This study aims to mitigate the ongoing decline of karez by analyzing the characteristics of changes in their annual runoff volume over the past 30 years, which is of great significance for agricultural irrigation, cultural heritage preservation, tourism development and so on.

Based on 13 years of discontinuous annual karez runoff data in the study area for the period 1990−2022, combined with year-by-year data on the exploitation of electro-mechanical wells and water supply from surface water sources, statistical analyses were performed using SPSS 20 to interpolate missing data, and trend and mutation analyses were used to determine their change curves and mutation years.

The results show that between 1949 and 2023 the number of karez decreased from 1084 to 169, at an average rate of about 16 karez dried up or disappeared per year, while the total flow rate declined from 16.11 m³/s to 3.6 m³/s. The correlation coefficients between the annual runoff volume of karez and the exploitation of electro-mechanical wells, water supply from surface water sources, the irrigated area and precipitation were −0.890, −0.149, −0.660, 0.764, respectively. A regression model established between karez annual runoff volume and the two factors (electro-mechanical wells exploitation and surface water supply) yielded an average relative error of only 1.8% between measured and predicted values, effectively addressing the problem of missing data. In addition, both the exploitation of electro-mechanical wells and the water supplied by surface water sources showed an overall fluctuating upward trend, whereas the annual runoff volume of karez underwent an abrupt increase in 2006, which may be related to the implementation of government regulations for the protection of karez.

Therefore, in view of the important cultural and engineering value of karez, greater efforts should be made in the future to protect them and thereby promote the sustainable use of water resources and high-quality development in the Turpan Basin.

Automatic picking of effective events is an important part of microseismic monitoring, and the accuracy of picking directly affects the precision and reliability of subsequent seismic source localization and seismic source mechanism inversion.

In this study, a 10-layer U-Net neural network model framework was constructed. Labeled images were created using original microseismic data from 3D finite-difference simulations and raw microseismic data from measured gas storage reservoirs. These images were then sliced into 128×128-pixel patches and input into the U-Net neural network for training.The predicted slices were subsequently merged into complete images, binarized, and finally used to extract the P-wave first arrivals of effective microseismic events. This approach achieves more accurate edge segmentation between background noise and effective signal, thereby improving the efficiency and accuracy of automatic picking of effective microseismic events.

The study quantitatively analyzed and compared the picking rate, mispicking rate, picking error of U-Net method and STA/LTA method.The test results showed that the picking performance of U-Net was better than that of STA/LTA method, and U-Net also demonstrated strongeranti-jamming ability and generalization ability.The impact of different label widths on the picking results of first arrivals was evaluated, and the results showed that labels generated based on the dominant period of the events yielded the optimal picking performance.

The U-Net-based first-arrival automatic picking algorithm established in this study constitutes an important part of an efficient and high-precision intelligent microseismic monitoring system for gas storage integrity, providing significant support for advancing microseismic monitoring technology in China.

To determine the rock type, age and tectonic setting of Mesozoic granites in Daliuhang, Jiaodong area, and to explore the relationship between the granite and gold mineralization,

the Mesozoic Yanshanian Linglong-type granites (Qijiagou monzonitic granite) and Guojialing-type granites (Gusidian monzonitic granite), which were located in the north of Qixia-Penglai gold metallogenic belt in eastern Jiaodong area, are selected to analyze whole-rock geochemistry, U-Pb dating and Lu-Hf isotope of zircon.

The results show that the U-Pb age of the zircon from Qijiagou monzonite is (172.8±1.5) Ma, with the εHf(t) values of the zircon ranging from −27.7 to −20.3. The zircon U-Pb age of Gusidian monzonitic granite is (127.3±0.8) Ma, with the εHf(t) values of zircon ranging from −15.7 to −13.4. The ⁸⁷Sr/⁸⁶Sr ratio of Gusidian monzonitic granite is 0.710704−0.711223, with the εNd (t) values ranging from −16.8 to −11.3.

The Qijiagou monzonitic granite is derived from the ancient lower crust, which is mainly from the North China Craton lower crust. The magma source of Qijiagou monzonitic granite may be mixed with the Yangtze Craton crust. The Gusidian monzonitic granite forms by partial melting of mafic rocks of lower crust, with mantle components added in the process. The diagenetic tectonic background was extensional, which may be caused by the subduction and retreatment of the Pacific plate. The Gusidian monzonitic granites have high coordination with the characteristics of Early Cretaceous gold mineralization in Jiaodong area, suggesting a genetic link between this granite and local gold mineralization in this area.

To investigate the failure mechanism of rocks at the mesoscopic scale,

This study proposes a novel modeling method that combines digital image processing (DIP) technology and particle flow code (PFC) to characterize mineral properties. The discrete element numerical model was calibrated using macroscopic mechanical parameters and failure modes obtained from conventional triaxial compression tests. Under geostress conditions, the influence of rock mineral properties on rock failure evolution and the effect of heterogeneous structures on microcracking behavior were analyzed.

The results show that the loading process of conventional triaxial compression tests can be divided into four stages: Crack closing stage, elastic deformation stage, crack growth stage, and crack explosion stage. Simulations based on computed tomography (CT) slices of three shale samples indicate that rock heterogeneity has a certain impact on the generation of rock microcracks and rock physical-mechanical parameters—weaker heterogeneity corresponds to higher peak strength (σ_max) and elastic modulus (E). In terms of crack propagation distribution, increased heterogeneity leads to a more complex microcrack distribution. From the perspective of the spatial distribution of rock microcracks, microcracks tend to occur preferentially at the interfaces between dolomite and quartz minerals.

The research findings provide important reference significance for deep underground oil and gas exploitation and disaster prevention engineering.

However, the two-dimensional profile cannot describe the 3D spatial morphology of the most dangerous sliding surface sliding mass.

To address the limitation, based on the stability analysis of the two-dimensional profile slope, the three-dimensional most dangerous sliding surface of the slope is fitted using the spline function by associating multiple profiles with the three-dimensional slope model. Firstly, the relationship between the two-dimensional profile and the three-dimensional slope space is established by setting the profile name, horizontal coordinate positioning and elevation positioning of the graphic elements in the profile line and the two-dimensional profile. Secondly, the most dangerous sliding surface lines of each profile are automatically generated by using the multi-profile resultant force method, and the most dangerous sliding surface lines of each two-dimensional profile are converted to three-dimensional slope space by using the coordinate transformation formula. Finally, the spline function interpolation is used to fit the most dangerous sliding surface lines in the three-dimensional space to construct the three-dimensional most dangerous sliding surface. Taking the southwest slope of an open-pit mine in Xilinhot, Inner Mongolia as an example, a three-dimensional engineering geological model of the slope is established, and five two-dimensional profiles for slope stability analysis are generated. Through this method, the three-dimensional most dangerous sliding surface and three-dimensional sliding mass are successfully generated and their rationality is verified.

The research results provide new insights for predicting the location, scale, and damage degree of potential slope sliding masses.

Cobalt is an important strategic metal, crucial for new energy technologies. Understanding its occurrence in ore deposits represents a key focus of international ore deposit research. The Qibaoshan Co-Pb-Zn deposit, located in the central segment of the Jiangnan orogenic belt, features ore bodies controlled by secondary folds within the core of the Gaodongshan anticline, which exhibit NE-trending lenticular or stratoid shapes. However, the occurrence state of cobalt in this deposit remains poorly constrained.

In this study, ore samples collected from different levels of the open pit were analyzed using backscattered electronc (BSE) imaging, energy dispersive X-ray spectroscopy (EDS), and electron probe micro analysis (EPMA).

The results show that cobalt occurs predominantly as independent minerals, including safflorite, cobaltite, skutterudite, and siegenite. Minor cobalt is hosted in solid solution within fine-grained pyrite and rammelsbergite. Rammelsbergite commonly exhibits mantles replaced by safflorite, and both minerals are in turn replaced at their rims by cobaltite and gersdorffite. Cobaltite and Cu-bearing siegenite also frequently replace the margins of chalcopyrite. These mineralogical relationships indicate that the early-stage ore-forming fluids were characterized by high arsenic activity, leading to the precipitation of rammelsbergite, safflorite, and skutterudite. As mineralization proceeded, arsenic activity decreased while sulfur activity increased, resulting in the formation of cobaltite and siegenite during the late stage.

The replacement textures and mineral assemblages of Co-Ni minerals in the Qibaoshan deposit resemble those typical of "five-element vein"-type deposits. Therefore, the Qibaoshan deposit is classified as a hydrothermal vein-type Co-Pb-Zn deposit with characteristics of "five-element vein".

