Hydraulic conductivity estimation by NMR data in unconsolidated geological materials: insights from SDR model calibrations

Novel HF pre-enrichment approach for high-precision molybdenum isotope analysis in low-Mo carbonates by MC-ICP-MS.

Investigation of structural and radiation shielding properties of natural granite, clay, natural cement, and quartz supplied from Hakkâri region.

Removal of Fe(II) from water using raw and calcinated weathered basalt: Influence of mineralogy and physical properties.

Abstract Olivine particles with different Fe concentrations were magnetically separated, and a calibration curve of them was obtained by a magnetic separator, which was designed and assembled for rapidly analyzing heterogeneous solid particles according to their variance of magnetic susceptibility per mass [= $${\chi }_{\text{m}}$$ χ m (emu/g)]. The system was based on a dynamical principle that acceleration of a magnetic translation initiated from an identical position in an area of a monotonically increasing field does not depend on sample mass m [g]; it uniquely depends on the intrinsic $${\chi }_{\text{m}}$$ χ m value assigned to the material. The olivine particles used in the experiment were tuned to a size of ~ 0.5–1.0 mm in diameter, and the resolution of identifying Fe concentrations is higher than 1 wt%, where Fe concentrations of olivine particles ranged from 0 to 10 wt%. The apparatus introduced in this study to detect Fe concentrations of olivine particles is easy to operate. It has a compact size so that it can be used in various activities to collect geochemical samples. Accordingly, the time and effort required in searching a target sample are considerably shortened both in laboratory and in field research. Fe concentrations of silicate materials are important in estimating the formation conditions of various geological materials; for example, in studying the redox conditions of the region where minerals in meteorites formed, and in estimating formation conditions of terrestrial rocks.

The instability of bank slopes with uneven and soft geological layers under a heaped load will influence the safe and normal operation of ports. Therefore, this paper takes the bank slope in Xiaqinglong Port for slope stability evaluation and treatment measure effectiveness analysis. Firstly, the geological conditions, material composition and potential failure modes of the bank slope were determined through a field investigation and engineering geological analysis. Moreover, the slope stability was evaluated and calculated using the finite difference method (FDM) and the limit equilibrium method (LEM) with Bishop and Morgenstern–Price and a method considering pile resistance. Moreover, passing flow analysis (PFA) was applied to optimize the treatment measure design, and the treatment measures’ effectiveness was analyzed with simulation results. The results indicated that (1) the upper soft and lower hard strata are the main cause of the bank slope’s instability and deformation under heaped loads; (2) PFA can effectively calculate the maximum resistance of the pile and optimize the pile arrangement, with three rows with spacing of 2.3 m and a length of 22 m; (3) with piles, the stability of the bank slope improves from unstable to stable, along with an increase in the stability coefficient and a reduction in displacement, as well as a maximum shear strain increment and plastic zones. The study provides certain contributions to stability evaluation and treatment design optimization to prevent the potential instability and failure of similar bank slopes under the action of heaped loads.

Laser ablation-high resolution inductively coupled plasma mass spectrometry (LA-HR-ICPMS) offers a powerful insitu analytical technique for determining elemental and isotopic compositions in geological materials. Its potential for precise Pb isotope and trace element analysis at low concentrations, however, requires accurate instrument tuning/optimization and systematic data processing. We assessed the performance of LA-HR-ICPMS for insitu Pb isotope and trace element measurements in synthetic reference glasses (NIST 610, NIST 612) and geological reference glasses (BHVO-2G, BIR-1G, BCR-2G, TB-1G, GSD-1G) with Pb concentrations as low as 0.4 μg/g. An optimized analytical protocol was developed, involving instrument tuning, background correction, and data reduction procedures to minimize elemental fractionation and enhance analytical precision, accuracy and throughput. LA-HR-ICPMS achieved Pb isotopic ratios with precision better than ± 3% RSD, consistent with published values, and trace element concentrations with RSDs generally below ± 10%. Elements at higher concentrations exhibit better precision (RSD < ± 3%), while those near detection limits show greater variability. Chondrite-normalized rare earth element (REE) patterns for basaltic glass standards matcheswell with published data, validating the method's reliability. Comparisons with published solution-based and other insitu datasets confirm the accuracy of our approach. This study demonstrates that LA-HR-ICPMS provides accurate, precise, and rapid insitu Pb isotopic and trace element determinations, with advantages over conventional wet-chemical methods in terms of minimal sample destruction, high sample throughput, and high spatial resolution. The ability to determine Pb isotopic signatures in basaltic glasses has important implications for constraining mantle dynamics, crustal recycling, provenance determination, and the ore-forming mechanisms.

