It has a great potential for oil and gas resources exploration in Qigu Formation of Fudong slope area, Junggar basin, and the exploration and development process has been restricted due to a lack of system understanding of sedimentary facies. In order to gain a detailed understanding of the sedimentary facies and identify the favorable reservoir facies, many data, such as field outcrops, cores and sections observation, analysis on heavy minerals and geochemistry, drilling, logging, and seismic data were used. The results show that: The provenances of Qigu Formation are the northern Karameili Mountain, the southern Bogda Mountain, and the eastern Beisantai salient. A braided delta deposit dominated the Qigu Formation, which can be divided into two subfacies (delta plain and delta front) and several microfacies based on sedimentary characters. Based on seismic attributes and sand contents, the favorable sandbodies are characterized. Favorable sandbodies and oil-bearing properties in Qigu Formation are predicted through space distribution analysis of sedimentary facies. Underwater distributary channels in the initial stage of Qigu Formation, distributary channels near deep fault or denudation areas are favorable reservoir facies belts for the forming of lithological accumulations.

To clarify the main controlling factors of interlayer oil enrichment, this study classifies hydrocarbon supply modes based on the spatial relationships between source rocks and reservoirs, including their relative development positions and vertical/lateral configurations. The oil-bearing properties under different hydrocarbon supply modes were characterized using indicators such as the proportion of oil-bearing wells, hydrocarbon charging thickness, charging intensity, and oil saturation, thereby revealing the differential enrichment characteristics of interlayer oil. The results show as follows. In the Jiyuan area of the Ordos basin, four types of hydrocarbon supply modes were identified: Vertical dual-source supply type, bottom source type, lower source type, and lateral source type. Among them, the vertical dual-source supply type and lateral source type exhibit superior oil-bearing properties, while the bottom source type and lower source type are comparatively less enriched. The oil content of the vertical dual-source supply types is primarily governed by the reservoir's storage capacity, whereas that of the bottom supply type is controlled by the interplay between dynamic forces and resistance. The oil content of the lateral source type depends on the connectivity of the sand bodies connecting the source rock, while the oil content of the lower supply type is significantly influenced by the fracture density of overlying sandstones.

Fine-grained sedimentary rocks have become an important field of oil and gas exploration in the depression lake basin. The study of fine-grained sedimentary petrography and sedimentary microfacies can provide a theoretical and practical basis for exploration and target selection. Taking the Chang 7 Member of Triassic Yanchang Formation in Ganquan area of Ordos basin as an example, the types and characteristics of lithofacies and sedimentary facies of Chang 7 Member were clarified by core observation, logging curve, grain size analysis, and oil test and production test. The distribution law of sedimentary facies was predicted, and its control effect on reservoir distribution was discussed. The results show that the sedimentary structures such as massive bedding, horizontal bedding, slump deformation, ball pillow structure, water discharge structure, and flame structure are developed in the Chang 7 Member of the study area. Plant fossils are enriched in Chang 7₁ and 7₂ Submembers, but not found in Chang 7₃ Submember. The probability curve of grain size shows three types: Single-stage suspension, two-stage gradual change, and wide and gentle arching. It is comprehensively reflected that the sedimentary environment of Chang 7 Member is semi-deep lake-deep lake and delta front. According to lithology and sedimentary structure, 10 lithofacies types and 4 lithofacies combination modes are divided, and 6 lithofacies are mainly developed, such as massive bedding fine sandstone facies, flow cross bedding fine sandstone facies, wave cross bedding siltstone facies, deformed bedding argillaceous siltstone facies, rhythmic bedding silty mudstone facies, and massive mudstone facies. Six sedimentary microfacies are identified, including underwater distributary channel, interdistributary bay, semi-deep lake-deep lake mud, turbidity current, sandy debris flow, and slip-slump. Underwater distributary channel sand body, turbidite sand body and sandy debris flow sand body can act as high-quality reservoirs, and the underwater distributary channel sand body is the main production layer in the study area.

Due to the complex pore-throat structures and strong heterogeneity of low-permeability reservoirs, a comprehensive classification and evaluation based on pore-throat characteristics and flow capacity is of great significance for guiding subsequent development. Taking the Chang 6 oil-bearing Formation in the southern Ordos basin as the research object, this study systematically evaluates the petrological characteristics, physical properties, microscopic pore-throat features, and flow capacity of the reservoir using an integrated suite of analytical methods, including thin-section petrography, scanning electron microscopy (SEM), X-ray diffraction (XRD), mercury intrusion capillary pressure (MICP), nuclear magnetic resonance (NMR), and oil–water relative probability. Based on K-means clustering method, the reservoir is classified and evaluated. On this basis, a comprehensive evaluation parameter is calculated, and furthermore, the factors controlling the quality differences among different reservoir types are discussed. The results indicate that the Chang 6 oil-bearing Formation in the study area is predominantly composed of fine-grained lithic feldspathic sandstones. The reservoir spaces are mainly residual intergranular pores and feldspar dissolution pores, and the pore–throat assemblages are characterized by medium-to-small pores coupled with fine throats. Accordingly, a comprehensive classification and evaluation system is established, dividing the reservoirs into four types: Types Ⅰ and Ⅱ are high-quality reservoirs, Type Ⅲ are moderate reservoirs, and Type Ⅳ are poor reservoirs. The distribution areas of different reservoir types correspond to distinct development strategies. The differences in reservoir quality are primarily controlled by sedimentary facies type, diagenetic intensity, and the content and type of clay minerals, among which a certain content of grain-coating chlorite could improve reservoir quality.

