This article aims to reveal the control rules of pre-existing faults in the Cambrian-Ordovician carbonate rocks in the Manjiaer Sag of the Tarim Basin on the development density of structural fractures, and to provide geological basis for reservoir fracture prediction and oil and gas exploration and development. This study is based on cores, FMI imaging logging and regional geological data, and uses quantitative characterization of fracture surface density, curve fitting analysis and mechanical property comparison methods to systematically analyze the control effects of fault distance, length, dip angle and mechanical properties on fracture density. The results show that the fracture surface density decays exponentially as the fault distance increases, and the fitting coefficient of determination reaches 0.9997. The density in the near-fault area can reach up to 2.81 m-1, and the far-end area is stable at 0.96~1.03 m-1. The fracture density increases linearly with the fault length and slowly increases with the fault inclination angle. The fitting coefficients of determination are 0.9997 and 0.91607 respectively, both of which are secondary control factors. There are differences in the control effects of faults with different mechanical properties. The median fracture surface densities in tension, torsion, and compression fault control areas are 2.75 m-1, 2.00 m-1, and 1.30 m-1, respectively. Pre-existing faults control the spatial distribution of fracture density through stress redistribution and damage zone development, and the fault mechanical properties determine the control strength and attenuation mode. The research results can provide support for carbonate reservoir evaluation and exploration deployment in the study area.
The Late Pleistoceneu2013Holocene transition was a pivotal interval of climateu2013environment reorganization. The Nihewan Basin in northern China, where more than 400 archaeological sites are distributed, provides an ideal setting for investigating prehistoric humanu2013environment interactions. Based on 12.5 m DEM data, this study used GIS-based spatial analysis to extract environmental variables, including elevation, aspect, slope, TRI, and distance to rivers. Non-parametric tests, Cliffu2019s Delta effect size analysis, and principal component analysis were employed to compare environmental preferences between the late stage of the Late Pleistocene and the Earlyu2013Middle Holocene and to explore the mechanisms underlying humanu2013environment coupling. The results show that (1) occupations in both periods were concentrated at elevations of 800-1000 m and within 2 km of rivers. In the Earlyu2013Middle Holocene, settlement preference shifted toward areas with lower surface roughness (u0026lt;4), gentler slopes (u0026lt;7u00B0), and sunny aspects. (2) PCA further indicates that prehistoric human activities were mainly concentrated in areas close to water, with gentle slopes and relatively flat terrain. During the Earlyu2013Middle Holocene, the environmental adaptation range of prehistoric humans narrowed compared with that in the Late Pleistocene, and they showed a greater preference for more humid environments and lower topographic positions. (3) The habitat selection and subsistence strategies of prehistoric humans shifted from highly mobile hunter-gathering to agricultural production with a degree of sedentary settlement, providing new quantitative evidence for understanding how prehistoric populations in East Asia adapted to environmental change.
Classical travel-time tomography struggles to resolve the heterogeneity within the medium.To address this challenge,this paper proposes a tomography method based on Hamiltonian Monte Carlo(HMC)sampling.In this method,forward modeling utilizes the fast marching method(FMM),governed by the Eikonal equation.For inversion,velocity parameters are expressed as probability distributions,and samples representing these parameters are obtained by employing a Markov chain.This chain is generated from the distributions.The Markov chain is controlled by an artificial Hamiltonian system.In this system,the models are treated as high-dimensional particles.These particles advance through trajectories in the extended phase space.HMC uses the derivatives of the forward equations to enable long-distance transitions between models.This approach enhances sample independence and maintains a high acceptance rate.Results demonstrate that this tomography method can accurately invert the position and shape of velocity anomalies,as well as the heterogeneity in stochastic medium models.This method provides a novel approach for seismic tomography.It can accurately characterize subsurface structures and is valuable for seismic exploration and geophysical studies.
