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Keywords = magmatic–metamorphic fluids

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30 pages, 4224 KB  
Review
Endogenic Gold Metallogeny in Heilongjiang Province, NE China: Implications for Tectonic Transition and Composite Metallogenic Systems
by Tiesheng Li, Sheng Lu, Mingxin Duan, Hui Gong, Zhichao Song and Lingyun Hu
Minerals 2026, 16(8), 859; https://doi.org/10.3390/min16080859 - 21 Aug 2026
Viewed by 131
Abstract
Heilongjiang Province, northeastern China, occupies a key metallogenic position between the eastern Central Asian Orogenic Belt and the western Pacific continental margin. This review integrates published geological, geochronological, fluid–inclusion, and H–O–S–Pb isotope data to evaluate tectonic controls on endogenic gold mineralization. Four principal [...] Read more.
Heilongjiang Province, northeastern China, occupies a key metallogenic position between the eastern Central Asian Orogenic Belt and the western Pacific continental margin. This review integrates published geological, geochronological, fluid–inclusion, and H–O–S–Pb isotope data to evaluate tectonic controls on endogenic gold mineralization. Four principal metallogenic episodes are recognized: Caledonian porphyry-related mineralization associated with Paleo–Asian Ocean subduction–accretion; Variscan skarn-forming magmatic–hydrothermal activity; Indosinian post-collisional structurally focused and epithermal hydrothermal activity; and Yanshanian mineralization characterized by Late Jurassic compressional reworking followed by a dominant Cretaceous Paleo–Pacific-related magmatic–hydrothermal pulse. Ore-forming fluids evolved non-monotonically from Paleozoic high-temperature magmatic fluids to more heterogeneous crustal, metamorphic, and meteoric–water–influenced systems. Zhengguang and Laozuoshan provide clear evidence for temporally distinct superimposed mineralization. Later hydrothermal reactivation could either remobilize and reconcentrate Au or leach, disperse, and obscure earlier mineralization. Exploration should therefore prioritize reactivated structural corridors where intrusive centers, reactive wall rocks, volcanic basins, and multi-stage alteration overlap. Full article
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16 pages, 62972 KB  
Article
Ancient Crustal Signatures in Mesozoic Magmatic Rocks of the Gan–Hang Belt: Zircon U-Pb Age and Trace Element Evidence from a Microdiorite Dike in Jiangshan, South China
by Junfeng Dai, Peng Zhang and Fuzong Li
Minerals 2026, 16(8), 846; https://doi.org/10.3390/min16080846 - 17 Aug 2026
Viewed by 274
Abstract
Geochronological investigation and geochemical tracing of xenocrystic zircons entrained in magmatic rocks serve as effective approaches for directly unraveling the material composition and architectural framework of the deep-seated ancient continental crust. Here, we present an integrated petrological, zircon petrographic, U-Pb geochronological, and trace [...] Read more.
Geochronological investigation and geochemical tracing of xenocrystic zircons entrained in magmatic rocks serve as effective approaches for directly unraveling the material composition and architectural framework of the deep-seated ancient continental crust. Here, we present an integrated petrological, zircon petrographic, U-Pb geochronological, and trace elemental study of a microdiorite dike from the Jiangshan area within the Gan–Hang tectonic belt, which is a key suture zone between the Yangtze and Cathaysia Blocks. Four distinct zircon types are recognized. Type I (2528 ± 21 Ma) is a metamorphic zircon that is derived from eclogite-facies metamorphism of a Neoarchean basement, revealing the existence of a Neoarchean continental crust in the deep South China Block. Types II (848 ± 53 Ma) and III (481 ± 93 Ma) are magmatic zircons representing captured Neoproterozoic and Early Paleozoic magmatic rocks, respectively. Type IV (137 ± 8.4 Ma) occurs as an overgrowth on its inherited cores and records the emplacement age of the microdiorite dike. Trace element compositions of Early Cretaceous zircons (type IV) show low Nb/Hf and elevated Th/Nb ratios, consistent with a magmatic arc setting. Combined with petrographic evidence of quartz xenocrysts and the diversity of captured zircons, we propose that the parental magma originated from partial melting of the subcontinental lithospheric mantle induced by slab-derived fluid flux, with the subsequent assimilation of diverse crustal materials during its ascent. This study not only constrains the Early Cretaceous arc magmatism in response to Paleo-Pacific Plate subduction but also provides evidence for Neoarchean crustal relics in the deep subsurface of the South China Block, with important implications for the deep compositional architecture and tectono-magmatic evolution of South China. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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19 pages, 7551 KB  
Article
Satellite Detection of Diffuse Tectonic CO2 Degassing in the East African Rift
by Cristina Flesia, Andrei Starkov, Alessio Casagli, Samantha Remigi and Maria Luce Frezzotti
Remote Sens. 2026, 18(15), 2586; https://doi.org/10.3390/rs18152586 - 4 Aug 2026
Viewed by 303
Abstract
Understanding the processes behind Earth’s CO2 degassing is crucial for clarifying how carbon is cycled by geologic processes on our planet. Earth’s carbon degassing results from magmatic and metamorphic processes controlled by large-scale plate tectonics. However, the nature and amount of diffuse [...] Read more.
