Search Results (389)

Fluorite, a key accessory mineral associated with rare earth element (REE) deposits, exerts a significant influence on REE migration and precipitation through complexation, adsorption, and lattice substitution within fluorine-bearing fluid systems. It therefore provides a valuable archive for constraining REE enrichment processes. The Weishan alkaline–carbonatite-related REE deposit, the third-largest LREE deposit in China, is formed through a multistage magmatic–hydrothermal evolution of the carbonatite system. However, limited mineralogical constraints on REE enrichment and precipitation have hindered a comprehensive understanding of its metallogenic processes and exploration potential. Here, cathodoluminescence imaging and LA-ICP-MS trace element analyses were conducted on fluorite of multiple generations from the Weishan deposit to constrain the physicochemical conditions of mobility and precipitation mechanisms of this REE deposit. Four generations of fluorite are recognized, recording progressive evolution of the ore-forming fluids. Type I fluorite, which coexists with bastnäsite and calcite, is LREE-enriched and exhibits negative Eu anomalies, indicating precipitation from high-temperature, weakly acidic, and reducing fluids. Type II fluorite occurs as overgrowths on Type I, while Type III fluorite replaces Type II fluorite, with both displaying LREE depletion and MREE-Y enrichment, consistent with cooling during continued hydrothermal evolution. Type IV fluorite, which is interstitial between calcite grains and associated with mica, is formed under low-temperature, oxidizing conditions, reflecting REE exhaustion and the terminal stage of fluorite precipitation. Systematic shifts in REE patterns among the four generations track progressive cooling of the system. The decreasing trend in La/Ho and Tb/La further suggests that these fluorites record dissolution–reprecipitation events and associated element remobilization during fluid evolution. Full article

In a seminal paper V.M. Goldschmidt pointed out that, in terms of volume of the constituent ions, Earth’s crust and mantle are basically a packing of negatively charged oxygen ions bound together by the volumetrically barely significant cations. Here, this statement is revisited using modern assessments of mantle composition and pressure-dependent ionic radii. It is found that the transition to the lower mantle marks a reduction in the O²⁻ crystal ionic volume percentage from 86 to less than 80%, significant enough to suggest an overall reduced compatibility of less abundant elements within the first few hundred km of depth below that transition from lower-mantle to upper-mantle rock. An equivalent drop across both, the 410- and 670 km mantle discontinuities occurs for large polyhedral sites, which are the potential hosts for incompatible elements. Accordingly, most large ionic lithophiles and rare earth elements in the lower mantle are highly enriched in one minor phase, davemaoite. It is proposed that those minor and trace elements that are less compatible with this mineral, such as some of the high-field strength elements, are concentrated in yet unknown accessory minerals that potentially affect geochemical signatures of deep mantle-derived igneous rocks. Full article

Mine tailings management poses a major challenge, with up to 99% of the mined material remaining as finely ground residues. This study analyzes a SERNAGEOMIN database from 653 Chilean tailing deposits using a multivariate framework that integrates completeness assessments, descriptive statistics, and hierarchical clustering on log-transformed and standardized chemical concentrations of 56 elements in order to identify dominant geochemical patterns. This study aims to provide an integrated and systematic interpretation of the Chilean database, the most comprehensive public dataset on mine tailings in Chile. The results reveal four distinct geochemical profiles: (i) silicate copper tailings, rich in Cu and associated with a SiO₂-Al₂O₃ matrix; (ii) Zn-Pb-Cd-As polymetallic tailings, with the highest concentrations of heavy metals and rare earth elements (REEs), representing both high environmental risk and potential economic value; (iii) carbonate-matrix tailings (CaCO₃ and limestone), characterized by high CaO and loss of calcination (LOI) but low trace metal contents, suggesting buffering potential against acid mine drainage (AMD); and (iv) clay-rich tailings (kaolin and Au-Cu-Au), marked by high Al₂O₃ and anomalous Co enrichments, indicating unexploited potential for critical metal recovery. These profiles support applications such as their use as source signatures in receptor models and the classification of tailing deposits lacking geochemical information. Full article