Electrical resistivity tomography(ERT)and seismic refraction tomography(SRT)are two important near-surface geophysical imaging methods.The resistivity is highly sensitive to factors such as water content and porosity,whereas the seismic velocity provides high-resolution imaging of layer interfaces and velocity structures.Due to the strong heterogeneity and multi-scale structural characteristics of near-surface media,as well as environmental noise and human activity interference,a single method is prone to generating multiple solutions and resulting in low imaging accuracy,making it difficult to accurately characterize complex near-surface structures.In this study,the authors propose an ERT and SRT joint inversion method based on the ensemble Kalman filter(EnKF),which enables the jointy constrained inversion of resistivity and velocity and provides uncertainty quantification results.By introducing structural consistency constraints during the inversion update process,the inversion accuracy of the resistivity and velocity models at layer interfaces and anomalous structures is improved,enhancing interface continuity.Model testing and field data from the Northeast Black Soil Test Field demonstrate that the proposed EnKF joint inversion strategy can effectively improve imaging resolution,providing a reliable framework for geophysical imaging and interpretation in complex near-surface applications.
Groundwater in basalt-covered areas primarily occurs within pore zones,cooling contraction fractures,primary joints,tectonic fractures,and weathered layers,resulting in a highly heterogeneous and discontinuous distribution pattern of the aquifers.This work investigates the groundwater system in the Changbai Mountain basalt region using electrical resistivity tomography(ERT).The study area is located in Baili Village,Longcheng Town,Helong City,Jilin Province,where three parallel survey lines of ERT were deployed.The subsurface electrical model of the study area was obtained using a smooth-constrained least-squares inversion method.The results revealed the presence of a localized shallow aquifer and a regionally developed fault zone.The regional fault zone plays a dominant role in controlling shallow groundwater migration and serves as a pathway for groundwater accumulation.The findings demonstrate that ERT is an effective tool for revealing the spatial distribution patterns of discrete groundwater in basalt-covered areas.
Monitoring air quality is a core scientific issue in atmospheric environmental research.Based on the hourly air quality index(AQI)data from 298 monitoring stations,a multi-scale analysis of air quality was conducted in the middle-lower reaches of the Yellow River from June 2016 to May 2020.Methodologically,unified quality control and missing-data imputation were applied to the hourly AQI records,after which annual,seasonal,and monthly mean AQI values were calculated using arithmetic averaging.The Kriging interpolation was applied to map multi-temporal spatial patterns,while the coefficient of variation and global/local spatial autocorrelation were used to quantify spatial disparity and clustering of AQI.Then,the effects of natural and socioeconomic factors were identified and cross-validated using the geographical detector and multiple linear regression.The results show that AQI exhibits a pronounced downward trend over time,with clear seasonal characteristics and cyclical variations at the monthly scale;spatially,AQI has long displayed a pattern of higher values in downstream and lower values in midstream,with high-concentration areas mainly clustered in the adjacent regions of Henan,Shandong and Shanxi provinces;significant positive spatial autocorrelation is observed at all temporal scales,with stable high-high and low-low clustering patterns;population density,civilian vehicle ownership,and industrial dust emissions show the strongest explanatory power,while air temperature and afforestation area exert moderating effects on AQI variations.This study is of potential significance to cross-provincial coordinated control and refined air pollution management.
Low-porosity and low-permeability reservoirs are developed in the Enping Formation and Wenchang Formation in the Lufeng Sag,the Pearl River Mouth Basin.Due to their complex pore structure and strong heterogeneity,conventional porosity-permeability relationship models exhibit low accuracy in permeability calculation,making it difficult to meet the actual production needs such as reservoir effectiveness identification and productivity prediction.Starting from the generation principle of porosity spectrum in electrical imaging,and combining with core experiments and forward simulation results,the authors systematically compared the differences between nuclear magnetic resonance(NMR)T2 spectra and porosity spectrum generated by conventional methods,deeply analyzed the reasons for the shortcomings of conventional porosity spectrum in characterizing rock pore structure,and proposed an improved porosity spectrum construction method based on pore volume statistics.The improved porosity spectrum shows excellent consistency with the NMR T2 spectrum,which can more accurately reflect the pore structure characteristics of the reservoir.On this basis,the pseudo-NMR Schlumberger-Doll Research(SDR)model is used for reservoir permeability evaluation,which significantly improves the calculation accuracy over conventional methods.It can better reflect the advantage of high resolution compared to nuclear magnetic logging,providing reliable data support for fine reservoir description and productivity prediction.
