Search Results (864)

The Cenomanian Bahariya Formation exposed at Gebel El Dist in the Western Desert of Egypt provides valuable surface analogues for evaluating the reservoir quality of subsurface Bahariya sandstones. The formation was analyzed using 27 oriented samples and 91 core plugs from quartz arenite (QA) and quartz wacke (QW) facies. Analyses included XRD, petrography, SEM, helium porosity–permeability, and capillary tests, as well as measurements of pore-throat radii (R) at 35% and 36% mercury saturation. X-ray diffraction analyses reveal a heterogeneous mineral composition dominated by quartz, feldspars, dolomite, pyrite, siderite, goethite, hematite, clay minerals, glauconite, and gypsum. QA displays higher porosity and permeability than QW, along with larger pore radii, and lower specific surface area per unit pore volume (Spv) and per unit grain volume (Sgv). Multivariate regression equations, specific to each facies, were developed to convert standardized XRD mineral percentages directly into pore-system and flow attributes (ϕ, k, r, Spv, Sgv, R35, R36), quantifying capillary-based recovery contrasts between facies. Across both facies, regressions linking mineralogy to ϕ, k, r, Spv, Sgv, R35, and R36 are strong (R² = 0.78–1.00). The established predictive equations provide a low-cost method to estimate reservoir quality from mineralogy alone, enabling rapid screening of Cenomanian Bahariya analogues and similar clastic reservoirs where core data are limited. Full article

Underground mine emergencies destroy communication infrastructure when situational awareness is most critical. Current systems rely on centralized network infrastructure, which fails during emergencies when miners are trapped and require rescue coordination. This paper proposes an energy-harvesting LoRa mesh network that addresses self-powered operation, interference management, and adaptive physical layer optimization under severe underground propagation conditions. A dual-antenna architecture separates RF energy harvesting (860 MHz) from LoRa communication (915 MHz), enabling continuous operation with supercapacitor storage. The core contribution is a decentralized scheduler that derives optimal timing offsets by modeling concurrent transmissions as a Poisson collision process, exploiting LoRa’s capture effect while maintaining network coherence. A SINR-aware physical layer adapts spreading factor, bandwidth, and coding rate with hysteresis, controls recomputing timing parameters after each change. Experimental validation in Missouri S&T’s operational mine demonstrates far-field wireless power transfer (WPT) reaching 35 m. Simulations across 2000 independent trials show a 2.2× throughput improvement over ALOHA (49% vs. 22% delivery ratio at 10 nodes/hop), 64% collision reduction, and 67% energy efficiency gains, demonstrating resilient emergency communications for underground environments. Full article

As a critical raw material in the semiconductor and new energy sectors, antimony is a strategic mineral resource for nations to safeguard industrial chain security. However, the scarcity of its resources and the complexity of its trade pattern underscore the urgency of antimony-related research. This study aims to reveal the structural characteristics of the global antimony trade network and explore the external factors influencing trade. Based on global antimony trade data from 2007 to 2022, the characteristics of the antimony trade network were analyzed using the complex network analysis method, and the influencing factors of antimony trade were examined via the fixed effects model. The results show that the global antimony trade network maintains a density of 0.05–0.06, with an average path length of 2.4–2.7 and a network diameter that mainly fluctuates between 5 and 6. The average clustering coefficient fluctuates within the range of 0.35–0.45. Overall, the network exhibits the characteristics of stable transmission efficiency, loose overall connectivity, and local agglomeration without a consistent upward or downward trend. Countries such as Germany, China, and the United States occupy core positions in the network. The fixed effects model indicates that GDP and LOGISTICS development are key factors promoting trade, while TARIFFS and REGULATORY policies have a significant inhibitory effect on trade. Therefore, ① Focus on the High-End Development of the Antimony Industry Chain and Promote the In-Depth Integration of Antimony Trade with the Semiconductor and New Energy Industries; ② Improve the Cross-Border Logistics and Warehousing System for Antimony Trade to Ensure the Efficient Circulation of Strategic Resources; ③ Promote; Promote Tariff Liberalization in Antimony Trade and Eliminate Market Access Barriers; ④ Strengthen the Government’s Strategic Support for the Antimony Industry to Enhance Global Discourse Power in Antimony Trade; Trade; ⑤ Maintain Macroeconomic Stability and Flexibly Manage Exchange Rates to Safeguard the Resilience of Antimony Trade. Full article