The voluminous Mesozoic volcanic rocks developed in the Great Xing’an Range, northeastern China, have received extensive attention in recent decades. However, the timing and petrogenesis, as well as the related geodynamic processes of the Late Mesozoic volcanism, are still controversial. In this paper, we present the whole-rock geochemistry and zircon U–Pb ages for the Late Mesozoic volcanic rocks from the western part of the central Great Xing’an Range, which provide considerable insights into the geodynamic setting of the region. The zircon U-Pb dating results indicate that two main episodes of volcanism occurred in the central Great Xing’an Range, including in the Late Jurassic (ca. 147 Ma) and Early Cretaceous (ca. 142–125 Ma). These Late Mesozoic volcanic rocks display similar geochemical compositions, which are mainly intermediate–felsic, alkaline, peraluminous to metaluminous, enriched in large ion lithophile elements and light rare earth elements, and depleted in high-field-strength elements, indicating arc affinities in the subduction zone. The trace element compositions suggest that the magmatism was related to a post-collisional extensional environment. Combined with the spatial distribution and temporal migration of the Mesozoic magmatic events in the whole northeastern China region, we propose that these Late Jurassic–Early Cretaceous volcanic rocks formed in a continental arc setting, which was mainly related to the rollback of the subducted Paleo-Pacific oceanic plate. Full article

Mid-Neoproterozoic magmatism provides important constraints for revealing the break-up history of the Rodinia supercontinent. Large-sized mid-Neoproterozoic magmatic rocks are distributed within the Dabie Orogen located on the northern Yangtze Block. This study performed zircon LA-ICP-MS geochronology, whole-rock major and trace elements, and zircon Lu-Hf isotope analyses on orthogneisses with a mid-Neoproterozoic protolith age of the northern Dabie Orogen. The analysis results show that the intrusion times of mid-Neoproterozoic granitoids and mafic rocks are all ~750 Ma, with ε_Hf(t) values ranging from −6.60 to −2.57 and a two-stage Hf model age of ~1.8 Ga. They are characterized by light rare earth element (LREE) enrichment and heavy rare earth element (HREE) depletion. In the primitive mantle-normalized trace element diagram, these rocks are enriched in La, Ce, Th, K, Zr, Nd, and Sm and depleted in Nb, Ta, P, Ti, and Sr, with negative Eu anomaly or no significant Eu anomaly. Based on the discrimination diagrams, most of the samples are plotted into the A-type granite field, and which was formed in a post-orogenic extension setting. Comprehensive analysis shows that these mid-Neoproterozoic magmatic rocks were produced by melting of juvenile crust of the Paleoproterozoic and late Mesoproterozoic, having a heterogeneous distribution of δ¹⁸O, indicating that these rocks were developed mainly through high-temperature meteoric-hydrothermal alteration during syn-rift magmatic activity. Full article

Magmatic zircon trace element compositions and their variation trends provide valuable insights into the nature and evolutionary processes of magmatic rocks. The Himalayan orogen contains widespread leucogranites. Despite extensive studies on these granites, the features and petrogenetic implications of trace element composition of zircons from the leucogranites remain poorly constrained. In this study, we present a comprehensive dataset comprising new cathodoluminescence (CL) images, U-Pb ages, and trace element compositions of zircons from the Himalayan leucogranites, and compare them to the previously reported trace element data of zircon from I-type granites. Our results show that zircons from the Himalayan leucogranites have high Hf, U, Y, P, Th, Sc, and heavy rare earth element contents (HREE), and low Nb, Ta, Ti, and light rare earth element contents (LREE), and can be divided into two types. Type I (low-U) zircons exhibit well-developed oscillatory zoning, and the U concentrations are mostly <5000 ppm. Type II (high-U) zircons display mottled or spongy textures and possess elevated U contents that are mostly >5000 ppm. Zircons from the Himalayan leucogranites have higher contents of U, Hf, Nb, Ta, and elevated U/Yb ratios, but lower Th/U, Eu/Eu*, Ce/Ce*, LREE/HREE, and Ce/U values than those from I-type granitic zircons. Furthermore, zircons in the Himalayan leucogranites have gradually decreasing Th, Ti, Th/U, Eu/Eu*, and Ce/Ce*, and increasing U, Nb, Ta, and (Yb/Gd)_N with increasing Hf. These geochemical features suggest the magmas involved in the genesis of leucogranites originated from the partial melting of metasedimentary sources under relatively reduced conditions, and underwent a high degree of magmatic fractionation. Full article