Understanding the processes behind Earth’s CO2 degassing is crucial for clarifying how carbon is cycled by geologic processes on our planet. Earth’s carbon degassing results from magmatic and metamorphic processes controlled by large-scale plate tectonics. However, the nature and amount of diffuse CO2 fluxes from faults in continental rifts remain largely unconstrained. Recent research reports important CO2 fluxes from deep faults over 17 × 104 km2 in the East African Rift System (EARS), highlighting the need for a more detailed inventory of diffuse soil emissions. Across such extensive regions, only satellite observations can provide the broad measurement range needed to meet the observational requirements for long-term, large-scale overlay datasets. While space-based data provide extended coverage for large-scale identification of CO2 emission sources, to date, only the column-averaged total CO2 atmospheric content has been measured from space. Range-resolved measurements of CO2 concentration with the vertical accuracy needed to detect diffuse soil emissions are not available from space, preventing direct quantification of Earth degassing over large regions. In this paper, we focus on a new approach to measuring soil CO2 fluxes by a statistical deconvolution of column measurements of global atmospheric CO2 content. Anthropogenic increase, seasonal climatology at a small regional scale, and soil fluxes are measured without the use of ancillary measurements or model simulations. We combine petrology of fluid and melt phases in mantle rocks with a new satellite data analysis to reveal, for the first time, large CO2 fluxes from the lithospheric mantle to the atmosphere in a much wider region than previously considered (22.4 × 105 km2), including the Ethiopian and East African domes, where magmatism is no longer active or absent. We infer that diffuse soil emissions are measurable from space, and that Earth’s tectonic carbon fluxes are considerably more relevant than currently considered, with a crucial impact on the balance of the global carbon cycle. Full article
(This article belongs to the Special Issue Remote Sensing Application in the Carbon Flux Modelling)
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27 pages, 68524 KB  
Article
Metallogenic Mechanism of the Mangyahedong Gold Deposit in the Qimantage Area, Qinghai Province, NW China: Constraints from Hydrothermal Apatite U-Pb Dating and Trace Elements of Pyrite
by Shaonan Li, Tingmei Huang, Hailin Xie, Yu Han, Sulong Chen, Bin Wang, Haiyun Ma, Wenjun Ma, Rucai Ma, Ming Ma, Siyu Jiang and Zhen Wang
Processes 2026, 14(13), 2185; https://doi.org/10.3390/pr14132185 - 3 Jul 2026
Viewed by 456
Abstract
The Mangyahedong gold deposit—recently discovered in the Qimantage segment of the East Kunlun orogenic belt—is a high-priority exploration target. Key unknowns include its mineralization age, the sources of sulfur and gold, and the tectonic–magmatic–hydrothermal controls on formation. These gaps have hindered genetic classification [...] Read more.
The Mangyahedong gold deposit—recently discovered in the Qimantage segment of the East Kunlun orogenic belt—is a high-priority exploration target. Key unknowns include its mineralization age, the sources of sulfur and gold, and the tectonic–magmatic–hydrothermal controls on formation. These gaps have hindered genetic classification and stage-specific research. We addressed them through integrated petrography, TIMA mineral mapping, in situ LA-ICP-MS analysis of pyrite from three mineralization stages, and U-Pb dating of hydrothermal apatite spatially and temporally linked to the main sulfide-precipitation event. The stages are: (I) early sericite–quartz alteration; (II) main ore stage—carbonate–chlorite–sulfide + native gold; and (III) late calcite–pyrite veins. Pyrite zoning shows that early pyrite cores are enriched in As and Au. In contrast, the main-stage pyrite has As-poor cores, with As, Au, and Co progressively enriched toward the rims. This zoning pattern indicates evolving fluid redox conditions and metal complexation during ore deposition. A 207Pb/206Pb age of 406 ± 13 Ma from apatite in gold-bearing quartz–sulfide veins constrains gold deposition to the Late Silurian–Early Devonian transition. Age, texture, and geochemistry collectively support a regional metamorphic–deformational origin, consistent with the orogenic gold model. Isotopic and elemental data point to the Qimantage Group volcanic rocks as the dominant source of ore-forming elements—indicating strong potential for discovery along strike and at depth. Full article
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22 pages, 14775 KB  
Article
Ages and Compositions of Titanite from the Bastielieke Tungsten Polymetallic Deposit, Southern Altay: Implications for Multiple-Stage Hydrothermal Events
by Mengjing Xu, Fengmei Chai, Yanwang Wu and Wen Wang
Minerals 2026, 16(7), 688; https://doi.org/10.3390/min16070688 - 30 Jun 2026
Viewed by 436
Abstract
The Bastielieke W-polymetallic deposit, located in the Xinjiang Altay metallogenic belt, records a complex hydrothermal history critical to understanding multi-stage metallogenic processes in the southern Altay. This study integrates in situ U-Pb dating of hydrothermal titanite and zircon with textural and compositional analyses [...] Read more.