Affected by climate change and human activities, groundwater resources in the Hengshui area have been over exploited year-round, which directly leads to severe ground subsidence, becoming one of the main geological disasters in this region.

Based on the accumulated settlement data of the main urban area of Hengshui City from January 2009 to December 2022, obtained from layered mark monitoring, this study investigates the ground subsidence mechanism of three compression layers (F1, F2, F3 layers from shallow to deep). First, the Gompertz model was used to fit the cumulative settlement of each compression layer. The first-order derivative of the fitting results was then calculated to determine the settlement rate of each layer. With 0.5 mm/month as the threshold, settlement initiation, rapid settlement rate growth, gradual settlement rate decline, and settlement stabilization of each layer are identified. The zero growth (ZG) model is then employed to divide the settlement of each layer into irreversible settlement sequence (GRC) and reversible rebound sequence (SWD), and the fluctuation characteristics of settlement and rebound periods are analyzed. Finally, the linear mixed model (LMM) is applied to analyze the contribution of environmental factors such as precipitation, evapotranspiration, shallow groundwater level, and deep groundwater level to the compression settlement (GRC_rate) during each layer's settlement period.

The results show that: ①The cumulative settlement fitting curves of each layers exhibit an "S" shape, and the settlement rate curves show a single-peak pattern, with a "slow-fast-slow" trend. The main settlement period start time, end time, cumulative settlement, and settlement rate of each layer differ; ② In terms of cumulative settlement and monthly settlement increment amplitude, F3 layer > F2 layer > F1 layer. In terms of rebound amplitude, F1 layer > F2 and F3 layers; ③ Evapotranspiration and shallow groundwater level contribute the most to the compression settlement of F1 and F2 layers, while shallow groundwater level and deep groundwater level are the primary contributors to the compression settlement of F3 layer.

The research results provide a reference for the prevention and control of land subsidence.

Gas hydrates are ice-like solid substances formed by natural gas such as methane under high-pressure and low-temperature conditions, and are widely found in continental margin sediments and permafrost zones, serving as important methane reservoirs in marine environment. On the one hand, methane released from the decomposition of seafloor gas hydrates enters the atmosphere and exacerbates the greenhouse effect. On the other hand, methane released into sediments and seawater can be converted into organic and inorganic carbon through microbial activities. Therefore, the burial of methane-derived carbon in sediments can effectively reduce the methane flux into the atmosphere and meditate the greenhouse effect.

The South China Sea is an ideal area for harboring gas hydrates due to its tectonic and sedimentary environment. In this area, numerous historical methane seepage events have been reconstructed. To understand the role of gas hydrates in the marine carbon cycle and climate change, it is crucial to obtain in-depth perspectives of the methane release records in the South China Sea. Especially, the transformation of methane in sediments and seawater, as well as the burial of methane-derived carbon are of great scientific significance.

In this paper, we review the triggering mechanisms of gas hydrate decomposition, the methods of reconstructing methane release events, and the transformation processes of methane in cold seeps, with more focuses on the organic geochemical processes in sediments and water column. We summarize the methane release process, methane-derived carbon transformation and burial, and introduce the cutting-edge methodology and related research work for identifying gas hydrate decomposition events based on carbonate, foraminifera, biomarkers and sediment carbon-sulfur-trace element systematics. At present, there remain knowledge gaps in the mechanisms of formation and burial of methane-derived organic carbon in marine cold seep environments during geological history periods. Additionally, there is a lack of understanding regarding the accurate quantification of methane-derived organic carbon burial and its role in the marine carbon cycle. Based on the previous work, we provide an outlook on the conversion of methane to organic carbon in cold seep environments and a theoretical basis for the future researches concerning the role of methane-derived carbon in the marine carbon cycle.

To address the limitations of low spatial resolution and poor accuracy in distinguishing rainfall processes of traditional critical rainfall thresholds,

this study takes Zigui County, Hubei Province as a case. Based on data from 472 landslides and 58 rainfall stations, an effective rainfall-duration (E-D) critical rainfall threshold was established; logistic regression was employed, with effective rainfall (E) and duration (D) as the independent variables and time probability (P) as the dependent variable, to fit the continuous probability thresholds for rainfall-induced landslides within the study area; finally, the accuracy of the threshold model was analyzed and validated from both temporal and spatial perspectives using historical landslide events and hazard assessment results.

The results indicate: ① Landslides in the region are primarily small to medium-sized shallow-deposited layer landslides, with a significant positive correlation between rainfall and landslides occurrences, with 86.63% of landslides occurring during the rainy season; ②The nonlinear fitting equation for the continuous probability threshold is $ 1/P=1+{{\mathrm{e}}}^{2.0792+0.24156\times D-0.04072\times E} $, with a fitting degree of 0.9497; ③ Using validation set of landslide samples, when the probability of landslide occurrence reaches 60%, the prediction accuracy of the continuous probability threshold model improves by 17.4%, and the hazard levels of four known landslides in the hazard assessment all increase.

The continuous probability threshold demonstrates superior accuracy in landslide disaster warning and spatial resolution for the study area, providing a scientific theoretical reference for local governments to conduct landslide risk warnings.

Quantitative characterization of hydrocarbon generation, expulsion, and retention intensity in high to over-mature shale gas reservoirs remains a critical challenge for deep resource evaluation. The Permian Wujiaping Formation (Wu Second Member) shale gas reservoir in the Hongxing area of the southeastern Sichuan Basin (with proven reserves exceeding 1011 m³) exhibits thin-layer distribution, strong heterogeneity, and multi-stage tectonic modification. These characteristics complicate precise reconstruction of the spatiotemporal evolution of generation-expulsion-retention processes using traditional evaluation methods.

This study established a multi-dimensional evaluation framework that integrates thermal simulation experiments, hydrocarbon potential methods, and generation kinetic modeling with mutual verification. This framework systematically reconstructs the complete evolutionary model of the Wu Second Member shale gas reservoir from generation to preservation, enabling quantitative characterization and spatial prediction of resource potential.

Thermal simulation results show a total hydrocarbon generation rate of 456 mg/g, comprising total gas generation of 349.68 mg/g (76.7%) and total oil generation of 106.59 mg/g (23.3%); oil-phase products were primarily expelled (103.35 mg/g) with limited retention (3.24 mg/g). Hydrocarbon potential evaluation indicates that the Wu Second Member shale entered the hydrocarbon generation threshold at R_o=0.5% and the expulsion threshold at R_o=0.8%, with an original hydrocarbon generation potential index reaching 550 mg/g. Present-day generation, expulsion, and retention intensities in the Hongxing area and surrounding regions reached maximum values of 90×10⁸, 68×10⁸, 28×10⁸ m³/km², respectively, with their centers highly spatially coupled in three key areas: Wanzhou-Hongxing-Enshi. Generation-kinetics modeling indicates that peak gas-generation intensity in the study area can reach 50 × 10⁸ m³/km², with a maximum gas-retention intensity of 16 × 10⁸ m³/km². Through a comprehensive analysis of crucial preservation factors (burial depth, structural stability, and sealing capacity), we quantitatively determine the present-day residual-gas intensity distribution, identifying the Hongxing-Wanzhou region as the optimal exploration target.

This study not only elucidates the spatiotemporal evolution patterns of hydrocarbon generation, expulsion, and retention in the Permian shale gas reservoir of the Sichuan Basin but also provides a theoretical foundation and practical guidance for the refined exploration of deep to ultra-deep shale gas reservoirs.

In the Zigui Basin of the Three Gorges Reservoir region, landslide-prone strata mainly composed of soft-hard interbedded strata are widely distributed. Under the long-term action of reservoir water immersion, erosion and rainfall, the formation rock and soil undergo deterioration and damage, which has become a key factor in reducing landslide stability and threatening engineering safety.

Taking rock and soil mass of soft-hard interbedded strata as the research object, finite discrete element method (FDEM) was used to calibrate the mechanical properties of hard and soft rocks in the soft-hard interbedded strata under different wetting-drying cycles. Subsequently, the mesh was redivided using an improved Voronoi diagram program, and the embedding function of zero-thickness cohesive elements was realized. An FDEM numerical model of a landslide-anti-slide pile system in soft-hard interbedded strata was proposed and established. Finally, the formation process of landslide cracks and the working mechanism of anti-slide piles under different wetting-drying cycles were studied.