Rare earth elements and yttrium (REY) are emerging contaminants of concern due to their widespread use in modern technologies, persistence, and unknown ecological effects. This study presents the first assessment of REY in seawater and sediments of Pula Bay, Croatia, a semi-enclosed, industrialized coastal system. Surface seawater and sediment samples were analyzed using ICP-MS, following optimized preconcentration and digestion protocols. PAAS-normalized REY patterns and λ Polynomial Modelling identified natural and anthropogenic fractionation signatures. Dissolved ΣREE in seawater ranged from 17.6 to 45.9 ng L⁻¹, with naturally elevated concentrations from continental runoff and evidence of anthropogenic Gd (up to 33%) linked to sewage outputs. Sediment ΣREE concentrations varied from 134.8 to 218.2 mg kg⁻¹, with spatial variation reflecting terrigenous and anthropogenic inputs. Local MREE_PAAS and HREE_PAAS enrichment associated with industrial and municipal inputs distinguished anthropogenic contributions from the lithogenic background. While seawater remains largely unaffected, pollution and risk assessments indicate moderate to high sediment contamination by MREEs and HREEs, showing potential concern for benthic organisms near industrial and urban hotspots. These findings highlight the combined influence of natural and anthropogenic processes on REY distribution in coastal systems and underscore the need for further studies of potential REY effects in impacted coastal environments. Full article

Mesozoic granitic rocks are widely developed in the Great Xing’an Range, and determining their emplacement age and genesis is crucial for reconstructing the tectonic-magmatic evolution of Northeast China. This paper reports the petrographic, geochronological, geochemical and zircon Hf isotopic characteristics of granites in the Huolin Gol area of the southern Great Xing’an Range to determine the formation age, source nature and geodynamic background of the rocks in this area. Zircon U–Pb dating results show that the granites in the study area were formed in the Early Cretaceous (134–130 Ma), rather than the Late Jurassic as previously thought. The granites have SiO₂ contents ranging from 75.02 to 78.53 wt.%, Na₂O = 3.55–3.89 wt.%, K₂O = 3.98–5.11 wt.%, Na₂O/K₂O = 0.72–0.97, A/CNK = 1.04–1.14. Their rare earth element (REE) distribution patterns are all right-inclined, with LREE/HREE = 3.89–12.41, (La/Yb)_N = 2.39–18.86, Eu/Eu* = 0.02–0.17. Trace element spider diagrams show significant enrichment in Rb, Th, U, K, Pb and LREEs, and depletion in Ba, Nb, Ta, Sr, P, Ti and HREEs. The zircon εHf(t) values range from +6.4 to +15.0, and the two-stage Hf model ages (T_DM2) range from 773 to 226 Ma. These characteristics indicate that the granitic rocks belong to the weakly peraluminous high-K calc-alkaline I-type granite, derived from partial melting of newly generated juvenile continental crust materials. Combined with the coeval magmatic associations, spatial distribution patterns, and regional tectonic evolution, we propose that the Early Cretaceous granitic rocks in the study area formed in an active continental margin setting, with their geodynamic mechanism linked to the subduction of the Paleo-Pacific Plate beneath the East Asian continent. Full article

