Expansive soil slopes widely encountered in transportation infrastructure are highly susceptible to rainfall-induced instability, and geobag reinforcement has recently been applied as a flexible technique for slope stabilization. Existing studies on geobag-reinforced slopes mainly focus on macroscopic stability, while particle-scale analyses considering moisture-induced swelling and strength degradation remain limited. In this study, a discrete element model of expansive soil slopes was developed using the MatDEM framework to investigate the behavior of geobag-reinforced slopes under rainfall infiltration and surcharge loading. Microscopic soil parameters were calibrated using laboratory test data, and rainfall infiltration, particle swelling, and moisture-dependent strength reduction were incorporated into the model. The results show that rainfall infiltration forms saturated, wetted, and unsaturated zones and induces progressive shallow sliding in untreated slopes. Geobag reinforcement reduces rainwater penetration and restricts soil particle movement, thereby improving slope stability. Increasing geobag width and slope ratio enhances the reinforcement effect, whereas increasing the expansive soil cover thickness leads to larger slope deformation. In addition, a simplified stability analysis model combining infinite slope theory with the mechanical behavior of geobag retaining structures was developed to evaluate the stability of reinforced slopes. The findings provide insight into the reinforcement mechanism and stability behavior of geobag-reinforced expansive soil slopes under rainfall conditions.

The Tonglushan ore field in the Edong district of the western Middle-Lower Yangtze River Metallogenic Belt hosts a major Cu-Fe-Au skarn system, yet the emplacement ages, petrogenesis, and metallogenic significance of its spatially distributed intrusions remain poorly constrained. We present integrated whole-rock geochemistry, zircon U-Pb geochronology, zircon trace-element and Hf isotopic data, and apatite Sr-Nd isotopic compositions for quartz monzodiorite porphyry, quartz monzodiorite, quartz diorite, and associated mafic microgranular enclaves (MMEs) from the Tonglushan ore field, together with supplementary data for the Dajipu quartz diorite from the Yangxin pluton. Zircon U-Pb ages indicate that the intrusive phases and their MMEs were emplaced synchronously at ca. 142-140 Ma. These rocks display high-K calc-alkaline affinities and weakly adakitic signatures, with elevated Sr/Y and (La/Yb)N ratios, and have isotopic compositions resembling those of coeval Krich mafic rocks in the MLYRB, suggesting derivation from an enriched lithospheric mantle source followed by extensive fractional crystallization. Petrographic and geochemical evidence indicates that the MMEs formed through injection and incomplete mixing of mafic and felsic magmas, with mafic recharge supplying heat, metals, and volatiles to the evolving system. Zircon oxybarometry and zircon-based water-content estimates further show that the more strongly mineralized intrusions were generated from relatively hydrous, oxidized, and more evolved magmas, whereas the relatively barren Zhengjiawan quartz diorite records lower H2O contents and lower to more variable oxidation states. These results indicate that magma fertility in the Tonglushan ore field was jointly controlled by enriched mantle source characteristics, fractional crystallization, mafic recharge, and the development of hydrous and oxidized magmatic systems. More broadly, our results highlight whole-rock and zircon geochemical parameters as useful indicators of intrusion fertility and magmatic controls on Cu-Fe-Au mineralization in arc-related systems.

Skarn systems commonly preserve mineral-scale geochemical signatures that can be used to constrain oreforming processes and provide effective exploration vectors. In this study, we combine in situ phlogopite RbSr geochronology with detailed petrography and in situ major and trace element analyses of garnet from different skarn zones to evaluate fluid evolution and geochemical vectoring indicators at the Tonglushan Cu-Fe-Au skarn deposit. Ore-related phlogopite yields a Rb-Sr isochron age of 136.8 +/- 4.2 Ma, indicating that skarn mineralization was temporally associated with Early Cretaceous magmatic activity. Garnet compositions define a systematic transition from dominantly grossular-rich assemblages in skarnified marble and endoskarn (with minor Fe-enriched domains) toward Fe-rich andradite in ore-bearing exoskarn. Variations in high field strength elements abundances, rare earth elements (REE) patterns, REE-Y relationships and Y/Ho ratios record a progressive evolution of the hydrothermal system from a low water/rock ratio, relatively closed regime toward a higher-flux, more open hydrothermal system characterized by intense fluid-rock interaction. The development of oscillatory zoning in exoskarn garnet provides independent microtextural evidence for episodic high-flux fluid infiltration during the main mineralization stage. Increasing Fe3+ contents and strong positive Eu anomalies further reflect the coupled evolution of oxygen fugacity, fluid acidity and Cl- activity during skarn formation, which facilitated efficient Cu-Fe-Au transport and precipitation. The ore-bearing exoskarn stage represents the peak of system openness and metallogenic efficiency. Elevated andradite contents, pronounced oscillatory zoning, light rare earth elements enrichment, consistent positive Eu anomalies on chondrite-normalized REE patterns, and Y/Ho behavior relative to the intrusive whole-rock Y/Ho field are identified as mineralogical and geochemical vectors toward ore-bearing zones. These results demonstrate that garnet geochemistry provides an effective geochemical framework for exploration targeting in the Tonglushan deposit and similar intrusionrelated skarn systems.

