Search Results (74)

The Pearl River Mouth Basin is a significant hydrocarbon basin in the northern part of the South China Sea, where deep hydrocarbon exploration has become increasingly important research in recent years. However, the current understanding of the source-to-sink and depositional systems of the Paleogene Zhuhai Formation is still limited, which restricts the exploration and discovery of large-scale sand bodies. Based on core observation, heavy mineral analysis, and well-seismic integrated analysis, this paper clarifies the development of a fan delta-tidal flat depositional and the source-to-sink systems of the Zhuhai Formation. The bedrock in the source region primarily consists of granite, Mesozoic sandstone, and tuff. The source region is divided into five parts (A1–A5), with seven main valleys (V1–V7) developed, supplying sediments to five depositional areas (S1–S5). Additionally, a fault-slope type coupled valley–fan depositional model is established for the study area, revealing the spatiotemporal distribution and main controlling factors of the fan delta system in a steeply dipping boundary fault environment. Catchment area, valley length, and cross-sectional area show a strong positive correlation with sedimentary system scale. Increased elevation difference enhances sediment transport potential energy, while reduced width-to-depth ratio strengthens hydrodynamic forces, promoting sedimentary sand body development and sedimentary system expansion. Full article

This study aims to investigate hydrogeochemical characteristics and groundwater quality in the Bashang Area in Chengde and to discuss factors controlling the groundwater quality. A total of 91 groundwater samples were collected and a fuzzy synthetic evaluation (FSE) method was used for assessing groundwater quality. Results show the groundwater chemistry in the study area is predominantly characterized by HCO₃⁻-Ca type waters. Rock weathering processes dominate the hydrogeochemical processes within the study area, while also being influenced by evaporation and concentration effects. The results of the fuzzy evaluation indicate that 94.5% of groundwater samples are of good quality and suitable for drinking (Classes I, II, and III), while 5.5% are of poor quality and unsuitable for drinking (Class IV). Among these, bedrock fissure water exhibited superior quality. Within clastic rock pore water, elevated levels of NO₃⁻ and F⁻ ions were observed in certain localized areas. The exceedance of NO₃⁻ concentrations stems from agricultural expansion, where the application of nitrogen fertilizers constitutes the primary driver of local nitrate pollution. Excessive F⁻ levels correlate with the region’s indigenous geological background. Fluoride-bearing minerals such as fluorite and biotite are widely distributed throughout the study area. Intensive evaporation concentrates groundwater, while the region’s slow groundwater flow facilitates the accumulation and enrichment of F⁻ within aquifers. Full article

In the field of engineering construction design, slope instability near water bodies remains a significant challenge. This issue is influenced by various factors, including fluid dynamics and external load disturbances. This study focuses on the design and stability evaluation of the slope in the Sejiang deformation area of the Baala Hydropower Station, applying three advanced techniques: PS-InSAR remote sensing for dynamic slope deformation data, FLAC3D stability simulation for numerical analysis of slope stability, and FLOW-3D wave calculation for quantifying secondary wave effects caused by potential landslides. By integrating these technologies, the study provides a multi-dimensional, quantitative evaluation of the secondary disasters triggered by landslides in this region. The findings are as follows: (1) The slope in the deformation zone exhibits a long-term “stable-creep” evolution, characteristic of a “stable-creep landslide” type; (2) Sliding failure primarily occurs along the interface between the bedrock and overburden layer due to shear deformation; (3) When the deformation body, with a volume of 2.1 million cubic meters, slides into the water at a velocity of 24 m/s, the calculated maximum water level height on the opposite bank reaches approximately 2925 m, near the top elevation of the dam, but still within the project’s preset safety threshold. The design methodologies and conclusions drawn from this study offer valuable insights for evaluating and designing the stability of near-water slopes in other hydropower stations. Full article