Hubei Province is a significant center for cultural and trade exchange in Central China. However, since no nephrite deposit has been discovered in Hubei, nephrite artifacts excavated within its jurisdiction must have been obtained from other regions. Tracing their provenance can contribute to our understanding of the trade exchange between ancient Hubei and other regions. In this study, the appearance, spectroscopy, and chemical compositions of nephrite artifacts excavated from the Fangjiagang Cemetery of the Eastern Zhou Dynasty, Hubei Province, were systematically studied, and their provenance was discussed. The characteristics of a weathered layer of raw nephrite material retained in one of the jade artifacts (M22:5) indicate it should be made from the placer nephrite of Hetian, Xinjiang. Infrared and Raman spectroscopy confirms that both the whitened and unwhitened areas in the samples are composed of tremolite, indicating that the whitening mechanism should be attributed to the etched structures caused by weathering rather than a change in the major mineral composition caused by high temperature. When no obvious appearance-based characteristics remain, chemical compositions become a crucial tool for discussing the provenance of jade artifacts. The chondrite-normalized rare earth element patterns for the samples suggest that their formation is associated with granite intrusion, implying that the placer nephrite of Hetian, Xinjiang; Xiuyan nephrite, Liaoning; Golmud nephrite, Qinghai; Xiaomeiling nephrite, Jiangsu; Vitim nephrite, Russia; and Chuncheon nephrite, South Korea, are potential sources. However, the trace element spider diagrams for the samples show a better match with those of the placer nephrite of Hetian. The placer nephrite of Hetian was used in Fangjiagang Cemetery, indicating that the trade exchange between the Eastern Zhou dynasty and the Hetian area had already been established. Full article

This study provides a comprehensive assessment of the geoecological status of selected mountain rivers in the North-Eastern Caucasus—specifically, the Sunzha, Sulak, Ulluchay, Karachay, and Atachay—through an analysis of chemical element concentrations, including heavy metals (HMs), in surface water, suspended particulate matter (SPM), and bottom sediments. The elemental composition was determined using inductively coupled plasma mass spectrometry (ICP-MS) on a PlasmaQuant MS Elite instrument (Analytik Jena, Germany), enabling high-precision quantification of 70 chemical elements. Element concentrations in surface water were compared against regulatory limits (e.g., maximum permissible concentrations (MPCs)) defined in international and national guidelines; concentrations in SPM were assessed relative to global average riverine values; and those in bottom sediments were evaluated with reference to average upper continental crust abundances (Clarke values). To trace potential sources of heavy metals entering the riverine systems, enrichment factors (EFs) were calculated for bottom sediments. The results indicate that surface water, suspended particulate matter, and bottom sediments in the investigated rivers exhibit enrichment in numerous chemical elements to levels exceeding their respective reference values (MPCs, global river means, or crustal Clarke values). Significant regional variations in abiotic parameters were observed. Water temperature ranges were 4.6–28 °C (Russian rivers) and 6.9–13.6 °C (Azerbaijan rivers). The pH of Russian rivers was circumneutral to mildly alkaline (7.12–8.83), whereas Azerbaijani rivers were distinctly alkaline, with values reaching 9.88. Reducing conditions in sediments (Eh as low as −206 mV) were prevalent at several stations across both regions. This enrichment reflects an overall unfavorable geoecological status of the studied river systems. Elevated concentrations of several rare earth elements (REEs), observed across multiple sampling locations, suggest a substantial lithogenic contribution linked to the geological structure of the catchments, including the composition of the drained rocks and the presence of ore-bearing formations. Furthermore, localized increases in the concentrations of key heavy metals—such as copper, zinc, cadmium, arsenic, and mercury—point to anthropogenic inputs, most likely associated with mining operations, industrial activities, or other human-induced sources. 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

