Search Results (3,342)

A large, low-grade Fe–Ti–V oxide deposit occurs within the Xiaohaizi Ultramafic–Mafic intrusion. Based on petrographic observations and electron probe microanalysis (EPMA) of amphibole, this study examines the magmatic evolution and ore-forming processes of the intrusion through analyses of amphibole occurrence, mineral chemistry, and crystallization conditions. Five textural types of amphibole were identified: (i) inclusions, (ii) co-crystallization with early silicates, (iii) reaction rims, (iv) co-crystallization with late Fe–Ti oxides, and (v) phenocrysts. The amphiboles are calcic varieties, mainly composed of magnesio-hastingsite, kaersutite, and tschermakite. Crystallization occurred at temperatures of 901–1013 °C and pressures of 254–424 MPa, with ΔNNO values ranging from −1.3 to +2.8 and estimated melt H₂O contents of 3.3–7.1 wt.%, corresponding to crystallization depths of 9.6–16.0 km. Importantly, the crystallization interval of the Fe–Ti oxides is defined by these amphibole-assemblage conditions, as evidenced by their direct intergrowth. Integration of mineralogical and geochemical data indicates that the Xiaohaizi intrusion underwent five distinct stages of magmatic evolution. During these stages, the crystallization of Fe–Ti oxides was accompanied by notable fluctuations in oxygen fugacity and melt water content. These results suggest that fractional crystallization played a dominant role in ore formation, with possible late-stage liquid immiscibility observed at the mineral scale. Overall, this study proposes that the Xiaohaizi Fe–Ti–V oxide deposit represents a magmatic conduit-type ore-forming system developed within a crystal mush. The enrichment of Fe–Ti oxides is strongly associated with hydrous melts and elevated oxygen fugacity conditions. Full article

Soil aggregate stability is a key indicator of soil health and is fundamental to soil processes such as water infiltration, nutrient cycling, carbon sequestration, erosion control, and ecosystem functionality. However, research concerning the impact of natural and anthropogenic factors on SAS across different climates, soil types, and management practices is lacking. This review synthesizes current understanding of physical, chemical, and biological mechanisms that govern the aggregate formation and stability and brings to light how the natural and anthropogenic drivers influence these processes. It highlights how clay mineralogy, root systems, microbial diversity, soil organic matter, and management practices shape the structure and turnover of aggregates essential for agricultural productivity. Key drivers of aggregate formation, categorized into natural (such as texture, clay mineral interaction, biota, and climate) and anthropogenic (such as tillage, land use changes, organic amendments) factors, have been critically evaluated. This review provides an insightful framework for soil management that may help enhance soil aggregation and promote sustainable agriculture and food security, especially under climate change. Full article

This study examines the influence of tectonically induced mineralogical and microfabric changes on the strength of different rocks within the Hanzel Fault Damage Zone (FDZ) in the Tethyan Himalayas, Pakistan. Integrating field observations, petrographic analysis, and laboratory experiments (uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), ultrasonic pulse-wave velocity (UPV), and porosity), this study systematically characterizes the spatial variations in intact rock strength across horizontal distance from the fault core to the outer limit of the FDZ. Seven rock units—granites (biotite granite, leucogranite schist, granodiorite schist, and diorite) and amphibolites (foliated amphibolite, amphibolite, and plagioclase amphibolite)—were sampled at varying distances (−500 to +4035 m) from the fault core. Results reveal that proximity to the fault core correlates with significant strength reductions (40%–70%): granitic rocks exhibit lower UCS (41–59 MPa) and BTS (4.8–6.7 MPa) compared to distal amphibolites and diorites UCS (75–107 MPa) and BTS (10–13.67 MPa). Petrographic analysis identifies key factors that reduce strength, including high mica content (up to 33%), pervasive micro-fracturing, S-C fabrics, and mineral alteration. These features increase porosity (up to 1.21%) and reduce UPV (2867–3315 m/s) in fault-proximal rocks. Moderate inverse relationships (R² = 0.68–0.72) between mica percentage and UCS/UPV confirm phyllosilicates as primary strength controls. The spatial variation in rock strength is attributed to ductile–brittle deformation processes, with foliated or schistose textures increasing in proximity to the fault core. This study demonstrates that tectonic processes significantly influence the mineralogy and microfabric within FDZs, leading to variations in rock strength with direct implications for stability in tectonically active regions. Full article