The results showed that: ① The number of simulated landslide cracks increased with the increase in the number of wetting-drying cycles, and the crack width also increased gradually. The simulation results were generally consistent with the field observations of the Majiagou landslide. ② The simulated cracks of the landslide-anti-slide pile system showed two evolutionary patterns: One is that the cracks spread downward from the rock mass on the top side of the pile along the pile body; the other is that the cracks gradually extended from around the anti-slide pile to the inside of the slide body, connecting with transverse cracks and vertical cracks, and finally forming large-scale through cracks. ③ With the increase in the number of wetting-drying cycles, the horizontal displacement, bending moment and shear force of anti-slide pile also increased. ④ The cracks in the soft-hard interbedded strata bedrock of the anti-slide pile showed localized development characteristics; as the number of wetting-drying cycles increased, the stress in the region gradually decreased, the displacement and strain gradually increased, and the corresponding cracks became increasingly dense.

The results of this study can provide support for the prevention and control of landslide in soft-hard interbedded strata under different wetting-drying cycles.

To improve the engineering properties of clay and increase the utilization of waste steel slag (SS).

Geogrid reinforcement was employed, followed by direct shear tests, cyclic shear tests, and post-cyclic direct shear tests conducted on steel slag-clay mix, sand-clay mix, and pure clay. The study investigated the strength characteristics, damping ratio, shear stiffness changes, and displacement of the mixed soil reinforcement-soil interface under various conditions, including different steel slag contents, vertical stress, moisture content, and shear amplitudes.

The test results indicate that steel slag significantly enhances the shear strength of the clay-reinforcement interface, with improvement being more effective than conventional sand-modified clay. The steel slag-clay mixed soil exhibited higher damping ratio and shear stiffness, suggesting better vibration damping and energy dissipation properties. Among the various mixtures, the steel slag-clay mix with 40% steel slag content demonstrated the best shear strength, damping ratio, and shear stiffness. Additionally, the shear strength of the steel slag-clay mixed soil increased after cyclic loading compared to pre-cyclic direct shear conditions. The results also show that moisture content has a more significant impact on shear strength, shear stiffness, and damping ratio than vertical stress and shear amplitude.

The steel slag-clay mixed soil exhibits improved damping and energy dissipation properties under cyclic shear loading. The experimental findings provide a theoretical basis for using steel slag as a substitute for sand to improve clay soils.

Under complex geological conditions, the mechanical properties of the surrounding rock in underground water-sealed storage caverns are weakened due to construction disturbances, accompanied by stress redistribution and deformation accumulation, leading to the higher risk of localized instability. The creep effect further exacerbates the deformation and plastic failure of the surrounding rock, posing a threat to the long-term stability of the cavern. Therefore, the study of surrounding rock stability should fully utilize monitoring data to assess the state of the surrounding rock and guide construction and operation.

Based on the comprehensive analysis of multi-source monitoring data, such as surrounding rock displacement, anchor stress, and borehole wave velocity, numerical experiments using orthogonal design were employed to invert the mechanical parameters of the rock mass. Additionally, pore water pressure, surrounding rock deformation laws, stress variation, and plastic zone distribution characteristics under layered excavation of the cavern during construction were analyzed. Finally, the stability characteristics of the underground water-sealed storage cavern under long-term water-sealing conditions were evaluated using a creep model of the underground cavern group.

The results show that the deformation of the surrounding rock sharply increases when passing through the monitored section during excavation, with a maximum increment of approximately 3 mm, and then tends to converge. The area affected by the J₁ jointed zone exhibits higher displacement. The overall stress of the anchor rod system is relatively low, and the stress of the anchor rod is synchronized with the deformation of the surrounding rock. The depth of the loosening zone of the surrounding rock is approximately 1.0 m. During construction period, the pore pressure in the excavation area approaches 0 MPa, and the seepage flow of cavern and deformation of surrounding rock are densely distributed along the J₁ jointed zone. The excavation of the middle and lower layers causes the displacement at the intersection of J₁ and the arch line to increase by 90.4% and 28.7%, respectively. The plastic zone in the sidewalls deepens layer by layer, with a maximum depth of 9.2 m. The long-term deformation characteristics of the surrounding rock are manifested as sidewall convergence > floor uplift > crown settlement. The cumulative deformation at the intersection of the J₁ and the arch line during the first year accounts for 92% of the total deformation over 30 years, with a maximum deformation of 27.1 mm. Under the creep effect, stress is gradually released, and the stress distribution tends to become more uniform. The plastic zone near the J₁ expands significantly, while the plastic range in the intact granite area is relatively small, indicating higher long-term stability, indicating that the geological structure-affected zone is the main instability risk zone.

This study provides engineering significance and reference value for stability evaluation during both the construction and operational phases of underground water-sealed storage caverns.

Xinjiang is located in the arid to semi-arid region of China. To conserve water resources, brackish water mulched drip irrigation technology is widely used for cotton cultivation. However, improper use of brackish water can lead to soil salinization. Regions with high cotton root density experience strong water absorption, resulting in soil moisture reduction and excessive salt accumulation, leading to decreased cotton yield. To ensure the soil habitat and cotton yield under brackish water mulched drip irrigation, the influence of cotton root distribution on field water and salt transport should be fully considered.

Based on the field experiments conducted at the cotton fields of the Bayingolin Irrigation Experiment Station in Xinjiang, this study obtains cotton root growth parameters to construct a growth model for cotton roots under brackish water mulched drip irrigation, quantitatively characterizing the spatiotemporal distribution patterns of cotton roots.

The study results indicated that: ① The spatial distribution of roots is influenced by soil moisture and salinity. During the budding to flowering stage, roots are more concentrated in the drip irrigation belt and inter-row positions. From the peak flowering to boll-opening stage, roots show significant decline beyond a depth of 50 cm, but develop in the soil depths of 90-130 cm. ② The predicted trend of the three-dimensional growth model of cotton roots is consistent with the actual observations, with MRE (the mean relative error) ranging from 0.2486 to 0.5378, RMSE (the root mean square error) from 2.4127 to 4.8710 cm/cm², and d (the index of agreement) from 0.7541 to 0.9529. The simulation results overall describe the distribution of cotton root length density (RLD). ③ The three-dimensional simulation of cotton root system takes into account the growth conditions in the field planting environment, achieving a dynamic three-dimensional growth effect. The model can effectively simulate the morphological structure of root system growth and development processes.

Based on in-situ dynamic monitoring by minirhizotron technique, CPlantBox can be used to construct the cotton root growth model under brackish water film drip irrigation. The research results lay the foundation for exploring the impact mechanism of spatial-temporal distribution of root morphology on field soil water migration and root zone water and salt distribution. This has important theoretical and practical implications for improving high and stable cotton yield in Xinjiang.

This study aims to investigate the numerical simulation method of karst water systems under external water recharge.

Taking the Ganxi Yuquan Cave karst water system in Enshi, Hubei as the research subject, a thorough investigation of the hydrogeological characteristics and supply methods of the karst water system was conducted. Underground water tracing tests and high-resolution monitoring of rainfall-surface-subsurface runoff dynamics were carried out. The MODFLOW-CFP numerical model was used to represent the dual medium characteristics of karst fissures and conduits. Focusing on the concentrated inflow of external water from non-karst areas at the entrance of karst conduits, the surface water model TOPMODEL was used to quantitatively characterize the production and exchange processes of external water from non-karst areas. This was set as the flow boundary condition at the entrance of the karst conduit in the MODFLOW-CFP model, achieving the coupling of surface and groundwater models, thereby improving the accuracy of representing external water in the MODFLOW-CFP model.

The research results show that when the coupled TOPMODEL and MODFLOW-CFP model is used to simulate the discharge at the outlet of the Ganxi Yuquan Cave karst water system, the relative peak errors compared to the measured values range from 0.7% to 19.7%, the peak lag time is within 3 hours, the correlation coefficient (R²) is 0.93, and the Nash-Sutcliffe efficiency (NSE) is 0.86. The model was validated, and the relative peak errors of the simulated outlet discharge of the Ganxi Yuquan Cave karst water system compared with the measured values ranged from 1.1% to 2.5%, with peak lag time within 2 hours, a correlation coefficient (R²) of 0.91, and a Nash-Sutcliffe efficiency (NSE) of 0.77, demonstrating good fitting accuracy.

These findings indicate that the coupled TOPMODEL and MODFLOW-CFP model developed in this study has practical value for simulating the rainfall-hydrological response of karst water systems with external water supply.

In order to obtain total suction, matric suction and osmotic suction during the evaporation process of saline soil, the dynamic variation characteristics of each suction force under different water and salt conditions and its influence on evaporation were clarified.