The Lower Cambrian Niutitang Formation was deposited precisely during the Cambrian Explosion period, a short-lived interval marked by drastic shifts in oceanic chemistry and climate. This stratigraphic sequence preserves a comprehensive record of early-ocean evolution and constitutes a world-class reservoir for rare and precious metals, widely termed the “poly-metallic enrichment layer”. Despite its metallogenic prominence, the genetic model for metal enrichment in the Niutitang Formation remains contentious. In this study, we employed inductively coupled plasma mass spectrometry (ICP-MS), carbon and sulfur analyzer, and X-ray fluorescence spectrometry (XRF) to quantify trace-metal abundances, redox-sensitive element distribution patterns, rare-earth element signatures, and total organic carbon contents. Results reveal that metal enrichment in the Niutitang Formation was governed by temporally distinct mechanisms. Member I records extreme enrichment in As, Ag, V, Re, Ba, Cr, Cs, Ga, Ge, Se and In. This anomaly was driven by the Great Oxidation Event and intensified upwelling that oxidized surface waters, elevated primary productivity and delivered abundant organic matter. Subsequent microbial sulfate reduction generated high H₂S concentrations, converting the water column to euxinic conditions. Basin restriction imposed persistent anoxia in bottom waters, establishing a pronounced redox stratification. Concurrent vigorous hydrothermal activity injected large metal fluxes, leading to efficient scavenging of the above metals at the sulfidic–anoxic interface. In Members II and III, basin restriction waned, permitting enhanced water-mass exchange and a concomitant shift from euxinic to anoxic–suboxic conditions. Hydrothermal metal fluxes declined, yet elevated organic-matter fluxes continued to sequester Ag, Mo, Ni, Sb, Re, Th, Ga, and Tl via carboxyl- and thiol-complexation. Thus, “organic ligand shuttling” superseded “sulfide precipitation” as the dominant enrichment mechanism. Collectively, the polymetallic enrichment in the Niutitang Formation reflects a hybrid model controlled by seawater redox gradients, episodic hydrothermal metal supply, and organic-complexation processes. Consequently, metal enrichment in Member I was primarily governed by the interplay between vigorous hydrothermal flux and a persistently sulfidic water column, whereas enrichment in Members II and III was dominated by organic-ligand complexation and fluctuations in the marine redox interface. This study clarifies the stage-dependent metal enrichment model of the Niutitang Formation and provides a theoretical basis for accurate prediction and efficient exploration of polymetallic resources in the region. Full article

The Cretaceous marks the peak of magmatic activity in southeastern (SE) China, which is attributed to the subduction of the paleo-Pacific plate beneath the South China Block. This region constitutes a significant igneous belt along the active continental margin of the western Pacific. Despite extensive research, the origin and evolution of Cretaceous felsic volcanic rocks are still debated. This study investigates the characteristics of zircon U-Pb-Hf isotopes and trace elements, and whole-rock geochemistry of Cretaceous volcanic rocks from the Wenzhou–Taizhou region in SE Zhejiang, and discusses their spatio-temporal patterns and petrogenesis. The results indicate that rhyolitic volcanic rocks formed during the period ca. 114 Ma and 95 Ma, representing two distinct magmatic episodes spanning the transition from the late Early to early Late Cretaceous. The late Early Cretaceous and early Late Cretaceous volcanic rocks are of a hybrid crust–mantle origin, as evidenced by their distinct Nb/Ta ratios, zircon ε_Hf(t) values, and variable trace element enrichments (Ti, Hf, U, Nb, and Yb). These compositional signatures suggest partial melting of late Paleoproterozoic to early Mesoproterozoic basement materials, with increasing mantle contributions over time. Both volcanic phases exhibit elevated Nb/Yb, Th/Nb, and U/Yb ratios, indicating a subduction-modified source akin to arc magmas. Together with calculated initial melt temperatures (<800 °C for Early Cretaceous, >800 °C for Late Cretaceous) and whole-rock rare-earth elements (REEs) distribution patterns (U-shaped with δEu = 0.37–0.65, seagull-shaped with δEu = 0.19–0.62, respectively), it is suggested that both phases of the volcanic magmas were generated through water-assisted (hydrous) melting, whereas the later phase formed at relatively higher temperatures and with a diminished water contribution via dehydration melting under extensional conditions. The generation of voluminous high-silica magmas in the SE China coastal region is probably linked to the rollback and retreat of the paleo-Pacific plate. Full article

