreats later. On the contrary, the ice in the low latitude areas freezes later and retreats earlier. 

To investigate the tectonic evolution of Paleo--Asian Ocean, the authors select Late Paleozoic intrusive rocks exposed in Bilihe area of central Inner Mongolia as objects, and constrain their formation ages, petrogenesis, magma sources and tectonic settings through petrographic, geochronological and geochemical analyses. Zircon U--Pb dating yields ages of (263. 7 ± 2. 8) Ma for the potassium feldspar granite and (273. 8 ± 1. 2) Ma for the granitic porphyry, indicating an Early --Middle Permian emplacement. Their εHf ( t) values range from - 8. 5 to 4. 0 and - 0. 4 to 2. 3, respectively. Geochemical data reveal both rock types exhibit high silica [w ( SiO2 ) = 61. 98%--70. 65% ] , alkali-riched [w (Na2O) = 2. 78%--2. 94% ] and potassium-eriched [w (K2O) = 3. 47%-- 3. 60% ] characteristics. The A / NK ratios vary from 1. 30 to 1. 75, A / CNK ratios vary from 0. 86 to 1. 10, and Rittmann indices vary from 2. 07 to 2. 53, the granite and porphyry are belonging to high-K calc-alkaline series, being classified as metaluminous to weakly peraluminous rocks. Both rocks display enrichment in light rare earth elements (LREEs) and large-ion lithophile elements ( LILEs: Cs, Rb, Ba, Th) , depletion in heavy rare earth elements (HREEs) and high-field-strength elements (HFSEs: Nb, P, Ti), along with weak Eu negative anomalies (δEu = 0. 62--0. 67 and 0. 49--0. 54). Moderately fractionated REE patterns [ (La / Yb) N = 8. 10--8. 30 and 6. 80-- 6. 92] with REE right-inclined chondrite-normalized curves suggest characteristics of volcanic arc granites. Th / La (avg = 0. 44) , Rb / Sr ( avg = 0. 65) and Th / Nb ( avg = 1. 35) ratios align with crustal compositions, indicating derivation from partial melting of crustal materials. The potassium feldspar granite exhibits broader εHf (t) variations and higher Mg values [w (MgO) = 3. 05%--3. 33% ] , implying mantle-derived influence. Integrated results suggest these rocks formed during the subduction of the Paleo --Asian Ocean beneath the North China Block. In Early--Middle Permian, the Paleo--Asian Ocean was not closed, and the northern margin of the North China Block situated in an active continental margin setting, marked by intense regional magmatism. 

In order to improve the accuracy of extracting erosion gully information based on remote sensing data, the erosion gully extraction model based on multi-source data fusion and object-based image analysis (OBIA) is proposed to extract the distribution information of erosion gully in Dehui City, Jilin Province, with a view to play an early warning role for the generation of erosion gully. The study fuses Sentinel--1 radar data, Sentinel--2 optical remote sensing images, and topographic data of the study area, and uses the multiresolution segmentation method to segment the features in the study area. Based on the results of multiresolution segmentation, intensity, texture, spectral, index, topographic and geometric features are extracted for constructing multi-dimensional sets, and the contribution of features is evaluated and optimized using the random forest Gini index to obtain the optimal set of features. The random forest extraction model based on OBIA was constructed to extract erosion gully information in the study area, and the extraction accuracy was evaluated using the method of generating random points and visually deciphering them. To further investigate the effect of multi-source data fusion on the accuracy of erosion gully extraction, based on the same sample dataset, the erosion gully in the study area was extracted for different data sources and its accuracy was compared. The results show that the overall accuracy of erosion gully extraction based on multi-source data fusion is 94. 03% , and the Kappa coefficient is 0. 839, indicating that the model has a good performance. Compared with a single data source, multi-source data fusion has higher extraction accuracy, and provides a large number of effective feature values for the random forest model. Erosion gullies in Dehui City are mainly distributed in the central and southwestern part of the city, and the erosion as a whole shows a northeastsouthwest belt direction, mostly distributed around the settlement and connected with certain water systems, and its erosion situation needs to be emphasized. 

 As urbanization continues to accelerate, it is difficult to acquire real-time data on potential pavement
 collapse hazards utilizing traditional methods. At present, efficiently monitoring pavement collapse has become a key
 challenge in the field of pavement safety. For this problem, the authors propose a method which combines time-series
 InSAR with wavelet transform. This method analyzes the change cycle of the subsidence point to obtain the deformation information, and extracts the temporal and spatial evolution characteristics of ground subsidence. For those areas
 with obvious spatial and temporal evolution characteristics, the accuracy of the InSAR results will be further verified
 by using the microtremor detection seismograph. We selected 52 Sentinel-1A images captured between March 2022
 and November 2023 to obtain the surface subsidence results in the central urban area of Changchun by the time-series
 InSAR method. The results showed that the maximum deformation rate was-30. 58 mm/ a, and the maximum cumu
lative subsidence was-73. 3 mm in the study area. A detailed analysis of the representative deformation area, Nanhu
 avenue, revealed a maximum deformation rate of- 28. 44 mm/ a, a maximum daily average deformation rate of-0. 93 mm/d, and a maximum cumulative subsidence of-56.4 mm. The analysis of significant subsidence points
 based on wavelet transform uncovered their subsidence evolution processes. The development of surface subsidence in
 severely affected areas was influenced by multiple periodic variations of different magnitudes and levels, with nested local
 cycles within these periodic time scales that affect the specific trends of subsidence development. Using microtremor
 detection seismograph to collect data from regions with obvious evolutionary characteristics, the authors generated a
 geological profile of Nanhu avenue. According to the profile, significant subsidence points exhibited a phenomenon of
 slurry infiltration. This further validated the accuracy of the subsidence monitoring results. Finally, by comparing the
 actual pavement collapse incident in the Nanhu avenue metro construction area to the subsidence results monitored in this
 study, the feasibility and accuracy of the proposed method in practical applications were validated.