The Bastielieke W-polymetallic deposit, located in the Xinjiang Altay metallogenic belt, records a complex hydrothermal history critical to understanding multi-stage metallogenic processes in the southern Altay. This study integrates in situ U-Pb dating of hydrothermal titanite and zircon with textural and compositional analyses of titanite to reconstruct this history. Three types of hydrothermal titanite, identified from pyroxene skarn (TtnI), epidote skarn (TtnII), and quartz–sulfide ore (TtnIII), display dissolution–reprecipitation textures and systematic compositional variations, indicating distinct fluid compositions and origins. TtnI, TtnII, and TtnIII yield U-Pb ages of 244.7 ± 7.8 Ma, 252.4 ± 5.5 Ma, and 250.6 ± 3.0 Ma, respectively, and hydrothermal zircon from pyroxene skarn yields an age of 249.9 ± 2.1 Ma, constraining the hydrothermal event to the latest Permian to Early Triassic. These ages are interpreted to record the timing of U-Pb system resetting during regional shear–thrust movements. Compositional variations among the three titanite types reveal a two-stage hydrothermal history. The earlier stage involved W–Cu mineralization and protolith titanite precipitation related to magmatic–hydrothermal fluids exsolved from Permian granites. The later stage was driven by regional shear–thrust movements and metamorphic–hydrothermal processes, which reset the titanite U-Pb systems, partially altered TtnI and TtnII, precipitated TtnIII, and remobilized metals. This model links the Bastielieke deposit to multi-stage hydrothermal processes and provides insights into similar metallogenic events along the southern margin of Xinjiang Altay. Full article
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19 pages, 1689 KB  
Article
Geothermal System Elements and Genetic Mechanism of High-Temperature Geothermal Resources in the Changbai Mountain Area
by Jialin Song, Nansheng Qiu, Qianqian Feng and Boning Tang
Energies 2026, 19(13), 2985; https://doi.org/10.3390/en19132985 - 25 Jun 2026
Viewed by 311
Abstract
The Changbai Mountain area, the largest Cenozoic intraplate volcanic field in eastern China, features abundant high-temperature hot springs and high geothermal potential. However, the genesis and aggregation patterns of its geothermal systems remain poorly understood. This study recalculates crustal and residual deep/mantle heat- [...] Read more.
The Changbai Mountain area, the largest Cenozoic intraplate volcanic field in eastern China, features abundant high-temperature hot springs and high geothermal potential. However, the genesis and aggregation patterns of its geothermal systems remain poorly understood. This study recalculates crustal and residual deep/mantle heat- flow components along a representative profile and synthesizes published geological, geophysical, geochemical, and geothermal evidence to characterize the main geothermal system elements, including caprock, reservoirs, water source, and migration pathways. Controlling factors are examined from three dimensions: deep dynamics, magmatic heat source, and fault characteristics. Results reveal a “Cold crust–Hot mantle” thermal structure. The heat-flow calculation indicates that crustal radiogenic heat contributes approximately 40% of the surface heat flow, implying a dominant deep heat contribution. The available evidence suggests the presence of potential hydrothermal reservoirs in carbonate and clastic rocks, possible HDR targets in deeper metamorphic rocks, and locally effective basaltic sealing units. Fault systems and meteoric recharge likely control fluid circulation. Geothermal systems are controlled by mantle upwelling and lithospheric thinning due to western Pacific Plate subduction, multi-source heat coupling, effective caprock sealing, and fault-controlled water–heat conduction. These results provide a conceptual framework for future geothermal exploration and testing. This study elucidates the aggregation patterns and genetic mechanisms, providing a theoretical basis for exploration and development. Full article
(This article belongs to the Section H2: Geothermal)
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22 pages, 564 KB  
Article
Deep Gas Sources in Deformable Porous–Fractured Media: Volcanic and Tectonic Systems
by Sebastiano Ettore Spoto
Physics 2026, 8(2), 53; https://doi.org/10.3390/physics8020053 - 11 Jun 2026
Cited by 3 | Viewed by 571
Abstract
Deep gas emissions in volcanic and tectonic environments are commonly interpreted as the surface expression of localized deep emitters. This representation is adequate for first-order description, but it is not physically complete. Deep degassing is more appropriately represented as a coupled source–storage–pathway system [...] Read more.