Chromium (Cr) and vanadium(V) are redox-active, geogenic contaminants observed to co-occur in groundwater in the North Carolina (NC) Piedmont region. On a landscape-scale, factors controlling Cr and V solubilization to groundwater in the Piedmont are understood to be largely associated with the regional geology. However, the specific mechanisms mediating (bio)geochemical interactions among heterogeneous geologic materials and redox active chemical inputs in the subsurface are poorly understood. The specific goal of this research was to elucidate the chemical controls on the solubilization of Cr and V from saprolite - chemically weathered rock between soil and bedrock - to groundwater. We conducted 40-day batch incubation experiments using chemically variable saprolites from the NC Piedmont to evaluate dynamics of Cr and V solubilization as influenced by interactions between common chemical inputs. Organic carbon (citric acid) additions stimulated dissolution of Cr and V to the aqueous phase, with abiotic controls generating greater concentrations of Cr and V than biotic incubations. Addition of the oxidant manganese (Mn)-oxide suppressed solubilization of Cr and V from the saprolites. Across all experiments, dissolved Cr and V concentrations were positively correlated (R2 = 0.81-0.99) with dissolved iron (Fe) concentrations. Overall, these results highlight how organic carbon inputs can modulate the cycling and solubilization of Cr and V in heterogeneous media, and our results may be impactful in making better predictive and vulnerability assessments plans, particularly in delineating abiotic vs. biotic roles driving Cr and V dissolution to groundwater.

Minerals bearing rare earth elements (REEs) are formed through long geological processes, among which monazite, bastnasite, xenotime, and ionic adsorption clays are the most economically exploited. Although Brazil has one of the largest reserves of REEs on the planet, its production is still not significant on the world stage. China remains dominant, with the largest reserves of REEs and controlling more than half of world production. Due to their important application in advanced clean and low-carbon energy technologies, REEs have become fundamental to the energy transition process. Technological applications related to catalyst synthesis, ceramics production, and metallurgy have been explored. Furthermore, the use of REEs in devices of great demand today, such as computer memory, rechargeable batteries, and mobile phones, has been cited. With the growing demand for these critical minerals, large mining companies are seeking to implement cleaner production policies in their processes and save natural resources to minimize the environmental impacts of the exploration. Robust analytical techniques have made it possible to characterize these elements in multi-element geological matrices, with the increasing exploration and identification of new REE mineral reserves.

Mining provides essential raw materials for various sectors but carries significant risks due to hazardous processes. Taking valuable minerals or other geological materials out of the earth is known as mining. Resources like coal and metals, placer, underground, and surface mining are essential, but they also have negative environmental effects, such as air pollution from blasting and water pollution. Air noise, frequently caused by industrial operations like mining and construction, can harm wildlife and human health. Transportation, equipment, and blasting activities are examples of sources. To reduce the negative effects of high noise levels on the environment, stress, and hearing loss, noise management and predictive models are crucial by establishing correlations between variables such as charge weight, distance, and geological conditions. Statistical predictor equations calculate blast-induced Air Overpressure (AOp). In India, DGMS regulations ensure mining and blasting operations minimise environmental impacts and keep AOp levels safe for nearby communities. In this study, SVR, RF, GB, BPNN, and an ensemble hybrid XGBoost–RF model were developed to predict blast-induced AOp and compared with traditional statistical prediction equations. The performance of these models was evaluated using four metrics: RMSE, MSE, MAE, and R². The results showed high accuracy for machine learning models, with R² values up to 0.9991 for the ensemble hybrid model, compared to much lower R² values for classical statistical approaches. These findings demonstrate the effectiveness of modern machine learning methods in predicting blast-induced Air Overpressure and highlight their superiority over traditional statistical models.