Previous studies have shown that the Eocene oil shale sequences in the Green River Basin contain long-period astronomical age information.The fine-scale chronological characteristics of the oil shale laminae remain largely unexplored.We selected finely laminated oil shales formed in deep-water environments characterized by stable water column stratification as the primary focus of this study,using microscopy and micro-area X-ray fluorescence(μ-XRF)techniques.By integrating high-resolution elemental data with time-series analysis,we identified significant periodic signals associated with solar activity(Hale and Schwabe cycles)and ENSO.The results indicate that the alternations of light and dark laminae in the Green River Formation oil shale correspond to alternating dry and wet climate regimes:the light laminae are dominated by carbonate minerals,reflecting drier and milder conditions,while the dark laminae are enriched in terrigenous clastics and organic matter,indicating periods of increased precipitation and warmer temperatures.The detected periodicities(23.5 years,13.3 years and 5.8 years)are highly consistent with modern observations,demonstrating that the lower Eocene Green River oil shale effectively records short-term solar activity and climate variability.Furthermore,our findings confirm that a persistent"permanent El Niño"state did not develop under Early Eocene greenhouse conditions,providing a refined chronological framework for high-resolution paleoclimate studies during greenhouse intervals.
The Mailong gold deposit is located in the eastern section of the East Kunlun orogenic belt and is one of the recently discovered important gold polymetallic deposits in the Qinhai Gouli region.The primary host rocks of the Mailong gold deposit consist of intermediate-acid intrusive rocks from the Varisian and Indosinian periods,as well as the Precambrian Jinshuikou Group,with mineralization controlled by northeast and northwest faults.The alteration of the host rocks is mainly characterized by silicification,sericitization,chloritization,and carbonatization.Based on the cross-cutting relationships of the veins,the hydrothermal mineralization of the gold deposit can be categorized into three stages:the quartz-pyrite stage,the quartz-polymetallic sulfide stage,and the quartz-carbonate stage.Microthermometry of fluid inclusions indicates that the Mailong gold deposit belongs to a low-density(0.73–0.86 g/cm3),medium-temperature(240–340℃),and medium-salinity(4.01–10.74 wt%NaCl)NaCl-CO2-H2O fluid system.The C-H-O isotopic analysis suggests that the mineralizing fluids is derived from magmatic water,with later contributions from atmospheric precipitation.In-situ S isotopic results indicate that the mineralizing materials mainly derive from igneous rocks.A comprehensive analysis concludes that the Mailong gold deposit is a mesothermal hydrothermal vein-type gold deposit controlled by structural factors.
The Solonker Suture records the termination of the Central Asian Orogenic Belt(CAOB),but its eastward extension beneath the Songliao Basin has not been clear.The Yaduwula ophiolite is one of the significant fragments within the Solonker Suture.LA–ICP–MS U–Pb dating of zircon grains from metamorphic basalts yield ages of 263±4 Ma and 274±3 Ma,constraining the Yaduwula ophiolite in the late Cisuralian and Guadalupian age.This might indicate that the subduction of Paleo-Asian Ocean continued until at least the Guadalupian(middle Permian).Geochemical analysis of the metamorphic basalts revealed enrichment in large ion lithophile elements(LILEs)and depletion in high field strength elements(HFSEs)and show the characteristics of a supra-subduction zone.The results provide the evidence for the closure time of the Paleo-Asian Ocean after the middle Permian and also suggest that the Yaduwula ophiolite may be considered the eastern extension of Solonker Suture.Our study provides further insights on the evolution of the southeastern Central Asian Orogenic Belt.