Deep gas emissions in volcanic and tectonic environments are commonly interpreted as the surface expression of localized deep emitters. This representation is adequate for first-order description, but it is not physically complete. Deep degassing is more appropriately represented as a coupled source–storage–pathway system in which volatile generation, compressible accumulation, phase change, hydraulic communication, and permeability evolution are dynamically linked. Starting from phase-wise mass conservation in deformable porous–fractured media, reduced equations for gas migration, pore-pressure diffusion, and thermo-poro-mechanical coupling are derived, showing how the distinction between gas-mass transport and pressure propagation provides a unified framework for volcanic and tectonic degassing. Deep pressure gradients are shown to arise from the competition between volatile supply and pathway leakance, while episodic discharge can occur when permeability evolves under effective stress, sealing, and failure. A minimal analytical source–storage–pathway model is further derived, yielding explicit criteria for valve onset, source charging and discharge times, and the distinction between pressure-led and mass-led responses. The framework is then applied to the published Campi Flegrei carbon dioxide (CO2) diffuse total output record, providing a real-data illustration of slow storage loading and rapid transient discharge. The analysis considers magmatic exsolution, hydrothermal mediation, metamorphic devolatilization, advective–diffusive near-surface filtering, and the inverse problem through which surface fluxes and gas compositions are used to infer deep source properties. The formulation links magmatic degassing, hydrothermal pressurization, tectonic fluid ascent, and fault-valve behavior within a common continuum-physics perspective and identifies the constitutive assumptions that most strongly control interpretation. Full article
(This article belongs to the Section Classical Physics)
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25 pages, 23809 KB  
Article
Fluorite Mineralization in the Chutuan and Jiashan Deposits, Sulu Orogenic Belt, Eastern China: Insights from Geochronology, Mineral Geochemistry, Fluid Inclusions and Stable Isotope Systematics
by Tao Kang, Meng-Ting Chen, Hai-Tao Ren, Yi-Hua Hu, Shuo-Hui Li, Peng Zhu, Zhao-Ying Chen and Yi-Jia Luo
Minerals 2026, 16(5), 537; https://doi.org/10.3390/min16050537 - 16 May 2026
Viewed by 539
Abstract
The Chutuan and Jiashan fluorite deposits are situated in the Donghai–Linshu area within the southwestern segment of the Sulu ultrahigh–pressure metamorphic belt. Both deposits share similar mineralization characteristics, with fluorite veins strictly controlled by fault structures and associated with mineral assemblages comprising fluorite, [...] Read more.
The Chutuan and Jiashan fluorite deposits are situated in the Donghai–Linshu area within the southwestern segment of the Sulu ultrahigh–pressure metamorphic belt. Both deposits share similar mineralization characteristics, with fluorite veins strictly controlled by fault structures and associated with mineral assemblages comprising fluorite, barite, quartz, and calcite. Two mineralization stages have been identified in both deposits: Stage I (quartz–fluorite–barite stage), representing the main ore–forming event, and Stage II (quartz–barite–calcite stage). This study focuses on integrated geochemical and geochronological analyses of fluorite from Stage I, providing new constraints on the genesis and metallogenic processes of these deposits. Direct Sm–Nd isotopic dating of fluorite yields an isochron age of 104 ± 16 Ma, indicating that mineralization occurred during the late Early Cretaceous. Fluid inclusion and stable isotope studies reveal that the ore–forming fluids constitute a complex hydrothermal system characterized by a wide temperature range (112–324 °C) and variable salinities (0.18–21.87 wt% NaCl eq.). The H–O isotopic compositions exhibit a distinct latitudinal trend, supporting a dominant meteoric water component. However, the presence of high–temperature, high–salinity fluid inclusions, along with a shift in some δD values towards the magmatic water field, suggests episodic mixing between meteoric water and deep–seated magmatic–hydrothermal fluids. Sr–Nd isotopic data (87Sr/86Sr = 0.711785–0.713424; εNd(t)= −27.7 to −27.5) potentially demonstrate that the ore–forming materials (Ca and REEs) were not derived from coeval magmatic rocks. Instead, they were primarily leached from the Precambrian Donghai Group metamorphic complex through extensive water–rock interaction. Based on these findings, the Chutuan and Jiashan deposits are classified as hydrothermal vein–type systems. Fluorite precipitation was governed by a combination of fluid cooling, water–rock interaction, and fluid mixing. Finally, a metallogenic model is established, offering important insights into the genesis of fluorite mineralization in the Sulu Orogenic Belt and analogous geological settings in eastern China. Full article
(This article belongs to the Special Issue Geochemistry and Genesis of Hydrothermal Ore Deposits, 2nd Edition)
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25 pages, 24157 KB  
Article
Source and Evolution of Ore-Forming Fluids in the Dulanggou Gold Deposit, Danba, Sichuan, China: Constraints from Fluid Inclusions and C–H–O Isotopes
by Yan Zhang, Bing Chen, Xiang Lai, Yangyan Xiang, Cuihua Chen, Ying Gu, Haoyang Xiao, Hesen Zhao, Yulong Yang, Mengyi Qiao, Haijun Zhang, Wenbin Cheng, Chaofei Luo, Yaru Zhang, Qiang Wang and Kaijun Yang
Minerals 2026, 16(5), 523; https://doi.org/10.3390/min16050523 - 14 May 2026
Viewed by 460
Abstract
The Danba–Dadu River gold belt on the western Yangtze Craton margin is a major gold province in China. The Dulanggou gold deposit is a large quartz-vein-type deposit recently discovered in this belt. Ore bodies are fault-controlled veins hosted in high-grade metamorphic rocks of [...] Read more.