A combination of a cold mirror dew point water potential meter and a parallel contact filter paper method was employed to analyze the dynamic processes of total suction, matric suction, and osmotic suction during soil evaporation with different salt contents, as well as their effects on soil evaporation. Four commonly used soil water characteristic curve models were selected, and the relationship between matric suction and water content was fitted by SWRC-Fit package.

The results indicate that the proportion of matric suction and osmotic suction to total suction continuously changes during the evaporation process of saline soil, with the latter always being higher than the former. Both moisture content and salinity affect the magnitude of soil osmotic suction, with salinity showing a more significant impact. The intensity and duration of soil evaporation are both affected by soil salinity.

Total suction, matric suction and osmotic suction in unsaturated soil during the evaporation process can be simultaneously obtained by WP4C and parallel contact filter paper method. The Fredlund and Xing model accurately fits the experimental data, maintaing good fitting accuracy throughout all evaporation stages, which further proves the reliability of the experimental method and data.

To deepen the understanding of spatial and temporal differences in rift formation and evolution among different tectonic units within the Pearl River Mouth Basin.

Based on 2D seismic profile data, this study analyzes differences in pre-existing structures, basement lithology, fracture systems, and tectonic evolution across tectonic units Using tectonic analysis, balanced cross-section restoration, and fracture activity rates calculation, Combined with magmatic activities and dynamics background, the causes of depression tectonics in the basin are explored.

A series of NE-trending thrust faults and conjugate NW-trending pre-existing thrust faults developed on the basement tectonics of the Pearl River Mouth Basin. NE-NEE -trending faults dominate in the western parts of the Zhu Ⅲ, Zhu Ⅱ, and Zhu Ⅰ Depressions, while near-EW- to NWW-trending faults dominate in the eastern Zhu Ⅰ and Zhu Ⅱ Depression, controlling the basin’s tectonic pattern during the rifting period. Rifting intensity weakens from east to west, and the eastern part of Zhu Ⅰ Depression exhibits higher fault activity.

During rifting, major faults during the rifting period inherited and developed along pre-existing basement faults. The main fault system within the same sedimentary trunk in the Zhu Ⅰ and Zhu Ⅱ Depressions evolved clockwise from NW-NEE-trending to EW-NW-trending and strike-slip dominated, with tensile and shear strengths modulated by differences in basement structure and lithology, and influenced by surrounding plate movement, magmatic activities, and regional stress field changes. In the late stage, the rift architecture transitions from a, narrow elongated graben/half-graben "thick lower part and thin upper part" in the north to a broad, gentle graben/half-graben with "thick upper part and thin lower part" in the south.

To investigate the influence of uncertainty in soil saturated hydraulic conductivity on solute transport,

Stochastic numerical simulations were conducted to examine the effects of saturated hydraulic conductivity uncertainty on ammonium-nitrogen (NH₄⁺-N) transport within a representative double-layer vadose zone of the Jianghan Plain.

The results show that, when considering the uncertainty of the saturated hydraulic conductivity of the upper soil, the migration depth of the NH₄⁺-N front, the peak concentration, and the depth of the concentration peak-along with their variation ranges, are all greater in the "coarse on top and fine on bottom" lithologic configuration than in the "fine on top and coarse on bottom" configuration. When considering the uncertainty of the saturated hydraulic conductivity of the lower soil, these three indicators are less sensitive to conductivity uncertainty in the "coarse-upper and fine-lower" structure, whereas the impacts are relatively more significant in the "fine-upper and coarse-lower" structure. Comparison of the simulation results indicates that the uncertainty of saturated hydraulic conductivity in sandy loam exerts a stronger influence on the magnitude and depth of NH₄⁺-N concentration peaks than that in silty loam. This suggests that, within double-layer vadose zones, the uncertainty of saturated hydraulic conductivity in coarse-textured soils plays a more significant role in controlling solute transport.

The findings provide a methodological reference for vadose-zone solute transport research in the Jianghan Plain and a scientific basis for the prevention and control of groundwater NH₄⁺-N pollution in the region.

Dissolved organic matter (DOM) in coastal groundwater is long-term mixed with from multiple sources, including terrestrial input, marine intrusion, and organic leachates from sediments. Quantitative estimation of the contributions of different sources is cruvial for understanding carbon transport and transformation processes in coastal aquifers.

In this study, coastal groundwater in Lianyungang City, Jiangsu Province was investigated using stable isotopic tracers, fluorescence indices, combined with end-member mixing analysis (EMMA) to identify and quantify DOM sources.

The results showed that DOM in coastal groundwater mainly derives from DOM in river water, seawater, and sediments, contributing 44% ±22%, 33% ± 10%, and 22% ± 13%, respectively. Groundwater in the northern part of the study area is affected by both seawater intrusion and freshwater recharge, exhibiting higher proportion of seawater DOM and stronger autochthonous characteristics. In contrast, groundwater in the southern part shows pronounced salinization, where elevated salinity enhances the mobilization of sediment-derived soluble organic matter, resulting in ground water DOM with a higher proportion of sediment-derived sduble organic matter contribution and humification characteristics.

This study highlights that DOM in coastal groundwater is jointly controlled by hydrodynamic and hydrogeochemical conditions. The integration of fluorescence indices with EMMA provides a reliable quantitative and efficient approach for source apportionment of DOM, offering new insights into the land–ocean continuum of the carbon cycle.

This study aims to analyze the impact of ancient landforms in Xiaoyuan area on the distribution of bauxite deposits.

This paper utilizes drilling and testing data from Xiaoyuan bauxite mining area, and employs the thickness of the Paizuo Formation and Jiujialu Formation (C₁b+jj) and the thickness of the Paizuo Formation (C₁b) to reconstruct the paleogeomorphic features of the Jiujialu Formation before and after sedimentation.

The results show that the bauxite ore bodies are distributed intermittently along the direction of decreasing paleolandform elevation, and the morphology of individual ore bodies is controlled by specific geomorphic features such as depressions and sinkholes. Along the descending gradient of ancient landforms, locally low-lying areas are favorable sites for the formation of bauxite deposits. Two prospective bauxite mining targets areas were predicted (Chayuan and Shizi).

The research results provide a reference for the exploration of bauxite resources.

The Upper Paleozoic sandstone reservoirs in the Xinzhao area, northern Ordos Basin are rich in natural gas and characterized by underpressure. The mechanisms of paleo-pressure evolution and underpressure formation are unclear, constraining the understanding of tight sandstone gas accumulation and the enhancement of natural gas production.

In this study, we comprehensively analyzed the petroleum charging history in the second member of the Shanxi Formation using fluid inclusion petrographic observation, micrometry, and laser Raman analysis. Subsequently, we obtained the paleo-pressure during the key period of reservoir formation. The paleo-pressure evolution history was reconstructed by the basin simulation method, and the coupling relationship between paleo-fluid pressure evolution and petroleum charging was established. The relationship between the causes of underpressure and tight gas accumulation is further discussed.

The results indicate that: ①CO₂ was captured in the second member of the Shanxi Formation in the Xinzhao area from 170 to 180 Ma, when the source rock was in the middle to low maturity stage, and the methane inclusion was captured in the peak of hydrocarbon generation from 138 to 121 Ma. ②Overpressure in the second member of the Shanxi Formation began to develop in the Early Jurassic and reached a maximum paleo-pressure and paleo-pressure coefficient of 50 MPa and 1.31, respectively, by the end of the Early Cretaceous. ③The decrease in formation pressure in the second member of the Shanxi Formation, caused by temperature decrease, pore rebound, and gas diffusion, accounted for 49%, 14.5%, and 36.5% of the total formation pressure decrease, respectively.

The tight gas reservoir of the second member in the Shanxi Formation has undergone a pressure evolution process from normal pressure to medium overpressure to normal pressure and finally to underpressure. Hydrocarbon generation supercharging and pressure conduction are the primary factors contributing to ancient overpressure. Temperature decrease and natural gas diffusion are the primary factors contributing to the formation of underpressure in the second member of the Shanxi Formation.

Deep Earth exploration is a multidisciplinary scientific endeavor aimed at uncovering the structure, dynamics, and evolution of continents and their margins. Understanding of the Earth’s interior is crucial for advancing scientific knowledge and comprehending the fundamental processes that shape our planet. Over the past half-century, many countries worldwide have implemented various deep Earth exploration programs, accumulating valuable experience and achieving significant breakthroughs in technology and methods. These advancements provide important references for deep Earth exploration in China.

This paper analyzes the technical approaches and achievements of representative deep Earth exploration programs in the United States, Europe, and Australia since the 21st century, summarizing the latest progress of these programs.