To investigate the rare earth element (REE) fractionation patterns, grades, and their influencing factors in different ore blocks of the Bayan Obo REE-Nb-Fe symbiotic deposit, and to provide guidance for research on REE patterns and directional mineral processing at Bayan Obo, elemental mass fraction was conducted using inductively coupled plasma mass spectrometry on samples from different ore blocks of TK13-04 core in the main orebody. Results show that two distinct REE fractionation patterns exist in the main orebody. The REE fractionation pattern of the middle dolomite Fe-REE ores differ from that of the upper and lower dolomite REE ores. The former exhibits an “initial upward inclination followed by rightward inclination” characteristic with increasing from La to Nd and then decreasing from Nd to Lu. In contrast, the latter shows a “rightward inclination” pattern with gradually decreasing from La to Lu. The middle dolomite Fe-REE ores have a lower mass fraction of total REEs compared to the upper and lower dolomite REE ores. The total REE mass fraction is closely related to the degree of light-to-heavy REE (LREE-HREE) fractionation, the REE fractionation pattern, and the total iron (TFe) mass fraction. Higher degrees of LREE-HREE fractionation and higher La/ Nd ratios correlate with higher total REE mass fraction. When the TFe is below 20%, there is no definitive correlation between TFe and the REE mass fraction. However, when the TFe mass fraction exceeds 20%, the total REE mass fraction decreases signifi cantly. Compared to the average proportions of individual light REEs (LREEs) in the mining area, the proportion of Ce in the middle dolomite Fe-REE ore block of TK13-04 is significantly lower ( ~37%), while the proportion of Nd is significantly higher ( ~40. 7%), exceeding the proportion of Ce that is typically the dominant REE in the deposit. The proportion of La in the middle dolomite Fe-REE ore block is also reduced ( ~9%) and the proportions of Pr and Sm are increased. Therefore, the middle dolomite Fe-REE ore blocks hold greater potential for the utilization of Nd, Pr, and Sm elements. For the utilization of La and Ce, development of the upper and lower dolomite REE ore block would likely yield more substantial benefits.

On the basis of field investigation and profiling, the authors divide the sedimentary phases of Middle Jurassic Xishanyao Formation in southern Changji by means of petrographic and petrological geochemical studies, and further explore provenance and basin-mountain coupling relationships. The results show that the main lithologies of the Xishanyao Formation in the study area are reddish-brown, greyish-green, greyish-white mudstones, siltstones, fine sandstones, and coarse sandstones, with local interbedded coal lines / seams and charcoal shales. The Xishanyao Formation in the study area is characterized by a subphase of deltaic plains and a subphase of deltaic frontal margins, and can be further divided into microphases such as branch channels, marshes and submerged branch channels. The obvious lateral variation of subphase of deltaic plains, and the discontinuity of the marshes in the space caused the poor comparability of seam and the thickness of the coal-forming. The average chemical index of alteration (CIA) of the mudstone samples is 79. 89, which indicates that the provenance area underwent moderate to strong chemical weathering. The average index of compositional variation ( ICV) of the mudstone samples is 0. 72, reflecting that the sediments underwent re-circling or experienced strong chemical weathering at the time of initial deposition, forming at a relatively stable tectonic environment. The granite and rhyolite clasts and the A-- CN--K diagram indicate that the source rocks were mainly derived from felsic igneous rocks in the upper crust. The occurrence of andesite and basalt clasts and the characteristics of La / Sc ratio indicate that there are minor additions of intermediate-basic source rocks. The La--Th--Sc, Th--Sc--Zr / 10, and Th--Co--Zr / 10 discriminant diagrams indicate that the tectonic background of the provenance area is in the continental island arc environment, and the source of detrital material is mainly from the Middle and South Tianshan Mountains, and there is no detrital material from the Bogda Mountains, which indicates that North Tianshan Mountains have not yet been uplifted at that time, and the height difference between the basin and mountain environments was small, with a large basin extent.

 

To analyze the petrological characteristics, grain size distribution characteristics, sedimentary facies types and spatial distribution regularity of the Lower Karamay Formation in Block Si 1, Karamay Oilfield, Well D16 is selected as the standard well in the study area, and its drilling cores are used as the main data source for observation and experiments. Core observation, rock mineral thin section identification and sieve analysis are used to obtain petrological data such as colors, lithologies, sedimentary structure and texture, rock mineral composition and contents, and grain size distribution statistics of the Lower Karamay Formation reservoir in Block Si 1. The sedimentary facies types of the Lower Karamay Formation in Block Si 1 are identified based on sedimentary facies markers such as core colors, lithologic assemblages, structure and texture, grain size probability accumulation curves, C-M diagram, and structural parameter scatter plots. At the same time, combined with the geophysical data of more than 100 wells in the study area, the method of well logging is used to radiate the sedimentary facies model of the D16 standard well to other wells in the study area. By pulling the well-connected profile, the distribution regularity of sedimentary microfacies and sand bodies on the profile are analyzed. According to the thickness contour map of sandstone, the distribution regularities of sedimentary microfacies and sand bodies on the plane are analyzed. The results show that the core colors of Well D16 are brown, light brown, light gray and gray-green, and the lithologies are divided into unequal-grained sandstone, medium-fine sandstone, argillaceous siltstone, silty mudstone and mudstone according to the grain size, and the sandstone is divided into lithic sandstone, feldspathic lithic sandstone and lithic feldspathic sandstone according to the rock mineral types. The roundness is sub-angular to sub-rounded, the sorting is medium to poor. Massive bedding and tabular cross-bedding are developed, the contact relationships of particles are mainly point-line contact, and the pores are mainly residual intergranular pores. The probability accumulation curves of grain size are two-stage or four-stage types, the C-M diagram has the characteristics of traction flow, and the points of the structural parameter scatter plots are concentrated in the delta plain and front interval. The sedimentary environment of the Lower Karamay Formation reservoir in Block Si 1 is shallow,weakly oxidized to weakly reduced. Two sedimentary subfacies, the braided river delta front and the shallow lake,and four sedimentary microfacies, including the subaqueous distributary channel, the subaqueous interdistributary,the estuarine dam and the coastal shallow lake mud, are identified. The main reservoir sand bodies of the Lower Karamay Formation are subaqueous distributary channel sand bodies, which are distributed in lens-shaped and layered forms on the cross section and in strip-shaped and sheet-shaped forms on the plane. 