The Danba–Dadu River gold belt on the western Yangtze Craton margin is a major gold province in China. The Dulanggou gold deposit is a large quartz-vein-type deposit recently discovered in this belt. Ore bodies are fault-controlled veins hosted in high-grade metamorphic rocks of the Devonian Weiguan Formation. Mineralization includes three stages: early (quartz–minor sulfide), main (quartz–abundant sulfide–native gold–Te–Bi minerals), and late (quartz–minor sulfide–calcite). Fluid inclusion studies show the following. Early-stage inclusions are mainly CO2–H2O-type (homogenization temperature 307–388 °C, salinity 0.4–7.1 wt.% NaCl eqv.) with minor NaCl–H2O-type. Main-stage inclusions are dominated by CO2–H2O and NaCl–H2O types, with minor pure CO2 inclusions (homogenization temperature 207–307 °C, salinity 0.2–11.2 wt.% NaCl eqv.). Late-stage inclusions are mainly NaCl–H2O-type (168–223 °C, 4.6–10.1 wt.% NaCl eqv.). Laser Raman analysis detects CH4 in the fluid. The ore-forming fluid is a reducing, medium–low temperature, low-salinity H2O–CO2–NaCl–CH4 system. Thermodynamic calculations of CO2–H2O inclusions yield total densities of 0.94–1.03 g/cm3 and total homogenization pressures of 170–276 MPa for the early stage, and slightly lower densities (0.94–1.01 g/cm3) with pressures of 170–246 MPa for the main stage, indicating a progressive pressure decrease during fluid evolution. Hydrogen and oxygen isotopes (early stage: δD −96.4‰ to −78.9‰, δ18OH2O 6.1‰ to 6.5‰; main stage: δD −104.3‰ to −75.1‰, δ18OH2O 5.3‰ to 7.1‰) indicate that the ore-forming fluid was mainly derived from primary magmatic water. Immiscible CO2–H2O and NaCl–H2O inclusion assemblages in the main stage suggest that fluid immiscibility was the key mechanism for gold precipitation. The Dulanggou deposit resembles classic orogenic gold deposits in host rocks, ore-controlling structures, mineral assemblages, and low-salinity CO2-rich fluids. However, its H–O isotopes and thermodynamic data point to a magmatic water source, distinct from the metamorphic water source of typical orogenic gold deposits. This highlights the diversity of fluid sources in orogenic gold systems along the western Yangtze Craton margin. Full article
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24 pages, 45229 KB  
Article
Genesis and Tectono-Metallogenetic Setting of the Dongwujiiazi Gold Deposit, NE China: Insights from Whole-Rock Geochemistry and H–O–S–Pb Isotopes
by Lichun Fu, Guihu Chen, He Yuan, Yingzheng Pei, Qiang Wei, Fangyue Wang and Ahmed S. Moftah
Minerals 2026, 16(5), 435; https://doi.org/10.3390/min16050435 - 23 Apr 2026
Viewed by 600
Abstract
The Dongwujiiazi deposit is a structurally controlled orogenic gold deposit situated in the eastern part of the Chifeng–Chaoyang gold belt along the northern boundary of the North China Craton. This study establishes a comprehensive metallogenic model for the Dongwujiiazi gold deposit by integrating [...] Read more.