Ore leaching constitutes a core step for achieving efficient utilization of mineral resources, primarily encompassing acid leaching and alkaline leaching methods. Currently, acid leaching technology has reached a high level of maturity and is widely applied in industry due to its advantages of fast reaction kinetics and broad applicability to various mineral types. However, the theoretical framework underpinning alkaline leaching systems remains relatively weak. Given the distinct advantages of alkaline leaching in processing ores containing alkaline gangue minerals, this review systematically examines chemical and microbial leaching techniques for metal ores under alkaline conditions. It focuses on elucidating the mechanisms and key influencing factors associated with different alkaline matrices, oxidants, external pressures, and microbial strains. Future development prospects are also discussed. The aim is to provide a theoretical foundation and practical guidance for advancing metal ore leaching technologies towards greener and more efficient directions. Full article

In the observation of tight sandstone cores, the variations in the hydrocarbon charging usually can be observed in the same geological age reservoirs, which manifest as differential oil staining on the core surface. In order to clarify the micro total pore–throat size distribution (TPSD) characteristics and oil content differences of different oil-bearing tight reservoirs, we drilled two types of oil-bearing cores in the Chang6 formation of Xiasiwan Oilfield, conducted casting thin section (CTS), scanning electron microscopy (SEM), and X-ray diffraction (XRD) to qualitatively and quantitatively analyze petrological and pore–throat characteristics. The TPSD of different oil-bearing cores were quantitatively characterized and compared by combining high-pressure mercury injection (HPMI) and constant rate mercury injection (CRMI). Meanwhile, we quantitatively evaluated the complexity of the pore–throat structure based on fractal theory. Our results reveal significant difference in the clay mineral contents between the two types of cores, despite both being classified as arkose. Due to higher contents of illite, calcite, and chlorite, the pores of oil-smelling sandstone are obviously affected by cementation. The result of TPSD characteristics shows that the oil-appearing sandstone samples exhibit well-developed big pores and throats, displaying bimodal distribution, and three-stage fractal characteristics in the TPSD curves. Conversely, oil-smelling sandstone samples manifesting a left-skewed bimodal, pore space contribution of the samples is more dependent on pores and throats smaller than 0.12 μm. The TPSD curves exhibit three-stage and four-stage fractal characteristics. Therefore, the differences in oil-bearing properties between the two types of cores are attributed to variations in mineral composition, diagenesis, clay mineral content, pore types, pore–throat size distribution (PSD), and pore–throat complexity. Our results provide crucial guidance for subsequent reservoir quality assessment in this study area and the development of tight sandstone reservoirs with similar geological characteristics. Full article

The dielectric response of clay-bearing rocks is complex, which seriously affects the evaluation of oil saturation. This paper introduces the dual-Debye model to characterize the dielectric dispersion characteristics of pore water and the Debye model to establish the dielectric dispersion characteristics of water-absorbing clay minerals. A dielectric dispersion simulation method is established to study dielectric dispersion characteristics of 12 clay-bearing digital cores of the publicly available Berea sandstones. The results show that the numerical simulation method is perfectly verified by using a pure clay-bearing rock, and the established method can effectively characterize the dielectric dispersion phenomenon of clay-rich sandstones. The clay content has a strong influence on the dielectric dispersion characteristics of clay-bearing rocks. The higher the clay content, the stronger the dielectric dispersion, and the contribution of pore water also needs to be considered. It is also crucial to consider the dielectric dispersion anisotropy related to the distribution of rock components, which will be beneficial for the saturation evaluation of clay-bearing reservoirs based on dielectric dispersion. Full article

