Environmental and Earth Sciences

Abstract: To determine the reprocessing potential of mining liabilities, a comprehensive evaluation of the tailings deposit at the former Halcon mining unit in central Peru was conducted. Direct and indirect methods were employed, including geophysical surveys, sampling through six drill holes up to 9.62 meters deep, textural analysis, mineralogical characterization (optical microscopy, SEM, XRD, and reflectance spectroscopy), and ICP-MS chemical analysis, complemented by geostatistical modeling for resource estimation. Geochemical and mineralogical results reveal highly oxidizing, acidic conditions (pH 1.83–4.91) and significant concentrations of Zn (5.46%), Pb (1.58%), Cu (1.67%), Ag (244 ppm), and Au (3.6 ppm). These economic minerals predominate in fine-grained fractions with high degrees of liberation, favoring metallurgical recovery. Geostatistical modeling estimated a total tailings tonnage of 87,642 tons, highlighting zones of high localized economic potential, particularly for Zn and Ag. Considering specific recovery scenarios, penalties, operational costs, and metal prices, a net financial benefit of approximately US$11.35 million was projected. This pioneering study demonstrates the feasibility of converting environmental liabilities into economic assets through strategic reprocessing initiatives, contributing a robust model for mine tailings valorization within the South American circular economy framework.

Abstract: Located 30 km south–southeast of Kabul in Logar province, Aynak is the largest and best-known copper orebody in Afghanistan. The deposit is hosted by the Loy Khwar Formation, a Neoproterozoic-Cambrian metasedimentary sequence of dolomite marble, carbonaceous quartz schist and quartz–biotite–dolomite schist. The primary ore minerals are chalcopyrite and bornite with less abundant pyrite and minor cobaltite, chalcocite, pyrrhotite, sphalerite and molybdenite. Sulphides occur as bedded laminae and disseminations, in metamorphic segregations, and in syn- to post-metamorphic cross–cutting veins. The geochemistry of sulphide-rich separates from Central and Western Aynak (n=31), analysed by ICP-MS, confirm and quantify previous petrographic observations indicating varying admixtures of sulphide species. Co and As enrichment in chalcopyrite-dominant samples is consistent with cobaltite whereas Co enrichment in the absence of arsenic suggests the presence of carrollite. Fluid inclusion analyses of secondary quartz-hosted inclusions indicate interaction with moderately hot (approximately150- 300⁰C; pressure-uncorrected), highly saline (32.1 to 47.4 equivalent wt% NaCl) chloride-rich brines. It is uncertain whether these fluid parameters relate to primary copper transport and deposition, or to remobilisation during metamorphism. Nevertheless, comparison with analogous sediment-hosted copper deposits suggests that highly saline basinal brines played an important role in the formation and evolution of the deposit. Occurrences of scapolite provide additional evidence for a model of brine-related mineralization. Together with previously published mineralogical, lithogeochemical and sulphur isotope evidence, these findings support a sedimentary–diagenetic origin for the Aynak copper deposit that is broadly comparable with sediment-hosted stratiform copper systems of the Central African Copperbelt.

Abstract: Hydrocarbon reservoirs remain a cornerstone of the global energy landscape; precise reservoir characterization is essential to evaluate the viability of crude oil production. Addressing the challenges inherent in low-permeability, low-porosity formations and near-wellbore environments is critical for maintaining sustainable production. Due to the heterogeneity of deep reservoir cores, non-destructive analytical methods are required for sample reuse. Nuclear Magnetic Resonance (NMR) techniques - specifically low-field (LF) NMR and Magnetic Resonance Imaging (MRI) - have emerged as essential tools for the spatial characterization of pore networks. While these methods are well-established for determining porosity and permeability in sandstones, the characterization of carbonates is more complex due to their intricate chemistry, multi-scale geological features, and geo-mechanical properties. This review article synthesizes the theoretical framework and practical applications of NMR for determining the petrophysical properties of sandstone and carbonate rocks, including porosity, permeability, and fluid saturations. We provide a concise historical overview and a technical evaluation of the primary equations used in LF-NMR data inversion. We examine recent advancements in LF-NMR and MRI applications, identify persistent challenges and future perspectives, and summarize key lessons learned from the recent literature. Hence, this review provides a comprehensive roadmap for applying magnetic resonance to rock core analysis.