Sedimentary environments serve as a critical constraint on hydrocarbon accumulation, while the geochemical characteristics of sediments provide an effective proxy for tracing paleoenvironmental evolution. To investigate the sedimentary characteristics of the Sha 3 Member of the Paleogene in the Weicheng-Guyunji area of the Dongpu depression, Bohai Bay basin, this paper conducts a systematic analysis of the target interval utilizing sequence stratigraphy, geochemistry, and geophysical well logging. Based on well logging curves, the Sha 3 Member in Well Y3 of the Dongpu depression is divided into three long-term sequences, which are designated as sequence Ⅰ, sequence Ⅱ, and sequence Ⅲ from bottom to top. Based on the geochemical characteristics of major, trace, and rare earth elements, this study evaluates paleosalinity, paleoclimate, paleo-redox conditions, and tectonic settings within these three sequences, and elucidates the geochemical characteristics and paleoenvironmental evolution of the Sha 3 Member in the Weicheng-Guyunji area of the Dongpu depression. The results indicate that the chondrite-normalized REE patterns of the three sequences in Well Y3 are generally consistent with those of post-Archean Australian shale (PAAS). These patterns exhibit a “V” shape and an overall right-inclined trend with a gentle variation. This indicates a relative enrichment of light rare earth elements and a relative depletion of heavy rare earth elements. The Sr/Ba ratios of the Sha 3 Member samples in the study area range from 0.50 to 16.33, with an average of 2.65, indicating that the depositional water body during the Sha 3 Member period was characterized by a saline to brackish environment. The Sr/Cu ratios range from 5.88 to 653.31, with an average of 90.41, suggesting that the study area experienced an overall arid and hot climate during this period. Similarly, the La_N/Yb_N ratios range from 7.85 to 12.25, with an average of 10.14, which further corroborates the dry and hot paleoclimate during the deposition of the Sha 3 Member. The V/(V+Ni) ratios range from 0.45 to 0.79, with an average of 0.69, indicating that the study area was characterized by an anoxic environment with weak water column stratification. Furthermore, the δCe values range from 0.90 to 1.02, with an average of 0.94, indicating that the deep water body of the Sha 3 Member was predominantly in a reducing environment. Overall, the climate in the study area during the deposition of the Sha 3 Member was predominantly arid, with reducing conditions and a saline to brackish water environment. Discrimination diagrams of La/Th versus Hf and La/Yb versus ΣREE indicate that the source rocks were composed primarily of intermediate to acidic felsic rocks, as well as mixed felsic/mafic rocks.

The Cretaceous Chijinbao Formation has developed a suite of black shales with high organic content， indicating significant potential for oil and gas exploration in the Beishan area of Gansu and Mongolia. Further research into the sedimentary paleoenvironment of these black shales is necessary to enhance our understanding. Based on the MGD1 Cretaceous core data in Zhagegaonao basin， samples were collected at equal intervals. The geochemical characteristics of black shale have been studied by X-ray fluorescence spectrometry， X-ray diffraction, and inductively coupled plasma mass spectrometry. The paleoclimate， paleosalinity， paleowater depth, and oxidation-reduction conditions of black shale formation were reconstructed with geochemical data and verified by palynological data. The black shales are mainly argillaceous shale. The provenance is predominantly feldspar rock，and they are near-source sediments，which have not undergone sedimentary recycling and have not been affected by later hydrothermal action. The paleoenvironment can be analyzed with its geochemical data. The comprehensive analysis of environmentally sensitive elements， such as Sr，Ba，Cu，B，V，Ni，Co，shows that the lower section of black shale in well MGD1 was deposited in the dry-hot，saline-water and reductive environment，and the paleowater depth rose with oscillation. The middle section of black shale was deposited in warm，humid，brackish water and reductive environment，and the paleowater depth kept high oscillation. The upper section of black shale was deposited in a dry-hot，saline-water and reductive environment，and the paleowater depth decreased slightly. The accumulation of organic matter in the black shale in well MGD1 is the result of the combined action of paleoclimate，paleosalinity，paleowater depth, and oxidation-reduction conditions. 