The Late Holocene flood history of the Cauvery River floodplain in the Poompuhar region was reconstructed using a multiproxy sedimentological approach applied to three trench cores. Lithostratigraphy, loss on ignition (LOI), magnetic susceptibility (MS), sand–silt–clay textural analysis, granulometric statistics (Folk and Ward), Passega CM diagrams, and grain angularity provide complementary evidence to differentiate high-energy flood deposits from background slackwater sediments. Grain-size processing and statistical analyses were carried out in R using the G2Sd package, ensuring reproducible quantification of mean size, sorting, skewness, kurtosis, and transport signatures. We identified 10 discrete high-energy event beds. These layers are characterised by >80% sand content, low LOI (<3.5%), and low frequency-dependent MS (χfd% < 2%), confirming rapid, mineral-dominated deposition. A tentative chronology, projected from the regional aggradation rate, suggests two major flood clusters: a maximum-magnitude event at ~3.2 ka and a synchronous cluster at ~1.6–1.8 ka. These events chronologically align with the documented phases of channel avulsion in the adjacent Palar River Basin, supporting the existence of a synchronised Late Holocene climato-tectonic regime across coastal Tamil Nadu. This hydrological evidence supports the hypothesis that recurrent high-magnitude flooding triggered catastrophic channel avulsion of the Cauvery distributary, leading to the fluvial abandonment and decline of the ancient port city of Poompuhar. Securing an absolute chronology requires advanced K-feldspar post-IR IRSL dating to overcome quartz saturation issues in fluvial deposits. Full article

The global demand for strategic minerals like scheelite is growing rapidly due to technological advancements and emerging industries, making it a key global resource. However, there is a lack of integrated research on utilization technology of scheelite from a global perspective and exploring its future development direction. Bibliometric methods have been widely applied due to their advantages in the analysis of qualitative and quantitative literature information. Based on 1137 publications from the Web of Science Core Collection spanning 1999 to 2024, this study systematically examines the global and Chinese research trajectories and emerging frontiers in scheelite resource utilization technologies. A paradigm shift from fundamental geological and material property studies to green beneficiation, low-carbon metallurgy, and intelligent process optimization has been revealed. Key global research hotspots include flotation separation, surface chemistry regulation, LA-ICP-MS micro-analysis, and photoluminescence properties, whereas China has developed distinctive strengths in complex polymetallic ore separation, leaching kinetics, and tailings valorization. Chinese institutions contribute over 54% of worldwide output, with Central South University leading in publication volume, collaboration networks, and academic impact. Future efforts should prioritize intelligent process control, the efficient separation of complex polymetallic ores, and the high-value recovery of secondary resources. Full article

Ultra-deep shale in the Mahu Sag, characterized by difficult-to-drill formations, exhibits high resistivity. This study uses XRD and petrophysical testing on 12 dry core samples (depths 4600–5000 m) to characterize mineral composition and evaluate resistivity-influencing factors. Mineralogical analysis reveals that brittle minerals, dominated by quartz and feldspar (>50%), constitute the primary components of the ultra-deep shale in the Mahu Sag, with quartz, feldspar, and carbonates collectively accounting for ~80%. Clay (~6%) and pyrite (<5%) contents are notably low, resulting in elevated resistivities of 10⁵–10⁷ Ω·m. Resistivity correlates negatively with pyrite (r = −0.588) and feldspar (r = −0.319) but positively with dolomite (r = 0.209), quartz (r = 0.017), and porosity (r = 0.749). At elevated temperatures (100 °C), resistivity declines owing to enhanced ionic conduction. These findings clarify high-resistivity mechanisms, supporting resistivity-based drilling parameter optimization. Full article

A pot experiment was carried out to evaluate the effects of composts, vermicomposts, and mineral fertilization on maize (Zea mays L.) growth, grain quality, soil chemical properties, and nematode communities. Eight treatments were tested, including organic amendments combined with mineral nitrogen, exclusive mineral fertilization, and an unfertilized control. Soil chemical properties, including pH, salinity, nitrogen compounds, and macro- and microelements, varied notably across treatments. Nematode community analysis revealed distinct patterns among treatments: Shannon diversity was moderate and relatively stable across most treatments, but a statistically significant reduction was recorded in treatment 7. In contrast, the Plant Parasitic Index (PPI) varied significantly, reflecting differences in community maturity and parasitic pressure. Bacterivores and fungivores indicated active nutrient cycling, while omnivores and predators reflected soil food web stability. Fertilization treatments significantly affected maize grain development. The highest thousand-kernel weight (TKW) was recorded in treatment 6 (+8.9% vs. control) and treatment 4 (+7.4% vs. control). The kernel number per cob was greatest in treatments 4 and 5 (+38% and +32%), with corresponding increases in grain mass per cob (+48% and +40%). The mean cob core weight ranged from 20.1 g in the control treatment to 30.2 g in treatment 1. The greatest increases compared to the control were observed in treatments 1 and 5, amounting to 50.2% and 44.8%, respectively. Overall, fertilization influenced grain quality, soil chemistry, and nematode communities, highlighting the importance of integrating organic and mineral amendments for sustainable crop production. Full article