 The Wuzhong-Lingwu area lies within the Taole-Hengshanpu thrust fault zone, characterized by complex geological structures. Aiming to address the exploration needs for active fault development and the unclear deep geothermal reservoir structures in the southern section of the Yinchuan Basin (Taole-Hengshanpu thrust fault zone), this study employs the microtremor-based spatial autocorrelation method (SPAC) using background noise. By analyzing the recorded Rayleigh wave signal data, the authors effectively inverted the high-resolution shear-wave velocity structure of the subsurface medium in the study area, investigated the subsurface structural development in the Wuzhong-Lingwu area, and evaluated the application of the background noise method in detecting subsurface faults and geothermal resources. The S-wave velocity structure inversion results obtained by the SPAC technique revealed key stratigraphic and structural features. Comparison with previous well-logging and electrical prospecting data confirmed the reliability of the recorded observations. The results indicate that the depth range of 700-1 000 m corresponds to the Upper Carboniferous (Ct) strata, where a slight decrease in S-wave velocity suggests the presence of an aquifer, consistent with the distribution of geothermal water resources in the area. Between 1 000 and 1 500 m, S-wave velocity increases again, indicating Ordovician (O) strata, with a thin, slightly lower-velocity layer at the top interface, also inferred to be an aquifer. Based on the velocity anomalies and spatial distribution of aquifers, it is concluded that the Upper Carboniferous aquifer (700-1 000 m) and the thin aquifer at the top of the Ordovician strata (1 000-1 500 m) possess favorable conditions for geothermal fluid storage and migration, making them highly promising target geothermal reservoirs. These two stratigraphic units are likely to host geothermal resources.

Electrical resistivity tomography ( ERT) method is a geophysical exploration technique based on the differences in resistivity of media. Due to its characteristics of non-destructive and high efficiency, it is widely used for detecting and evaluating subsurface anomalies. The authors take a gold mine goaf as the subject, numerical simulations for analyzing potential anomalous characteristics in goaf areas, and field investigations to verify the applicability of ERT in detecting goaf collapse zones, which providing a scientific basis for goaf management. Focusing on Wenner, dipole-dipole, Wenner--Schlumberger, and pole-pole electrode arrays, RES2DMOD forward modeling software was used to construct models of a single isolated low-resistivity anomaly and a semi-high and semi-low resistivity anomaly to simulate fully water-filled and partially water-filled conditions of goafs. The data were processed by using RES2DINV inversion software with the least-squares method for inversion calculations. The results show that the dipole-dipole array exhibited the best performance for the fully water-filled anomaly, which accurately locate and describe the geometric shape and resistivity characteristics of low-resistivity anomalies with high resolution. For the partially water-filled semi-high resistivity and semi-low resistivity anomaly, the inversion accuracy of all arrays decreased, but the dipole-dipole array still outperformed the others, effectively reflected the distribution characteristics of the anomalies. In field investigations, the dipole-dipole array was employed for data acquisition. The processed data revealed a low-resistivity zone at the position approximately 115 m (30 m in depth) in the study area. Based on geological and hydrogeological conditions, the low-resistivity zone was inferred to be a goaf collapse zone. The findings indicate that the dipole-dipole array effectively reflects the extent and characteristics of goaf collapse zones, providing valuable insights for estimating the approximate range and developmental depth of anomalous areas.

To further strengthen the research and development of Cu--Ni sulfide deposits in Jilin Province, the authors select the Shirengou gabbro in eastern Jilin Province as the study target. Through the analysis of whole-rock geochemistry, zircon Lu--Hf isotopes and platinum-group element ( PGE) of the gabbro body, the magma origin, evolution, petrogenesis and tectonic setting have been investigated. The Shirengou gabbro is primarily composed of pyroxene, amphibole, plagioclase and biotite. Major element compositions exhibit the characteristics of low silica [w( SiO2 ) = 45. 25%- 45. 75% ] , low titanium [w( TiO2 ) = 0. 98% - 1. 00% ] , high magnesium [w( MgO) = 19. 66% - 19. 90% , Mg# = 63. 52 --63. 97 ] , and low alkali contents [ w ( Na2O + K2O) = 2. 91%--2. 98% , Na2O / K2O = 2. 23 --2. 31 ]. The A / CNK ratios range from 0. 75 to 0. 76. In TAS and w ( SiO2 ) --w ( K2O) diagrams, the samples fall into the calc-alkaline field. Trace element compositions show enrichment in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs, e. g. , Ba, Rb, K) , and depletion in heavy rare earth elements ( HREEs) and high-field-strength elements ( HFSEs, e. g. , Nb, Ta, Ti) , without obvious Eu anomaly. The m / f ratios vary from 1. 73 to 1. 76, indicating favorable conditions for Cu--Ni sulfide mineralization. Ratios such as La / Nb, Ce / Pb, Th / U, and Nb / U differ significantly from mantle or crustal values, suggesting crust-mantle contamination. In (Nb / La) -- (La / Yb) diagram, the samples fall into the lithospheric mantle field. Zircon 176Hf / 177Hf ratios range from 0. 282 674 to 0. 282 805, with εHf (t) values of + 0. 80 to + 5. 87, and the single-stage model ages ( TDM1 ) of 907-- 646 Ma, indicating a magma source derived from depleted mantle with crustal contamination. The Cu / Pd ratio (34. 8 × 103 ) exceeds the primitive mantle value, while the Pd / Ir ratio is 9. 07, suggesting that PGE characteristics are primarily related to magmatic processes. The primary magma originated from high--Mg basaltic melts in the lithospheric mantle. The PPGE (Pt, Pd) concentrations are significantly higher than IPGE, and the Ni / Cu ratio is 6. 31, further supporting the Shirengou gabbro as a favorable ore-forming intrusion. Combined with its Late Triassic emplacement age, the Shirengou gabbro likely formed in a post-collisional extensional setting following the closure of the Paleo--Asian Ocean. 