Understanding how carbon is stored and stabilized in temperate agricultural soils is central to addressing one of the defining environmental challenges of our time—climate change. In this review, we bridge quantitative bibliometric insights with a qualitative synthesis of the mechanisms, regional differences, management practices, and models governing soil organic carbon (SOC) dynamics. We systematically analyzed 481 peer-reviewed publications published between 1990 and 2024, retrieved from Scopus and Web of Science, using bibliometric tools such as VOSviewer to map research trends, collaboration networks, and thematic evolution. The bibliometric analysis revealed a marked increase in publications after 2010, coinciding with growing global interest in climate-smart agriculture and carbon sequestration policies. Comparative synthesis across temperate sub-regions—such as the humid temperate plains of Europe, the semi-arid temperate zones, and the temperate black soil region of Northeast China—reveals that the effectiveness of common practices varies with soil mineralogy, texture, moisture regimes, and historical land-use. Reduced tillage (average SOC gain of 0.25 Mg C ha⁻¹ yr⁻¹), cover cropping (0.32 Mg C ha⁻¹ yr⁻¹), and organic amendments such as compost and biochar (up to 1.1 Mg C ha⁻¹ yr⁻¹) consistently enhance SOC accumulation, but with region-specific outcomes driven by these contextual factors. Recognizing such heterogeneity is essential for developing regionally actionable management recommendations. Recent advances in machine learning, remote sensing, and process-based modeling are enabling more accurate and scalable monitoring of SOC stocks, yet challenges remain in integrating micro-scale stabilization processes with regional and global assessments. To address these gaps, this review highlights a multi-method integration pathway—combining field measurements, mechanistic modeling, data-driven approaches, and policy instruments that incentivize adoption of evidence-based practices. By combining quantitative bibliometric analysis with regionally informed mechanistic synthesis, this review provides a holistic understanding of how knowledge about SOC in temperate agroecosystems has evolved and where future opportunities lie. The findings underscore that temperate agricultural soils, when supported by appropriate scientific practices and enabling policy frameworks, represent one of the most accessible natural climate solutions for advancing climate-resilient and sustainable food systems. Full article

Sphalerite (ZnS), the primary zinc-bearing mineral in most sulfide deposits, exhibits poor natural floatability and requires activation by metal ions such as Cu²⁺ or Pb²⁺. Copper sulfate (CuSO₄) is the most common activator, but its use at high dosages introduces sulfate accumulation and necessitates separate pre-conditioning to prevent the formation of inactive copper xanthates. This study investigates a novel copper–amine complex, Zn Flooter (ZnFL), as an alternative activator for sphalerite flotation. ZnFL is a liquid reagent containing stabilized ionic copper with a significantly lower sulfate content. Contact angle and flotation tests were conducted on two sphalerite-bearing ores of different mineralogy (Pb–Zn and Cu–Zn types). Contact angle tests showed that ZnFL (68–71°) enhances sphalerite surface hydrophobicity more effectively than CuSO₄ (61–66°). In flotation, ZnFL at 100 g/t achieved recoveries and grades comparable to those for CuSO₄ at 500 g/t, while allowing simultaneous addition with the collector without loss of performance. ZnFL also exhibited improved sphalerite/pyrite selectivity and did not negatively affect froth stability. These results demonstrate that ZnFL can provide equivalent or superior activation efficiency at a lower dosage and with simplified operation. Further studies on adsorption mechanisms and water chemistry effects are recommended to validate its industrial potential as a sustainable activator for sphalerite flotation. Full article