Assessing the value of bacteria, plants, fungi and arthropods characterized via DNA metabarcoding for separation of forensic-like surface soils at varied spatial scales.

Abstract Obtaining accurate estimates of the absolute intensity of the past geomagnetic field (paleointensity) is one of the major challenges in paleomagnetic research. Paleointensity data are typically determined by replacing the ancient thermoremanent magnetization (TRM) acquired in an unknown field with a laboratory TRM acquired under controlled conditions. A major source of uncertainty in paleointensity experiments arises from cooling rate effects, as the two TRMs are acquired under significantly different cooling conditions. Néel theory for single‐domain (SD) particles predicts that ancient (slow‐cooled) TRM is larger than laboratory (fast‐cooled) TRM, and that the ratio between them is linearly proportional to the logarithm of the cooling rate ratios. Here, this relationship is tested for non‐ideal SD materials, providing an empirical basis for the validity of cooling‐rate correction experiments. Eighty‐two archeological baked‐clay artifacts and basalt samples were given eight TRMs under an exponential cooling process, using seven different cooling‐rate constants spanning 2.5 orders of magnitude, resulting in cooling times ranging from 30 min to 1 week. These samples exhibited a range of domain state properties, including SD, vortex, strongly interacting particles, and mixtures of different populations. The results show that the ratio of slow‐to fast‐cooled TRMs is a linear function of the logarithm of the exponential cooling rate constants, regardless of the domain state. Cooling rate corrections, calculated for more than 2,100 archeological specimens using three different exponential cooling constants, are analyzed and provide practical guidelines for TRM effects in typical archeological materials. The results highlight that cooling rate correction should always be measured.

Editor’s note: This is the last paper in the Geology and Mining series, which has aimed to introduce early career professionals and students to various aspects of mineral exploration, development, and mining in order to share the experiences and insight of each author on the myriad of topics involved with the mineral industry and the ways in which geoscientists contribute to each. The 29 chapters plus two others have been compiled into a book, sponsored by BHP and edited by Dan Wood and Jeffrey Hedenquist, which is now available Open Access on the SEG store (www.segweb.org/store). It will soon be available on GeoScienceWorld, and a limited print run will produce hard copies for purchase. Abstract Mine tailings, the residual materials from mineral extraction, present one of the mining industry’s most complex environmental and engineering challenges. Comprising finely ground rock and residual chemicals, tailings require meticulous management to prevent ecological harm and ensure public safety. For exploration geologists, understanding this is not a downstream consideration but a fundamental responsibility that begins at discovery. The consequences of mismanagement are stark; since 2010, major tailings dam failures have caused numerous fatalities, contaminated thousands of kilometers of waterways, and triggered billions of dollars in remediation costs. These disasters underscore the critical need for specific planning and risk mitigation starting with the exploration phase to prevent similar outcomes. This paper provides exploration geologists with a comprehensive overview of the tailings management life cycle, covering material characterization, surface and underground disposal methods, risk mitigation strategies, best practices in monitoring and closure, and opportunities with tailings reprocessing. It demonstrates that integrating tailings considerations into the earliest phases of exploration—by informing site selection, characterizing geologic materials, and identifying geohazards—offers the most effective and economical path to minimizing long-term liabilities. By embracing their roles as the first stewards of a project, geologists can lay the foundation for safer, more sustainable mining outcomes.