The Dongwujiiazi deposit is a structurally controlled orogenic gold deposit situated in the eastern part of the Chifeng–Chaoyang gold belt along the northern boundary of the North China Craton. This study establishes a comprehensive metallogenic model for the Dongwujiiazi gold deposit by integrating whole-rock geochemistry (major and trace elements), in situ trace elements and REEs in zircon, multi-isotope systems (H, O, S, Pb), and precise zircon U–Pb geochronology. Five types of intrusive and associated rocks are identified within the main biotite-pyroxene gneiss host of the Dongwujiiazi gold deposit: mylonitized granitic pegmatite, mylonitized porphyritic monzogranite, propylitized fine-grained quartz monzodiorite, quartz monzonite, and porphyritic dolerite. The gold-bearing polymetallic sulfide ores are composed of pyrite, chalcopyrite, sphalerite, galena, digenite, and native gold. Zircon grains in the Dongwujiiazi gold ore (2502 ± 15 to 2539 ± 18 Ma) are inherited from surrounding Neoarchean gneiss, recording older crustal sources rather than forming contemporaneously with the gold mineralization. H–O isotopes indicate that the ore-forming fluids were mixed in origin, involving both magmatic and metamorphic components. S and Pb isotopes suggest that the mineralizing sulfur was mainly derived from a magmatic source, while lead originated predominantly from lower crustal materials associated with the surrounding high-grade metamorphic rocks. In this study, we present a new metallogenic model for the Dongwujiiazi gold deposit, in which slab-derived and lower-crustal metamorphic fluids interacted with ascending magmas, resulting in fluid mixing and gold precipitation within structurally controlled zones of gneissic host rocks. Combined geochemical and isotopic evidence (H–O, S, Pb) indicates contributions from both magmatic and metamorphic sources, supporting formation as an intracontinental orogenic gold system in an active continental margin. Full article
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16 pages, 8508 KB  
Article
Ediacaran Thermal Disturbance in the NW Amazonian Craton: Insights from Zircon and Apatite U–Pb Geochronology of the Guaviare Complex, Colombia
by Amed Bonilla Pérez, Nathan Cogné and Carlos Alfonso Zafra Mejía
Geosciences 2026, 16(4), 154; https://doi.org/10.3390/geosciences16040154 - 8 Apr 2026
Cited by 1 | Viewed by 893
Abstract
The northwestern Amazonian Craton exposed in eastern Colombia preserves a complex Proterozoic tectonothermal history. In this study, we present new zircon and apatite U–Pb geochronological data from orthogneisses of the Guaviare Complex (Termales Gneiss unit) to constrain the timing of crust formation, metamorphism, [...] Read more.
The northwestern Amazonian Craton exposed in eastern Colombia preserves a complex Proterozoic tectonothermal history. In this study, we present new zircon and apatite U–Pb geochronological data from orthogneisses of the Guaviare Complex (Termales Gneiss unit) to constrain the timing of crust formation, metamorphism, and subsequent thermal events. Zircon U–Pb data define a dominant concordant population at ca. 1.30 Ga, interpreted as the crystallization age of an igneous protolith. This age is consistent with Mesoproterozoic A-type magmatism previously recognized in the region and consistent with emplacement under intracratonic extensional conditions, as suggested by previous studies. A limited number of discordant zircon analyses indicate Pb loss and/or partial isotopic resetting between ~1.0 and 0.6 Ga, although no well-defined metamorphic zircon population is identified. Meanwhile, apatite U–Pb analyses from key samples yield consistent lower intercept ages between 633 ± 16 Ma and 543 ± 8 Ma, indicating a widespread Ediacaran thermal disturbance that may have affected the Guaviare Complex, temporally overlapping with alkaline magmatism in the northwestern Amazonian Craton, including the San José del Guaviare Nepheline Syenite. However, alternative mechanisms such as fluid-assisted Pb mobility, regional reheating, or prolonged cooling cannot be excluded. Finally, the combined zircon–apatite dataset highlights the value of multi-chronometer approaches for resolving complex thermal histories in cratonic domains. Full article
(This article belongs to the Section Structural Geology and Tectonics)
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19 pages, 6446 KB  
Article
Fluorapatite from a Pegmatite with Miarolitic Cavities in the Larsemann Hills, East Antarctica: ID-TIMS U-Pb Ages and LA-ICP-MS Trace-Element Constraints on the Late Pan-African Orogenic Evolution
by Ivan A. Babenko, Nailya G. Rizvanova, Sergey G. Skublov, Yuri A. Bishaev, Irina V. Talovina, Olga L. Galankina and Alexander V. Kuznetsov
Geosciences 2026, 16(3), 133; https://doi.org/10.3390/geosciences16030133 - 23 Mar 2026
Cited by 1 | Viewed by 901
Abstract
Pegmatites with miarolitic cavities have not previously been reported from the Larsemann Hills, East Antarctica, and their age and origin remain poorly constrained. We report the first geochemical and geochronological data for fluorapatite from a newly discovered pegmatite with miarolitic cavities in the [...] Read more.