The precise characterization of surface rupture zones and associated co-seismic displacement fields from large earthquakes provides critical insights into seismic rupture mechanisms, earthquake dynamics, and hazard assessments. Stereo-photogrammetric digital elevation models (DEMs), produced from high-resolution satellite stereo imagery, offer reliable global datasets that are suitable for the detailed extraction and quantification of vertical co-seismic displacements. In this study, we utilized pre- and post-event WorldView-2 stereo images of the 2024 Ms7.1 Wushi earthquake in Xinjiang to generate DEMs with a spatial resolution of 0.5 m and corresponding terrain point clouds with an average density of approximately 4 points/m². Subsequently, we applied the Iterative Closest Point (ICP) algorithm to perform differencing analysis on these datasets. Special care was taken to reduce influences from terrain changes such as vegetation growth and anthropogenic structures. Ultimately, by maintaining sufficient spatial detail, we obtained a three-dimensional co-seismic displacement field with a resolution of 15 m within grid cells measuring 30 m near the fault trace. The results indicate a clear vertical displacement distribution pattern along the causative sinistral–thrust fault, exhibiting alternating uplift and subsidence zones that follow a characteristic “high-in-center and low-at-ends” profile, along with localized peak displacement clusters. Vertical displacements range from approximately 0.2 to 1.4 m, with a maximum displacement of ~1.46 m located in the piedmont region north of the Qialemati River, near the transition between alluvial fan deposits and bedrock. Horizontal displacement components in the east-west and north-south directions are negligible, consistent with focal mechanism solutions and surface rupture observations from field investigations. The successful extraction of this high-resolution vertical displacement field validates the efficacy of satellite-based high-resolution stereo-imaging methods for overcoming the limitations of GNSS and InSAR techniques in characterizing near-field surface displacements associated with earthquake ruptures. Moreover, this dataset provides robust constraints for investigating fault-slip mechanisms within near-surface geological contexts. Full article

Artisanal and small-scale gold mining (ASGM) poses significant environmental challenges globally, particularly due to mercury (Hg) use. As an example, in Ecuador, Hg use still persists, despite its official ban in 2015. This study investigated the geogenic and anthropogenic contributions of potentially toxic elements (PTEs) in the Ponce Enriquez Mining District (PEMD), a region characterized by hydrothermally altered basaltic bedrock and Au-mineralized quartz veins. To assess local baseline values and identify PTE-bearing minerals, a comprehensive geochemical, mineralogical, and petrographic analysis was conducted on bedrock and mineralized veins. These findings reveal distinct origins for the studied PTEs, which include Hg, As, Cu, Ni, Cr, Co, Sb, Zn, and V. Specifically, Hg concentrations in stream sediments downstream (up to 50 ppm) far exceed natural bedrock levels (0.03–0.707 ppm), unequivocally indicating significant anthropogenic input from gold amalgamation. Furthermore, copper shows elevated concentration primarily linked to gold extraction. Conversely, other elements like As, Ni, Cr, Co, Sb, Zn, and V are primarily exhibited to be naturally abundant in basalts due to the presence of primary mafic minerals and to hydrothermal alterations, with elevated concentrations particularly seen in sulfides like pyrite and arsenopyrite. To distinguish natural geochemical anomalies from mining-related contamination, especially in volcanic terrains, this study utilizes Upper Continental Crust (UCC) normalization and local bedrock baselines. This multi-faceted approach effectively helped to differentiate basalt subgroups and assess natural concentrations, thereby avoiding misinterpretations of naturally elevated element concentrations as mining-related pollution. Crucially, this work establishes a robust local geochemical baseline for the PEMD area, providing a critical framework for accurate environmental risk assessments and sustainable mineral resource management, and informing national environmental quality standards and remediation efforts in Ecuador. It underscores the necessity of evaluating local geology, including inherent mineralization, when defining environmental baselines and understanding the fate of PTEs in mining-impacted environments. Full article