In order to explore the electromagnetic wave detection response characteristics of shallow underground buried targets in a specific medium and meet the urgent needs of urban underground pipeline management and unknown target detection, a high-performance antenna for ground penetrating radar system was innovatively designed based on the in-depth analysis of the rectangular waveguide theory. Firstly, according to the propagation characteristics of electromagnetic waves in the rectangular waveguide, the basic model of the antenna was constructed, the cut-off frequency of the antenna was calculated, and the monopole probe was selected as the effective excitation source. Secondly, the high frequency structure simulator (HFSS) of Ansys electronics desktop (AEDT) simulation platform was used to carry out numerical simulation and optimization of the antenna model. By in-depth analysis of the influence of the installation position and insertion depth of the monopole probe in the rectangular waveguide on the transmission characteristics of the antenna, the S11 reflection coefficient, voltage standing wave ratio (VSWR) and radiation pattern of the antenna were accurately adjusted. Finally, in order to verify the accuracy of the theoretical analysis and simulation results, the antenna was fabricated with aluminum foil board material, and the ground penetrating radar system was built with vector network analyzer (VNA) in a controlled sand trough environment for field testing, and the detection height of the antenna was adjusted to cover underground targets at different depths. Experimental results show that the antenna can stably and accurately identify all preset targets. The ground penetrating radar antenna based on rectangular waveguide shows excellent directionality, ultra-wideband and high resolution after finely adjusting the insertion depth of the probe and the distance between the probe and the short-circuit surface of the rectangular waveguide to achieve the best matching of antenna impedance, which provides an efficient and accurate new tool for urban underground space management and unknown target detection.

 The Chaganhua Subsag, one of the subsags in the Changling Fault Depression, Songliao Basin, is divided into two parts: the northern and the southern. The spatial relationships between the source rocks and reservoir rocks and the interstitial physical properties of the volcanic rock hydrocarbon reservoirs are similar in the northern and southern parts. However, exploration and development reveal that the distribution and activity periods of the faults in the southern and northern parts of the subsag are different, and volcanic rock hydrocarbon reservoirs in the northern part of the subsag are more than those in the southern part. In this study, seismic interpretation data were used to statistically analyze the occurrence and activity period of the main active faults in the Chaganhua Subsag,2D hydrocarbon accumulation simulations were processed with key well-crossing profiles on the basis of the source rock burial history. The matching relationships between the activity periods of the main active faults and the hydrocarbon charging periods in the southern and northern parts of the Chaganhua Subsag were compared. The controlling effects of fault activity on hydrocarbon migration and accumulation, and the causes of the differences in the distributions of volcanic rock reservoirs in the northern and southern parts of the subsag were analyzed. The results revealed two hydrocarbon charging periods of volcanic reservoir in the Chaganhua Subsag. One period was the Early Cretaceous Denglouku stage, and the other was from the end of the Early Cretaceous Quantou stage to the Late Cretaceous Qingshankou stage. Three levels of faults were developed in the Mesozoic strata under an extensional structural environment. The secondary faults were the important factors in hydrocarbon migration and accumulation.Many secondary faults developed with long activity period in the northern part of the Chaganhua Subsag. Their activity period was as long as from the Early Cretaceous Huoshiling stage to the end of the Quantou stage or even to the end of the Late Cretaceous Qingshankou stage. The hydrocarbon charging period as well matched the fault activity period. The secondary faults in the northern part of the subsag performed the main migration paths, in the volcanic hydrocarbon accumulations under the coordinating of unconformities. In the southern part of the subsag,the secondary faults were less developed with short activity periods from the Early Cretaceous Shahezi stage to the Denglouku stage. These faults were bad for matching the hydrocarbon charging periods, and had little control effects on hydrocarbon accumulation in the southern part of the subsag, and played a limited role in hydrocarbon migration. Some of these faults with long activity periods could be beneficial for hydrocarbon migration with the assistance of advantageous volcanic facies belts. The fault activity periods and their matching relationships to hydrocarbon charging periods are the main reasons for the differences in volcanic rock hydrocarbon reservoirs between the southern and northern parts of the Chaganhua Subsag.

In order to explore the electromagnetic wave detection response characteristics of shallow under-
ground buried targets in a specific medium and meet the urgent needs of urban underground pipeline management
and unknown target detection, a high-performance antenna for ground penetrating radar system was innovatively
designed based on the in-depth analysis of the rectangular waveguide theory. Firstly, according to the propagation
characteristics of electromagnetic waves in the rectangular waveguide, the basic model of the antenna is constructed,
the cut-off frequency of the antenna is calculated, and the monopole probe is selected as the effective excitation
source. Secondly, the high frequency structure simulator (HFSS) of Ansys electronics desktop (AEDT) simulation
platform was used to carry out numerical simulation and optimization of the antenna model. By in-depth analysis of
the influence of the installation position and insertion depth of the monopole probe in the rectangular waveguide on
the transmission characteristics of the antenna, the S11 reflection coefficient, voltage standing wave ratio (VSWR) and
radiation pattern of the antenna were accurately adjusted. Finally, in order to verify the accuracy of the theoretical
analysis and simulation results, the antenna was fabricated with aluminum foil board material, and the ground
penetrating radar system was built with vector network analyzer (VNA) in a controlled sand trough environment for
field testing, and the detection height of the antenna was adjusted to cover underground targets at different depths.
Experimental results show that the antenna can stably and accurately identify all preset targets. The ground penetrating
radar antenna based on rectangular waveguide shows excellent directionality, ultra-wideband and high resolution
after finely adjusting the insertion depth of the probe and the distance between the probe and the short-circuit
surface of the rectangular waveguide to achieve the best matching of antenna impedance, which provides an efficient
and accurate new tool for urban underground space management and unknown target detection.

 In order to explore the distribution of high quality reservoirs within the Cretaceous volcanic edifice in the M region in the eastern uplift zone of the Santos Basin, Brazil, volcanic lithology, lithofacies, stages, types of edifice and their relationship with reservoirs were studied in the Cretaceous volcanic strata in the M region, based on the drilling cores, conventional logging curves, three-dimensional seismic data and logging physical properties,with the methods of volcanic petrology and volcanic stratigraphy.The results show that four types of volcanic edifice were identified in the M region, including onshore basaltic tabular lava edifice, onshore basaltic fill-type lava edifice, subaqueous basaltic thick-layer lava edifice, and subaqueous basaltic compound lava edifice.Furthermore, the volcanic rocks in the M region were divided into five eruption stages, of which eruption stage 2 (E2) is characterized by the deposition of onshore basaltic tabular lava edifice, stage 3 (E3) consists of the subaqueous basaltic thick-layer lava edifice and subaqueous basaltic compound lava edifice, stage 4 (E4) comprises merely subaqueous basaltic compound lava edifice, and stage 5 (E5) is composed of onshore basaltic fill-type lava edifice.Additionally, the reservoir physical properties vary among four types of volcanic edifices, with the subaqueous basaltic compound lava edifice exhibiting the best properties, subaqueous basaltic thick-layer lava edifice being moderate, and the onshore basaltic tabular lava edifice and onshore basaltic fill-type lava edifice demonstrating the worst properties.Based on these findings, it is considered that in the M region, the reservoir associated with E4 featuring subaqueous basaltic compound lava edifice is the best, the reservoir of E3 comprising subaqueous basaltic thick-layer lava edifice and subaqueous basaltic compound lava edifice ranks second, the reservoirs of E2 and E5 which involve onshore basaltic tabular lava edifice and onshore basaltic fill-type lava edifice are considered the least favorable.Therefore,volcanic rocks from E3 and E4 can be targeted as key areas for subsequent oil and gas exploration in the study area.