Abstract: The fifth member of the Upper Triassic Xujiahe Formation (T₃x⁵) in the southwestern Sichuan Basin contains widely developed organic-rich source rocks, which represent a crucial interval for hydrocarbon exploration in the region. This study systematically evaluates the organic geochemical characteristics, spatial distribution, and hydrocarbon generation potential of these source rocks using total organic carbon (TOC) analysis, organic matter typing, vitrinite reflectance (Ro) measurements, and basin modeling. The results show that the upper and lower submembers have average TOC values of 3.19% and 3.41%, respectively, with organic matter predominantly of mixed sapropelic-humic type (Type II₂). TOC content generally increases from uplift areas to depressions, reflecting the control of depositional environment on organic matter preservation. Thermal maturity exhibits a westward increase and eastward decrease, with the southwestern part reaching high to over-mature stages (Ro generally >1.3%), while the eastern part remains in the condensate-wet gas window. Thickness of the upper submember ranges from 60 to 320 m, with depocenter in the central-southern part of western Sichuan; the lower submember is 60-200 m thick, centered in the Chengdu-Deyang area. Basin modeling, which integrates burial and thermal histories, estimates a cumulative gas generation of approximately 192×10¹² m³ (192 trillion cubic meters), with the highest generation intensity coinciding with the western Sichuan depression. It is concluded that the T₃x⁵ source rocks possess excellent material bases and huge resource potential. Tight sandstone reservoirs adjacent to the gas kitchen should be prioritized in future exploration, with differentiated strategies adapted to various maturity zones.

Abstract: The Siberian Traps has been a reference object for geologists for many years in understanding the origin of Large Igneous Provinces on Earth. Data from high-magnesium rocks in its northern region have traditionally been used to create genetic models. However, the central and southern parts, consisting of the basaltic rocks, remain significantly unexplored, despite their important role in volcanic evolution within the province. This article presents new structural, mineralogical, and geochemical data from the tuff-lava sequence in the central region of the Tunguska syneclise. The studied sections are located along the Lower Tunguska River Valley, near Tura, Babkino, and Vanavara, in the Podkamennaya Tunguska Valley. They consist of pyroclastic rocks belonging to the Korvunchansky Formation, which are overlain by basalts and tuffs of the Nidymsky and Kochechumsky Formations (Early Triassic, 251 Ma). Major and trace element analysis of 64 samples shows that basalts from all formations are relatively similar in composition, belonging to the tholeiite type with MgO concentrations ranging from 4.2% to 7.8%. Trace element patterns exhibit negative Ta-Nb anomalies and positive Pb anomalies, which are typical of the Siberian Platform basalts. Tuffs, on the other hand, differ from the basalts by having higher SiO₂ and K₂O contents and steeper rare earth element (REE) patterns. Isotopic analysis (Sr-Nd) confirms this difference and suggests that basalts and tuffs originated from two distinct magma sources. The Nidymsky basalts have positive εNd values (+2.21 to +3.10), similar to those of the Morongovsky and Mokulaevsky basalts in the Norilsk area. Tuffs, on the other hand, exhibit negative εNd (-1.33 to -4.5) and elevated 87Sr/86Sr (>0.706), in comparison with basalts (0.704-0.706). Geological observations reveal that pyroclastic rocks play a significant role in the initial stages of volcanic activity. The main result of this study is that tuffs from the Korvunchansky and Khakanchansky Formations (in the south and north of the region, respectively) are identical in their geochemical characteristics. This similarity suggests the existence of a single pyroclastic cover over the Siberian Platform. These tholeiitic pyroclastic rocks, which are similar in composition to the lower crust, mark the beginning of trap magmatism, rather than picrites, as suggested by the plume model.