Simulating potential glacier collapses can provide crucial support for local disaster prevention and mitigation efforts. The Xiaomagou Glacier in the Amnye Machen Mountains, Qinghai–Tibetan Plateau, has experienced five collapses in the past two decades. Field investigation and remote sensing observations indicate that the topography and bedrock characteristics of the Qushi’an No. 22 Glacier, which is 3.5 km south of the Xiaomagou Glacier, are similar to those of the Xiaomagou Glacier. More importantly, the mass movement of the Qushi’an No. 22 Glacier since 2018 closely resembles that of the Xiaomagou Glacier exhibited before its previous collapses. Therefore, in the context of rising temperatures, it is possible that the Qushi’an No. 22 Glacier will collapse in the near future. Based on remote sensing imagery and the glacier’s surface elevation changes, we reconstructed the 2004 collapse process of the Xiaomagou Glacier via numerical simulation. The key parameters of the mass flow model were optimized based on the actual deposition area of the 2004 collapse. The model with optimized parameters was then used to simulate the potential Qushi’an No. 22 Glacier collapse. Two collapse scenarios were set for the Qushi’an No. 22 Glacier. In Scenario 1, the lower half of the tongue detaches; in Scenario 2, the whole tongue detaches. Simulation results show that, in Scenario 1, the maximum mass flow depth is 72 m, the maximum mass flow speed is 51.6 m/s, and the deposition area is 5.40 × 10⁶ km²; in Scenario 2, the maximum mass flow depth is 75 m, the maximum mass flow speed is 59.7 m/s, and the deposition area is 6.32 × 10⁶ km². In both scenarios, the deposition area is much larger than that of the Xiaomagou Glacier 2004 collapse, which had a deposition area of 2.21 × 10⁶ km². The simulation results suggest that the Qushi’an No. 22 Glacier collapse could devastate the pastures and township roads lying in front of the glacier, seriously affecting local transportation and livestock farming; furthermore, it may deposit in the Qinglong River, forming a large, dammed lake. At present, the Qushi’an No. 22 Glacier remains in an unstable state. It is crucial to strengthen monitoring of its surface morphology, flow speed, and elevation. Full article

Suyukou Gully, located on the eastern slope of the Helan Mountains in northwest China, is a typical debris-flow-prone catchment characterized by a steep terrain, fractured bedrock, and abundant loose colluvial material. The area is subject to intense short-duration convective rainfall events, which often trigger destructive debris flows that threaten the Suyukou Scenic Area. To investigate the dynamics and risks associated with such events, this study employed the FLO-2D two-dimensional numerical model to simulate debris flow propagation, deposition, and hazard distribution under four rainfall return periods (10-, 20-, 50-, and 100-year scenarios). The modeling framework integrated high-resolution digital elevation data (original 5 m DEM resampled to 20 m grid), land-use classification, rainfall design intensities derived from regional storm atlases, and detailed field-based sediment characterization. Rheological and hydraulic parameters, including Manning’s roughness coefficient, yield stress, dynamic viscosity, and volume concentration, were calibrated using post-event geomorphic surveys and empirical formulations. The model was validated against field-observed deposition limits and flow depths, achieving a spatial accuracy within 350 m. Results show that the debris flow mobility and hazard intensity increased significantly with rainfall magnitude. Under the 100-year scenario, the peak discharge reached 1195.88 m³/s, with a maximum flow depth of 20.15 m and velocities exceeding 8.85 m·s⁻¹, while the runout distance surpassed 5.1 km. Hazard zoning based on the depth–velocity (H × V) product indicated that over 76% of the affected area falls within the high-hazard zone. A vulnerability assessment incorporated exposure factors such as tourism infrastructure and population density, and a matrix-based risk classification revealed that 2.4% of the area is classified as high-risk, while 74.3% lies within the moderate-risk category. This study also proposed mitigation strategies, including structural measures (e.g., check dams and channel straightening) and non-structural approaches (e.g., early warning systems and land-use regulation). Overall, the research demonstrates the effectiveness of physically based modeling combined with field observations and a GIS analysis in understanding debris flow hazards and supports informed risk management and disaster preparedness in mountainous tourist regions. Full article