The Wulong gold mine is located in the Liao-Ji Paleoproterozoic gold polymetallic mineralization belt, and is one of the typical large-scale deposits within the Dandong Wulong-Sidaogou gold mineralization catchment area. In this study, based on the geological characteristics of the deposit and its ore-controlling factors, we constructed a deep three-dimensional geological structure model by integrating geological interpretation of large-scale gravity and magnetic data with inversion of the geodetic-audio-electromagnetic (GEM) data. Combined with geochemical anomalies of mineralization elements and the spatial distribution patterns of ore bodies, we extracted prospecting criteria and delineated target zones for deep ore bodies in the mining area. The study shows that mineralization in the Wulong gold mine is mainly of quartz vein type, with minor vein-fine vein tectonic alteration rock type. The NNE- to NS-trending fractures, NW-trending fractures, and Early Cretaceous magmatic intrusions are the key ore-controlling factors. The ore bodies exhibit a clustered and belt-like distribution with equal spacing, and the upper parts branch while merging in the lower part. The highly magnetic geological body, caused by the intrusion of Early Cretaceous granodiorite into the Middle and Late Jurassic biotite granite, represents the ore-forming geological body. Silicification and sericitization are the main wall-rock alteration indicators for prospecting. The anomalous range of mineralization factors F₁ (Ag-Pb-Zn-As-Sb-Hg-Au) and F₂ (Au-Bi-W), which represent the main stages of gold metallogenesis, serve as geochemical prospecting indicators. Geophysical indicators include high-magnetic geological bodies, gravity highs, and fracture structures within and along their margins, as well as low-resistivity and high-polarization electrical anomalies. The study determines that deep ore-forming structures and ore-forming geologic bodies are still active in the mining area. In combination with the characteristics of known ore bodies, we propose seven target zones for further exploration.

The Erdaokan silver deposit in Heilongjiang Province, located in the northern segment of the Great Khingan Range, is an independent hydrothermal vein-type silver deposit. Orebodies are mainly hosted in two members of the Devonian Niqiuhe Formation: The sedimentary member and the pyroclastic member. The wall rocks have undergone sericite-quartz alteration and silicification alteration via hydrothermal processes, forming two corresponding types of altered rocks. Taking the sericite-quartz altered rock and pyritized silicified altered rock representing the two members as research objects, this paper conducts systematic analyses of detrital zircon morphology, U-Pb geochronology, trace elements and Hf isotopes to investigate their provenance properties. The results indicate that zircons in the sericite-quartz altered rock from the lower sedimentary member are dominated by euhedral magmatic zircons. Their U-Pb age peaks are concentrated in the Early Devonian (397-395 Ma), with a small amount of Mesoproterozoic zircons (1 276 Ma). Zircons in the pyritized silicified altered rock from the upper pyroclastic member yield concordant U-Pb ages in the Late Devonian (369-358 Ma), with a few Paleoproterozoic and Mesoproterozoic zircons (1 924-1 593 Ma). With the exception of individual detrital zircons in the sericite-quartz altered rock, most detrital zircons exhibit trace element patterns characterized by HREE enrichment and LREE depletion, accompanied by pronounced positive Ce anomalies and distinct negative Eu anomalies, indicative of typical magmatic zircons. The Early Devonian zircons from the sericite-quartz altered rock have ε_Hf(t) values of 10.5-14.5, with two-stage Hf model ages ranging from 713 Ma to 469 Ma. The Late Devonian zircons from the pyritized silicified altered rock have ε_Hf(t) values of -23.3-7.4, with two-stage Hf model ages ranging from 2 811 Ma to 889 Ma. These characteristics suggest that the provenance of the lower sedimentary member is primarily intermediate-mafic volcanic rocks formed by the eruption of weakly enriched mantle-derived magmas in the Early Devonian, mixed with minor Mesoproterozoic strata. The provenance of the upper pyroclastic member is mainly derived from the reworking of ancient continental crust, as well as deep-seated intermediate-felsic intrusive rocks formed by the mixing of ancient crust and mantle-derived materials, with the addition of minor Paleoproterozoic to Mesoproterozoic strata. Integrating previous studies and trace element characteristics of detrital zircons, this study concludes that the Early Devonian sedimentary area was in a post-collisional extensional tectonic setting, while the Late Devonian sedimentary area was in a subduction continental arc tectonic setting.

