Search Results (591)

The Sichuan–Yunnan–Guizhou Pb-Zn metallogenic belt (SYG metallogenic belt), a crucial metallogenic unit on the southwestern margin of the Yangtze Block, is a key part of the South China low-temperature metallogenic domain. The incorporation mechanisms and distribution of trace elements (e.g., Ge, Ga, Cd) widely enriched in Pb-Zn sulfides throughout this region remain poorly understood. This study investigates main-ore-stage sulfides (sphalerite and pyrite) from the Maoping Pb-Zn deposit using in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses and mapping to systematically elucidate the partitioning and occurrence of these trace elements. The key findings are as follows: (1) Sulfides show distinct elemental partitioning: sphalerite preferentially concentrates Cd, Ag, Ge, Ga, and Se, whereas pyrite is significantly enriched in Mn, Ni, As, and Co. (2) Sphalerite is the primary host for many trace elements. Cadmium, Ge, Mn, Cu, and Ag mainly enter the sphalerite lattice by substituting for Zn²⁺. Coupled substitution mechanisms, such as Zn²⁺ ↔ Cd²⁺, 2Zn²⁺ ↔ Ge²⁺ + Cu²⁺, and 2Zn²⁺ ↔ Ga³⁺ + Cu⁺, facilitate the incorporation of Ge and Ga. (3) The sphalerite exhibits a trace element assemblage of high Cd-Ge and low Fe-Mn, which is geochemically similar to typical Mississippi Valley-type (MVT) deposits and differs significantly from sedimentary exhalative (SEDEX) and magmatic–hydrothermal deposits, indicating a medium- to low-temperature metallogenic environment. Based on these geochemical signatures and epigenetic textures, we confirm that the Maoping Pb-Zn deposit exhibits similarities with MVT deposits. Nevertheless, distinct differences in the tectonic setting and metal grades suggest it is a unique SYG-type Pb-Zn deposit. Full article

The Weishan rare earth element (REE) deposit, located in western Shandong, North China Block, is a typical carbonatite REE deposit and constitutes the third largest light REE resource in China. Its mineralization is closely related to the multi-stage evolution of a carbonatite magma–hydrothermal system. However, the mechanisms governing REE enrichment, migration, and precipitation remain insufficiently constrained from a mineralogical perspective, which hampers the understanding of the ore-forming processes and the establishment of predictive exploration models. Apatite is a pervasively developed REE phase in the Weishan deposit which occurs in multiple generations, and thus represents an ideal recorder of the magmatic–hydrothermal evolution. In this study, different generations of apatite hosted in carbonatite orebodies from the Weishan deposit were investigated using cathodoluminescence (CL), electron probe microanalysis (EPMA), and in situ LA-ICP-MS trace element analysis. Three types of apatite were identified. In paragenetic sequence, Ap-1 occurs as polycrystalline aggregates coexisting with calcite, is enriched in Na, Sr, and LREEs, and shows high (La/Yb)_N ratios, suggesting crystallization from an evolved carbonatite magma. Ap-2 and Ap-3 display typical replacement textures: both contain abundant dissolution pits and dissolution channels within the grains, which are filled by secondary minerals such as monazite and ancylite, and thus exhibit characteristic features of fluid-mediated dissolution–reprecipitation during the hydrothermal stage. Ap-2 is commonly associated with barite and strontianite, whereas Ap-3 is associated with pyrite and monazite and is characterized by relatively sharp grain boundaries with adjacent minerals. From Ap-1 to Ap-3, total REE contents decrease systematically, whereas Na, Sr, and P contents increase. All three apatite types lack Eu anomalies but display positive Ce anomalies. Discrimination diagrams involving LREE-Sr/Y and log(Ce)-log(Eu/Y) indicate that apatite in the Weishan REE deposit formed during the magmatic to hydrothermal evolution of a carbonatite, and that the dissolution of early magmatic apatite, followed by element remobilization and mineral reprecipitation, effectively records the progressive evolution of the ore-forming fluid. Full article

Siliceous rocks of various colors and types are extensively developed within the Middle–Lower Ordovician carbonate along the Northwest Tarim Basin. Their genesis provides important insights into the evolution of basinal fluids and the associated diagenetic alterations of the carbonates. Based on petrographic, geochemical, fluid inclusion, and petrophysical analyses, this study investigates the origin of siliceous rocks within the Middle–Lower Ordovician carbonate formations (Penglaiba, Yingshan, and Dawangou formations) in the Kalpin area, Tarim Basin, and investigates the impact on hydrothermal reservoirs. The results reveal two distinct episodes of siliceous diagenetic fluids: The first during the Late Ordovician involved mixed hydrothermal fluids derived from deep magmatic–metamorphic sources, formation brines, and seawater. Characterized by high temperature and moderate salinity, it generated black chert dominated by cryptocrystalline to microcrystalline quartz through replacement processes. The second episode developed in the Middle–Late Devonian as a mixture of silicon-rich fluids from deep heat sources and basinal brines. In conditions of low temperature and high salinity, it generated gray-white siliceous rocks composed of micro- to fine crystalline quartz, spherulitic-fibrous chalcedony, and quartz cements via a combination of hydrothermal replacement and precipitation. A reservoir analysis reveals that the multi-layered black siliceous rocks possess significant reservoir potential amplified by the syndiagenetic tectonic fracturing. In contrast, the white siliceous rocks, despite superior petrophysical properties, are limited in scale as they predominantly infill late-stage fractures and vugs, mainly enhancing local flow conduits. Hydrothermal alteration in black siliceous rocks is more intense in dolostone host rocks than in limestone. Thus, thick (10–20 m), continuous black siliceous layers in dolostone and the surrounding medium-crystalline dolostone alteration zones, are promising exploration targets. This study elucidates the origins of Ordovician siliceous rocks and their implications for carbonate reservoir properties. The findings may offer valuable clues for deciphering the evolution and predicting the distribution of hydrothermal reservoirs, both within the basin and in other analogous regions worldwide. Full article