Six frontiers and key potential directions of deep Earth exploration are summarized, including seismic tomography for deep Earth structure detection, magnetotellurics for mineral resource exploration, GNSS monitoring for Earth's motion and state changes, coupled surface-to-deep Earth processes, advanced data processing, analysis and modeling capabilities, and open data sharing. These are expected to provide informational support and references for the “SinoProbe-II” deep exploration program, the “Earth CT” international cooperative research program, and the National Science and Technology Major Projects focused on deep Earth and mineral resources exploration in China.

The Naneng gold deposit is an important medium-sized Carlin type gold deposit in southeastern Yunnan, and studying its genesis is of great significance for searching for such gold deposits in southeastern Yunnan.

Two generations of pyrite (PyI and PyII) were found to develop in the Naneng gold deposit during detailed field survey and indoor observation, and trace elements and sulfur isotopes of gold-bearing minerals are analyzed by LA-ICP-MS to constrain the source of ore-forming materials and ore genesis.

LA-ICP-MS analyses show that PyI contains a small amount of Au (mean 6.37×10⁻⁶), which is relatively enriched in elements such as Co, Ni, Se, W; The distribution characteristics of trace elements in PyII and PyI are similar, but the content of Au (mean 68.02×10⁻⁶) is relatively high, and As, Sb, Cu elements are enriched in PyII; The average Au content of arsenopyrite is 36.02×10⁻⁶, and arsenopyrite is mainly enriched in elements such as As、Ni、Sb、Se、Au, while Zn, Ag, Hg and Tl elements are low. In addition, gold-bearing minerals in the Naneng gold deposit have consistent in situ δ³⁴S values, ranging from 13.7‰ to 16.5‰, indicating that the S of gold-bearing minerals mainly come from the surrounding rocks.

It is preliminarily concluded that PyI was formed in a relatively stable environment by medium to low temperature hydrothermal fluid from the same source rich in trace elements such as Au、As、Sb, and a small amount of Au precipitated simultaneously with PyI in the form of solid solution (Au⁺). In the PyII stage, the intense tectonic activity in the area caused ore-forming fluid to upswell, and after sulfidation reaction with surrounding rock strata, the concentration of H₂S in the fluid decreased, Au-HS complex became unstable, and Au supersaturated precipitation was enriched in PyII in the form of nanoscale inclusions (Au⁰).

Landslides are geological disasters that cause significant damage to both natural and social environment. Effective landslide susceptibility assessment is crucial for disaster prevention and mitigation. Existing landslide databases are often used as the primary data source for susceptibility assessments. However, due to delays in updates, these databases suffer from issues such as poor timeliness and incompleteness. Moreover, traditional landslide susceptibility assessment methods primarily rely on static data (e.g., topography, geology, and hydrology) and lack dynamic data (e.g., surface deformation), making it difficult to fully characterize the deforming landslides and reducing assessment reliability.

This study combined optical remote sensing technology and synthetic aperture radar interferometry (Interferometric Synthetic Aperture Radar, InSAR) to identify landslides in the study area and obtain surface deformation as a dynamic evaluation factor. In combination with static evaluation factors, two methods—joint training and weighted superposition—were employed, alongside the Maximum Entropy (MaxEnt) model and the Iterative Self-Organizing (ISO) clustering algorithm to assess and categorize landslide susceptibility in Shimian County.

The findings are as follows: (1) By integrating optical remote sensing and InSAR technologies, 139 landslides are identified in the study area. High-risk landslide zones in Shimian County are predominantly located along riverbanks and roadsides. The distribution of landslide disaster points aligns well with the zoned areas. (2) Incorporating the InSAR deformation factor enhances the susceptibility accuracy by 6.1% (AUC=0.921) and substantially reduces the occurrence of false positives and false negatives, thereby improving overall model accuracy.

This study demonstrates the advantages of incorporating InSAR deformation data into landslide susceptibility models, offering valuable support for landslide disaster prevention in Shimian County.

Deep Q-network (DQN) is a classical deep reinforcement learning algorithm, which is an unsupervised inversion approach that has recently been applied to invert one-dimensional magnetotelluric data. It has the advantages of not requiring a training dataset, being less dependent on the initial model, and being able to obtain the probability distribution of inversion results through multiple inversions. However, it suffers from the issue that the inversion results are not concentrated.

To address this issue, this paper proposes the use of deep reinforcement learning with a smooth constraint to invert magnetotelluric data (Smooth DQN, SDQN). This method is based on the framework of reinforcement learning, considers the inversion problem as a Markov decision problem, and defines the terms environment, reward, agent, and so on. Then, the model constraint term of regularized inversion is introduced into the reward function, guiding the agent to continuously adjust the resistivity parameters of the prediction model to obtain results that are more consistent with the model constraints.

The experimental results of the theoretical model inversion show that, compared with the DQN inversion and Occam inversion methods, the results of the proposed method are more stable when the observed data are inverted with the same number of iterations and different noise levels. The inversion results of the magnetotelluric measured data in the Tashi Kang Mine area of Tibet are largely consistent with the Occam inversion results and align with the existing geological interpretations.

The experimental results show that this method has the advantages of more concentrated inversion results and stronger anti-noise capability for the observed data, and it is a new tool for solving the problem of magnetotelluric inversion.

To investigate the groundwater salinization process influenced by the combined effects of the Late Pleistocene and Holocene transgression, modern seawater intrusion, and evaporation, two shallow aquifer groups were selected as the research objects in the Cangzhou area.

Based on a series of paleo-environmental evolution data, a two-dimensional palaeo hydrogeological model was established using SEAWAT software to simulate the evolution process of groundwater salinity since the Holocene.

The results suggest that the current distribution of shallow groundwater salinity is impacted by the Holocene transgression/regression. The palaeo seawater infiltrated downward in a finger-like pattern, with an average infiltration rate 23 mm/a. The brine formed by the palaeo transgressions has infiltrated to depths of −140 m to −160 m B.S.L. The palaeo seawater captured and stored during the Late Pleistocene transgression and Holocene transgression events still remains in the aquifer and has not been completely desalinated. The salt transport process in coastal groundwater has yet to reach equilibrium. The palaeo-saltwater formed by ancient transgressions continues to seep downward at a low rate, and the groundwater salinization process is ongoing, which may lead to further deterioration of water quality in deeper aquifers.

The research results can provide a reference for water resources management in coastal areas.

There are a large number of high and steep slopes in mountainous areas in China. Due to their concealed and hazardous nature,it is currently difficult to obtain usable data for extracting and analyzing geometric parameters and structural plane information of dangerous rock masses on high and steep slopes using a single non-contact measurement method. However, for the refined investigations of dangerous rock masses, the characteristic parameter information of structural planes is a top priority.

Therefore, this paper fused the point cloud data obtained from airborne LiDAR, ground LiDAR and UAV oblique photogrammetry through multi-source data, integrated the advantages of the multi-source data, and used the fused point cloud to analyze dangerous rock masses on high and steep slopes. Parameters such as scale boundaries, back edge characteristics and occurrence information were extracted.

The results showed that the multi-source data fusion method adopted in this study effectively integrated the advantages of various data types.The values of extracted parameters, including scale boundaries, back edge features, and structural plane characteristics, all exhibited deviations within ±5°, meeting the requirements of the survey specifications.

These research findings provide a new approach for detailed investigations of dangerous rock masses in vegetation-covered areas.

By analyzing the characteristics of geological core drilling, we systematically classify and summarize methodologies for trajectory control.

The following results are obtained: First, the primary objective of primary directional boreholes is to obtain the core of the target layer. Design methods for parameters such as inclination angle, orientation, and displacement alongside their depth-dependent variations were analyzed. The applicable conditions and drawbacks were clarified, providing ideas for the use of primary directional boreholes in drilling construction of depths less than 500 meters. It was pointed out that deep boreholes should be used in conjunction with other measures. Second, in terms of packed hole assemblies for geological drilling, we analyzed the use of conventional hole assemblies and large-diameter hole assemblies, and proposed the mechanical theory of the wire coring string with packed hole assembly. Third, regarding controlled directional drilling technology, we analyzed its application in drilling deviation correction and lateral drilling obstacle avoidance. We pointed out the advantages and disadvantages of different methods, indicating that small-diameter bottomhole power drilling tools have obvious advantages. However, due to the requirements of geological coring technology, they have many limitations in geological core drilling.

This study reviews the status of geological core drilling trajectory control technologies, identifies key influencing factors, and evaluates various control techniques to enhance exploration precision.