The northern Jiangsu region, located on the southeastern margin of the North China craton, is a potential target for primary diamond exploration. Although numerous I_b-type diamonds have been discovered in the dolerite of the Langan area, Anhui, no significant breakthrough has been made in diamond exploration in northern Jiangsu. The petrogenesis of these dolerites and their primary diamond mineralization remain poorly understood, which hampers further exploration. This study systematically analyzed the geochemical characteristics of two diamond-bearing and four potentially diamond-bearing dolerite samples from northern Jiangsu, and compared them with the diamond-bearing dolerite from Laozhaishan in the Langgan area. The results show that there are no significant geochemical differences between diamond-bearing and non-diamond-bearing dolerites. Both are tholeiitic sub-alkaline basalts formed in an intraplate setting, enriched in large-ion lithophile elements (e.g., Rb, Ba, La, Eu) and high-field-strength elements (e.g., Nb, U, Nd, Ti). Some diamond-bearing dolerites may have experienced minor crustal contamination, but its effect is limited. The source characteristics indicate a transitional mantle origin, with rare-earth and trace-element patterns intermediate between OIB and E-MORB, suggesting a plume-related origin. The estimated source depth is typically 60-140 km, consistent with the stability depth of I_b-type diamonds, suggesting that the dolerite in northern Jiangsu could serve as a suitable host rock for diamonds. However, the search for primary diamond deposits in dolerite remains challenging. Based on previous research, I_b-type primary diamonds have a relatively short residence time in the mantle. Once they are transported out of the diamond stability field during their early formation, their growth ceases, resulting in limited economic value. Future exploration should therefore more on locating kimberlites or lamproites.

The India-Eurasia collision is one of the most significant Cenozoic geological events on Earth. However, the understanding of the collisional process and its remote magmatic response remains highly controversial. This study presents zircon U-Pb geochronology, whole-rock geochemistry, and Sr-Nd isotopic data for Eocene intrusive rocks from the Yaduo and Yawa areas in the Central-Southern Qinghai-Xizang Plateau, and discusses their petrogenesis. We integrate these data with a regional comparison of contemporaneous Eocene magmatic rocks, to constrain the India-Eurasia collision process and its remote response from a magmatic perspective. The diorite porphyry from the Yaduo area of the Southern Qiangtang terrane was formed at ~37 Ma and exhibit adakitic characteristics, interpreted as derived from fractional crystallization of lithospheric mantle-derived basaltic melts. The granitoidsfrom the Yawa area in the Lhasa terrane were formed at 55-54 Ma, and belonging to weakly peraluminous I-type granites, originating from partial melting of crustal materials. Based on these data, integrated with a comprehensive comparison of Eocene intermediate-felsic magmatic rocks in the southern Qinghai-Xizang Plateau, we propose that the initial India-Eurasia collision occurred at ~58 Ma; At ~52 Ma, crustal thickening resulting from the collision reached its peak, followed by slab breakoff, which triggered extensive magmatism; After ~45 Ma, the continued northward subduction of the Indian continental lithosphere drove intracontinental subduction of the lithosphere of the Lhasa terrane beneath the South Qiangtang terrane.

Dinosaur eggshell is an important evidence to understand the palaeontological environment of dinosaurs, as well as their evolution and extinction. The pore in the eggshell is more suitable for the reproductive habits of different types of dinosaurs. In this study, a honeycomb egg dinosaur eggshell found in Heyuan, Guangdong Province, was taken as the research object. The CT image pore of the dinosaur eggshell obtained by Micro-CT scanning was built into three-dimensional modeling, and the size, shape, arrangement, spatial characteristics, and development degree of the pore were analyzed ualitatively and quantitatively. Firstly, the processed CT data were converted into point cloud data by Python, and then reconstructed in three dimensions using the ball pivoting. Secondly, the processed CT data is modeled in three dimensions by Avizo. Finally, the point cloud data of one typical air hole is studied, and random slices are selected for quantitative research. The results showed that:1) Some of the pore was not connected, the pore was blocked, and the blocked pore gradually reduced from the inner and outer surfaces to the middle pore, staggered and distributed in space, with asymmetry; Some of the pore was connected, running through the inner and outer surfaces, and well developed, so that oxygen flowed into the embryo for respiration and development. 2) The pore was widely developed, the pore in the diameter section was conical and columnar, and the pore in the string section was single round, oval, polygonal, etc., the surrounding matrix was like hexagon, arranged closely, and multiple hexagons formed a honeycomb structure, with obvious poretal intervals. 3) The pore size and channel height of eggshell pores exhibit a trend of being larger near the outer surface than near the inner surface, while the pores that penetrate both surfaces have larger pore sizes and heights than the previous two.4) The well-developed honeycomb pore revealed that the hatching site of the egg of this dinosaur might be a buried environment; The cone pore showed that the pore size gradually decreased from the near outer surface to the middle, which was speculated to prevent chemical erosion and water dispersion.