Rare earth elements (REEs) are critical mineral resources that play a pivotal role in modern technology and industry. Currently, the global supply of light rare earth elements (LREEs) remains adequate. However, the supply of heavy rare earth elements (HREEs) is associated with substantial risks due to their limited availability. Ion-adsorption type rare earth deposits (IAREDs), which represent the predominant source of HREEs, have become a focal point for exploration activities, with a notable increase in global interest in recent years. This study systematically collected stream sediments and stream water samples from the Jiaping IARED in Guangxi, as well as from adjacent granitic and carbonate background areas, to investigate the exploration significance of geochemical surveys for IAREDs. Additionally, mineralized soil layers, non-mineralized soil layers, and bedrock samples from the weathering crust of the Jiaping deposit were analyzed. The results indicate that stream sediments originating from the Jiaping IARED and granite-hosted background regions display substantially elevated REE concentrations relative to those from carbonate-hosted background areas. Moreover, δEu values in stream sediments can serve as an effective indicator for differentiating weathering products derived from granitic and carbonate lithologies. Within the mining area, three coarse-grained fractions of stream sediments (i.e., +20 mesh, 20–60 mesh, and 60–150 mesh) exhibit REE concentrations comparable to those observed in both granite-hosted and carbonate-hosted background regions. However, the HREEs content in the finer -150-mesh stream sediments from Jiaping IARED is markedly higher than that in the two background regions. The (La/Sm)_N versus (La/Yb)_N ratios of -150-mesh stream sediments in the Jiaping IARED may reflect the mixing processes involving HREE-enriched ore layer, non-mineralized layer, and LREE-enriched ore layer. This observation implies that fine-grained (-150-mesh) stream sediments can partially inherit the REE characteristics of mineralized layers within IAREDs. Scanning electron microscopy (SEM) observations indicate that the enrichment of REEs in fine-grained stream sediments primarily originates from REE-rich accessory minerals derived from parent rocks and mineralized weathering crusts. A comparative analysis reveals that the concentrations of REEs in stream water collected during the rainy season are significantly higher than those collected during the dry season. Moreover, the levels of REEs, especially HREE, in stream water from the Jiaping IARED substantially exceed those in background areas. Collectively, these findings suggest that the geochemical signatures of REEs in rainy season stream water possess diagnostic potential for identifying IAREDs. In conclusion, the integrated application of geochemical surveys of stream water and -150-mesh stream sediments can effectively delineate exploration targets for IAREDs. Full article

Unprecedented, long-term pumping is occurring in aquifers worldwide, necessitating a greater understanding of the impacts from significant water table drawdown. Drawdown-induced hydraulic disconnection can significantly alter rates of inter-aquifer exchange and recharge, yet it remains an understudied phenomenon in multi-aquifer systems. This study investigates the potential for drawdown-induced hydraulic disconnection and its impact on inter-aquifer fluxes between a perennially recharged alluvial aquifer and a heavily pumped bedrock aquifer. We employed three-dimensional, transient, variably saturated flow modeling, incorporating multiple realizations of varying sandstone channel fraction (20–75%), to simulate evolving saturation patterns and alluvium-to-bedrock (A-B) flow rates. The results demonstrate the initiation and propagation of inter-aquifer unsaturated zones within sandstone channels underlying thinner low-permeability mudstones, leading to a substantial reduction in A-B flow, with the normalized flow response function (ABRF) decreasing by up to 98%. Complex saturation patterns, dictated by sandstone–mudstone heterogeneity, emerged as controls for water table elevation, disconnection status, and flow pathways. Multiple linear regression (R² up to 0.88) identified the bedrock aquifer sandstone fraction and the vertical span of saturated, connected channels as significant predictors of maximum A-B flow. Substantial variability in maximum A-B flow rates across scenarios with identical sandstone fractions (coefficient of variation 0.17 to 0.29) demonstrates the impact of geologic heterogeneity and saturation state on inter-aquifer exchange rates. The results of this study illustrate that hydraulic disconnection is not limited to near-surface environments and that geologic heterogeneity is a key factor controlling inter-aquifer fluxes in heavily pumped multi-aquifer systems. Full article