Cities around the world are facing growing challenges related to climate change, urban sprawl, infrastructure strain, and digital transformation. In response, smart and sustainable urban development has become a global focus, aiming to integrate technology and environmental stewardship to improve the quality of life. The smart and sustainable city concept is typically applied at the city scale; however, its impact is most tangible at the neighborhood level, where residents interact directly with infrastructure, services, and community spaces. A variety of global frameworks have been developed to assess sustainability and technological integration. However, these models often fall short in addressing localized needs, particularly in regions with distinct environmental and cultural contexts. In Saudi Arabia, Vision 2030 emphasizes livability, sustainability, and digital transformation, yet there remains a lack of tailored tools to evaluate smart and sustainable progress at the neighborhood scale. This study develops HayyScore, a localized evaluation framework and prototype digital platform developed to assess neighborhood performance across five core categories: (i) Environment and Urban Resilience, (ii) Smart Infrastructure and Governance, (iii) Mobility and Accessibility, (iv) Quality of Life and Social Inclusion, and (v) Economy and Innovation. The HayyScore platform operationalizes this framework through an interactive web-based tool that allows users to input data through structured forms, calculate scores, receive category-based and overall certification levels, and view results through visual dashboards. The methodology involved a comprehensive review of global frameworks, expert input to define localized indicators, and iterative prototyping of the platform using Python 3.13.5 and Streamlit 1.45.1. To demonstrate its practical application, the prototype was tested on two Saudi neighborhoods: King Abdullah Petroleum Studies and Research Center (KAPSARC) and King Fahd University of Petroleum and Minerals (KFUPM). Key platform features include automated scoring logic, category weighting, certification generation, dynamic performance charts, and a rankings page for comparing multiple neighborhoods. The platform is designed to be scalable, with the ability to add new indicators, support multilingual access, and integrate with real-time data systems in future iterations. Full article

Gallium (Ga) enrichment in sphalerite has been widely recognized; however, its enrichment mechanisms remain insufficiently understood. The South Hunan district, located at the intersection of the Nanling Region and the Qin-Hang Metallogenic Belt in South China, is characterized by abundant Jurassic magmatic-hydrothermal Pb–Zn deposits, which typically host Ga-depleted sphalerite. Recently, Ga-enriched sphalerite (up to 385 ppm by LA-ICP-MS) has been identified in newly drilled cores at Zhaojinci, adding complexity to the regional Pb–Zn metallogenic framework. EPMA elemental mapping and LA-ICP-MS time-resolved spectra indicate that Ga is homogeneously distributed within sphalerite, excluding the presence of micron-scale Ga-bearing mineral inclusions. A strong positive correlation between Ga and Cu concentrations suggests that Ga incorporation is facilitated by the coupled substitution of Zn²⁺ by Cu⁺. Sphalerite geothermometry yields formation temperatures of 118–138 °C (average 126 °C for GGIMF is and ~129 °C for SPRFT), accompanied by intermediate sulfur fugacity conditions (lg fS₂ = −22.9 to −21.2), which appear to favor Ga enrichment in sphalerite. The trace element geochemistry of the Zhaojinci sphalerite (Ga-Ge-Cd-enriched and Mn-In-Sn-Co-depleted), combined with its formation under low-temperature (120–180 °C) and intermediate fS₂ conditions (within the pyrite stability field), is consistent with MVT-like mineralization. This interpretation is supported by multiple lines of geological evidence, including the strict confinement of stratabound Pb–Zn mineralization to the Devonian Xikuangshan Formation limestone, structural control by syn-sedimentary normal faults, pervasive dolomitization of the host rocks, and the absence of genetic relationship to magmatic activity. Moreover, the sphalerite geochemical signature, corroborated by an XGBoost-based machine learning classifier, reinforce the MVT-like affinity for the Zhaojinci mineralization. This study not only emphasizes the importance of low-temperature and intermediate-fS₂ conditions in Ga enrichment within sphalerite, but also highlights the significance of discovering MVT-like sphalerite for Pb–Zn resource exploration in the South Hunan district, providing valuable new insights and directions for mineral prospecting in this geologically important region of South China. Full article