Post-collisional Cu-Au-Ni-Co-Pt-Pd-Sc porphyry [Duck Creek porphyry system (DCPS)] with overlying Au-Te-Bi-W-HRE epithermal mineralisation [Highway epithermal system (HES)] has been discovered in the core of the Mitakoodi anticline, southwest of Cloncurry. Xenotime and monazite geochronology indicate mineralisation occurred between ~1490 and 1530 Ma. Host rock lithologies show widespread potassic and/or propylitic to phyllic alteration. Paragenesis of porphyry sulphides indicates early crystallisation of pyrite, followed by chalcopyrite, with bornite forming by hydrothermal alteration of chalcopyrite. Cu sulphides also show the effect of supergene oxidation alteration with rims of covellite, digenite and chalcocite. Redox conditions deduced from the V/Sc systematics indicate that the DCPS contains both highly oxidised (typical of porphyries) and reduced lithologies, typical of plume-generated tholeiitic and alkaline suites. Ni/Te and Cu/Te systematics plot within the fields defined by epithermal and porphyry deposits. Duck Creek chalcophile and highly siderophile element (Cu, MgO and Pd) systematics resemble data from porphyry mineral systems, at Cadia, Bingham Canyon, Grasberg, Skouries, Kalmakyr, Elaisite, Assarel and Medet. SAM geophysical inversion models suggest the presence of an extensive porphyry system below the HES. A progressive increase in molar Cu/Au ratios with depth from the HES to the DCPS supports this conclusion. Three metal sources contributed to the linked DCPS-HES viz., tholeiitic ferrogabbro, potassic ultramafic to mafic system and an Fe and Ca-rich alkaline system. The latter two imparted non-crustal superchondritic Nb/Ta ratios that are characteristic of many deposits in the eastern Mount Isa Block. The associated tholeiite and alkaline magmatism reflect mantle plume upwelling through a palaeo-slab window that had accreted below the eastern flank of the North Australian craton following west-verging collision by the Numil Terrane. Discovery of this linked mineral system provides a new paradigm for mineral exploration in the region. Full article

The Hadamengou gold deposit, hosted in the Precambrian metamorphic basement, is a super-large gold deposit occurring along the northern margin of the North China Craton. Despite extensive investigation, the genesis of the gold mineralization is poorly understood and remains highly debated. This study integrates a comprehensive dataset, including fluid inclusion microthermometry and C-H-O-S-Pb isotopes, to better constrain the genesis and ore-forming mechanism of the deposit. Hydrothermal mineralization can be divided into pyrite–potassium feldspar–quartz (Stage I), quartz–gold–pyrite–molybdenite (Stage II), quartz–gold–polymetallic sulfide (Stage III), and quartz–carbonate stages (Stage IV). Four types of primary fluid inclusions are identified, including pure CO₂-type, composite CO₂-H₂O-type, aqueous-type, and solid-daughter mineral-bearing-type inclusions. Microthermometric and compositional data reveal that the fluids were mesothermal to hypothermal, H₂O-dominated, and CO₂-rich fluids containing significant N₂ and low-to-moderate salinity, indicative of a magmatic–hydrothermal origin. Fluid inclusion assemblages further imply that the ore-forming fluids underwent fluid immiscibility, causing CO₂ effusion and significant changes in physicochemical conditions that destabilized gold bisulfide complexes. The hydrogen–oxygen isotopic compositions, moreover, support a dominant magmatic water source, with increasing meteoric water input during later stages. The carbon–oxygen isotopes are also consistent with a magmatic carbon source. Sulfur and lead isotopes collectively imply that ore-forming materials were derived from a hybrid crust–mantle magmatic reservoir, with minor contribution from the country rocks. By synthesizing temporal–spatial relationships between magmatic activity and ore formation, and the regional tectonic evolution, we suggest that the Hadamengou is an intrusion-related magmatic–hydrothermal lode gold deposit. It is genetically associated with multi-stage magmatism induced by crust–mantle interaction, which developed within the extensional tectonic regimes. Full article