Abstract: Petrology, as one of the fundamental branches of geology, has consistently sought to answer fundamental questions regarding the origin, evolution, and diversity of igneous and metamorphic rocks. This review article, adopting a comprehensive approach without relying on new field data, examines the conceptual and methodological evolution of petrology from its formative years to contemporary research horizons. In the first section, the theoretical framework governing igneous petrology—including concepts of fractional crystallization, partial melting, magmatic series, and the tectonic setting of magmatism—is critically evaluated. In the second section, the principles of phase equilibria, metamorphic facies, pressure-temperature-time paths, and the role of fluids in rock metamorphism are elaborated. Furthermore, the application of geochemical methods, including stable and radiogenic isotopes, alongside novel approaches such as machine learning applications and thermodynamic modeling, are introduced as contemporary research perspectives. The article concludes by emphasizing that the ultimate goal of petrology is the integration of micro-scale observations with macro-scale tectonic theories to construct a unified picture of Earth's evolutionary history.

Abstract: This article describes the mineralogical and geochemical features of the Marsyaty sedimentary deposit of Fe and Mn ores in the Northern Urals (Russia). Oolitic ironstones are localized in coastal sandstones of the Cenomanian age. Сarbonate Mn ores lies within siliciclastic sediments of the Lower Paleocene and are separated from the oolitic ironstone by a layer of gravel. Authigenic iron oxyhydroxides, chamosite/bertierite and superimposed siderite predominate in the ironstones; kaolinite, apatite, perhamite, calcite and dolomite are minor and rare. Rhodochrosite and rencieite are major minerals of the Mn ore; layer Mn-silicates (caryopilite, parsettensite?) are minor and rare. Both ore types contain authigenic glauconite, montmorillonite, sulfides (sphalerite/wurtzite, galena, pyrite), gibbsite/boemite, REE phosphates. The detrital component of both types of ores is represented by clasts of quartz, ilmenite, zircon, monazite, epidote, titanite, muscovite, and feldspars. The δ13Сcarb varies from -18.5 to -23.3 in carbonate ironstone and -10.0 to -41.0 ‰ PDB in manganese ore. The light isotopic composition of carbon and numerous organic relics indicate the participation of microbes in both types carbonate ore formation process. It is concluded that iron and manganese ores belong to a joint transgressive series of sedimentary rocks that arose sequentially during the evolution of the West-Siberian basin. The unique feature of the Marsyaty deposit is that, within a limited area and over a short geological period, favorable conditions were realized first for the accumulation of iron and manganese, and then only for manganese.

Abstract: Accurate prediction of gold enrichment is critical for mineral exploration and resource evaluation, particularly in data-limited environments where only geochemical information is available. This study evaluates machine learning (ML) models against linear baselines for predicting relative gold enrichment defined as ln(Au/G10), where G10 represents the geometric mean of ten predictor elements (S, Fe, Al, Si, Mn, Sr, Ni, Cu, K, Ti). A total of 53,126 samples from a sulphide-hosted orogenic gold system were subjected to compositional data analysis (CoDA) preprocessing, including multiplicative replacement of below-detection values, closure to a constant sum, centred log-ratio (CLR) transformation of predictor variables, and robust outlier filtering using the Minimum Covariance Determinant (MCD) method. After screening, 41,626 samples were retained for modelling. Comparative modelling included linear baselines—Ordinary Least Squares (OLS), Ridge, Lasso, and Huber—and non-linear ML algorithms: Random Forest (RF), Support Vector Regression (SVR), k-Nearest Neighbours (kNN), and Multi-Layer Perceptron (MLP). Under the non-circular formulation, nonlinear models consistently outperformed linear baselines. Random Forest achieved the strongest validation performance (R2 ≈ 0.51), followed closely by MLP and SVR, while linear models remained substantially weaker (R2 ≈ 0.31). SHapley Additive exPlanations (SHAP) applied to the Random Forest model identified sulphur (S) and iron (Fe) as the most influential predictors, consistent with sulphide-controlled gold mineralization processes in orogenic systems. The model predicts relative gold enrichment based solely on multielement geochemistry, providing a robust and interpretable proxy for mineralization intensity in data-constrained environments. This study demonstrates that machine learning models, when combined with CoDA-correct preprocessing and a non-circular target formulation, can provide geologically meaningful and methodologically robust predictions of gold enrichment. The workflow offers a transparent and reproducible framework for early-stage exploration targeting using multielement geochemistry.