To comprehensively investigate the influence of fracture characteristics on rock mass strength and deformation failure, this study employs the discrete element method software PFC^3D to conduct deformation and failure tests on fractured sandstone under varying confining pressures and fracture inclinations. By integrating the macroscopic mechanical properties throughout the entire deformation and failure process and analyzing the progressive failure characteristics based on the evolution of the number of microcracks, a damage variable D is defined according to the number of microcracks, and a damage constitutive relationship is established that can reflect the asymptotic failure of fractured rock masses. The results indicate that: The fractured sandstone has obvious confining pressure effect, the larger the confining pressure, the larger the compressive strength; Under the same confining pressure, the compressive strength of fractured sandstone shows the trend of decreasing and then increasing with the increase of fracture inclination angle. The deformation and damage process of fractured sandstone corresponds to the evolution curve of the number of microscopic cracks with a stage, based on the curve of the number of cracks, a smooth section, a linear growth section, an upward concave growth section and the last tends to be flat section of the stage division, to determine the corresponding characteristics of the stress point. During the progressive damage process, the microcracks of 0° and 90° fractured rock samples were almost spread throughout the whole sample, and themicrocracks of 30°, 45° and 60° fractured rock samples tended to be generated along the pre-fractured and the upper and lower loading surfaces. At each characteristic stress point, the total number of cracks increases with the increase of confining pressure, and the larger the confining pressure, the larger the proportion of shear cracks, and the total number of cracks decreases and then increases with the increase of the inclination angle of the pre-fracture. The constitutive relationship established based on the number of microcracks is reasonable and can well reflect the basic mechanical characteristics of fractured sandstone.

Rainfall infiltration and groundwater level fluctuations are important factors to induce loess slope instability. In this paper, triaxial drained shear tests were conducted under two constant stress modes with increasing pore pressure (CQD) or decreasing confining pressure (RPD), the strength attenuation and shear deformation of saturated remolded loess under two pore pressure models were studied. The incremental strain rate method was proposed to identify the instability point of loess samples. The test results show that: In the CQD test, when the pore pressure growth rate of the sample increases, it is more prone to instability; In the RPD test, when the confining pressure of the sample decreases faster, the instability occurs earlier, and the initial consolidation pressure and initial void ratio have influence on the occurrence of instability in the sample under the two loading modes. For saturated loess samples with similar initial state (void ratio and confining pressure), the mean effective stress is higher at the instability point in the RPD sample and the occurrence of instability is also earlier. During the process of instability to the end of test, the reduction of effective principal stress in the RPD sample was found about twice that of the CQD sample. It can be inferred that in the CQD test, the reduction of effective stress of the loess sample is in a local range due to the accumulation of local excess pore pressure, while in the RPD test, the overall effective stress of the saturated loess sample decreases due to the influence of static pore pressure, and it is more prone to instability than in the CQD case.

To investigate how the degradation of physical and mechanical parameters of moraine soils under freeze-thaw cycles affects the stability of glacial lake moraine dams, this study focused on Nuquegou in Shannan City on Qinghai-Xizang Plateau. Field investigations were first conducted on high-outburst-risk glacial lakes and moraine dams, during which moraine sandy soil and moraine silty soil samples were collected on-site. Subsequently, eight evaluation factors were selected using the analytic hierarchy process (AHP) to assess the hazard risk of 18 glacial lakes in the Nuquegou watershed. Laboratory standard triaxial tests and falling-head permeability tests were then performed on both soil types subjected to varying numbers of freeze-thaw cycles to analyze the evolution patterns of moraine dam stability. Finally, the Massflow numerical simulation software was employed to reconstruct the complete dynamic disaster chain process, spanning moraine dam failure, glacial lake outburst, flooding, and subsequent debris flow. The results indicate the following: 1) In the early stages of freeze-thaw cycles (0-5 cycles), the cohesion of both moraine sandy and silty soils exhibited a pronounced degradation trend, with degradation rates of 12.21% and 7.89%, respectively. Meanwhile, the internal friction angle fluctuated slightly as the number of cycles increased, whereas the permeability coefficient increased continuously, indicating that freeze-thaw cycles exert a sustained effect on soil microstructure and pore distribution. 2) The stability coefficient of the moraine dam experienced its maximum attenuation rate (－0.022 2) during the early stages  of freeze-thaw cycles. This attenuation pattern aligned with the degradation of the strength parameters of the moraine soils, confirming that soil strength characteristics are a critical factor governing moraine dam stability. 3) Under the worst-case scenario of complete failure of the BH06 moraine dam, the simulated glacial lake outburst triggered a flash flood that subsequently transformed into a debris flow. The maximum flow velocity reached 5.1 m/s, resulting in a final debris flow deposition thickness of 4.5 m and an accumulation area of 4 220 m², which partially blocked the main channel of the watershed. In summary, the significant strength degradation of moraine soils during the early stages of freeze-thaw cycles drives a rapid decline in moraine dam stability, potentially triggering glacial lake outbursts and cascading disaster chains.