In recent years,significant breakthroughs have been achieved in the exploration of deep volcanic rocks in the Junggar Basin,highlighting their substantial exploration potential.The complex distribution of volcanic reservoirs is attributed to the multi-phase tectonic evolution within the basin,with their superior reservoir properties playing a crucial role in natural gas formation.However,due to the combined effects of multi-cyclic volcanic eruptions and tectonic activities,predicting volcanic facies distribution and favorable reservoirs remains highly challenging.This study focuses on the third member of the Jiamuhe Formation in the Zhongguai Uplift.By integrating drilling and petrophysical data with well-seismic analysis techniques,a seismic identification model for volcanic reservoirs has been established.The findings reveal that different facies exhibit distinct seismic response characteristics.Andesite,rhyolite,volcanic breccia,and volcanic clastic rocks show variability in amplitude,frequency,and continuity.Using structural-guided filtering,high-resolution coherence analysis,and 3D body carving techniques,the locations of volcanic craters and eruption centers were successfully identified,further clarifying the distribution patterns of volcanic facies.By combining multi-attribute clustering analysis and seismic attribute extraction,a volcanic facies zone distribution map was generated,and favorable exploration directions for volcanic reservoirs were proposed.The study provides technical guidance for the exploration of deep volcanic oil and gas reservoirs in the Junggar Basin and holds significant application value.
Five new small theropod teeth and one manual ungual have recently been recovered from the Upper Cretaceous Nenjiang Formation in the Songliao Basin.The specimens were examined for their morphological characteristics,leading to the identification of four distinct taxa.The first taxon consists of three foliodont teeth characterized by a pronounced basal constriction and large hook-like distal denticles,which can be attributed to Troodontidae.The second taxon is represented by an elongated tooth featuring prominent longitudinal ridges,allowing for its assignment to Paronychodon.The third taxon is a blade-like tooth with notably small distal denticles,corresponding to Richardoestesia.The fourth taxon comprises a manual ungual characterized by a transversely wide and nearly symmetrical proximal articular surface,fully enclosed ventral foramina,a flattened ventral surface,and the absence of a flexor tubercle,resembling Alvarezsauridae.These specimens significantly enhance the known dinosaur diversity of the Nenjiang Formation and provide crucial insights for understanding the terrestrial ecosystem in Northeast Asia during the Late Cretaceous.
Slope units are divided according to the real topography and have clear geological characteristics,making them ideal units for evaluating the susceptibility to geological disasters.Based on the results of automatically and manually corrected hydrological slope unit division,the Longhua District,Shenzhen City,Guangdong Province,was selected as the study area.A total of 15 influencing factors,namely Fluctuation,slope,slope aspect,curvature,topographic witness index(TWI),stream power index(SPI),topographic roughness index(TRI),annual average rainfall,distance to water system,engineering rock group,distance to fault,land use,normalized difference vegetation index(NDVI),nighttime light,and distance to road,were selected as evaluation indicators.The information volume model(IV)and random points were used to select non-geological disaster units,and then the random forest model(RF)was used to evaluate the susceptibility to geological disasters.The automatic slope unit and the hydrological slope unit were compared and analyzed in the random forest and information volume random forest models.The results show that the area under the curve(AUC)values of the automatic slope unit evaluation results are 0.931 for the IV-RF model and 0.716 for the RF model,which are 0.6%(IV-RF model)and 1.9%(RF model)higher than those for the hydrological slope unit.Based on a comparison of the evaluation methods based on the two types of slope units,the hydrological slope unit evaluation method based on manual correction is highly subjective,is complicated to operate,and has a low evaluation accuracy,whereas the evaluation method based on automatic slope unit division is efficient and accurate,is suitable for large-scale efficient geological disaster evaluation,and can better deal with the problem of geological disaster susceptibility evaluation.