Abstract: This study investigates the provenance, weathering history, and tectono-sedimentary evolution of Lower Ediacaran siliciclastic rocks of the Imiter Formation (Saghro Group, Imiter Sub-inlier, Anti-Atlas, Morocco) deposited along the northern margin of Gondwana. An integrated approach combining petrography, whole-rock major and trace element geochemistry, rare earth elements (REE), Sm–Nd isotopes, and organic geochemistry (TOC and δ¹³Cₒᵣg) was used to constrain sediment sources and deposi-tional conditions. Geochemical proxies, including Th/Sc, La/Sc, and Zr/Sc ratios, to-gether with REE distribution patterns, indicate that the sediments were mainly derived from felsic to intermediate rocks of the upper continental crust, with only minor sedi-ment recycling. The negative εNd(t) values (−8.5 to −6.2) and Paleoproterozoic Nd model ages (1.6–2.1 Ga) further suggest erosion of evolved crustal sources related to the West African Craton. Weathering indices (CIA, CIW, PIA) suggest weak to moder-ate chemical weathering under predominantly arid conditions. Redox-sensitive proxies (V–Ni, V/Cr, V/(V+Ni)) and low TOC contents (0.1–0.3 wt.%) indicate deposition under mainly oxic to dysoxic conditions with only transient reducing episodes. Tectonic dis-crimination diagrams, supported by regional magmatism, point to sedimentation within an extensional basin evolving from active margin to continental rift conditions during the late Pan-African orogeny. The Imiter Formation records a system dominat-ed by crustal recycling, syn-rift tectonics, and dynamic redox conditions in a shallow marine environment.

Abstract: To reveal the solute sources, migration and enrichment mechanisms of water bodies in the endorheic lake region of the Qiangtang Plateau, Tibetan Plateau, and to clarify the hydrogeochemical cycling patterns in alpine arid zones, this study took typical en-dorheic lake areas in the region as the research object, conducted a systematic hydro-geological survey, collected 28 groups of water samples of various types (including springs, rivers, thermal springs, freshwater lakes, salt lake brines, atmospheric precip-itation and glacial meltwater), tested their major ions, trace elements and physical properties, and comprehensively investigated the hydrogeochemical characteristics, evolution laws and solute sources of water bodies, quantified the dominant control-ling factors and established a conceptual hydrogeochemical model by combining methods such as PHREEQC modeling, principal component analysis (PCA) and Pear-son correlation analysis; the results show that water bodies in the study area exhibit a distinct evolutionary gradient, from the low-salinity HCO₃-Ca recharge end-member, through transitional HCO₃·SO₄-Ca(Mg) water, to highly mineralized Cl-Na(SO₄·Cl-Na) salt lake brine, with synchronous enrichment of Li, B, As and other elements; solute sources are controlled by a ternary coupling mechanism of evaporative concentration, rock weathering and leaching, and deep geothermal fluid input, while cation ex-change and mineral dissolution-precipitation further regulate ionic ratios; As, Li, B and Cl⁻ display conservative migration in non-hydrothermal waters, whereas thermal springs show unique geochemical signatures due to the input of deep-seated fluids; PCA reveals that evaporative concentration (contribution rate 55.39%) is the dominant controlling factor, rock weathering (17.09%) provides the basic solute load, and the coupled process of deep fluid mixing and carbonate precipitation (14.21%) regulates elemental fractionation, and this study constructs a conceptual model of "multi-source recharge–water–rock interaction–evaporative concentration", which clarifies the evo-lutionary laws of regional water bodies and provides a scientific basis for water cycle research and green exploration of strategic mineral resources in salt lakes of the en-dorheic regions on the plateau.