Skarn deposits host economically significant mineralization closely associated with magmatic processes. However, the key magmatic factors controlling metal associations remain poorly constrained. The JiguanzuiTaohuazui Cu-Au deposit, located in the Edong ore district, eastern China, hosts two primary types of skarn mineralization: Cu-Fe-Au and Au-Cu. To investigate the magmatic controls on these mineralization types, zircon and apatite samples from associated intrusions (Cu-Fe-Au mineralized quartz monzodiorite, Au-Cu mineralized quartz diorite, and ore-barren diorite) were analyzed using laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) and electron microprobe. Our results indicate that the oxygen fugacity of the orerelated intrusions (quartz monzodiorite and quartz diorite) is significantly higher than that of the ore-barren diorite. This variation in oxygen fugacity is likely attributed to distinct fractional crystallization processes: amphibole-dominated fractionation in the fertile intrusions versus plagioclase-dominated fractionation in the ore-barren diorite. Notably, the Cu-Fe-Au-related quartz monzodiorite, which crystallized from a more oxidized magma, exhibits a higher degree of evolution compared to the Au-Cu-related quartz diorite. Zircon trace elements and saturation temperatures suggest that the quartz monzodiorite magma had higher water content than that of the quartz diorite and barren diorite. Furthermore, apatites in ore-related intrusions exhibit lower Cl contents (0.26-0.79 wt%) and elevated F/Cl ratios (2.66-11.44) relative to ore-barren diorites, which display Cl contents of 0.76-1.24 wt% and F/Cl ratios of 1.16-2.48. The depletion of chlorine in the ore-related apatite suggests that fluid exsolution may have occurred. Collectively, high magmatic oxygen fugacity and high water content were the critical factors triggering the formation of the Jiguanzui-Taohuazui Cu-Fe-Au and Au-Cu mineralization.

Precise characterization of pore-scale heterogeneity and mineralogical constraints is crucial for predicting CO2 sequestration performance in low-permeability reservoirs. In this study, we integrated pristine sealed-core data with multi-scale experimental techniques, including MICP, CRMI, NMR, and sensitivity flow tests, to investigate the Chang 4+5 Member in the Ordos Basin, focusing on the comparative behavior of extra-low and ultra-low permeability facies.The results reveal a pronounced bifurcation in microscopic pore architecture. Although pore sizes remain comparable, the ultra-low permeability facies exhibits a significantly higher pore-to-throat (P/T) ratio (up to 1231.8) and a diminutive median throat radius (R50 = 0.026μm) relative to the extra-low permeability facies (R50 = 0.527μm), which severely restricts fluid flow and impairs permeability. Sensitivity evaluations demonstrate that velocity-induced formation damage is the dominant impairment mechanism, driven by kaolinite migration, while acid and water sensitivities are regulated by chlorite precipitation and I/S mixed-layer hydration.We further propose a semi-quantitative geometric model to elucidate the geometrical amplification effect, where the fourth-power relationship between flow conductance and throat radius makes ultra-low permeability zones disproportionately vulnerable to even marginal mineral expansion or precipitation. Based on these findings, we suggest a facies-specific sequestration strategy: prioritizing dissolution-enhanced extra-low permeability intervals for primary storage while using ultra-low permeability zones as internal hydraulic baffles to optimize plume migration and secondary trapping security. This study provides a scientific foundation for optimizing injection parameters and ensuring long-term containment security in highly heterogeneous low-permeability systems.