Regional early warning of rainfall-induced landslide has been a research hotpot in recent years, with the primary challenge being the formulation of rainfall threshold models. Based on hourly rainfall data, this study introduces peak rainfall (M) to construct a three-dimensional characterization model, which can provide a scientific basis for regional rainfall-induced landslide early warning.

The research was conducted using data from 104 rainfall-induced landslide events recorded between 2010 and 2022 in the three northern districts of Ningbo City (Cixi, Jiangbei, and Zhenhai). Firstly, the spatial distribution of rainfall stations associated with landslides was delineated using Voronoi diagram method to reveal the effective rainfall characteristic information landslide hazards. Secondly, the rainfall intensity-rainfall duration (I-D) threshold model was established based on landslide inventory, with critical threshold curves defined using quantile regression. Finally, to address the limitations of the I-D model, peak rainfall (M) was incorporated to propose an improved I-D-M model. The accuracy of both models was evaluated and compared using ROC curves and historical landslide cases to identify the optimal threshold model for regional early warning.

The results demonstrate that the I-D-M model, incorporating peak rainfall (M), achieves higher warning accuracy than the conventional I-D model. Probability of landslide occurrence increased by 8% for yellow warnings, 17% for orange warnings, and 16% for red warnings, indicating the significant role of peak rainfall on landslide initiation. The quantile regression-based I-D-M threshold model can be effectively applied as a criterion for implementing three-tiered (red, orange, yellow) rainfall landslide early warning in the study area.

The proposed three-dimensional rainfall threshold model provides theoretical and practical insights for improving regional landslide early warning systems, demonstrating enhanced predictive capability and operational applicability.

The preferential rupture of splay faults in continental transform fault systems during strike-slip earthquakes remains a widely debated issue. Deciphering the underlying mechanism is crucial for advancing the understanding of earthquake physics and improving seismic hazard assessment.

This study introduces a novel finite element framework to simulate fault nucleation, which identifies nucleation zones based on the interaction between background tectonic stress and fault geometry. Within this framework, faults are treated as frictional contact between two blocks. Stress-strain conditions derived from quasi-static simulations serve as initial conditions for dynamic rupture simulations, with the abrupt transition from static to dynamic friction modeled. The region of maximum slip obtained in the first step of the dynamic simulation corresponds to the area of minimum static friction in the quasi-static model, thereby defining the earthquake nucleation zone. Simultaneously, we investigate the key factors impacting the nucleation site of the 2023 M_W 7.8 Kahramanmaraş earthquake using a simplified 3D elastic-plastic model.

The results show the high accuracy of the proposed earthquake nucleation simulation method and reveal that the mechanical coupling between the splay Nurdağı Fault (NF) and the main fault exhibits nonlinear characteristics, influenced by variations in the geometric structure of the NF. The pronounced deflection of the NF, especially with depth, significantly accelerates earthquake nucleation and leads to the shift of the nucleation location to the NF.

This study address as the challenge of high degrees of freedom in finite element models when balancing static rock pressure (pre-stress) and gravitational effects, thereby improving the accuracy of nucleation simulation. Furthermore, our physics-based simulation successfully reproduces the coseismic slip pattern derived from kinematic finite fault inversion. This study provides a robust explanation for why large strike-slip earthquakes can nucleate on splay faults.

Focusing on the application of coarse-grained soil fillings in alpine mountainous regions, this study aims to analyze the reinforcing effect of geocell-reinforced coarse-grained soil under freeze-thaw cycles.

Cyclic freeze-thaw tests and large-scale triaxial unconsolidated-undrained (UU) compression tests were conducted on both geocell-reinforced and unreinforced coarse-grained soil.

The results show that the reinforcing effect of the geocell is significant when the axial strain exceeds 2%, compared to unreinforced coarse-grained soil. However, the shear strength, elastic modulus, and cohesion of the geocell-reinforced coarse-grained soil generally decrease as the number of freeze-thaw cycles increases, while the difference of the internal friction angle between the geocell-reinforced and unreinforced coarse-grained soil is small, with a maximum of value 2.08°. Therefore, by introducing the reinforcing effect coefficient, it is proven that the geocell reinforcement effect can be well quantified.

It is concluded that the geocell still demonstrates a certain reinforcing effect with an increase within 15 freeze-thaw cycles, although the reinforcement effect of the geocell decreases with the increase in freeze-thaw cycles.

Drilling data are sparse in the depression area of the Xinglong structural belt within the Linhe depression of the Hetao Basin, and the distribution patterns and evolution mechanism of the pressure system remain unclear.

Integrating data from drilling, logging, seismic surveys, and related tests with geophysical methods and geological context, this study conducts a comprehensive analysis of the stratigraphic pressure distribution, genesis, mechanism, and evolution history of the Linhe Formation in the Xinglong Tectonic Belt of the Linhe Depression in the Hetao Basin. The analysis employs basin-scale numerical simulation, fluid inclusion analysis, and testing techniques.

The results indicate that the Linhe Formation's pressure distribution in the study area follows a "high in the north and low in the south, high in the west and low in the east" pattern. Among them, the source rock strata of the Linhe Formation exhibit pronounced lateral zonation: the inner zone and trough area-middle zone zone exhibiting the characteristics of extremely strong overpressure/strong overpressure-weak overpressure-normal pressure. The reservoirs of the Linhe Formation develop overpressure only in the inner zone and trough area, while most other areas exhibit normal pressure. Longitudinally, the overpressure top interface generally lies within the Wuyuan Formation. From top to bottom, overpressure in the Wuyuan Formation, with thick-bedded mudstone, is primarily undercompacted. Hydrocarbon generation pressurization dominates overpressure formation in the Linhe Formation's source rocks, and the principal cause of overpressure in the Linhe Formation reservoirs is pressure transmission. The Linhe Formation's overpressure originated during the rapid burial of the Wuyuan Formation (approximately 5.3 Ma), driven by the dual control mechanism of thermal evolution and undercompaction-hydrocarbon generation in the source rocks, yielding weak overpressure. Overpressure intensification occurred during the Quaternary (approximately 2.6 Ma), with inner-belt reservoir pressures increasing to strong overpressure through pressure transfer. However, overpressure was not preserved in other areas due to strike-slip tectonic adjustment, resulting in normal pressure.

This study clarifies the accumulation dynamics of the Linhe Depression and guides subsequent oil and gas exploration and development.

In marine natural gas hydrate exploration, gas-hydrate-bearing layers-simultaneously contain natural gas hydrates and shallow gas-exhibit highly complex electrical logging responses. This complexity poses significant challenges for both qualitative identification and quantitative evaluation.

To address this issue, this study fully leverages the differential responses of multiple geophysical logging methods to hydrate and shallow gas occurrences and proposes a novel joint inversion approach that fuses sonic and resistivity logging from various sources to improve the accuracy of gas-hydrate-bearing layer saturation calculations. Guided by the “synchronous increase and decrease” logging response characteristics of gas-hydrate-bearing layers in ultra-shallow unconsolidated sandstone reservoirs of the South China Sea, reservoir intervals were comprehensively selected to feature low natural gamma, low shale content, high porosity, and stable-thickness sandy formations. Qualitative identification was performed using porosity difference, neutron density crossover, and shear modulus methods. The neutron-density crossplot technique was employed to determine porosity, and by incorporating gas saturation into the three-phase Biot equation and Archie's formula, a cyclic iterative inversion method was used to simultaneously estimate P-wave velocity and resistivity, optimizing joint error minimization to derive the saturation of gas-hydrate-bearing layers.

Within the identified reservoir intervals, gas-hydrate-bearing layers can be effectively distinguished by combining hydrocarbon or hydrate indicators from absolute resistivity values and the synthetic resistivity curve overlap method, neutron-density crossplots for shallow gas indications, and elevated shear-modulus values relative to the background. The joint inversion method integrating sonic and resistivity logging is feasible and reliable for calculating gas-hydrate-bearing layer saturation. Applied to Well Z in Block L, the joint inversion yielded an 81.25% match with core-derived saturation. For Well Y in Block L, agreement between the joint inversion results and independent hydrate or shallow gas saturation models was approximately 85%.

The study provides critical insights into the identification and estimation of the saturation of in-situ gas-hydrate-bearing layers, offering a solid technical foundation for the refined assessment of hydrate resources in deepwater environments.