Abstract: Geochemical anomaly detection plays a critical role in mineral exploration, yet conven-tional methods are often limited by compositional effects, sensitivity to outliers, and in-sufficient consideration of spatial relationships. To address these issues, this study pro-poses an integrated analytical framework that combines compositional data analysis and spatial statistics for robust geochemical anomaly identification. The framework incor-porates isometric log-ratio (ILR) transformation to eliminate the closure effect, robust principal component analysis (RPCA) to extract stable geochemical patterns, local indi-cators of spatial association (LISA) to characterize spatial clustering, and compositional balance analysis (CoBA) to enhance anomaly signals. The method is applied to the Barkol Lake area in the Eastern Tianshan, a key metallogenic belt within the Central Asian Orogenic Belt. The results reveal significant geochemical anomalies characterized by Cu-associated element assemblages (e.g., Cu–Ni–Cr), which are spatially correlated with major fault zones and volcanic–intrusive complexes. The identified anomalies show strong consistency with known mineral occurrences and delineate several prospective targets for copper polymetallic mineralization. Compared with conventional approaches, the proposed framework demonstrates improved robustness to outliers, enhanced sensi-tivity to weak anomalies, and better integration of compositional and spatial constraints. These advantages highlight its effectiveness for geochemical anomaly detection and mineral prospectivity mapping in complex geological settings.

Abstract: The Late Triassic Bolila Formation in the central Qiangtang Basin is a critical carbonate succession, yet its depositional age and reservoir‑forming mechanisms have long been contentious. This study presents an integrated sedimentological, detrital zircon U–Pb geochronological, carbon‑oxygen isotopic, and reservoir petrological investigation of the Quemudongda section. Detrital zircon ages constrain the deposition to 225.7–235.7 Ma (Carnian–Norian), correcting its previous Jurassic assignment. Stable carbon and oxygen isotope signatures (δ¹³C up to +4.0‰, δ¹⁸O as low as –14.3‰) corroborate the Late Triassic age and indicate a warm, humid paleoenvironment. The section reveals a steep‑rimmed platform‑margin association dominated by hexactinellid‑calcareous sponge reefs intercalated with seven slump‑breccia layers, recording three evolutionary stages from reef initiation to decline. Reservoir properties are controlled by the interplay of sedimentation, dolomitization, and fracturing. Early dolomitization generated intercrystalline porosity, but subsequent high‑temperature burial recrystallization produced xenotopic textures that severely reduced matrix porosity (average 2.8%). Tectonic microfractures provide the main permeability pathways (0.001–8.5 mD), resulting in a fracture–pore dual‑porosity system. Breccia dolostone exhibits significantly better physical properties (average porosity 3.71%, permeability 2.412 mD) than reef dolostone. The platform‑margin reef‑shoal complex, overlain by Bagong Formation source rocks, forms a favorable lower‑reservoir / upper‑source assemblage. The breccia dolostone–fracture overlap zone represents the sweet spot for hydrocarbon exploration. These findings offer new insights into carbonate platform‑margin evolution and provide a scientific basis for reservoir prediction in the Qiangtang Basin.

Abstract: We present a new whole-rock geochemical dataset for intrusive rocks of the late Variscan Serre batholith (Calabria, southern Italy), a well-exposed section of tilted con-tinental crust emplaced between ~305 and 292 Ma. The dataset includes major, trace and rare earth element (REE) analyses for 74 samples collected from the main plutonic units, ranging from tonalites and quartz-diorites at deeper structural levels to peraluminous granites at shallower levels, as well as leucosomes from associated migmatitic metase-diments. Analytical data were obtained using X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). The dataset integrates new and previously published geochemical data into a con-sistent and reusable format, including sample locations (WGS84), lithological classification and stratigraphic attribution. Sampling sites are also provided as a downloadable geo-spatial (.kmz) file for visualization in GIS platforms. The dataset is made available as a supplementary Excel file. These data are intended to support a wide range of applications, including petro-genetic studies of granitoid magmatism and investigations of water–rock interaction processes in crystalline aquifers. The dataset represents a valuable resource for both fundamental and applied geoscientific research.