Kink bands are localized folds or bends formed in layered materials, such as millefeuille. They are common in rocks within the earth’s crust that have undergone compression deformation. While the formation of kinks has been studied extensively, their effects on material strength remain unclear in geologic materials. This study investigates the relationship between kink formation and compressive strength through experiments on crustal-material biotite. In our results, kink bands are observed pervasively in samples and show hardening behavior. The observed kinks have symmetric tilt boundaries, satisfying the rank-1 connection condition, a key condition for material strengthening. Therefore, the hardening behavior observed in this study is due to “kink strengthening”. Furthermore, we reviewed whether kink bands of various scales in geologic materials satisfy the rank-1 connection and discussed its effect on the strength. Notably, it is indicated that the formation of mega kinks (km-scale kinks) strengthens the crust and influences earthquake rupture.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-17812-6.

Photo‐induced Force Microscopy (PiFM) is a nanoanalytical, surface‐sensitive new‐frontier technique that provides in situ infrared spectroscopy at a spatial resolution of ~ 5 nm 2 , which is approximately one billion times higher than traditional FTIR. These advantages led to significant discoveries in Earth and environmental sciences, as well as related disciplines. However, the high resolution and surface sensitivity of PiFM makes it highly susceptible to surface contamination. Factors such as sample preparation, handling and storage can introduce particulate and/or molecular layer contaminants, which may interfere with data analysis and lead to misinterpretation of results. In this study, we systematically investigated common laboratory materials, including gloves, mounting materials, polishing agents and storage solutions as potential sources of particulate and molecular contaminants and compiled a library of reference spectra available to all users of nano‐scale molecular analyses. Further, we determined the contaminant signatures of human skin and gloves on AFM substrates and provided recommendations for sample preparation, handling and storage as well as strategies for contamination mitigation to ensure better‐informed analysis of structurally and compositionally complex geological materials. We identified molecular and particulate contaminants through their specific IR absorption bands, and provide recommendations to selectively avoid or remove them, thereby improving the reliability of nanoscale molecular analyses by PiFM, ultimately increasing confidence in new discoveries.

As critical strategic resources for modern high-tech industries, accurate quantitative analysis of light rare earth elements (LREEs) holds significant importance in resource exploration, new energy materials research, and ecological monitoring. Traditional laser-induced breakdown spectroscopy (LIBS) suffers from matrix effects and spectral interference, posing challenges to achieve high quantitative accuracy in low-concentration LREEs detection in geological matrices. This study proposes a novel double-pulse LIBS (DP-LIBS) spectral calibration method integrating plasma imaging information. DP-LIBS was employed to enhance the spectral intensity of trace elements in natural rock samples. An ICCD camera was used to capture plasma images simultaneously with spectral acquisition. By establishing a correlation between the plasma temperature and image brightness, correction factors were calculated to calibrate the original signals. Quantitative analysis of the calibrated spectra reveals the determination coefficients (R2) for LREEs reached up to 99.86%, the root-mean-square error (RMSE) was as low as 0.10, and the optimal relative standard deviation (RSD) was 0.95% (Pr). After calibration, the limits of detection (LODs) for La, Ce, Pr, Nd, Eu, and Sm were 6.24, 9.56, 4.25, 1.27, 0.57, and 3.58 ppm, respectively. In addition, spike-and-recovery experiments were conducted, and the recovery values of the six LREEs were generally within the range of 92.04 to 119.18%. In summary, this spectral calibration method overcomes the limitations of traditional LIBS in ultraprecise quantitative analysis of trace elements, effectively suppresses matrix effects, and provides a new paradigm for the accurate analysis of LREEs in complex matrices.