The collapse and damage of inclined rock and soil masses caused by subsidence in mining goaf areas pose serious geological risks.These hazards are not only highly destructive and widespread but also occur suddenly,endangering mine operations and human safety.Traditional stability evaluation methods often overlook the variations in thrust caused by the settlement of goaf blocks at the leading edge locking section,making it difficult to dynamically evaluate mine slope stability.This limits the effectiveness of early warning and prevention strategies for geological disasters in mines.To address these challenges,this study introduces a dynamic stability evaluation method tailored for mine slopes,targeting the landslide formation mechanisms in mining goaf areas.The first involves constructing a settlement analysis model for the goaf areas to calculate the settlement range of the rock mass above the goaf and the resulting impact forces.The proposed model helps analyze how settlement affects the stress field of slopes.Therefore,the traditional unbalanced thrust method is modified.During stability evaluation,the safety factor of the slope's locking section under the subsidence effect of the goaf was analyzed.When the safety factor of the locking section(SFk)is less than 1,the residual strength needs to be considered to calculate the overall safety factor(SF)of the slope.If SFk exceeds 1,the section remains intact,allowing the SF to be calculated under original working conditions.The Jiweishan case in Wulong,Chongqing,illustrates the limitations of traditional methods,which neglected the settlement and locking section damage,overestimating the safety factor at 1.355.The improved method,accounting for these effects,found the locking section's safety factor at 0.667,indicating damage and an overall landslide safety factor of 0.979.This finding aligns with the observed failure and instability mechanism of the mine goaf landslide.When the weight of the settlement slope at the rear edge is large,settlement causes instantaneous shear failure of the landslide locking section,substantially reducing the stability of the Jiweishan landslide.The settlement-horizontal displacement ratio(SHDR)of the slope is crucial in dynamic stability analysis for goaf areas.An SHDR greater than 0.73 indicates significant stability variations,leading to instability under working conditions previously deemed safe.This improved method offers a more accurate assessment of mine slope stability by considering goaf settlement and locking section damage,providing a valuable tool for managing similar geological disasters.

In the North China region, measures such as restricting groundwater extraction and promoting cross-basin water diversion have effectively alleviated the problem of excessive groundwater exploitation. Nevertheless, the continuous rise in groundwater levels may alter the mechanical properties of foundation soil layers, potentially leading to geotechnical hazards such as foundation instability and the uneven settlement of structures. This study employs FLAC3D software to simulate the displacement, deformation, and stress–strain behavior of buildings and their surrounding strata during the dynamic recovery of groundwater levels, aiming to assess the impact of this process on structural integrity. Research findings indicate that the maximum building settlement within the study area reaches 54.8 mm, with a maximum inter-column differential settlement of 8.9 mm and a peak settlement rate of 0.16 mm/day. In regions where differential settlement aligns with the interface between the floor slab and walls, tensile stress concentrations are observed. The maximum tensile stress in these zones increases progressively from 1.8 MPa to 2.19 MPa, suggesting a potential risk of tensile cracking in the concrete structures. The influence of groundwater level recovery on buildings exhibits distinct phase characteristics, and the response mechanisms of different lithological strata vary significantly. Therefore, particular attention should be given to the physical properties and mechanical behavior of strata that are highly sensitive to variations in moisture content. These findings hold significant reference value for the sustainable development and utilization of underground space in the North China region.

The diversity of topographic and geological conditions significantly affects the kinematics and failure mechanisms of reservoir-induced landslides, especially those with rear reservoirs, which remain understudied. Taking the Shuiyunshan slow-moving landslide as a case study, this study investigates its failure mechanisms through a combination of field investigations, InSAR monitoring, and numerical simulations. The results reveal that the landslide is primarily driven by effective rainfall accumulation in a rear concave catchment area and sustained infiltration and erosion from rear reservoirs. The rear concave catchment area, which is 1.04 times the volume of the landslide body, alters the infiltration process of atmospheric rainfall. Approximately 61.9