Phosphorus is one of the elements necessary for life and the proper growth of organisms, including humans, yet its natural resources are very limited. The bioavailability of phosphorus is especially critical during the initial phases of plant growth. A deficiency at this stage cannot be fully compensated for later, even despite increased phosphorous supplementation. Global reserves of phosphate rocks, the main source of phosphorus used in fertilizer production, are gradually being depleted. This situation prompts the need to search for alternative sources and to pay closer attention to the sustainable management of available resources. In this article, we focus on the Vistula–Bug interfluve in southeastern Poland, where relatively high phosphate concentrations have been documented. Our goal is to present geochemical and mineralogical data from bedrock in the areas richest in phosphorus and to discuss their significance in the context of domestic phosphorous management, with particular reference to southeastern Poland. We also discuss phosphate fertilizer production in Poland and its use in agriculture as well as phosphorus content in groundwater and surface water in the study area, with emphasis on the most readily assimilable forms, orthophosphates. Finally, we address the challenges of sustainable phosphorous management at both the local and global scale. Full article

Red ceramics remain essential in construction worldwide, but face challenges associated with high energy demand and CO₂ emissions. Sustainable alternatives require valorization of local georesources and adoption of circular economic approaches. This study evaluated two ceramic pastes formulations designed from locally available raw materials in southern Portugal: batch AD2, a 1:1 blend of residual clays from Corval, and batch XB1, a 1:1 blend of residual clay from Corval and a clay-schist from Barrancos. Raw materials were selected to balance contrasting properties, i.e., smectite-rich clays with high plasticity and shrinkage versus illitic (coarser) schists with lower plasticity and tempering effects. Batches were extruded, dried, fired at 1100 and 1150 °C, and tested for shaping moisture, shrinkage, water absorption, flexural strength, and mineralogical evolution. Results showed that the residual clays batch required high shaping moisture (20.04%) but achieved controlled drying shrinkage and high dry strength due to the smectite/temper balance. After firing, the material exhibited total shrinkage of 9.12 ± 0.28 and 9.78 ± 0.11%, water absorption of 11.57 ± 0.30 and 9.85 ± 0.27%, and flexural strength of 13.95 ± 2.30 and 14.85 ± 2.68 MPa, with mullite formation enhancing its performance. Clay and schist batch, after drying at 110 °C displayed low shaping moisture (6.22%), minimal drying shrinkage (0.15 ± 0.06%), and moderate fired (1100 and 1150 °C) shrinkage (1.59 ± 0.06 and 2.77 ± 0.04%). Water absorption decreased from 12.10 ± 0.77 to 9.91 ± 0.80% as the temperature increased, while flexural strength rose significantly from 13.60 ± 0.74 to 19.69 ± 1.54 MPa. Both blends developed desirable red tones without efflorescence. These findings demonstrated that residual clays and clay-schist can be effectively blended to produce sustainable, high-quality red ceramics, meeting structural requirements while promoting resource efficiency, reducing transport, and supporting decarbonization strategies. Full article

Hyperspectral data from CRISM have proven invaluable for analyzing the mineralogical composition of the Martian surface. However, processing such datasets remains challenging due to their high dimensionality and systematic noise, such as striping artifacts caused by the pushbroom imaging technique. Building on previous research, this study introduces a framework that forms the basis for an automated pipeline that combines preprocessing, dimensionality reduction using UMAP, k-means clustering, and an adaptive stripe correction filter to generate mineral maps of the Martian surface. Additionally, the pipeline integrates a noise variance estimation step based on PCA to assess the feasibility and expected efficacy of stripe removal before applying the filter. We validate the methodology across multiple CRISM datasets, including regions such as Jezero Crater, Nili Fossae, and Mawrth Vallis. Comparative analyses using metrics such as the CH index, DB index, and SC demonstrate improved clustering performance and robust mineralogical mapping, which indicates a step toward more reliable and automated clustering of CRISM data. Furthermore, the pipeline leverages spectral libraries for automated mineral classification, yielding results comparable to expert-defined maps while addressing discrepancies caused by residual noise or clustering limitations. This study represents a step toward fully automated, scalable geospatial analysis of CRISM Martian surface data, offering a robust framework for processing large hyperspectral datasets and supporting future planetary exploration missions. In the future, we intend to deploy an automated analysis pipeline as a freely accessible web service. Full article