The Lake Chad basin is one of the regions in Africa with the most prominent water conflicts, and the water crisis has seriously constrained economic development and social stability, and also affected the relations among countries in the basin. This paper carries out literature search and collation from the shrinkage of Lake Chad, the reduction of river runoff, the shrinkage of wetlands, groundwater and water conflicts, etc., comprehensively summarizes the evolution of the water crisis in the Lake Chad basin, and systematically summarizes the causes of the water crisis in the basin. The following conclusions are drawn from the literature analysis: 1) The water crisis in Lake Chad is mainly manifested at the natural level by the drastic shrinkage of the surface of Lake Chad since the 1960s, the drastic decline of the runoff of rivers, the degradation of wetlands, the depletion of groundwater resources in many regions, the frequent occurrence of water disputes and conflicts, the deterioration of the conditions for economic and social development, and the rapid spread of the accompanying terrorist organizations. 2) The multi-decadal drought from the 1960s to the 1980s was a major cause of the shrinkage of river runoff and lakes in the Lake Chad basin, and at the same time prompted a surge in the construction of water conservation projects in the region. The cluster of water conservancy projects, mainly dam projects, not only reduced the river runoff volume, but also changed the seasonal distribution of river runoff, aggravated the degradation of wetlands, and reduced the amount of groundwater recharge in the coastal areas, thus further exacerbating the water resources crisis. 3) The rapid increase in water demand brought about by rapid population growth has further intensified the contradiction between supply and demand of water resources in the Lake Chad basin, while the lack of a unified and effective mechanism for coordinated cooperation in the basin has impeded the improvement of the level of water resources management in the basin, thus limiting the improvement of the overall capacity of the countries in the basin to cope with the water crisis. In conclusion, the water crisis in the Lake Chad basin is still a hot issue in the international community.Analyzing and solving the problem from multiple perspectives will be an important direction for the development of the water crisis in the Lake Chad basin.

Acid mine drainage is one of the major factors causing soil environmental degradation in mining areas, and it is crucial to conduct ecological risk assessment on it. In this evaluation process, indicator weight allocation plays a key role. To address the problems of insufficient consideration of reverse indicators and high subjectivity in manual weighting in existing weighting methods, this study proposes a weighting method based on fuzzy cognitive map (FCM). Eight core risk factors (including reverse indicators) were screened, the hyperbolic tangent function was used to construct the fuzzy cognitive map, weights were calculated through iterative convergence, and sensitivity analysis and Pearson correlation test were integrated for validation, and finally the method is applied to a field evaluation in a mining area of Anhui Province. The results show that the potential ecological risk index of pollutants has the highest weight (0.856), the weights of fracture rate, roadway scale, etc. are all higher than 0.770, and the ecological restoration measure has a negative weight (-0.749). Sensitivity analysis shows that the model has high stability. The Pearson correlation coefficients are all above 0.85. In the field evaluation, after introducing the FCM-based weights, the low-risk area decreased by 5.3%, and the medium-high-risk area increased by 6.5%. A previously overlooked high-risk area at the mixed shaft in the mining area was successfully identified, and the evaluation results are more consistent with the actual situation.

Carrying out comprehensive quality evaluation is a vital component in the development and utilization of urban underground space resources. Recently, the economy of Rizhao City has developed quickly, but underground space is not being used to its full potential. Due to the rapid economic growth of Rizhao City in recent years and the low rate of underground space utilization, it is urgent to conduct a thorough quality evaluation of underground space resources to establish a foundation for their rational development and utilization. This study evaluates the geological suitability and potential value of the underground space development in the main urban area of Rizhao City, the study area, establishing the geological suitability evaluation system and the potential value evaluation system, and combining the analytic hierarchy process and the most unfavorable discrimination model. Furthermore, a weighted method model and a constraint discriminant model were used to evaluate the quality of underground space resources. The evaluation effect of the two models was compared and analyzed. The results indicate that the subsurface space resources in the research area, which make up roughly 80% of the total area, are mostly of high or medium comprehensive quality. About 20% of the total area is made up of low-comprehensive quality areas, which are primarily found in the northern part of the study area and other sporadic distribution areas. The northern concentrated distribution area is primarily the area with low potential value for underground space development. Geological catastrophes include the destruction of historical sites, water supplies, and high-rise buildings, and seawater incursion primarily affects dispersed distribution areas. Furthermore, as compared to the weighted model, the evaluation results of the constrained discriminant model are more consistent with the actual circumstances of the study area, making it more appropriate for the comprehensive quality assessment of underground space resources in the study area.

Zhangbei County, as a typical agricultural and pastoral area, is an important ecological defense line in Northern China. In order to investigate the status and influencing factors of eco-environmental vulnerability in the area and provide a reference for ecological environment protection, this paper adopts the sensitivity-resilience-pressure (SRP) model, considers six influencing factors (terrain, meteorology, groundwater, vegetation, biodiversity and human activities) from three aspects of ecological sensitivity, ecological resilience and ecological pressure, and selects 16 evaluation indicators. Methods such as analytic hierarchy process-entropy weight method, spatial autocorrelation analysis and geographic detector were used to analyze the spatial pattern and spatial autocorrelation of eco-environmental vulnerability in Zhangbei County, and the main driving forces were discussed. The results are as follows: 1) The ecological environmental vulnerability of Zhangbei County was mainly characterized by potential, slight and mild vulnerability, accounting for 77.79% of the total area, while the moderately and severely vulnerable areas accounted for 16.76% and 5.45%, respectively. 2) In terms of spatial distribution, from west to east, there was a gradual transition from severely and moderately vulnerable areas to mildly and slightly vulnerable areas, and the vulnerability of built-up areas was significantly higher than that of rural areas, with obvious spatial differences. 3) The distribution of eco-environmental fragile areas in Zhangbei County exhibited significant spatial agglomeration. The “high-high” agglomeration areas are mainly distributed in the severely and moderately vulnerable areas; The “low-low” agglomeration areas are mainly distributed in the potentially and slightly vulnerable areas. 4) The eco-environmental vulnerability of Zhangbei County is driven by the interaction of multiple indicators, among which vegetation factors, groundwater factors and climate factors are the main factors affecting its distribution pattern.