Gravity and magnetotelluric sounding are commonly used techniques in geophysical exploration, with wide applications in mineral and geothermal resource exploration. However, a single geophysical inversion is often affected by the limitation of observational data and the ambiguity of inversion, making it difficult to provide detailed and comprehensive geological interpretations of actual underground anomalous structures. The gravity method can distinguish geological structures well in the horizontal direction, but it is difficult to distinguish deep or shallow anomalies in the vertical direction. Magnetotelluric sounding has a depth range of tens to hundreds of kilometers and strong deep resolution in the vertical direction, but its resolution in lateral geological structural changes is weak. In order to overcome the limitations of the two methods and combine their respective inversion advantages, the authors propose a new method for two-dimensional spatial coupled constrained inversion of magnetotellurics and gravity based on semantic segmentation ( spatial constrained inversion). This algorithm constrains the interrelationships between different physical property values by recognizing and fusing the features of the target area, thereby improving the inversion accuracy. Compared with traditional methods, this algorithm only performs inversion on the target area, keeping the non-target area unchanged, effectively reducing the dimensionality of the inversion solution, reducing the multiplicity of inversion solutions, and reducing computational complexity. The model test results show that the proposed algorithm can significantly improve the resolution of inversion and clearly reveal abnormal boundary information, providing more accurate results for geological structure analysis. Finally, this method successfully identified strong mineralization targets in Yongxin gold mining area of Duobaoshan, Heilongjiang Province, and finely delineated the boundaries of underground anomalous bodies, providing strong technical support for subsequent drilling and positioning.

A typical example of three-dimensional composite hydrocarbon accumulation exists in southwest of Bozhong Sag and obvious seismic wave velocity anomalies have been revealed by drilling in the lower member of Minghuazhen Formation. In order to clarify the unclear distributions and causes of these seismic wave velocity anomalies in the lower member of Minghuazhen Formation in southwest of Bozhong Sag, the authors analyzed the relationships between seismic wave velocity with faults, lithology and structure in different oil-bearing units based on investigating the planar distribution of the velocity anomalies. It was found that the influencing factors of velocity anomalies vary among different oil-bearing units, and for the first time, it was discovered that structure has a regular impact on velocity anomalies. The average velocity anomalies are obtained by decompaction based on the average velocity field, which was derived from the stacking velocity field. Detailed analyses were conducted on the factors that cause velocity anomalies, such as faults and sand-to-strata ratios, to explore the geological causes of velocity anomalies in the lower member of Minghuazhen Formation. The results show that the main factors affecting the velocity anomalies are faults, structural amplitude, and sand-to-strata ratio in order of influence. However, these factors vary under different geological conditions and need to be considered comprehensively. In the area where faults are well-developed, the fault zones significantly increase the velocity anomalies, larger anomalies are closer to the faults. In the area without faults, structural amplitude is the main factor affecting velocity, higher velocities are corresponding to greater amplitudes. While, lithology is the main factor affecting velocity in low amplitude structure, higher content of sandstone results lower velocities.

 

Multiple wells in the carbonate gas reservoirs of the Lower Permian Qixia Formation in the central
 Sichuan region of the Sichuan Basin have encountered industrial gas flows, but the anisotropy of the single well
 reservoir is strong and the physical parameters are obviously different, so it is difficult to guide the well location
deployment of this type of gas reservoir by conventional geophysical means. Therefore, to clarify the main controlling
 factors of the Qixia Formation gas reservoir, accurately predict the distribution of thin dolomite reservoirs, and
 further improve the development efficiency of the gas reservoir, the authors combine core, logging, seismic and
 other data to first determine the main controlling factors for the enrichment and high yield of the Qixia Formation gas
 reservoir in the study area, and summarizes the rock physical characteristics and seismic response patterns of the
 dolomite reservoir. Innovation has formed key technical processes for thin reservoir prediction, such as high-resolution
 processing technology, qualitative reservoir prediction based on wavelet reconstruction, fine characterization of ancient
 landforms constrained by layers, inversion technology constrained by reconstruction curves, and fracture and cave
 prediction technology constrained by porosity curves. This has improved the ability to vertically resolve thin reservoirs of
 1-8 m in the research area, and ultimately characterized a favorable area for the development of dolomite reservoirs
 as 75 km2. The research results indicate that: (1) There is an obvious positive correlation between the thickness
 of fracture-vuggy dolomite thin reservoir, fracture-cave development degree and productivity in the Qixia Formation
 gas reservoir in the study area. (2) Before the sedimentation of the Qixia Formation (paleogeomorphology), reservoirs
 were developed in the lower part, and the reservoir properties in the slope area during the karst period were better.
 (3) The reservoirs of Qixia Formation in the study area are mainly developed in the middle and upper parts, and
 the seismic profile shows the reflection characteristics of “weak peaks” in the middle and upper parts, and the more
 the reservoirs are developed, the more obvious the response characteristics of “weak peaks” are. This article
 combines seismic facies, paleogeomorphology, reservoir thickness, and fracture distribution parameters for the first
 time to establish a series of key technologies for predicting dolomite reservoirs suitable for the study area, achieving
 effective prediction of the spatial distribution of thin reservoirs in the Qixia Formation and laying the foundation for
 increasing reserves and production in oil fields.