The Jiao-Liao-Ji Belt within the North China Craton had undergone a complex tectonic evolution,marked by extensive Paleoproterozoic magmatism that produced a diverse range of mafic to felsic mag-matic rocks.These events provide valuable geological records for understanding the tectonic evolution of the Jiao-Liao-Ji Belt.This study focuses on the Paleoproterozoic Chibaisong meta-gabbro in southern Jilin,investigating the source of mafic magma,petrogenesis,and tectonic setting through systematic petrological analysis,zircon U-Pb dating,and geochemical studies.The findings contribute to constraining the dynamic mechanisms of Paleoproterozoic extensional rifting in the Jiao-Liao-Ji orogenic belt.Geochemical data indi-cate that the samples exhibit low SiO2(47.99–50.66 wt.％),TiO2(0.75–3.20 wt.％),Nb(3.22–8.09 ppm),and Ta(0.22–0.51 ppm)contents,along with high TFeO3(11.97–15.82 wt.％)and MgO(5.67–12.66 wt.％)concen-trations.They also show low Nb/La ratios and high(Th/Nb)N values,consistent with the geochemical charac-teristics of tholeiitic basalts.The samples display low total rare earth element concentrations,weak or absent Eu anomalies,slight enrichment in light rare earth elements,relatively flat heavy rare earth element patterns,and depletion in Nb,Ta,and Ti.The meta-gabbro from southern Jilin exhibits geochemical similarities to Pa-leoproterozoic metamafic rocks from other regions of the Jiao-Liao-Ji Belt,resembling enriched mid-ocean ridge basalts(E-MORB)with Nb,Ta,and Ti depletion.Integration of previous studies and geochemical data suggests that the 2.16–2.10 Ga metamafic rocks in the Jiao-Liao-Ji Belt experienced contamination by older crustal material.These results indicate that the 2.16–2.10 Ga metamafic rocks are unlikely to be associated with island arc,continental arc,or mid-ocean ridge settings.Instead,they are more likely related to intraplate magmatism associated with continental rifting.
Evaluation of backfilling effectiveness plays a crucial role in the geological environment management and restoration of abandoned open-pit quarries,providing a scientific basis for subsequent greening efforts.Backfill soil,predominantly composed of silty clay,demonstrates high water retention capacity and elevated moisture content,leading to a pronounced resistivity contrast with the bedrock exposed by quarrying activities.To investigate the distribution of backfill soil subsurface and assess backfilling effectiveness in the study area,this study conducted a comprehensive geophysical investigation utilizing the high-density electrical resistivity tomography(ERT).A total of 19 ERT survey lines were deployed across three distinct areas in Liuyao Village,Huaibei City,Anhui Province,China.The inversion results,derived from both two-dimensional(2D)and three-dimensional(3D),reveal distinct electrical properties of the subsurface materials:the backfill soil layer shows low resistivity features,the fill stone layer exhibits medium to high resistivity,and the bedrock shows the highest resistivity.The 2D inversion results,from the data measured using the Wenner array effectively capture the spatial distribution and structural features of the backfill soil layer.The findings indicate a gradual east-west thinning of the clay layer within the quarry.Furthermore,the northern pit area exhibits a uniform distribution of backfill soil layer,indicative of effective backfilling operations.In contrast,the southern pit area lacks a well-defined clay layer,suggesting suboptimal backfilling effectiveness.
The large-scale acquisition and widespread application of remote sensing image data have led to increasingly severe challenges in information security and privacy protection during transmission and storage.Urban remote sensing image,characterized by complex content and well-defined structures,are particularly vulnerable to malicious attacks and information leakage.To address this issue,the author proposes an encryption method based on the enhanced single-neuron dynamical system(ESNDS).ESNDS generates high-quality pseudo-random sequences with complex dynamics and intense sensitivity to initial conditions,which drive a structure of multi-stage cipher comprising permutation,ring-wise diffusion,and mask perturbation.Using representative GF-2 Panchromatic and Multispectral Scanner(PMS)urban scenes,the author conducts systematic evaluations in terms of inter-pixel correlation,information entropy,histogram uniformity,and number of pixel change rate(NPCR)/unified average changing intensity(UACI).The results demonstrate that the proposed scheme effectively resists statistical analysis,differential attacks,and known-plaintext attacks while maintaining competitive computational efficiency for high-resolution urban image.In addition,the cipher is lightweight and hardware-friendly,integrates readily with on-board and ground processing,and thus offers tangible engineering utility for real-time,large-volume remote-sensing data protection.