Shallow geothermal energy is a clean and stable renewable energy source. Ground-coupled heat pumps represents are a commonly used technology for developing and utilizing shallow geothermal energy in building heating and cooling systems. This technology extracts heat from the subsurface without pumping groundwater; thus causing minimal disturbance to the underground environment. The borehole heat exchanger serves as the primary component of heat exchange in ground-coupled heat pump systems, with the U-shaped configuration being the most prevalent. However, research and application of coaxial borehole heat exchangers in shallow geothermal energy remain relatively limited.

his study focuses on the shallow coaxial borehole heat exchanger and conducts numerical simulations to investigate their heat transfer performance, analyze sensitivity factors, and compare their efficiency with that of a U-shaped borehole heat exchanger.

The findings demonstrate that when traditional PE pipes are employed for both the inner and outer pipes of a coaxial borehole heat exchanger, thermal short-circuiting occurs between the annular fluid and the inner pipe fluid, resulting in a 23% reduction in heat transfer efficiency. The sensitivity factors influencing coaxial borehole heat exchangers performance are ranked as follows: Inlet temperature, initial soil temperature, circulating flow rate, thermal conductivity of casing and inner pipe materials, and thermal conductivity, backfill material. Under identical conditions, the U-shaped borehole heat exchanger exhibits an 8.57% higher heat transfer efficiency compared to coaxial borehole heat exchanges. However, when a coaxial borehole heat exchanger’s casing is constructed from steel and its inner pipe is insulated, its heat transfer efficiency exceeds that of the U-shaped borehole heat exchanger by 21.64%.

The research results can provide a reference for the research and application of shallow-buried pipe technology.

To further evaluate the quality of source rocks in the Fengcheng Formation of the Hashan area and the factors influencing their quality,

this study starts with the sedimentary background, conducts a detailed evaluation of the source rocks in the Fengcheng Formation by lithofacies, identifies lithofacies with high-quality source rocks, and on this basis, analyzes the factors affecting source rock quality to clarify the directions for exploration.

The results show that among the mudstones in the Fengcheng Formation of the Hashan area, the volcanic clastic-bearing mixed lithofacies exhibits the highest organic matter abundance, while the dolomitic mixed lithofacies has the greatest hydrocarbon generation potential. The kerogen of the mudstones in the Fengcheng Formation of the Hashan area is mainly Type I–II. The maturity of mudstones in the western section of Hashan ranges from 0.8% to 0.97%, and in the middle section, it is mainly between 1.2% and 1.37%.

The quality of source rocks in the Fengcheng Formation of the Hashan area is mainly controlled by sedimentary environment, hydrocarbon-generating parent material, maturity, alkaline minerals, and volcanic activity. Organic matter in dolomitic mixed lithofacies and alkaline mineral-bearing mixed lithofacies is more enriched in deep-water, reducing, medium-to-high salinity, and arid environments. In contrast, organic matter in terrigenous clastic lithofacies and volcanic clastic-bearing mixed lithofacies is more enriched in relatively shallow-water, oxygen-poor, low-salinity, and arid–semi-arid environments. Green algae (Dunaliella-like) that developed in high-salinity areas of the sedimentary center exhibit higher oil and gas conversion rates, enabling the mudstones of dolomitic mixed lithofacies to have high hydrocarbon generation potential even with low organic matter abundance. An increase in maturity and alkaline minerals reduces the measured values of TOC (Total Organic Carbon) and hydrocarbon generation potential, while an appropriate amount of volcanic clastics provides favorable conditions for the enrichment of organic matter.

The uranium reservoir is the foundation of sandstone-type uranium mineralization. Therefore, studying the genesis of uranium reservoirs is the essential for understanding uranium mineralization processes and evaluating uranium mineralization potential.

This paper conducts a genetic analysis of the uranium reservoir in the Saihan Formation in the central part of the Ulanqab Depression in the Erlian Basin based on analyses of the sand dispersal system, detrital components of sediments, heavy mineral assemblages, and elemental composition.

The study found that the average contents of quartz, feldspar, and rock fragments in the sandstone are 51%, 27%, and 12%, respectively. The average values of Fe₂O₃^T/K₂O and SiO₂/Al₂O₃ are 0.12 and 8.61, respectively, with an average CIA value of 61.83. The average Eu/Eu* value is 0.75. A total of 23 major heavy minerals were identified in the sandstone, with average ATi and ZGi values of 35.2 and 48.8, respectively, and ZTR values ranging between 24.2% and 71.6%.

These characteristics indicate that the sandstone types in the Saihan Formation are feldspathic sandstone and lithic sandstone, with the parent rocks primarily composed of intermediate-acidic magmatic rocks. The chemical weathering intensity of the parent rocks in the source area is moderate, reflecting strong chemical weathering under warm and humid conditions. The tectonic setting of the parent rocks in the source area is mainly continental margin, with the provenance primarily derived from the Sonid Uplift. Based on comprehensive analysis, it is concluded that during the Permian-Triassic and Cretaceous-Jurassic periods, intermediate-acidic granites formed in the Sonid Uplift under continental margin tectonic setting. Under warm and humid climatic conditions, these rocks underwent intense weathering, and the resulting detrital materials were transported by fluids into the basin, forming the uranium-bearing sandstone of the upper Saihan Formation.The uranium was enriched, through uranium mineralization processesand formed sandstone-type uranium deposits.

The Quele area of the Kuqa Depression features favorable geological conditions, abundant oil and gas resources, well-developed salt structures, and complex fault systems, collectively creating ideal conditions for upward hydrocarbon migration and the resulting surface hydrocarbon microseepage alteration anomalies. This study investigates the characteristics of hydrocarbon microseepage during upward migration in the area and examines its relationship with shallow faults, providing a theoretical basis for further structural analysis of oil and gas reservoirs.

This study primarily utilized Sentinel-2A satellite imagery as the main data source. Principal Component Analysis (PCA) was applied to identify the spatial distribution patterns of hydrocarbon microseepage. By combining seismic profile interpretation and field investigations, we comprehensively analyzed the hydrocarbon microseepage characteristics in the Quele area.

The results reveal significant spatial variability in hydrocarbon microseepage across the Quele area. In regions such as the eastern Awate fold belt, Kalayuergun slip fault zone, and the Quele salt nappe (Quele fault), hydrocarbon microseepage anomalies are more pronounced, with observable surface manifestations. In contrast, the Miskantage anticline area exhibits relatively weak hydrocarbon microseepage, with nearly no discernible surface alteration signs.

The study demonstrates a strong correlation between hydrocarbon microseepage alteration and surface-exposed faults in the Quele area. Field investigations and seismic profile analysis further indicate that the fault on the southern flank of the Miskantage anticline is a hidden fault, not extending through the strata to the surface, and therefore not inducing surface hydrocarbon microseepage alteration.

The research objective of this study is to explore the effects of freeze-thaw cycles on the dynamic mechanical properties and microstructural characteristics of sandstone.

Comprehensive experimental investigations were conducted on sandstone samples subjected to different numbers of freeze-thaw cycles, specifically 0, 30, 60, 90, and 120 cycles. The experimental methodology comprised three principal components: dynamic impact compression tests performed at precisely controlled velocities of 3, 6, and 9 m/s, nuclear magnetic resonance testing, and scanning electron microscopy.

The experimental results demonstrate that freeze-thaw sandstone exhibits predominantly crushing failure under dynamic impact loading. The investigation revealed several significant trends: as both the number of freeze-thaw cycles and the impact velocity increase, the sandstone experiences substantially enhanced fragmentation, as evidenced by smaller fragment sizes, an increased number of fragments, a higher proportion of fine powder, and corresponding increases in fractal dimension values. When subjected to identical impact velocities, the dynamic mechanical properties of sandstone continuously deteriorate with increasing freeze-thaw cycles, while all dynamic mechanical performance indicators consistently exhibit pronounced rate-dependent effects. In addition, a dynamic peak stress attenuation model for freeze-thaw sandstone was established, demonstrating that impact velocity can partially offset the damage induced by freeze-thaw cycles, thereby reducing the attenuation constant and prolonging the half-life of freeze-thaw sandstone. Furthermore, a fractal dimension–dynamic strength evolution equation was developed, enabling the fractal dimension to serve not only as a quantitative descriptor of post-impact fragmentation but also as a predictive tool for estimating dynamic strength. With an increasing number of freeze-thaw cycles, the size and number of pores and cracks in sandstone increase, aggravating structural damage. Building upon these comprehensive results, the study further investigated the fundamental damage mechanisms of sandstone under freeze-thaw action, concluding that freeze-thaw damage in sandstone is a complex phenomenon arising from the synergistic interaction of multiple factors.

This research provides valuable references and practical insights for rock engineering applications in cold-region environments.

Under the combined impacts of global climate change and human activities, groundwater quality is facing severe threats. The problem of high-fluoride groundwater has emerged as a pressing environmental challenge in coastal regions.