 Tiejiashan granite in the Anshan area, Liaoning Province, represents the oldest known K-rich granite in the North China Craton. This study integrates petrography, zircon U-Pb geochronology, whole-rock geochemistry, Lu-Hf isotopic and deformation structural analysis to elucidate the petrogenesis, tectonic setting, and dynamic mech anism of Mesoarchean K-rich granite. Zircon U-Pb geochronological data indicates that the Tiejiashan K-rich granite formed during the Mesoarchean (3. 0-2. 9 Ga). The samples exhibit high w (SiO2 ) (68.03%-71.24%), w(TFe2 O3 )(3. 31%-4. 90%), w(K2 O + Na2 O) (7.73%-7.99%), and high Ga/Al ratio, coupled with low w (MgO) (0.53%-0.80%). Rare earth elements exhibit distinct negative Eu anomalies (δEu = 0. 21-0. 31). The rocks are obviously enriched in large ion lithophile elements (LILE, e. g. Rb, Th, U, and K), while depleted in high field strength elements (HFSE, e. g. Nb, Ta, P, and Ti). Additionally, they display high zircon saturation temperatures ranging from 822 ℃ to 926 ℃. Based on these geochemical characteristics, the Tiejiashan granite is classified as an A-type granite. No Mesoarchean mafic rocks have been identified in the Anshan area. Petrographic and geochemical analyses reveal that the Tiejiashan granite demonstrates metaluminous to peraluminous affinities. The Tiejiashan granite has low εHf (t) values (-8. 23 to- 14. 75), with TDM2 model ages between 4. 0 and 3. 7 Ga, suggesting derivation from the partial melting of ancient crustal material. Variations in components such as TiO2 , CaO, MgO, P2 O5 , Sr, and Zr show linear correlations with w (SiO2 ) on Harker diagrams, indicating experienced continuous magmatic evolution and differentiation. Combining the geochemical data and tectonic deformation characteristics, it is inferred that lithospheric mantle underplating induced regional extension in the Anshan area during the Mesoarchean. Heat from the lithospheric mantle likely triggered partial melting of the lower crust and facilitated rapid diapiric ascent of magma, lead to the formation of Tiejiashan granite.

 This study focuses on two fine-flake graphite metallogenic belts in the Shanxi Fault Uplift and South Qinling regions of Henan Province. Through field geological surveys, sample testing, and comprehensive analysis, the authors systematically investigated the distribution characteristics, enrichment regularity, and genetic mechanism of fine-flake graphite. Research indicates that fine-flake graphite ore bodies primarily occur in the Chishangou Formation of the Yinyugou Group within the Shanxi Fault Uplift and the Dagou Formation of the Douling Group in South Qinling, demonstrating significant stratigraphic specificity. Spatiotemporal distribution analysis reveals that the ore-hosting strata are mainly Paleoproterozoic, with deposits exhibiting a northwest-southeast trend, consistent with regional structural trends. The ore bodies are strictly strata-bound and conformable with the host strata. The ore-forming materials originate from a combination of organic and inorganic sources, with the deposit type classified as regional metamorphic. Further research demonstrates that the fine-flake characteristics of graphite are primarily influenced by tectonic stress, metamorphism and migmatization. These findings provide a scientific basis for a deeper understanding of the metallogenic patterns of fine-flake graphite deposits in Henan Province.

    Electrical resistivity tomography (ERT) method is a geophysical exploration technique based on
the differences in resistivity of media. Due to its characteristics of non-destructive and high efficiency, it is widely
used for detecting and evaluating subsurface anomalies. The authors take a gold mine goaf as the subject, numerical
simulations for analyzing potential anomalous characteristics in goaf areas, and field investigations to verify the
applicability of ERT in detecting goaf collapse zones, which providing a scientific basis for goaf management.
Focusing on Wenner, dipole-dipole, Wenner--Schlumberger, and pole-pole electrode arrays, RES2DMOD forward
modeling software was used to construct models of a single isolated low-resistivity anomaly and a semi-high and
semi-low resistivity anomaly to simulate fully water-filled and partially water-filled conditions of goafs. The data were
processed by using RES2DINV inversion software with the least-squares method for inversion calculations. The results
show that the dipole-dipole array exhibited the best performance for the fully water-filled anomaly, which accurately
locate and describe the geometric shape and resistivity characteristics of low-resistivity anomalies with high resolution.
For the partially water-filled semi-high resistivity and semi-low resistivity anomaly, the inversion accuracy of all arrays
decreased, but the dipole-dipole array still outperformed the others, effectively reflected the distribution
characteristics of the anomalies. In field investigations, the dipole-dipole array was employed for data acquisition.
The processed data revealed a low-resistivity zone at the position approximately 115 m (30 m in depth) in the study
area. Based on geological and hydrogeological conditions, the low-resistivity zone was inferred to be a goaf collapse
zone. The findings indicate that the dipole-dipole array effectively reflects the extent and characteristics of goaf collapse
zones, providing valuable insights for estimating the approximate range and developmental depth of anomalous areas.

 Geochemical characteristics and potential evaluation of hydrocarbon source rocks are the core component of the petroleum system and play a crucial guiding role in the exploration and development of hydrocarbon resources. To systematically assess the hydrocarbon generation potential of source rocks in the Shahezi Formation within the Lishu Fault Depression of the Songliao Basin and to clarify their geochemical characteristics and distribution patterns, the authors utilized core observations and well log interpretations to identify the macro sedimentary facies and vertical distribution of organic-rich mudstone intervals. A series of geochemical analyses (total organic carbon content measurement, rock pyrolysis, kerogen carbon isotope analysis, reflectance in oil testing, and gas chromatog raphy-mass spectrometry of saturated hydrocarbon biomarkers) were employed to quantitatively characterize key parameters of the source rocks. The research results indicate that the lower part of the Sha1 Member and the middle part of the Sha2 Member of the Shahezi Formation are developed with mudstone deposits belonging to coastal-shallow lacustrine and semi-deep to deep lacustrine subfacies, which constitute the main source rock intervals of the Lishu Fault Depression. The depositional environment ischaracterized by weak redox conditions, and the migration of the depositional center controls the distribution of high-quality hydrocarbon source rocks. In terms of organic geochemical characteristics, the source rocks of the Shahezi Formation exhibit high organic matter abundance, with TOC values ranging mainly from 1. 0% to 6. 8% and an average of 2. 5%. The vast majority of samples exceed the quality hydrocarbon source rocks threshold (w(TOC)≥ 2. 0%). The kerogen is predominantly Type Ⅲ, followed by Type Ⅱ 2 , with a few samples exhibiting characteristics of TypeⅡ1 and TypeⅠ. Thermal maturity assessment indicates that the hydrocarbon source rocks have reached the mature to over-mature gas generation stage (Ro >1. 3%, average Tmax = 455.1 ℃). Comprehensive evaluation indicates that the Shahezi Formation in the Lishu Fault Depression of the Songliao Basin is characterized by an enrichment in main hydrocarbon source rocks, high organic matter abundance dominated by gas-prone types, high thermal maturity having entered the gas generation stage, and distinct spatial differentiation, demonstrating excellent hydrocarbon generation potential.