Many large-scale landslides have occurred along the active Pingding-Huama fault in Zhouqu segment, Gansu, China. To better understand the failure mechanisms of these landslides, we use the Yahuokou landslide as a detailed case study. Field investigation was conducted to retrace the kinematics of the landslide and corresponding timeline of triggering mechanics. Dynamic triaxial tests were conducted to quantify the effect of rainfall and rockfall load on the physical and mechanical character of the landslide materials with in-situ stress level. Numerical simulation was used to evaluate the landslide stability under rainfall and rockfall load. The results show that a smaller initial rockfall of the limestone blocks along the upper headscarp of the landslide triggered a series of larger failure events that propagated through the greater landslide complex. We proposed that continuous rainfall and this rockfall load increased the pore water pressure and significantly reduced the shear strength parameters of the sliding materials. In addition, the rockfall load destroyed the structure of the shallow soil with buried depth <5 m, increasing the pore volume and water absorption capacity, which may cause the water content of the soil to exceed its liquid limit, and finally promoted plastic flow. Stability calculation further showed that rainfall alone was not sufficient to induce the landslide failure, but rather the coupled action of rainfall and rockfall load was needed. The conclusions drawn from this study outline complex failure mechanics of the Yahuokou landslide and may be helpful in understanding the fault-zone landslides widely distributed along the Pingding-Huama fault.

Background: Primary biliary cholangitis (PBC) is a chronic biliary autoimmune liver disease characterized by intrahepatic cholestasis. Swertia mussotii Franch. (SMF) is a Tibetan medicine with hepatoprotective and anti-inflammatory activities. In this study, the therapeutic effect and potential mechanisms of SMF on PBC were investigated by bioinformatics analysis and in vitro experimental validation, with the aim of promoting the progress of SMF and PBC research. Methods: We first explored the therapeutic effects and key targets of SMF on PBC using a network pharmacology approach, further screened the core targets using the GSE79850 dataset, and finally validated the results using molecular docking techniques and in vitro experiments. Results: By bioinformatics analysis, we identified core targets of SMF for PBC treatment (STAT3, JAK2, TNF-alpha, and IL-1 beta) and important signaling pathways: JAK-STAT, TNF, and PI3K-AKT. The molecular docking results showed that the significant components of SMF had good binding properties to the core targets. In vitro experiments showed that SMF extracts improved the extent of epithelial-mesenchymal transition in human intrahepatic biliary epithelial cells and had a significant reversal effect on epithelial-mesenchymal transition process markers and potential targets in PBC. Conclusion: SMF may exert its therapeutic effects on PBC by acting on important targets such as STAT3, JAK2, TNF-alpha, IL-1 beta, Vimentin, and E-cadherin and the pathways in which they are involved.

With the construction of the Three Gorges Reservoir dam, frequent reservoir landslide events have been recorded. In recent years, multi-row stabilizing piles (MRSPs) have been used to stabilize massive reservoir landslides in China. In this study, two centrifuge model tests were carried out to study the unreinforced and MRSP-reinforced slopes subjected to reservoir water level (RWL) operation, using the Taping landslide as a prototype. The results indicate that the RWL rising can provide lateral support within the submerged zone and then produce the inward seepage force, eventually strengthening the slope stability. However, a rapid RWL drawdown may induce outward seepage forces and a sudden debuttressing effect, consequently reducing the effective soil normal stress and triggering partial pre-failure within the RWL fluctuation zone. Furthermore, partial deformation and subsequent soil structure damage generate excess pore water pressures, ultimately leading to the overall failure of the reservoir landslide. This study also reveals that a rapid increase in the downslope driving force due to RWL drawdown significantly intensifies the lateral earth pressures exerted on the MRSPs. Conversely, the MRSPs possess a considerable reinforcement effect on the reservoir landslide, transforming the overall failure into a partial deformation and failure situated above and in front of the MRSPs. The mechanical transfer behavior observed in the MRSPs demonstrates a progressive alteration in relation to RWL fluctuations. As the RWL rises, the mechanical states among MRSPs exhibit a growing imbalance. The shear force transfer factor (i.e. the ratio of shear forces on pile of the nth row to that of the first row) increases significantly with the RWL drawdown. This indicates that the mechanical states among MRSPs tend toward an enhanced equilibrium. The insights gained from this study contribute to a more comprehensive understanding of the failure mechanisms of reservoir landslides and the mechanical behavior of MRSPs in reservoir banks.