On 16 June 2022, high-frequency disturbances were observed in the three-orientation borehole apparent resistivity data in Tianshui. Their change pattern and amplitude were similar to those observed before the 20 April 2013 Lushan M_S 7.0, 22 July 2013 Minxian-Zhangxian M_S 6.6, and 8 August 2017 Jiuzhaigou M_S 7.0 earthquakes. Data collection and organization, anomaly investigation and analysis, and interference verification and treatment were conducted through a series of procedures, primarily including natural environment and site environment investigations, observational system verification, power frequency interference testing, identification of interference sources, line maintenance, and operational monitoring. It is found that Tianshui borehole apparent resistivity anomaly is not a pre-earthquake geophysical anomaly, but a high-frequency disturbance caused by the coupling of transformer grounding leakage current and the supply current during the instrumental measurement. This anomaly verification case provides a reference for power supply circuit planning, observation system maintenance and wire leakage anomaly investigation of borehole apparent resistivity stations.

As a potential seismic noise source, train-induced seismic sources feature strong energy and can be utilized for near-surface passive surface wave imaging. However, train signals are highly directional, repetitive and non-stationary, which violates the assumption of a uniform source distribution in seismic interferometry. This leads to crosstalk during seismic interferometric processing and reduces the signal-to-noise ratio (SNR) of virtual shot gathers. Cross-coherence interferometry is applicable to sources with inherent coherence and delivers superior performance when processing coherent noise-source signals such as traffic-induced seismic noise. In this study, the processing workflow for train-induced seismic data is improved by introducing cross-coherence interferometry into seismic interferometry imaging using train noise. A comparative analysis is conducted between cross-correlation interferometry and cross-coherence interferometry in terms of imaging performance. The feasibility and effectiveness of the proposed method are verified using both synthetic and field data. High-quality virtual shot gathers are  obtained to extract dispersion curves, which are subsequently adopted for inversion. Finally, subsurface velocity profiles are constructed, achieving near-surface surface wave dispersion imaging with train-induced seismic sources. The results demonstrate that cross-coherence interferometry can effectively suppress crosstalk and markedly improve the SNR of virtual shot gathers when processing train-induced seismic signals.

Seismic exploration methods are widely used to investigate shallow crustal structures, and double-difference tomography is a commonly employed high-precision imaging technique. However, due to issues such as insufficient arrival-time picks and limited ray-density coverage in field data, the inversion results of double-difference tomography often exhibit uncertainties. To address this problem, this paper proposes a method based on the whale optimization algorithm (WOA)-optimized convolutional neural network (CNN) (WOA-CNN) for predicting seismic arrival times, thereby improving the reliability of double-difference tomography results. The feasibility of this method is evaluated through its application to velocity-structure imaging in the Jinchuan mining area. The Jinchuan large nickel-copper-platinum group element sulfide deposit is located in Gansu Province, China, and has been mined for over 50 years. As shallow ore bodies become depleted, the demand for deep mineral exploration has become increasingly urgent. To investigate the deep structure of the mining area, 69 short-period three-component seismometers were deployed in the Jinchuan mining area, continuously collecting seismic data for 27 days. Using the LOC-FLOW location method, 309 mining-induced seismic events were accurately located, including 4 316 P-wave arrival-time picks as input for the double-difference tomography. However, due to the limited number of P-wave arrivals, the imaging results were unsatisfactory. Subsequently, the WOA-CNN was used to predict the arrival times of the 309 events, obtaining a total of 11 124 P-wave arrival-time picks. By incorporating the predicted arrival times, the three-dimensional P-wave velocity structure of the study area was successfully constructed. Analysis combined with previous research results verifies the existence of two independent rock bodies in the deep part of the mining area, and this finding is highly consistent with existing geological data. Additionally, the typical “funnel-shaped” structure of the shallow ore body along the Ⅱ-36 survey line was verified. Based on the velocity variation patterns, it is inferred that there is still significant exploration potential below 2 km in the eastern section of the Jinchuan mining area.