Soil organic carbon (SOC) and soil inorganic carbon (SIC) are key components of soil carbon pools in arid ecosystems, playing a crucial role in regional carbon cycling and climate change mitigation. However, the interactions between these two forms of carbon in arid alpine ecosystems remain underexplored. This study was conducted in the Heihe River Basin (HRB) in the northeastern Qinghai–Tibet Plateau, focusing on the distribution and dynamics of SOC and SIC in deep soil layers. Using data from 329 samples collected from 49 soil profiles extending to the bedrock, combined with path analysis, we explored the inter-relationships between SOC and SIC and quantified the influence of environmental factors. The results showed that (1) SOC exhibited a unimodal distribution with elevation, peaking at 3300–3600 m, while SIC continuously decreased with elevation, with reduction rates ranging from −0.39% to −31.18%; (2) SOC and SIC were significantly positively correlated (r = 0.55, p < 0.01), with SOC decreasing with depth and SIC showing an inflection point at 50 cm depth; (3) SOC was primarily driven by nutrient factors, such as total nitrogen (TN), with a path coefficient of 0.988, while SIC was influenced by abiotic factors, including potential evapotranspiration (PET), with a coefficient of −1.987; (4) SOC density accounted for 81.62% of the total soil carbon pool, playing a dominant role in carbon storage, whereas SIC density exhibited dynamic changes, particularly at depths of 110–150 cm. These findings advance our understanding of deep soil carbon dynamics in arid alpine ecosystems and provide critical data for improving carbon management strategies in similar regions. Full article

In this study, the evolution process of a landslide model under continuous rainfall conditions with a rainfall intensity of 30 mm/h is studied in depth based on an outdoor rainfall model test of a colluvial slope as the research material. The response law of pore water pressure and settlement amount is also obtained, and the influence of bedrock inclination angle on the development and deformation failure of the colluvial landslide is discussed. When the dip angle of the bedrock is 40°, it is prone to sudden slip-type landslides, and the evolution process is as follows: tensile cracks appear at the trailing edge, and these cracks continue to increase, leading to overall sliding. When the bedrock dip angle is 30°, traction landslides are prone to occur, and the evolution process is as follows: there is sliding at the foot of the slope, tensile cracks appear in the middle, sliding occurs in the middle, and tensile cracks appear in the upper part, leading to overall sliding. Before the landslide starts, the pore water pressure rises significantly. In the process of landslide evolution, the fine particles move to the foot of the slope with the rainwater, and the larger the angle of the slope, the greater the number of fine particles that accumulate at the foot of the slope, and the higher the elevation and the larger the scale of the trailing edge of the sliding body during sliding. Full article

The weathered bedrock aquifer in the Jurassic coalfield of northern Shaanxi Province is a direct water-bearing aquifer, and accurately predicting its water-bearing properties is essential for preventing and controlling water hazards in mining operations. Traditional Bayes discriminant methods have limitations in predicting water-bearing properties, particularly because not all primary factors influencing water-bearing properties meet the criteria for multivariate normal distribution. In this paper, the southern flank of the Ningtiaota Minefield is taken as an example, with the weathered bedrock aquifer as the research object. Six main controlling factors are selected: weathered bedrock thickness, core recovery rate, degree of weathering, lithological combination, elevation of the weathered bedrock surface, and sand-to-base ratio. A kernel density estimator–Bayes (KDE–Bayes) discriminant method for predicting water-bearing properties is presented. The kernel density estimation was carried out on the three main controlling factors that do not conform to a normal distribution—weathered bedrock thickness, core recovery rate, and sand-to-base ratio—and, in conjunction with other primary factors, a KDE–Bayes model was constructed for predicting the water-bearing properties in the southern flank of the Ningtiaota Minefield, based on which a detailed prediction of the water-bearing properties of the south flank of the Ningtiaota Minefield was conducted. By analyzing the actual dewatering data from the S1231 working face and past water inrush (or outburst) incidents, the feasibility and accuracy of this prediction method are demonstrated, providing valuable insights for predicting the water-bearing properties of weathered bedrock aquifers in the Ningtiaota Coal Mine and similar mining conditions. Full article