Rima Bode is located on the central nearside of the Moon, with its rich volcanic landforms, which is considered an ideal region for studying lunar geological evolution. In this study, we systematically analyzed the geomorphological characteristics, composition, spatial thickness variations in basalts and pyroclastic deposits, thermophysical properties, and chronology of Rima Bode using the Kaguya Multiband (MI) data, Moon Mineralogy Mapper (M3) data, Terrain Camera (TC) data, and the CE-2 Microwave Radiometer (MRM) data. The main results are as follows. (1) The basalts can be categorized into three distinct units (Regions II, III, and IV), and the distribution range of pyroclastic deposits was redefined. Using the crater excavation technique, the deposit thicknesses were constrained to 4.3–51.9 m for pyroclastic deposits and 2.3–269.2 m for basalts, establishing a quantitative stratigraphic framework; (2) this study reveals that pyroclastic deposits exhibit abnormally brightness temperature (TB) behaviors, with slower diurnal TB change rates, indicating their high thermal inertia. (3) Chronological analysis indicated that volcanism lasted for ~0.38 Ga, with at least four distinct episodes of volcanic eruptions, suggesting complex magmatic processes and continued thermal activity within this region. These findings establish a comprehensive geological framework for the Rima Bode region, thereby deepening our understanding of its geological evolution. Full article

This work investigates the geochemical response of carbonate reservoir rocks to CO₂-enriched fluids, focusing on mineralogical changes and potential geological storage consequences. Laboratory experiments involved Žarošice field (Czech Republic) dolomite rock and in situ representative pore water. The findings show that CO₂ injection causes carbonate and feldspar dissolution, causing a detectable porosity increase (~0.25 percentage points). These findings lay the groundwork for assessing the potential of using dolomitized carbonate rocks for pilot CO₂ sequestration projects in Central Europe. Full article

Hainan Island has experienced a superposition of multiple phases of tectonic movements and magmatic activities, leading to numerous controversies regarding the genesis, spatiotemporal distribution, and tectonic setting of its Yanshanian granites. Accurately determining the characteristics of magmatic rocks during this period is crucial for clarifying the regional tectonic evolution. This study focuses on Diaoluoshan granite in the southeastern part of Hainan Island. Through petrological, mineralogical, zircon U-Pb geochronological, and geochemical analyses, it aims to identify the genetic type, formation age, and magma source properties of this pluton, thereby revealing the Late Yanshanian tectonic setting of Hainan Island. The results show that the zircon U-Pb dating of Diaoluoshan granite yields an age of 102.5 ± 2.8Ma, indicating its formation in the late Early Cretaceous. This granite is a high-K calc-alkaline I-type granite, with silica (SiO₂) content ranging from 63.9% to 77.3%. The pluton exhibits significant negative anomalies of Ta, Nb, P, and Ti, as well as relatively obvious positive anomalies of Rb, Th, U, and K. The biotite in the granite has a magnesium oxide (MgO) content ranging from 12.84% to 13.13%, showing characteristics of crust–mantle material mixing. The magma of this pluton was derived from the partial melting of the lower continental crust mixed with the uprising and underplating mantle mafic magmas, driven by the subduction of the Paleo-Pacific Plate and its slab rollback. This study confirms that during the Late Yanshanian, Hainan Island was in an extensional rift environment driven by the subduction of the Paleo-Pacific Plate and its slab rollback, but without a well-developed volcanic front. It provides key geological evidence for the study of Yanshanian tectono-magmatic evolution in South China. Full article