Abstract: With growing global REE demand, the investigation of cryptic clay-hosted rare earth element (REE) enrichment provides a better understanding of potential new prospects. This study is focused on novel REE enrichment (up to 1.38 wt.% TREO) identified in the regolith overlying the Doradilla Sn skarn prospect, northern New South Wales, Australia. The REE mode of occurrence was investigated through petrographic, field emission scanning electron microscopy (FE-SEM), micro-X-ray fluorescence (µ-XRF), and Laser Raman analyses. Secondary REE-bearing phosphate minerals are the dominant host of the REE in the regolith at Doradilla. The presence of water identified through Laser Raman confirms these minerals as rhabdophane-(La) (La(LREE,Ca)(PO₄)·_nH₂O), hosting most LREE, and churchite-(Y) (Y(HREE,Ca)(PO₄)·2H₂O), hosting most HREE. Through confirming the majority of REE being hosted in hydrated, and therefore, secondary minerals, this cryptic REE-enrichment is confirmed to be the result of secondary mineralization driven entirely by regolith-derived processes. This study highlights the importance of detailed mineral characterization in confirming the deportment of REEs in clay-hosted settings, and suggests that new protoliths (in this case a Sn skarn) have the potential to form significant, secondary REE enrichment in the overlying clay-hosted, regolith environment.

Abstract: Debris avalanche deposits related to the edifice collapse of the summit area of Zao Volcano have been identified for the first time at the volcano’s eastern foot. These deposits extend approximately 11–15 km from the summit. Based on their spatial distribution and clast petrology, the deposits are interpreted to have originated from the Umanose caldera. Deposit thickness ranges from 20–30 m in the western and northern parts to over 50 m in the eastern part, with an estimated volume of approximately 0.3 km³, comparable to that of the summit caldera depression. Matrix facies occur at most outcrops, whereas block facies are found at only three sites. The vertical drop-to-runout distance ratio (H/L) is less than 0.09, which falls within the typical range for debris avalanches but indicates relatively high mobility. Based on its volume and stratigraphic relationships, the collapse is interpreted to have been caused either by a phreatic eruption or by a non-eruptive large-scale failure of a hydrothermally altered zone beneath the summit area. The collapse is considered to mark the onset of the latest activity stage of Zao Volcano, and the petrological characteristics of the magma differ markedly from those of the preceding stage.

Abstract: The Paleozoic rocks of Egypt's Western Desert remain under limited exploration. Complex subsurface structures create stratigraphic challenges that hinder petroleum exploration. Organic microfacies analysis offers a precise and effective tool to address these challenges and enhance our understanding of environmental changes. The Faghur-1X well penetrated the Devonian Zeitoun Formation, yielding numerous successful core recoveries. Seven of these cores were analyzed to delineate lithological and stratigraphical variations. Three distinct organic microfacies types were identified within the studied section. These organic microfacies reveal significant paleoenvironmental shifts that represent key correlative events within the Devonian. These include liptinite-dominated-medium organic density distal facies (A) (cores 19-A, 18-B, 17-A); vitrinite-dominated-high organic density proximal facies (B) (cores 14-A, 20-A/Band 20-C); ironstone rich and low organic density condensed section/distal facies (cores 18-A, 16-A, 15-A, 15-B). These organic facies exhibit unique characteristics resulting from the interaction of organic matter with the rock matrix and environmental processes. These unique characteristics facilitate intra-basinal stratigraphic correlation. While commonly applied to hydrocarbon source rock evaluation, this study investigates the stratigraphic significance of organic microfacies for resolving subsurface geological problems.

Abstract: The origin of uranium-series imbalance and radiogenic lead excess has long been a subject of debate. Here, based on a novel theory of neutrino oscillation-induced radioactive decay and magma formation, a unified mechanism is proposed to explain uranium-series imbalance, radiogenic lead excess, and excess argon formation. This mechanism indicates that magma originates from the upper mantle, formed by the melting of its constituent materials due to accelerated radioactive decay induced by atmospheric neutrino oscillations. During magma formation, radioactive decay rates typically increase due to Mikheyev-Smirnov-Wolfenstein (MSW) resonance perturbations from neutrino oscillations. This effect causes radioactive isotopes to decay over a shorter period than their normal half-lives would suggest, resulting in overestimated ages based on decay laws. Consequently, radioactive daughter isotopes and radiogenic isotopes become enriched relative to their parent isotopes. The accelerated melting of radioactive materials due to increased decay rates means that both the excess of radioactive daughter isotopes and radiogenic isotopes accompany the magma formation process. When using radiometric dating, careful consideration of the mineral's formation environment is essential. Generally, minerals formed in the crust or at the Earth's surface exhibit relatively normal radiometric ages, whereas minerals formed in the mantle or glassy materials solidified from magma tend to show radiometric ages that are older to varying degrees.