The effect of the epikarst on the development of drawdown dolines and subsidence dolines is described. For this, the resistivity values of the bedrock determined by Vertical Electrical Sounding (VES) measurements were used. The higher resistivities below drawdown dolines are explained by the deeper position of the piezometric surface, while the low resistivity values below subsidence dolines can be traced back to the more elevated position of the piezometric surface. Resistivities increasing towards the centre of drawdown dolines refer to cavity heterogeneity increasing towards the centre and increasing vertical percolation rate, while decreasing resistivity values indicate an increasing degree of cavity fill above the piezometric level. At their asymmetrical variety, the bedrock of their opposite slope is of asymmetric resistivity, which is explained by the different elevations of the piezometric surface and the latter by different infiltration that took place on slopes with different inclinations. The same resistivity values of the doline with a flat floor indicate the homogeneous cavity formation of the epikarst. This latter results in homogeneous vertical infiltration, which favours horizontal dissolution. The piezometric surface is not deflecting below the subsidence dolines because resistivity differences are small between the bedrock below the doline and the bedrock of its environment. Below subsidence doline, above the piezometric surface, cavities develop (the resistivity is higher relative to the resistivity of the environment), and then the cavities become filled by suffosion (therefore, the resistivity below the doline is lower relative to its environment). The passage below the doline develops into a shaft as a result of its concentrated water supply and the epikarst is separated into parts. Full article

Climate and geological diversity have been proven to make an important contribution to biodiversity. Volcanic ecosystems often have a long geological history and diverse bedrock, thus shaping a variety of habitats. Understanding the relative importance and role of the contemporary climate and geological bedrock environment in volcanic biodiversity still needs further exploration. To address this knowledge gap, we investigated the patterns of plant diversity and phylogenetic structure at the community level in Qiniangshan Mountain, while also exploring the relationship between biodiversity and regional environmental factors (e.g., climate and bedrock types). In the Qiniangshan Mountain plant communities, species richness is higher at mid-to-high elevations. Montane communities exhibit higher species richness compared to coastal communities. There are significant differences in species richness among plant communities on different bedrock, with the highest species richness found on pyroclastic lava. Bedrock, along with climate factors related to energy and precipitation, collectively influence the patterns of species richness in plant communities. The Net Relatedness Index (NRI) of plant communities is influenced by climate factors and aspects, while the Nearest Taxon Index (NTI) is affected by both bedrock and climate factors. The Phylogenetic Diversity Index (PDI) is primarily related to climate factors. Climate and bedrock collectively influence the patterns of species richness and phylogenetic structure within Qiniangshan Mountain’s plant communities. These findings highlight the profound impact of both climate and bedrock on montane vegetation and community biodiversity. Full article

The effective characterization of landscape water balance components—evapotranspiration, runoff, recharge, and soil storage—is critical for understanding the integrated effects of the water balance on vegetation dynamics, water availability, and associated environmental responses to climate change. An improved parameterization of these components can improve assessments of landscape stress and provide useful insights for predicting and managing vegetation responses to climate change. Hydrology models typically are not able to address water availability below the mapped soil profile, but we refined a landscape hydrology model, the Basin Characterization Model, by balancing measures of actual evapotranspiration (AET) with modeled subsurface soil water holding capacity, including bedrock storage. The purpose of this study was to characterize the effective rooting depth (the depth of soil and bedrock storage required to support AET) for 35 native vegetation types in California in order to quantify soil and bedrock water use, which ranged from 0 to 3.1 m for most vegetation types, exceeding mapped soil depths. This resulted in the quantification of bedrock water use, increasing available water 67% over that calculated by mapped soils alone. We found that mid-elevation vegetation types with lower water and energy limitations have the highest evapotranspiration rates and deepest effective rooting depth. We also evaluated the resilience to drought with this more spatially realistic characterization of water and vegetation interactions. Full article