The concentrations of natural radioactive elements in the groundwater environment are regulated by several factors, including aquifer geology, groundwater hydrochemical properties, and changes in environmental conditions. Many studies have explored these factors, but few have systematically elucidated the mechanisms underlying the dissolution of radioactive elements from their host minerals into groundwater. This study investigated the petrological, mineralogical, and weathering properties of aquifer materials and their effects on the leaching of uranium (U) and thorium (Th) into groundwater. The time required for the U concentration to reach the drinking water standard (30 μg/L) was estimated through artificial weathering experiments performed under diverse environmental conditions. Rock core samples were obtained from three sites differing in their geology and groundwater U concentrations. Mineralogical analyses revealed that thorite, a representative radioactive mineral that contains large amounts of U and Th, was present in samples from all collection sites. Thorite minerals differed in terms of their sizes, shapes, cracks, and chemical compositions between samples from different sites, indicating that geological features, mineral alteration characteristics, and environmental conditions controlled the behavior of U and Th. These factors appear to play crucial roles in regulating the mobility and potential long-term leachability of U and Th. Artificial weathering experiments confirmed that a neutral pH with surplus bicarbonate ions favored U leaching. Under these environmental conditions, aquifer U concentrations were estimated to require 8.7–226 years to reach the drinking water standard, depending on the groundwater dissolved oxygen content. Our results provide scientific evidence that may be used for managing radioactive elements in the groundwater environment, and are likely to inform new environmental policies and regulatory standards. Full article

Climate change is expected to increase the frequency of extreme soil moisture events, such as winter waterlogging followed by spring drought, particularly in temperate regions of Europe, North America and Northeast China. While N₂O emissions from paddy soils under waterlogging and subsequent drainage have been widely studied, knowledge of upland arable soils under wheat cultivation remains limited. We hypothesized that: (1) in upland soils, combined waterlogging and drought reduces N₂O emissions compared to continuous waterlogging, and (2) plant presence mitigates soil nitrate accumulation and N₂O emissions across different moisture regimes. A greenhouse experiment was conducted using intact upland soil cores with and without wheat under four moisture treatments: control (60% water-holding capacity, WHC), drought (30% WHC), waterlogging, and waterlogging followed by drought. Daily and cumulative N₂O fluxes, soil mineral nitrogen (NH₄⁺-002DN and NO₃⁻-N), and total nitrogen uptake by wheat shoots were measured. Prolonged waterlogging resulted in the highest cumulative N₂O emissions, whereas the transition from waterlogging to drought triggered a sharp but transient N₂O peak, particularly in soils without plants. Wheat presence consistently reduced N₂O emissions, likely through nitrate uptake, which limited substrate availability for incomplete denitrification. Moisture regimes strongly affected nitrate dynamics, with drought promoting nitrate accumulation and waterlogging enhancing nitrate loss. These findings highlight the vulnerability of upland soils in regions prone to seasonal moisture extremes. Effective management of soil moisture and nitrogen, including the promotion of plant growth, is essential to mitigate N₂O emissions and improve nitrogen use efficiency under future climate scenarios. Full article

The decline in the injectivity of injection wells is a serious problem in geothermal systems. In this article, we analyse the mechanisms responsible for the reduction in permeability in Lower Jurassic sandstones during the injection of cooled formation brine. Flow experiments were conducted on rock cores using three types of brines with varying degrees of contamination. The studies included microscopic analysis, scanning electron microscopy (SEM) and mercury intrusion capillary pressure (MICP) before and after the experiments. The results showed that the main factor in the decrease in permeability is the formation of a filter cake from secondary iron minerals on the front surface of the core. Filter cake formation was observed in all samples, with ferrous sediment penetrating to a maximum depth of 1.5 cm from the core front. In addition, the mobilisation of clay particles was observed, which accumulate in pore constrictions, causing additional flow restriction. Mercury porosimetry revealed significant increases in hysteresis values in the front zone (from 16.5 to 42%), indicating complex pore connectivity changes without substantial porosity reduction. The rate of injectivity decline correlates strongly with the fluid flow velocity. The results of the study provide a scientific basis for optimising reinjection processes in geothermal systems and developing strategies to prevent formation damage. Full article