The detection of unexploded ordnance(UXO)is critical for battlefield clearance and civilian safety.This study presents the development of a software for automated simulation based on the high frequency structure simulator(HFSS)and the MATLAB application programming interface(API),which together form the HFSS-MATLAB-API.This interface enables control over HFSS and conducts frequency-domain electromagnetic simulations for various types of UXO,including anti-tank mines,grenades,mortars,and aerial bombs.The software automates modelling,solving,data extraction,and analysis through MATLAB,enhancing the efficiency of simulation and enabling flexible settings for target models,coil parameters,and subsurface media.The research utilizes numerical simulation methods to analyze the response characteristics of different types of UXO in electromagnetic induction and explores the impact of the rotation angle of the target model on the attenuation characteristics of the measurement line.The results indicate that the electromagnetic response of UXO varies significantly based on type,burial depth,and spatial orientation.The findings provide a theoretical foundation for the electromagnetic detection,target identification,and classification of UXO.
To investigate the Early Cretaceous magmatic activity and tectonic evolution in the Xiaoqinggou mining area of Jilin Province,the authors conducted petrological,geochemical,and isotopic analyses of diorite rocks.The findings show that the zircons exhibit distinct magmatic growth zoning,confirming their magmatic origin.LA-ICP-MS zircon U-Pb dating yielded an age of 128.7±2.2 Ma,corresponding to Early Cretaceous.Geochemical data reveal that the diorite rocks are high and potassium but low in sodium,classifying them within the peraluminous,high-potassium calc-alkaline series.They are enriched in large ion lithophile elements(e.g.,K,Ba and Rb)and depleted in high field strength elements(e.g.,Nb,Ta and Ti).The δEu values range from 1.07 to 1.14,indicating weakly positive Eu anomalies.Regional comparisons and integrated studies suggest that the Xiaoqinggou diorite rocks formed in a volcanic island arc setting,associated with the westward subduction of the Paleo-Pacific plate beneath the Eurasian continent in an extensional tectonic environment.This study provides a theoretical basis for further exploration of the Xiaoqinggou deposit.
There is an issue of groundwater overexploitation in Ningjiang District,Songyuan City,Jilin Province,which has led to land subsidence.To investigate the influence of hydrological elements on surface deformation in Ningjiang District,surface deformation data were obtained by the small baseline subset interferometry synthetic aperture radar(SBAS-InSAR)technique.Initially,Sentinel-1B data were utilized to observe surface deformation in Ningjiang District from 2017 to 2021 with SBAS-InSAR.Subsequently,the geographical detector was employed to quantitatively assess the relationship between land subsidence and its influencing factors.Furthermore,multivariate singular spectrum analysis(M-SSA)was employed to identify periodic fluctuations in surface deformation and groundwater level,revealing the temporal lag between fluctuations in surface deformation and groundwater level.The findings demonstrate that the distance to water bodies accounts for the largest share of subsidence variation,with subsidence shaped by the combined impact of many factors.The results of interaction detection indicate that the interplay between the distance to water bodies and precipitation exhibits the most significant joint explanatory capacity for surface deformation.The observed seasonal cyclical fluctuations in groundwater level and surface deformation indicate a substantial influence of groundwater on surface deformation in the Ningjiang District.
The Longfengshan structural belt lies in the southern Changling Depression.The Yingcheng Formation is the primary gas-bearing unit.The Yingcheng Formation has low permeability and contains deep,tight gas that is challenging to extract.Industrial gas flow has been achieved from the B218 and B220 well blocks in the sandstone layer of the first member of Yingcheng Formation(Ying Ⅰ),indicating the potential of this sandstone group for gas production.Although oil and gas are widely distributed in the Ying Ⅰ sandstone layer,production capacity varies significantly across the formation.into six sublayers.Drilling,logging,and laboratory testing data were integrated to subdivide the Ying Ⅰ sandstone layer into six sublayers.Core and well logging analyses indicate a braided river delta depositional environment.Data and seismic inversion identify the Ying Ⅰ-5 sublayer as the primary exploration target.The effective reservoir in the eastern fan body,where porosity ranges from 5％to 13％and maximum effective thickness reaches 34 m.This study basis for optimizing well placement and estimating gas reserve parameters in the Ying Ⅰ sandstone layer of the Longfengshan area.The findings can guide the development of other tight gas reservoirs.