The determination of rare earth elements (REEs) in refractory materials by inductively coupled plasma (ICP) spectrometry with conventional sample introduction using pneumatic nebulization requires the dissolution of these samples, which is difficult. This work presents an optimized method using electrothermal vaporization (ETV) coupled to ICP optical emission spectrometry (OES) for the direct determination of REEs in refractory geological materials. Solid sampling eliminates the dissolution step, thereby increasing sample throughput. Furthermore, the small sample mass required with ETV allows faster analysis with greater sensitivity than with nebulization by eliminating the dilution inherent to dissolution and introducing more sample into the plasma compared to nebulization. Point-by-point internal standardization with an argon emission line compensates for the visible sample loading effect on the plasma. Multivariate optimizations of the carrier, bypass, and CF4 reaction gas flow rates, along with optimization of the pyrolysis temperature and cooling time between the pyrolysis and vaporization steps, enhanced analyte signals by 2.9-11 times compared to a previous ETV-ICPOES method for the analysis of slag. Adding at least 30 μL of high-purity water to the graphite boat containing solid samples enhanced sensitivity by 61% on average and enabled external calibration using standard solutions, which provided accurate results for 14 REEs (Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tm, Y, and Yb). In contrast, only REEs with certified concentrations in the CRMs encompassing those in the sample could be determined by using CRMs for external calibration.

We propose that a new term, aquitardifer, be added to the hydrogeologic nomenclature. Aquitardifer, a blend of the terms aquitard and aquifer, accounts for geologic materials that have properties of both as traditionally defined. Several examples of aquitardifers are provided, as is justification for and applicability of the term.

ABSTRACT The quantitative separation of fluorine from geological materials through pyrohydrolysis presents a significant challenge, especially when fluorine is present in the form of CaF2, which exhibits high stability. To overcome this, accelerators (compounds like V2O5 and U3O8) are added to expedite the fluorine recovery. A pyrohydrolysis method using concentrated H2SO4 is proposed for complete fluorine separation from geological materials. The pyrohydrolysis distillates were analyzed by ion chromatography to quantify fluoride. To validate the method, fluorine content was analyzed in six certified reference materials (CRMs): BCR-032 (Merck); USGS-G-2, USGS-AGV-1, USGS-GSP-1, and USGS-GXR-3 (United States Geological Survey); NIST-NBS-1645 (National Bureau of Standards). Additionally, samples and reference materials were analyzed using particle-induced gamma emission (PIGE) for fluorine to validate the developed method. Furthermore, several samples, including IAEA reference materials Soil-1, Soil-5, and Soil-7, with unknown fluorine content, were analyzed. High-purity concentrated H2SO4 was identified as a suitable accelerator for routine sample analysis due to its requirement in smaller quantities, and applicability to variety of geological materials containing trace to percentile-level fluorine. The method exhibited a limit of detection of 4 µg.g−1 for a 50 mg sample, and the uncertainty (±1s) ranged from 3% to 7%.

Aeolian sand is the primary geological material for construction in desert regions, and its stabilization with industrial solid wastes-based geopolymer (ISWG) provides an eco-friendly treatment replacing cement. This study comparatively investigated the enhancement effects of chemical activators and expansive agents on compressive strength of aeolian sand stabilized by ISWG (ASIG). Three chemical activators—NaOH, Ca(OH)2, and CaCl2—along with two expansive agents—desulfurized gypsum and bentonite—were considered. Through X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, mercury intrusion porosimetry and pH values tests, the enhancement mechanisms of the additives on ASIG were elucidated. Results demonstrate that the expansive agent exhibits significantly superior strengthening effects on ASIG compared to the widely applied chemical activators. Chemical activators promoted ISWs dissolution and hydration product synthesis, thereby densifying the hydration product matrix but concurrently enlarged interparticle pores. Desulfurized gypsum incorporation induced morphological changes in ettringite, and excessive desulfurized gypsum generated substantial ettringite that disrupted gel matrix. In contrast, bentonite demonstrated superior pore-filling efficacy while densifying gel matrix through a compaction effect. These findings highlight bentonite superior compatibility with the unique microstructure of aeolian sand compared to conventional alkaline activators or expansive agents, and better effectiveness in enhancing the strength of ASIG.