Pore systems in continental shales are controlled by lithofacies and show strong heterogeneity, which challenges shale oil development. The Qingshankou Formation in the Songliao Basin is a major shale oil play in China. Previous studies have focused on macroscopic reservoir properties, with limited analysis of pore differences among lithofacies. This study integrates mineralogy, organic geochemistry, and multi-scale pore structure characterization to examine four typical lithofacies: argillaceous, siliceous, calcareous, and mixed shales. Results show that pore evolution in the Qingshankou Formation can be divided into five stages: immature (Ro < 0.6%), low maturity (0.6% < Ro ≤ 0.8%), middle maturity (0.8% < Ro ≤ 1.0%), high maturity (1.0% < Ro ≤ 1.2%), and over maturity (Ro > 1.2%). The overall pattern follows a “three declines and two increases” trend. Due to differences in mineral composition and organic matter (OM), each lithofacies displays dis-tinct pore characteristics, which further influence oil-bearing potential and mobility. Siliceous shale, rich in felsic minerals, exhibits well-preserved pores and a developed micro-fracture network, providing the largest pore volume and average diameter. This facilitates the storage and flow of free oil, making it the preferred exploration target. Argillaceous shale, characterized by abundant clay minerals and OM, supports micropore development and offers the highest specific surface area (SSA). This yields significant adsorbed oil potential, highlighting its value as a secondary exploration target. This study clarifies the lithofacial controls on pore development in continental shales, providing a scientific basis for predicting favorable intervals and optimizing exploration strategies in the Qingshankou Formation and analogous basins. Full article

Phosphate rock is a vital natural resource classified by the European Commission as a critical raw material (CRM), extensively mined for its agricultural, industrial, and technological applications. While primarily used in fertilizer production, phosphate deposits also contain significant concentrations of trace metals, notably rare earth elements (REE), which are essential for renewable energy, electronics, and defense technologies. In response to growing demand, the recovery of REE from phosphate ores and processing by-products, particularly phosphogypsum (PG), has gained international attention. This review provides a comprehensive analysis of the global phosphate industry, examining production trends, market dynamics, and the environmental implications of phosphate processing. Special focus is placed on the geochemical behavior and mineralogical associations of REE within phosphate ores and industrial residues, namely PG and purification sludge. Although often treated as waste, these by-products represent underexplored secondary resources for REE recovery. Technological advancements in hydrometallurgical, solvometallurgical, and bioleaching methods have demonstrated promising recovery efficiencies, with some pilot-scale studies exceeding 70%–80%. However, large-scale implementation remains limited due to economic, technical, and regulatory constraints. The circular economy framework offers a pathway to enhance resource efficiency and reduce environmental impact. By integrating innovative extraction technologies, strengthening regulatory oversight, and adopting sustainable waste management practices, phosphate-rich countries can transform environmental liabilities into strategic assets. This review concludes by identifying key knowledge gaps and suggesting future research directions to optimize REE recovery from phosphate deposits and associated by-products, contributing to global supply security, economic diversification, and environmental sustainability. Full article

Planetary mapping has progressively evolved due to the increasing availability of high-quality data and advancements in analytical techniques applied to both surface and subsurface features. In particular, the enhanced spatial resolution and broader coverage provided by cameras and spectrometers aboard orbiting spacecraft around planetary bodies, now enable the production of more detailed geostratigraphic maps. Which maps go beyond the traditional planetary approach, with mineralogical data contributing significantly to the development of more comprehensive final products. Proclus crater is a fresh crater, 28 km in diameter, located on the northwest rim of the Crisium basin, where crystalline plagioclase, as well as pyroxenes and olivine, have been detected. Here, preliminarily, the geomorphological map showed the different surface textures and lineaments of the crater, and a spectral unit map highlighted the different spectral units present in the area. The spectral unit map has been produced by using supervised classification, where the spectral endmembers were extracted by the mean of an automatic tool. The mineralogical interpretation retrieved from spectral endmembers supports the definition of six main spectral units and, moreover, indicates how two of them could be divided into subunits. Those subunits show the systematic variation in plagioclase, low-Ca and high-Ca pyroxene, and their relative abundances. Finally, the geostratigraphic maps associate compositional heterogeneity with different units of the crater, suggesting that this crater was originally characterized by lithologies rich in plagioclase, but mixed with variable low amounts of mafic phases. Since Proclus is a relatively small crater and the units better exposing the mineral’s original heterogeneity are principally distributed in the walls, the spectral units seem to suggest the presence of magma traps during the plagioclase floating during the lunar primary crust formation and constitute heterogeneous terrains within the Highland. Full article