Focusing on the Wanshan Archipelago, Zhuhai, Guangdong Province, this study investigates the distribution characteristics and enrichment mechanisms of fluoride in groundwater, and analyzes the impacts of geological conditions on hydrochemical properties.

The results show that fluoride concentrations in the groundwater of the Wanshan Archipelago vary between 0.17 and 3.22 mg/L, with 53% of the samples exceeding the fluoride standard. Significant variations in hydrochemical types exist among different islands. Excessive fluoride concentrations are mainly distributed on islands such as Dong'ao and Wailingding, predominantly detected in groundwater at depths of 100–150 m. Analysis of mineral dissolution, precipitation, and water-rock interactions indicates that fluoride enrichment is closely associated with fluorite dissolution in aquifers, cation exchange reactions, and alkaline conditions (high pH). Furthermore, seawater intrusion in some regions may also promote fluoride enrichment.

This study provides crucial data and theoretical basis for understanding the formation mechanisms of high-fluoride groundwater in island settings, and offers scientific support for the protection and management of local groundwater resources.

Block Fan 151 is a low-permeability beach-bar sandstone reservoir with poor overall physical properties and high heterogeneity, resulting in low oil recovery and significant amounts of residual oil during development. It is essential to analyze the influence of reservoir heterogeneity on the distribution of residual oil and identify enrichment areas. Furthermore, calculating the reservoir heterogeneity comprehensive index plays a crucial role in quantitatively characterizing heterogeneity. Therefore, improving the accuracy of calculating the comprehensive index can provide a basis for predicting favorable areas for oilfield development and finding residual oil.

To improve the accuracy of the comprehensive reservoir heterogeneity index calculation, this study proposes the AHP-CRITIC combined weighting method. This method determines the composite weight of evaluation indicators using both subjective and objective data, overcoming the limitations of a single weighting approach.

Quantitative analysis of the heterogeneity of the 2⁴ layers in the Upper Es4 Member of Block Fan 151 shows that the heterogeneous comprehensive index I ranges from 0.27 to 0.73, with about 63% of the values falling between 0.4 and 0.65.

The target formation in the study area exhibits moderate to strong heterogeneity, and the distribution of high values of the comprehensive heterogeneity index I aligns closely with the high-value areas on the residual oil saturation contour map. This indicates that the AHP-CRITIC combined weighting method effectively assigns weights to the evaluation parameters and establishes a quantitative evaluation criterion for the heterogeneity of this reservoir. This approach offers a new method for the quantitative characterization of reservoir heterogeneity.

Lithology identification is a crucial step in the process of oil and gas detection and exploration, providing important guidance for exploration positioning, reservoir evaluation, and the establishment of reservoir models. However, traditional manual lithology identification methods are time-consuming and labor-intensive. Although classical deep learning models achieve high identification accuracy, they often have a large number of parameters. To enhance model accuracy while reducing the number of parameters, the aim of this research is to make the model suitable for real-time lithology identification.

This paper first collected a dataset of 3016 rock images consisting of eight types of rocks, including dolomite and sandstone. Based on the lightweight convolutional neural network ShuffleNetV2, the paper proposes a Rock-ShuffleNetV2 lithology identification model (hereafter referred to as the RSHFNet model). The model incorporates the Convolutional Block Attention Module (CBAM) and Multi-Scale Feature Fusion Module (MSF) into the basic network to enhance feature extraction capabilities and improve identification performance. Additionally, the number of stacked ShuffleNetV2 units is optimized to reduce the model's parameters.

The experimental results show that the RSHFNet model achieved an accuracy of 87.21%, which is a 4.98% improvement over the baseline model. Furthermore, the model's parameters and floating-point operations were reduced to 8.69×10⁶ and 9.3×10⁷, respectively, representing 67% of the model's parameters and 63% of the floating-point operations of the baseline model. This reduction significantly decreases the model's size. Additionally, the RSHFNet model demonstrates superior overall performance compared to existing convolutional neural networks.

The proposed RSHFNet lithology identification model offers high recognition accuracy and strong generalization capabilities while being more lightweight, providing a new approach for real-time lithology identification in the field.

Karst groundwater resources are vital water sources in China. Due to the combined effects of global climate change and intense human activities, such as coal mining, groundwater quality in the Jinci Spring area has deteriorated. Identifying water environmental issues and understanding the groundwater pollution mechanisms in the karst critical zone of this area are crucial for the protection of karst groundwater resources.

The groundwater quality in the spring area was evaluated using the entropy weight method and water quality index. Based on the water quality assessment, isotopic tracing of sulfate oxygen and nitrate nitrogen in groundwater was further performed to trace pollution sources. Additionally, the pollution pathways in karst groundwater were identified through the analysis of inorganic carbon isotopes, strontium isotopes, and sulfur isotopes.

The results showed that the average sulfate concentration in karst groundwater was 572.07 mg/L, while the nitrate concentration in pore water reached 424.72 mg/L, indicating obvious sulfate and nitrate pollution in the groundwater from the study area. Sulfur isotopes in the polluted karst water exhibited a remarkable negative deviation, and the strontium and carbon isotopic characteristics of nitrate-polluted karst water resemble to those of deep pore water.

The primary source of excessive sulfate in groundwater is sulfide oxidation and gypsum dissolution, while sewage discharge and manure input are the important sources of nitrate contamination. The main pollution pathways in karst aquifers include reverse recharge from pore water and cascade recharge from upper-layer goaf water. This study provides important scientific evidence for the control of karst groundwater pollution and the rational development and utilization of karst water resources in the Jinci Spring area.

The interpretation results of SBAS-InSAR exhibit multiple solutions, making it uncertain to directly use the interpreted deformation points for identifying potential landslide-prone areas. Therefore, taking the north bank of the Qingjiang River (Changyang Section) as the study area, this study proposed a method to comprehensively optimize SBAS-InSAR interpretation results by incorporating landslide susceptibility evaluation.

First, the deformation points interpreted by SBAS-InSAR were analyzed using clustering and outlier detection (Anselin Local Moran's I), and low-value cluster deformation points were retained. Subsequently, eight factors, including elevation, slope, and slope aspect, were selected to evaluate and generate a landslide susceptibility zoning map using the information value method. The reliability of the landslide susceptibility evaluation was confirmed by an ROC curve, with an AUC value of 0.844.

The optimized SBAS-InSAR results were obtained by filtering low-value cluster deformation points based on a threshold value (v ≤ -10 mm/a) and incorporating the landslide susceptibility zoning map. Field verification in selected areas shows that the number of deformation points was reduced after optimization, and their distribution characteristics were more consistent with the historical landslide development in the study area. Additionally, taking the Yupingcun landslide group and the Pianshan landslide as typical cases, the surface deformation values monitored by SBAS-InSAR and GNSS at the same time were compared. In the case of the Yupingcun landslide, the difference between surface displacement values monitored by SBAS-InSAR and GNSS ranged from 0 to 7.87 mm, with an average difference of approximately 2.23 mm and an RMSE of 3.67.

The proposed optimization method for SBAS-InSAR interpretation was demonstrated to be both practical and reliable, providing valuable insights into the application of InSAR technology in the field of geological disasters.

In the Kuqa Depression, the Triassic and Jurassic periods feature five sets of source rock sequences that developed as alternating lake and swamp facies. These sequences can be classified into coal, carbonaceous mudstone, and dark mudstone based on lithology. The source rocks are characterized by high TOC abundance, significant thickness, and wide distribution. However, due to the vertical distribution of multiple source rock layers and the strong heterogeneity in lithological distribution, conventional methods such as the ΔlgR method perform poorly in TOC logging quantification.

To better understand the hydrocarbon resource potential and assess reserves in the Kuqa Depression, this study first identified the lithological characteristics of the source rocks through core analysis. Further geological characterization was achieved using geochemical analysis data. The ΔlgR method was initially applied for quantitative TOC logging evaluation, followed by the application of LithoScanner logging for lithological identification of the source rocks. Subsequently, LithoScanner logging was utilized for quantitative TOC evaluation.

Overall, the Triassic and Jurassic source rocks are primarily composed of type II1, II2, and III organic matter, with medium to high maturity. The quality of these source rocks ranges from medium to good. The method of using LithoScanner logging to identify different lithological source rocks and quantitatively evaluate TOC demonstrated a significantly higher accuracy compared to the ΔlgR method.

The findings provide valuable guidance for assessing the hydrocarbon resource potential in the Kuqa Depression and expand the application scope of LithoScanner logging data.