Research on the Mesozoic–Cenozoic magmatism and the tectonic framework within the Lhasa Terrane is voluminous. However, the sparse documentation of Early Cretaceous magmatism in this region fuels ongoing debate over the prevailing tectonic regime during this time period (i.e., normal subduction vs. flat subduction). The present study investigates the Luerma pyroxenite and Boyun granitoid in the Western Lhasa Terrane through zircon U-Pb dating, whole-rock geochemistry, mineral chemistry, and Sr-Nd-Hf isotopes. The findings date the formation of Luerma pyroxenite at 115 Ma and Boyun granites at 113 Ma to the Early Cretaceous period (115–113 Ma). SiO₂ content of pyroxenite is relatively low (34.27–44.16 wt.%), characterized by an enrichment in large ion lithophile elements (LILEs), light rare earth elements (LREEs), and a depletion in heavy field strength elements (HSFEs), indicative of a metasomatic origin. The εNd (t) and εHf (t) values of the Early Cretaceous ultrabasic rocks range from +2.1 to +2.7 and −0.8 to +10.1, respectively, suggesting their derivation from an enriched mantle source with asthenospheric material incorporation. The Early Cretaceous granodiorites and their mafic enclaves belong to the high-K calc-alkaline series, and show enrichment in LILEs (e.g., Rb, Ba, U, and Th) and depletion in HFSEs (e.g., Nb, Ta, Ti, and Zr). The acidic rocks and their developed mafic enclaves exhibit the geochemical characteristics of trace elements found in island arc magmas. Their εNd (t) values are (−6.0–−5.0), while their εHf (t) values are (−11.7–−1.8); the MMEs εHf (t) values are (−4.1–+0.9). In summary, the Early Cretaceous pyroxenite in the Gangdese Belt originated from a combination of asthenospheric and enriched lithospheric mantle melts, while the granitoids were generated by partial melting of the mantle wedge, a process driven by metasomatism resulting from the slab-derived fluids. At the same time, heat from upwelling mantle-derived melts induced the partial melting of lower crustal materials, leading to the formation of acidic magmas through varying degrees of mixing with basic magmas. This study suggests that Early Cretaceous magmatic activity occurred within a northward subduction setting, characterized by the rotation and fragmentation of the Neo-Tethys oceanic crust. Full article

Inatlar limestone, which is dated to the Middle Jurassic–Lower Cretaceous, is exposed between the villages of Kabulbaba and Söğütalan in the Mustafakemalpaşa district of Bursa, Turkey. This study investigates its mineralogical, petrographic, and geochemical characteristics, focusing on major, trace, and rare earth element (REEs) compositions to interpret the depositional environment, paleoenvironmental conditions, and diagenetic processes. Petrographic analysis identified four main limestone types: siliceous, micritic, fossiliferous, and dolomitic. REEs geochemistry indicates enrichment in heavy REEs (HREEs), depletion in light REEs (LREEs), and characteristic anomalies with negative Ce and Eu and positive La, suggesting an open marine depositional environment and early diagenesis. Trace element data point to deposition in settings ranging from continental margins to open marine environments. Ni and V concentrations reflect a spectrum of depositional conditions, including terrestrial, transitional (oxic–dysoxic), and marine anoxic settings. Z values support the theory that the limestones have a marine origin. δ¹³C and δ¹⁸O isotope values indicate deposition in both hydrothermal and typical marine carbonate environments. Y/Ho and Er/Nd ratios reveal the influence of terrestrial input, as well as diagenetic and detrital material. Furthermore, V/(V + Ni) ratios reflect fluctuating oxic to suboxic/anoxic conditions, while Ni/Co ratios indicate predominantly euxinic and, to a lesser extent, anoxic conditions. Altogether, these geochemical signatures suggest that the Inatlar limestone was deposited in a dynamic marine system characterized by variable redox states and salinity fluctuations. Full article