[Objective]Debris flows caused by short-term heavy rainfall are a frequent occurrence in Zhejiang Province and pose a serious threat to the lives and property of mountain residents.Therefore,the assessment of debris flow risk has significant theoretical and practical value for disaster management in the province.To investi-gate the hazard of debris flows caused by short-term heavy rainfall,the Wushankeng watershed was selected for re-search by means of field investigations and remote sensing interpretations,combined with numerical simulation.[Methods]The obtained results revealed the geological environment,development characteristics and disaster chain formation mechanism of debris flow in the watershed.The RAMMS numerical simulation software was used to simulate the debris flow depth and the velocity under different rainfall frequencies,and the hazard assessment was carried out based on these movement characteristics.[Results]The results of the research indicated that loose rock and soil at steep slopes experienced shallow landslides under the effect of short-term heavy rainfall.Then,under the control of the slope and gully topography,it migrated to the mouth of the gully,and during the movement,the scale of the debris flow was expanded by erosion.Finally,it was deposited in the wide and gentle accumulation area.As the intensity of the study area rainfall increased to a 50-year or 100-year occurrence,the scale of the deb-ris flow increased,but it was limited by the gentle topographical conditions of the accumulation area,and it was un-able to effectively discharge at the mouth of the gully.However,the indicators of mud depth and flow velocity in the resident areas upstream of the accumulation fan significantly increased,and the area of high-intensity areas in the accumulation area increased from 7 276 m2 to 12 660 m2.Combined with the results of debris flow activity anal-ysis,the combination of rainfall monitoring in the formation area,constructing rigid,flexible,or slit check dams in the circulation area of the main channel,and setting up drainage channels in the accumulation area can effectively protect the lives and properties of residents.[Conclusion]The research results can provide reference for debris flow hazard assessment and engineering treatment in the study area and Zhejiang Province.

The Turkey–Syria earthquakes that occurred on February 6, 2023, have caused significant human casualties and economic damage. Emergency services require quick and accurate assessments of widespread building damage in affected areas. This can be facilitated by using remote sensing methods, specifically all-day and all-weather Synthetic Aperture Radar (SAR). In this study, we aimed to improve the detection of building anomalies in earthquake-affected areas using SAR images. To achieve this, we employed Recurrent Neural Network (RNN) to train coherence time series and predict co-seismic coherence. This approach allowed us to generate a Damage Proxy Map (DPM) for building damage assessment. The results of our study indicated that the estimated proportion of building damage in Kahramanmaras was approximately 24.08%. These findings were consistent with the actual damage observed in the field. Moreover, when utilizing the mean and standard deviation of coherence time series, our method achieved higher accuracy (0.761) and a lower false alarm rate (0.136) compared to directly using coherence with only two views of SAR data. Overall, our study demonstrates that this method provides an accurate and reliable approach for post-earthquake building damage assessment.

Objective The resurrections of ancient landslide deposits are one of the primary geological hazards in the Qinghai-Tibet Plateau and surrounding areas of China and pose significant safety threats to major transportation and water conservancy projects under construction in western China. Therefore, it is crucial to investigate the formation and evolution mechanism of ancient landslides and evaluate the stability of their deposits. This research can provide theoretical support for the early recognition and prevention of the resurrection of ancient landslide deposits. Methods The ancient landslide deposits in Jiangdingya, Zhouqu County, Gansu Province, have experienced local resurrection several times in the past decade, creating severe threats to the lives and property of local people by blocking the Bailong River. To determine the morphology and structural characteristics of the ancient Jiangdingya landslide deposits, this study utilized field investigations and unmanned aerial vehicle (UAV) tilt photography. Based on this, the evolution mechanism and dynamic process of the landslide were analysed, and the stability of the deposits was qualitatively evaluated using InSAR deformation data. Results The results show that the ancient landslide at Jiangdingya is a typical large-scale earthquake landslide, with its sliding body located in a downslope position in three directions, forming a multilevel stepped deposit shape. The dynamic process of an ancient landslide under seismic loads can be divided into several stages, including vibration and cracking in the upper-middle part, shearing and landslide initiation in the front edge locking segment, tearing and landslide acceleration in the rear edge, obstruction and landslide deceleration in the front edge, and stabilization. Conclusion Due to the overall downwards movement of the ancient landslide under seismic loads, there are a large number of intact rock masses in the upper deposits, which are relatively stable. However, the middle and lower deposits are mostly composed of weak structures such as fault fracture zones and fragmented rock masses, which have poor stability and are highly likely to resurrect in the future. This study provides important insights into the formation and evolution of ancient landslides and the evaluation of their stability, which can help prevent future landslides and protect local communities.