Tight sandstone reservoirs are characterized by poor petrophysical properties, strong heterogeneity and complex sandbody connectivity. Volumetric fracturing in horizontal wells is the primary technique for the efficient development of such reservoirs. A comprehensive evaluation of reservoir quality, spatial distribution of hydraulic fractures, fracture-network connectivity and stimulated reservoir volume is critical for determining single-well productivity. In this study, downhole microseismic monitoring was used to monitor fracture development during the entire fracturing process of six wells in three blocks in the mid-eastern Ordos basin. Continuous production performance tracking was carried out to comprehensively evaluate the stimulation effectiveness of gas wells. The results show that the scale of hydraulic fracturing controls the stimulated reservoir volume, and the increasing fracturing scale is positively correlated with fracture propagation. When the fracturing scale reaches a certain level, an obvious marginal effect occurs in the fracture network. Under the same fracturing stimulation scale, the larger the scale of high-quality sandbodies, the better the hydraulic fracturing effectiveness. Fracturing cluster spacing should be designed according to the mechanical properties of reservoir rocks. A higher the reservoir brittleness index requires a larger designed cluster spacing. When cluster spacing is uniformly distributed, a complex fracture network with interacting fractures can be formed after fracturing. A better match between high-quality reservoir conditions and fracturing stimulation scale leads to higher the single-well productivity.

Karst is a typical geological hazard in urban environments, and its development can affect the stability and safety of the infrastructures. Compared with the surrounding bedrock, the S-wave velocity of karst is relatively lower, and appear as low-velocity anomalies. Surface waves within ambient noise are highly sensitive to the S-wave velocity of underground media, with the higher-mode surface waves demonstrating even greater sensitivity to such low-velocity anomalies. However, the conventional staged inversion schemes for multimode dispersion curves rely on global optimization algorithms, resulting in substantial computational costs. To address this limitation, we propose an improved inversion workflow. In the first stage, the preconditioned steepest descent method, a local optimization algorithm, is employed to invert the identified fundamental-mode dispersion curve. In the second stage, the pattern search algorithm is utilized to invert all available dispersion data. During the iteration, the Kuhn-Munkres algorithm is implemented to dynamically assign the mode-orders to unlabeled dispersion points. The efficacy of the proposed method in characterizing shallow low-velocity interlayers is validated via synthetic tests based on a four-layer geological model containing a soft interlayer. Furthermore, the method is applied to the field passive-source data acquired in the karst development area of Longgang District, Shenzhen, to evaluate its practical utility. The results demonstrate that the higher-mode dispersion data serve as observational constraints independent of the fundamental-mode data, effectively enhancing the accuracy and vertical resolution of the inversion, and improving the delineation of soft interlayers. Additionally, the proposed approach successfully identified the underlying karst development area along the survey line. Notably, energy loss and modal aliasing of higher-mode surface waves dispersion are common phenomena in shallow surface wave data. Therefore, the dynamic mode-order identification is essential for robust multimode surface wave inversion.

Identifying architectural elements from well-log curves is an essential task in fine-scale reservoir characterization. In recent years, machine learning methods have been widely applied to architectural element identification; however, the identification accuracy is generally low for lower-order architectural element with low-proportion. In this study, we propose a hierarchical architectural element identification method based on a bidirectional stacked long short-term memory network and random forest (RF), and apply it to the third- and fourth-order architectural element in braided-river reservoirs of the Chengtan 3 block, Ordos basin. First, the temporal network model is employed to extract rhythmic features from well-log curves and identify fourth-order architectural element such as floodplain, channel, and braid bar. On this basis, an RF method with gamma-threshold constraints is used to further identify braid bar intercalated mud layers. In the application of identifying third- and fourth-order architectural elements in the 8th member of the Lower  Shixihezi Formation,  the comparison with existing machine learning approaches shows that the optimized hierarchical identification method achieves an accuracy of at least 94% on the validation set for reservoir architectural element characterization, outperforming direct machine learning approaches and providing higher identification precision.

Raft aquaculture is a key method for farming aquatic products, and utilizing remote sensing technology for its accurate monitoring is an essential approach for controlling aquaculture density and supporting scientific planning. However, because the spatial distribution of raft aquaculture is heavily influenced by waves and specular reflection, significant information loss occurs in many raft aquaculture areas on remote sensing images. To improve extraction precision and accuracy, this paper proposes an extraction method based on the improved Criminisi and SAM (segment anything model) algorithms specifically for raft aquaculture elements with information loss. First, the dark channel prior is used to locate and classify the areas affected by information loss. The Criminisi algorithm is then improved by optimizing priority calculation, sample block generation, and matching criteria to effectively restore the information loss zones. Finally, the SAM algorithm is applied to achieve zero-shot extraction of raft aquaculture elements. In addition, experiments using a Gaofen-6 image dataset were conducted to compare the proposed method with two advanced deep learning-based algorithms, RSMamba (remote sensing mamba) and Swin Transformer. The experimental results demonstrate that the proposed algorithm achieves both the accuracy rate and completeness rate of at least 90%, with an error rate not exceed 0.02%, indicating superior performance.