In order to investigate the diversity and complexity of sedimentary reservoirs, to clarify the sedimentary characteristics and sand body development rules of the Cretaceous Shushanhe Formation (K1s) in Tahe Oilfield, Tarim Basin, and to analyze the relationship between sedimentary microfacies and reservoir sand body distribution,core analysis and logging analysis methods were used to identify lithological markers, mainly including rock color,composition, sedimentary texture, sedimentary structure, rock type and lithological associations, and to identify logging markers, including qualitative logging curve characteristics and quantitative logging data characteristics.Adopting systematic sedimentological analysis methods, mainly geological methods, the authors summarized lithology and logging sedimentary facies markers, and established sedimentary microfacies classification standards, and analyzed sedimentary facies types and their evolutionary characteristics vertically and on the profile through the study of single-well facies and profile facies.We also analyzed the plane characteristics of sedimentary microfacies by using ratio of sand to stratum, and the distribution pattern of sandstone in the region by using thickness of sand body.Based on the core and logging data, a sedimentary microfacies division standard was established, one singlewell sedimentary facies diagram and two horizontal and vertical profile facies diagrams were drawn; while the sedimentary microfacies plane and sand body distribution of four small layers were completed, and the regional braided river delta front sedimentary model was summarized.The Upper Member of Shushanhe Formation (K1s3) in TP12 -8 well area belongs to the shallow water gentle slope braided river delta front sedimentation system, which identifies three sedimentary microfacies of the subaqueous distributary channel, the subaqueous interdistributary channel and the channel edge, and the provenances come from the southern area of Tuofutai.Because the sedimentary environment is a large oxidized wide shallow lake basin, it has unique sedimentary characteristics.Different from the general subaqueous deposition, the color of sediments in the TP12-8 well area is oxidized, such as brown.Sand body is stacking developed, mainly fine sandstone, accounting for about 75% of the total area on the plane, and the thickness of the sand body can reach 1.4-23.9 m.The subaqueous distributary channel is the main sedimentary face in the study area, and the mouth bar does not develop.After the channel enters the lake, it continues to extend,running through the whole study area in a strip shape, with a width of 1.5-9.0 km.

The coupled models for selecting statistical methods and machine learning models to achieve better prediction results for geological hazard susceptibility assessment, as well as the interpretation of the contribution of model feature factors, are further studied in this paper. Two statistical methods (information value, IV and certainty factor, CF) and two machine learning models (support vector machine, SVM and random forest, RF) are combined to construct four hybrid models. Taking Panshi City as an example, the study investigates the effect of coupled models on the accuracy improvement compared to single statistical models, and selects the most accurate model to explain the contribution of various hazard-causing factors to the prediction results. The interactive self organization (ISO) clustering algorithm is first used to select non-harzard samples. Then, the information value (IV) method and the certainty factor (CF) method are combined with support vector machine (SVM) and random forest (RF) to obtain four coupled models (IV-SVM, CF-SVM, IV-RF, CF-RF) for training, respectively. The performance of the models is evaluated using confusion matrix and receiver operating characteristic curve. The natu ral break method is then used to generate the geological hazard susceptibility classification map (with five levels: very low, low, moderate, high, and very high). The geological hazard intensity index is used to evaluate the clas sification accuracy, and geological hazard susceptibility assessment is conducted. Finally, the Shapley additive ex planations algorithm is used to explain the best-performing model. The results show that the performance of the four coupled models is generally better than that of the single statistical models, with the CF-RF model achieving the best accuracy evaluation results of accuracy (0. 896), precision (0. 872), F1 score (0. 899), and AUC value (0. 959), which is an improvement of 0. 066, 0. 098, 0. 054, and 0. 059, respectively, compared to the single CF model. Most historical geological hazard points are distributed in high and very high susceptibility zones, and the geological hazard intensity index increases as the susceptibility level increases. Among them, the CF-RF model has the best classification effect. The Shapley additive explanations algorithm can help understand the reasons behind the model􀆳s decisions and the occurrence patterns of geological hazards. The study indicates that land use and road construction are the main inducing factors for geological hazard susceptibility in the study area.

Water source quality safety is a major livelihood issue. With numerous water quality indicators and complex influencing factors, timely evaluation of water source quality is particularly important. Most current evaluation methods are relatively macro-level assessments based on existing quality standards, lacking relatively micro-level scien tific evaluation of water bodies in water source areas across different periods. Therefore, establishing a comprehensive evaluation system can provide a theoretical basis and technical support for pollution risk early warning in drinking water sources and for improving water environment quality. Based on the single-factor index evaluation method and the Nemero index method, the authors introduce the concept of an environmental capacity index to construct a multi-factor comprehensive environmental capacity index evaluation model and a Nemero method environmental capacity index model. These two models were used to conduct a comprehensive evaluation of a drinking water source in Dafeng District, Yancheng City, Jiangsu Province. Furthermore, based on the water quality evaluation, a health risk assessment was introduced to analyze the human health risks associated with the water source, comprehensively ensuring drinking water safety. The evaluation results indicate that the overall environmental quality of this water body shows a trend of improvement, while the chemical oxygen demand (COD) indicator shows a deteriorating trend; all other indicators show improving trends. Environmental quality in August was relatively poor within the year. The established multi-factor comprehensive environmental capacity index model and the Nemero method environmental capacity index model both can be used to evaluate water bodies in water source areas with stable categories. Among them, the improved Nemero method environmental capacity calculates the weight of each pollution factor, avoiding the neglect of certain pollutants with low concentration but high hazard. The total health risk of the water source area was around 1. 81 × 10-4 a-1-2. 30 ×10-4 a-1, classified as high risk. Carcinogenic arsenic contributed the most to this risk, followed by carcinogenic hexavalent chromium. Compared to non-carcinogenic risks, carcinogenic substances are the main source of potential risk through the drinking water pathway.