Pegmatites with miarolitic cavities have not previously been reported from the Larsemann Hills, East Antarctica, and their age and origin remain poorly constrained. We report the first geochemical and geochronological data for fluorapatite from a newly discovered pegmatite with miarolitic cavities in the Larsemann Hills. Large Fe-rich fluorapatite crystals (up to 5 cm) contain abundant oriented monazite-(Ce) inclusions and display elevated REE (1397–7966 ppm), relatively high Y (945–4192 ppm), and low Sr (52.2–83.5 ppm). Their trace-element signatures plot within the fields of partial melts, high-grade metamorphic rocks, and evolved fluid-rich magmatic systems. U–Pb dating of fluorapatite yields concordant ages of 519 ± 4 Ma (ID-TIMS) and 521 ± 31 Ma (LA-ICP-MS), indicating crystallization during the D4 stage of the Pan-African orogeny. The isotopic equilibrium between apatite and monazite inclusions suggests synchronous formation and late-stage fluid overprinting. Combined geological, geochemical, and isotopic evidence shows that the pegmatite formed in situ as a product of anatexis of the Broknes paragneisses and evolved within a volatile-rich magmatic–hydrothermal system. These results provide the first direct age constraints on pegmatites with miarolitic cavities in Antarctica and shed new light on the final stages of East Gondwana assembly. Full article
(This article belongs to the Section Geochemistry)
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22 pages, 13981 KB  
Article
Geological Characteristics and Genesis of the Greisen-Hosted Nb-Ta Mineralization in the Qidashan Iron Deposit, Liaoning Province, China, and Its Implications
by Yang Xiao, Rongzhen Gao, Qing Sun, Jianfei Fu, Yuzeng Yao, Sanshi Jia and Jiale Chen
Minerals 2026, 16(3), 312; https://doi.org/10.3390/min16030312 - 16 Mar 2026
Viewed by 1170
Abstract
The newly identified greisen-hosted Nb-Ta mineralization in the Qidashan iron deposit, Liaoning Province, China, offers a unique opportunity to explore how hydrothermal processes contribute to the enrichment of critical metals. In this study, an integrated analytical approach of petrographic observation and scanning electron [...] Read more.
The newly identified greisen-hosted Nb-Ta mineralization in the Qidashan iron deposit, Liaoning Province, China, offers a unique opportunity to explore how hydrothermal processes contribute to the enrichment of critical metals. In this study, an integrated analytical approach of petrographic observation and scanning electron microscopy–energy-dispersive spectrometer (SEM-EDS), electron probe microanalyzer (EPMA), and laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) U-Pb dating of columbite-group minerals (CGMs) were employed to systematically decipher the paragenetic sequence, micro-structure, elemental composition and mineralization age of CGMs, aiming at the genesis of greisen-hosted Nb-Ta mineralization. The mineralization is characterized by the abundant occurrence of CGMs. Three generations of CGMs and two mineralization stages are distinguished: stage I contains CGM Is and CGM IIs, with Nb2O5 ranging from 25.7 to 69.56 wt.% and Ta2O5 from 5.8 to 52.5 wt.%; stage II contains CGM IIIs, with Nb2O5 between 59.5 and 71.5 wt.% and Ta2O5 between 3.5 and 16.2 wt.%. CGM Is consist of euhedral, homogeneous crystals of more than 100 μm, exhibit low Ta/(Nb + Ta) ratios (0.05–0.06) and high Mn/(Fe + Mn) ratios (0.19–0.26), and belong to columbite-Fe. CGM IIs generally overgrow on CGM Is with hydrothermal overprinting textures, and show significant compositional gaps compared to CGM Is, exhibiting higher Ta/(Nb + Ta) ratios (0.13–0.55) and restricted Mn/(Fe + Mn) ratios (0.15–0.18), with some belonging to columbite-Fe and others to tantalite-Fe, which reveals a transition from magma to “hydrosilicate fluid”. CGM IIIs are mainly anhedral and homogeneous, with a grain size of less than 50 μm. However, some CGM IIIs overgrow on CGM IIs and/or CGM Is with patchy textures indicative of subsequent hydrothermal overprinting of hydrosilicate fluid, forming a coarse-grain size over 100 μm. CGM IIIs are characterized by lower Ta/(Nb + Ta) ratios (0.03–0.14) and variable Mn/(Fe + Mn) ratios (0.08–0.26), and they belong to columbite-Fe. LA-ICP-MS U-Pb dating yields weighted mean 206Pb/238U ages of 2646 ± 15 Ma for stage I and 2500 ± 28 Ma for stage II, indicating two-stage Nb-Ta mineralization. The early mineralization may correlate with the partial melting of volcanic–sedimentary rocks due to the geothermal anomalies associated with ~2.7 Ga submarine volcanism, and the late mineralization formed by the magmatic hydrothermal activities related to emplacement of the Qidashan granite in 2.5 Ga. We therefore propose that the two-stage greisen-hosted Nb-Ta mineralization probably widely occurred in these sedimentary–metamorphic iron deposits in the Anshan–Benxi area and even in the northern edge of the North China Craton, and it may provide new insights for evaluating the Nb-Ta resource potential in similar Algoma-type iron deposits globally. Full article
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34 pages, 10465 KB  
Article
Metallogenic Mechanism of Decratonic Gold Deposit: Geochemical Evidence from Dongbaligou Gold Deposit and Its Ore-Forming Intrusions in Southern Jilin
by Jiuda Sun, Zhongyuan Xu, Xiaofei Yu, Kai Chen and Zhuoyi Wang
Minerals 2026, 16(3), 235; https://doi.org/10.3390/min16030235 - 26 Feb 2026
Viewed by 1061
Abstract
This text systematically investigates the Laotudingzi monzogranite (a gold-hosting intrusion) and the Dongbaligou gold ore deposit in the Laoling gold ore belt through comprehensive geochronological, whole-rock geochemical (macroelement and microelement), strontium-neodymium-lead-hafnium isotopic and in situ sulfur-lead isotopic analysis of pyrite, combined with hydrogen-oxygen [...] Read more.