Abstract: The Upper Campanian phosphorite series in Egypt, which overlies the Nubian Group, exhibits pronounced lateral lithological variations. Glauconitic, dolomitic, calcareous, and cherty sediments, together with bituminous shales, form diverse lithofacies associations that reflect the region's complex depositional environments. These lithofacies, associated with the Duwi Formation, are marine deposits originally formed in anoxic, organic-rich environments and later reworked into shallower, oxygenated settings during sea-level fluctuations. This study presents a detailed geological, petrographic, and geochemical characterization of these phosphorite deposits in North Aswan, Egypt, across five localities: Wadi Hilal, East Sibaiya, Um Higarah, Um Salama, and Um Tundbah. The lithostratigraphic succession is dominated by the Upper Cretaceous Duwi Formation, which unconformably overlies the Middle-Campanian Qusseir shale and conformably underlies the Middle-Maastrichtian Dakhla shale. Petrographically, the phosphorites comprise phosphatic grains (pellets and bioclasts such as bone fragments and shark teeth), non-phosphatic grains (quartz), and cements of silica, calcite, and iron oxides. Geochemically, P₂O₅ content ranges from 17.4 to 31.24%, uranium concentrations vary between 40.59 and 245.84 ppm, and total rare earth elements (∑REEs) range from 47.83 to 270.37 ppm. The studied phosphorites are suitable for phosphoric acid production, with potential for uranium recovery as a by-product.

Abstract: The Idrija mercury deposit represents one of the largest mercury formations globally, ranking second only to the Almadén deposit in Spain. The deposit has been exploited for more than five centuries and represents one of the most historically significant and extensively studied mercury mines worldwide. The Karoli orebody is characterized by a high abundance of pyrite (from 50 to 90%) and exceptionally rich cinnabar mineralization, with mercury contents locally reaching up to 78%. This study aims to provide a preliminary yet detailed characterization of the ores from the Idrija mercury deposit and to establish their textural and genetic characteristics. We implemented microscopic examination of thin sections, complemented by LA-ICP-MS trace element analyses of pyrite. Three different pyrite types were identified: fine-grained framboidal Py1, subhedral to euhedral Py2, and larger, well-developed euhedral Py3. LA-ICP-MS analysis of Py3 pyrite grains revealed low trace element concentrations, with maximum values remaining below 100 ppm. These observations suggest that the hydrothermal fluids were mercury-rich but of low salinity, which may have limited the incorporation of trace elements into pyrite. Our research provides new insights into the formation of the Karoli orebody. We envision that further investigations of fluid composition, salinity, and fluid inclusions could significantly enhance understanding of the Idrija mercury formation and evolution.

Abstract: The Wailukum area in North Maluku Province, Indonesia, is an ultramafic rock complex with a high degree of serpentinization. The mineral composition of ultramafic and mafic rocks strongly influences scandium (Sc) distribution and enrichment during lateritization. This study aims to analyze the element distribution, mineral composition, and rock identification in three types of geological materials in a lateritic profile which contains Sc, specifically bedrock, saprolite, and limonite. The analytical methods used are petrography, X-ray Diffraction (XRD), X-ray Fluorescence (XRF), and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Results show that in the bedrock, Sc is mainly associated with clinopyroxene minerals such as augite and diopside. In the saprolite, Sc content decreases due to higher mobility but remains partly associated with clinopyroxene. In the limonite zone, Sc reaches maximum enrichment. Among rock types, gabbro contains the highest absolute Sc concentration (23.25 ppm in bedrock and up to 58.5 ppm in limonite), while wehrlite records the greatest enrichment ratio, with a 9.18-fold increase from bedrock to limonite. In contrast, gabbro shows the lowest enrichment ratio (2.52-fold) despite its high initial Sc content. These patterns indicate that Sc enrichment is controlled by clinopyroxene as the primary host in bedrock, its relative stability during weathering.