 In order to reveal the surface deformation characteristics and fault movement mechanism of the Luding
 earthquake of 5 September 2022, to mitigate the impact of seismic hazards, and to enhance disaster prevention and
 mitigation capabilities, the authors extracted the coseismic deformation results by using D-InSAR technology and
 inverted the geometric and kinematic parameters of the seismic faults by combining with the dislocation model. The
ascending orbit images on 26 August and 19 September 2022 and the descending orbit images on 2 September and
 14 September 2022 of the Sentinel-1 satellite from the European Space Agency are selected for the study. Through
 the dual-track differential interferometric processing, errors such as topographic phase and atmospheric delays are
 eliminated, and the coseismic deformation results are obtained with high accuracy. The results show that the surface
 deformation induced by the earthquake is significant, and the maximum uplift of 0. 16 m and 0. 13 m, and the
 maximum subsidence of 0. 24 m and 0. 18 m are detected in the ascending and descending orbits, respectively, which
 provide reliable observation constraints for the subsequent inversion of fault parameters. Based on the acquired
 ascending and descending orbits InSAR coseismic deformation results, the Okada elastic half-space dislocation model
 is used for the fault parameter inversion, and the optimal geometric parameters and kinematic characteristics of the
 seismic fault are determined by the nonlinear optimisation method. The inversion results show that the seismic fault
 has a strike of 169°, spreads along the NNW-SSE direction, has a dip of 72°, and a slip angle of-3°. In addition,
 the total seismic moment obtained from the inversion is about 2. 46 ×1019 N·m, corresponding to a magnitude of
 MW 
6.8, which is basically consistent with the observation results from global earthquake monitoring and research
 institutions.

 The magmatic rocks exposed in Xiyinkeng area (Jurong City, Jiangsu Province) belong to the Anjishan complex. The rock type is mainly granodiorite porphyry, which is intruded by a small amount of intermediate-basic dykes such as quartz diorite porphyrite, diorite porphyrite, and diabase porphyrite. To determine the timing of mag matism (crystallization/ emplacement age) and geodynamic background, this paper conducted petrographic, zircon U-Pb chronology, and geochemical characteristics research on Xiyinkeng magmatic rocks. Zircon U-Pb dating in dicated that granodiorite porphyry crystallized at (104. 45 ±0. 29) Ma, followed by the emplacement of quartz dio rite porphyrite at (104. 66 ±0. 52) Ma, and subsequently diabase porphyrite intrusion at (101. 37 ±0. 34) Ma, all occurring during the Early Cretaceous. Geochemical data show that the magmatic rocks in Xiyinkeng area are characterized by high potassium [w (K2 O) 1. 96%-4. 05%] and high alkalinity [w (Na2 O) 2. 29%-4. 68%], with A/ NK values ranging from 1. 38-2. 15, A/CNK values ranging from 0. 62-0. 96, and Littmann indexes ranging from 1. 76-2. 59, indicating that they are metaluminous calc-alkaline series I-type granites. The diabase porphyrite exhibits higher rare earth elements enrichment (ΣREE = 144. 61 × 10-6- 182. 84 × 10-6, avg. 163. 73 × 10-6), with LREE/HREE, (La/Yb)N , and (Gd/Yb)N ratios of 10.81-12.76, 13.60-17.62, and 2.16 2. 33, respectively. In contrast, the rare earth element contents of granodiorite porphyry, quartz diorite porphyrite and diorite porphyrite are lower than those of diabase porphyrite (ΣREE = 94. 43 × 10-6-143. 47 × 10-6, avg. 118. 79 × 10-6). The light and heavy rare earth element ratios (LREE/ HREE) range from 14. 43-24. 48, the (La/ Yb)N and (Gd/Yb)N are 22. 16-43. 70 and 2. 57-2. 87 respectively. The rocks are relatively enriched in large ion lithophile elements (Rb and La) and relatively depleted in high field strength elements (Nb, Ti and Ta), showing obvious characteristics of island arc magmatic rock. The Nb/ Ta ratio is 11. 57-24. 68, which is close to that of continental crust, indicating the presence of a large amount of crustal material. Combined with previous research results, it is believed that the magmatic rocks in the Xiyinkeng area was formed in a back-arc extensional environment during the subduction and retreat of the Pacific Plate. It is the product of interaction between the lower crust and mantle materials, classified as crust-mantle granite.

Gejiu tin mine in Yunnan is a super-large polymetallic ore concentration area dominated by tincopper, altered vein-type ore bodies within rock masses have been identified in recent years. To clarify the orecontrolling conditions and metallogenic regularities of these intra-rock altered vein-type ore bodies and to provide theoretical support for exploring new prospecting targets around Laochang ore field, the authors carry out detailed field investigation and measurement of the known ore bodies in Fengliushan ore section within the western depression zone of Laochang ore field, Gejiu mining area and three levels (1 800 m, 1 700 m and 1 600 m) of the joints and fractures (including ore veins) exposed by the internal tunnels through the comprehensive analysis of mine data. Statistical analyses were conducted on the orientation and dip angles of different joint sets, their ore-controlling and ore-hosting characteristics, and their relationship with regional fault tectonics. The results show that there are three major groups of well-developed joints and fractures in Fengliushan ore section, including NE-, NW- and nearly EW-trending, with most dip angles ranging from 60° to 80°. These features like the fracture distribution patterns in Gejiu mining area. Interactions among fractures from different orientations form favorable “X-type” tectonic structures conducive to mineralization. Among these, the nearly EW-trending fractures are the most prominent and commonly host tourmaline-quartz veins or chalcopyrite-pyrite-cassiterite-scheelite mineralization veins, maybe the radius tensional joints and fractures formed in the process of emplacement-condensation of granitic rock mass. In contrast, the NE- and NW-trending fractures primarily represent late-stage mineralization-disrupting structures that postdate and damage earlier EW-trending ore-controlling ( ore-hosting) fractures. A total of 284 ore-bearing fractures were measured, predominantly oriented nearly EW-trending, indicating that nearly EW-trending joints serve as the primary ore-controlling structures.