This text systematically investigates the Laotudingzi monzogranite (a gold-hosting intrusion) and the Dongbaligou gold ore deposit in the Laoling gold ore belt through comprehensive geochronological, whole-rock geochemical (macroelement and microelement), strontium-neodymium-lead-hafnium isotopic and in situ sulfur-lead isotopic analysis of pyrite, combined with hydrogen-oxygen isotopic studies of hydrothermal quartz. The results demonstrate a significant Early–Middle Jurassic magmatic-mineralization event in southern Jilin Province (Ji’nan). The gold mine is structurally controlled by detachment fractures within the Laoling metamorphic core complex, which developed in an extended environment. The metallogenic materials are primarily derived from adakitic magma, supporting a “decratonic-type” genetic model. By integrating geochronological, geochemical, and isotopic datasets from the ore-related intrusions and gold deposits, as well as fluid inclusion characteristics, we elucidate the metallogenic mechanism linking Jurassic gold mineralization to subduction-related cratonic destruction. The process involved lower crustal thickening induced by Paleo-Pacific Plate subduction, lithospheric destabilization via gravitational foundering and delamination, and syn-extensional magmatism that sourced ore-forming fluids during cratonic lithosphere thinning. This work establishes a genetic framework connecting plate subduction, lithospheric removal, and gold endowment in convergent margin settings. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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28 pages, 6974 KB  
Article
Metamorphic Fluids with Magmatic Overprint in the Huayagou Gold Deposit, West Qinling Orogen, Central China: Evidence from Apatite and Tourmaline In Situ Geochemistry
by Fei Teng, Jiangwei Zhang, Wendi Guo, Leon Bagas, Kang Yan, Yuxiang Teng, Ying Wei, Ningchao Zhou, Yongbao Gao and Liyong Wei
Geosciences 2026, 16(2), 80; https://doi.org/10.3390/geosciences16020080 - 13 Feb 2026
Cited by 2 | Viewed by 1102
Abstract
Recent exploration has demonstrated significant prospecting potential at the Huayagou Au deposit in Longnan mineral Field, Gansu Province, West Qinling Orogen, Central China. However, the nature and evolution of the auriferous fluids responsible for gold enrichment remain poorly constrained, hindering effective exploration targeting [...] Read more.
Recent exploration has demonstrated significant prospecting potential at the Huayagou Au deposit in Longnan mineral Field, Gansu Province, West Qinling Orogen, Central China. However, the nature and evolution of the auriferous fluids responsible for gold enrichment remain poorly constrained, hindering effective exploration targeting of high-grade ores. In this study, apatite and tourmaline closely associated with gold mineralization are investigated as mineralogical recorders of fluid composition and evolution. Integrated petrographic observations, TIMA phase mapping, cathodoluminescence imaging, electron probe microanalysis, and in situ trace element analyses were used to distinguish magmatic, metamorphic, and syn-ore hydrothermal generations of apatite and tourmaline, together with in situ Nd isotopic analyses of apatite and B isotopic analyses of tourmaline. Syn-ore hydrothermal apatite is characterized by homogeneous blue cathodoluminescence, fluorapatite compositions, strong LREE depletion, and εNd(t) values overlapping those of Triassic magmatic apatite, whereas Early-Devonian magmatic and metamorphic apatites display more distinct signatures. Tourmaline records a systematic evolution from early dravite to late schorl, accompanied by trace element enrichment and a shift toward heavier δ11B values. These mineralogical and isotopic features, together with published sulfur isotope constraints, indicate that gold mineralization at Huayagou was dominantly controlled by structurally focused metamorphic fluids, with localized Triassic magmatic–hydrothermal overprinting enhancing gold enrichment in high-grade ores. The Huayagou Au deposit is, therefore, best interpreted as an atypical orogenic gold system, highlighting enhanced exploration potential in structurally favorable zones at depth, particularly in the western part of the district where Triassic magmatism is inferred. Full article
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