The construction of the Three Gorges Reservoir dam in China has led to an increase in reservoir landslide events. To mitigate these geohazards, multiple rows of stabilizing piles (MRSP) have been employed to stabilize massive reservoir landslides. This study utilizes centrifuge and numerical modeling to investigate the behavior of unreinforced landslides and MRSP-reinforced landslides in reservoir areas. The failure mechanisms of unreinforced landslides, as well as the mechanical behavior and stabilizing mechanisms of MRSP under reservoir water level (RWL) fluctuations, are examined. The results indicate that elevated downward seepage forces contribute to pre-failure sliding, but are not the sole cause of catastrophic failure. Instead, rapid pre-failure sliding leads to soil particle compression and crushing in the saturated sliding zone, resulting in excess pore water pressure and accelerated overall failure. This excess pore water pressure-dependent mechanism explains the observed “step-like” deformation pattern and rapid failure pattern in reservoir landslides. Furthermore, the study reveals the formation of soil arches between adjacent MRSP groups, causing stress concentration on boundary columns and necessitating reinforcement. The finding challenges traditional one-dimensional load transfer ratios, advocating for a two-dimensional approach that accounts for variations across rows and columns. Notably, the study also highlights significant variations in load transfer laws within MRSP under different RWL operations, emphasizing the need for a more nuanced understanding of MRSP behavior.

Red clay landslides are widely distributed worldwide, resulting in severe loss of life and property. Although rainfall-induced red clay slopes have received extensive attention, the role of cracks in the evolutionary process of red clay slopes and their connection to failure mechanisms is still poorly understood. A comprehensive approach integrating field investigation, laboratory tests, and numerical simulations was conducted to study the 168 red clay landslides in Xinshao County, China. The results show that red clay is prone to forming cracks at high moisture content due to its low swelling and high shrinkage properties. The failure mode of red clay slopes can be summarized in three stages: crack generation, slope excavation, and slope failure. Furthermore, the retrospective analysis and numerical simulations of the typical landslide in Guanchong indicated that intense rainfall primarily impacts the shallow layer of soil within approximately 0.5 m on the intact slope. However, cracks change the pattern of rainfall infiltration in the slope. Rainwater infiltrates rapidly through the preferential channels induced by the cracks rather than uniformly and slowly from the slope surface. This results in a significant increase in both the depth of infiltration and the saturated zone area of the cracked slope, reaching 3.8 m and 36.2 m 2 , respectively. Consequently, the factor of safety of the slope decreases by 13.4% compared to the intact slope, ultimately triggering landslides. This study can provide valuable insights into understanding the failure mechanisms of red clay slopes in China and other regions with similar geological settings.

A recent mineral exploration programme in the East Kunlun Orogen (EKO) identified the new Hacipushanbei Pbpolymetallic deposit. The ores are hosted in faults in granitic rocks and are marked by high Pb grades up to 22.5 %. U-Pb dating of calcites associated with mineralization yields an intersection age of 208 +/- 9 Ma, indicating a late Triassic mineralization event. Fluid -inclusion analysis reveals that the ore-forming fluids are characterized by medium -to -high temperature, medium-to-low salinity, and low density. Fluid boiling or immiscibility during ore -formation is also noted. Three sub -generations of pyrite (Py1-1, Py1-2, and Py2) are recognized in the early mineralization stages. In situ trace element analysis shows low Co and Ni contents in Py1-1 and Py1-2 but high contents in Py2. Conversely, Au and As concentrations are the highest in Py1-2. Variations in As contents are systematically coupled with Au. Additionally, sphalerite in the second stage contains higher amounts of Co, Cu, Cd, and In, via a wide range of isomorphic elemental substitutions of X4+(Sn4+ and Ge4+) + X3+(In3+, Sb3+, and Ga3+) + X+(Ag+ and Cu+) <-> 4Zn2+ and the associated In enrichment. The average delta 34S values of in situ and single minerals of Py1-1, Py1-2, Py2, Sp2, Ccp2, and Gn3 are 2.3 %o, 3.3 %o, 2.6 %o, 2.4 %o, 2.2 %o, and 0.9 %o, respectively. These values display a trend of initial increase and then decrease, consistent with thermodynamic fractionation. These data collectively indicate that the ore-forming fluid originated from a deep-seated magma chamber, and subsequent fluid immiscibility led to the formation of high -grade ores. Given the conspicuous association of Pb-polymetallic deposits with magmatic rocks in the EKO, we envisage that our genetic model can be applied, to some extent, to evaluate the potential of some mineral exploration targets.

Hainan, a well-known center of tropical agricultural production in south China, has received little attention regarding groundwater fluoride contamination. This study investigates the occurrence of fluoride in the western coastal area of Hainan Island and discusses factors affecting groundwater fluoride contamination in various aquifers and areas with different land-use types using hydrochemistry and multivariate statistical analysis. A total of 100 groundwater samples were collected from the western coastal area of Hainan Island. The results show that the groundwater fluoride concentration is as high as 4.18 mg/L and that F−-high (>1 mg/L) groundwater accounts for 9% of total groundwater. The proportion of F−-high fissure water is about two times that of F−-high pore water. Among the different land-use types, the proportion of F−-high groundwater from highest to lowest is as follows: bare land > cultivated land > woodland > construction land > grassland. The main factor affecting fluoride in pore water is the leaching of fluorine/aluminum-containing minerals such as phlogopite and calcite in the vadose zone, which is characterized by the co-enrichment of fluoride and aluminum in pore water. The leading cause of fluoride in fissure water is the leaching of fluorine-containing fertilizers, and continuous irrigation promotes the cation exchange of sodium, strontium, and calcium, which is characterized by the co-enrichment of fluoride with sodium and strontium in fissure water. Consequently, it is advised to minimize the excessive use of fluoride fertilizers and increase groundwater quality monitoring in order to decrease the emergence of F−-high groundwater in the western coastal area of Hainan Island.

In this paper, we investigated the significance of intergranular friction weakening on the dynamics of the Jiweishan rock avalanche. First, high-velocity-friction tests simulating the shearing between the surfaces of adjacent grains were conducted to obtain a model of friction weakening of grains inside granular debris during transport. Then, the model was incorporated into an improved discrete element method that could consider intergranular friction weakening to simulate the dynamic course of the Jiweishan rock avalanche. Finally, we compared the results from the numerical models with and without granular friction weakening to investigate its influence on the dynamics of the rock avalanche. The results of the high-velocity-friction tests revealed that intergranular shearing could significantly reduce the friction of granular surfaces; this was determined by the overall results for normal stress, shear velocity and shear displacement. Our modeling results indicated that the rapid increase in normal stress and shear velocity were the main reasons for the rapid decrease in intergranular friction coefficients in the falling and collision stages. However, the friction coefficients further decreased due to increasing shear displacement between rock debris in the flowing stage. Furthermore, obvious intergranular friction coefficient distribution characteristics in rock avalanche deposits could be observed from our modeling; they tended to decrease with increased depth in the deposit and increasing distance from the source. With intergranular friction weakening, a faster velocity (-10.0-15.5 m/s) and a longer transport time (-12-44 s) of the rock debris were modeled due to the lower frictional energy consumption caused by intergranular friction weakening. Finally, the transport distance considering intergranular weakening was -395-711 m longer than that without weakening. Further analysis showed that intergranular friction weakening may be applied to explain the high mobility of rock avalanches. The results of our study may improve predictions of the speed and travel distance, and consequently the risk assessment, of widely distributed rock avalanches worldwide.

Due to the influence of atmospheric phase delays and terrain fluctuation in complex mountainous areas, traditional PS-InSAR technology often fails to select enough measurement points (MPs) and loses effective MPs during phase unwrapping. To solve this problem, this paper proposes an adaptive network construction algorithm, which combines the permanent scatterer (PS) points with the distributed scatterer (DS) points. Firstly, to ensure the extraction quality of the DS points, the covariance matrix of DS points is estimated robustly. Secondly, based on the traditional Delaunay triangulation network, an adaptive network construction method is proposed, which can adaptively increase edge redundancy and network connectivity by considering the edge length, edge coherence, edge number, and spatial distribution. Finally, a total of 31 RADARSAT-2 SAR images that cover the Zongling landslide group in Guizhou Province were used to prove the effectiveness of proposed method. The results show that the quantity of available DS points can be increased by 23.6%, through the robust estimation of the covariance matrix. In addition, it is demonstrated that the proposed network construction algorithm can balance the number, distribution, and quality of edges in the dense and sparse areas of MPs adaptively. This adaptive network construction approach can maintain good connectivity and avoid losing effective MPs to the greatest extent, especially when the scattering points are far away from the reference points. In short, the proposed algorithm improves the number of effective MPs and accuracy of phase unwrapping.