Ultrapotassic lamprophyre dykes are spatially closely related to gold deposits in collision tectonic belts. However, the potential implication of these lamprophyre dykes to gold deposits remains poorly constrained. Abundant ultrapotassic lamprophyre dykes in the Baiyun gold deposit of Liaodong Peninsula, NE China, are closely associated with Au orebodies. This presents an excellent opportunity to investigate the genesis and tectonic significance of these dykes, as well as their potential connection to gold mineralization. Here, based on LA-ICPMS zircon U-Pb age, petrogeochemistry, and Sr-Nd-Hf isotopic composition characteristics, we studied the ultrapotassic lamprophyre dykes in the Baiyun gold deposit. Zircon U-Pb dating of lamprophyre dykes is 225.7 ± 1.3 Ma, which is consistent with the previous auriferous pyrite Re-Os data results within error, indicating that the lamprophyre dykes and gold deposits formed simultaneously in the Late Triassic, which coincided with the exhumation of the deeply subducted South Chin Block (SCB). The lamprophyre dykes belong to the shoshonitic series (K₂O + Na₂O = 6.39–7.57 wt.%, K₂O/Na₂O = 3.99–8.74) and are enriched with magnesium (MgO = 5.33–6.40 wt.%, Mg^# = 58–65), barium (Ba = 2225–3046 ppm), and strontium (Sr = 792–927 ppm), and their (⁸⁷Sr/⁸⁶Sr)_i isotopic composition ranges from 0.712514 to 0.714831, ε_Nd(t) ranges from −15.4 to −14.1, and zircon ε_Hf(t) values range from −14.3 to −12.5. These correspond to Paleoproterozoic model ages between 2.1 and 2.3 Ga, which are comparable to the ultra-high-pressure metamorphic rocks with the SCB nature found in the Dabie–Sulu orogenic belt. The results demonstrate that the overlying lithospheric mantle was possibly metasomatized by subducted SCB-derived melts before magma generation under the North China Block (NCB) in the Late Triassic. The lamprophyre dykes with high Nb/U and Th/Yb values, enriched Ba, Sr, REE, Na₂O + K₂O, K₂O/Na₂O, and the LOI demonstrate that the metasomatic agents were hydrous, high-pressure melts. These melts likely resulted from the partial melting of subducted continental crust, which is attributed to phengite breakdown in the subduction continental channel. The silica-rich melts migrate from the plate into the sub-continental lithospheric mantle (SCLM) and form potassic- and volatile-enriched metasomatized SCLM. Subsequently, the partial melting of metasomatized SCLM due to the decompression and thinning may be the main mechanism to generate the syn-exhumation ultrapotassic magma in a post-collision setting. This study suggests that the SCLM, metasomatized by melts derived from continental crust, plays a key role in generating volatile-rich hydrous SCLM during the continental subduction and collision stage. In contrast, during the post-collision stage, as tectonic forces transition from compressional to extensional, the abundant volatiles and ultrapotassic magma produced from the partially melted and metasomatized lithospheric mantle may significantly contribute to the transportation, enrichment, and precipitation of gold through magmatic-hydrothermal processes, facilitating the formation of gold deposits. Full article

Ataúro Island, located in the inner Banda Arc, provides a natural laboratory to investigate the interplay between magmatic evolution, hydrothermal circulation, and near-surface weathering in an active arc–continent collision setting. This study presents the first systematic island-wide geochemical baseline for Ataúro Island, based on multi-element analyses of stream sediments integrated with updated geological, structural, and hydromorphological information. Compositional Data Analysis (CoDA–CLR–PCA), combined with anomaly mapping and spatial overlays, defines a coherent three-tier geochemical framework comprising: (i) a lithogenic component dominated by Fe–Ti–Mg–Ni–Co–Cr, reflecting the geochemical signature of basaltic to andesitic volcanic rocks; (ii) a hydrothermal component characterized by Ag–As–Sb–S–Au associations spatially linked to structurally controlled zones; and (iii) an oxidative–supergene component marked by Fe–V–Zn redistribution along drainage convergence areas. These domains are defined strictly on geochemical criteria and represent geochemical process domains rather than proven metallogenic provinces. Rare earth element (REE) systematics further constrain the geotectonic setting and indicate that the primary geochemical patterns are largely controlled by lithological and magmatic differentiation processes. Spatial integration of geochemical patterns with fault architecture highlights the importance of NW–SE and NE–SW structural corridors in focusing hydrothermal fluid circulation and associated metal dispersion. The identified Ag–As–Sb–Au associations are interpreted as epithermal-style hydrothermal geochemical enrichment and exploration-relevant geochemical footprints, rather than as evidence of confirmed or economic mineralization. Overall, Ataúro Island emerges as a compact natural analogue of post-arc geochemical system evolution in the eastern Banda Arc, where lithogenic background, hydrothermal fluid–rock interaction, and early supergene processes are superimposed. The integrated geochemical framework presented here provides a robust baseline for future targeted investigations aimed at distinguishing lithogenic from hydrothermal contributions and evaluating the potential significance of the identified geochemical enrichments. Full article

This study focuses on the mineralogy and mineral chemistry of the accessory minerals occurring in the Kastoria pluton situated in NW Greece, which intrudes the Pelagonian nappe having crystallized during the Late Paleozoic (~300 Ma). The pluton consists of porphyritic granite (GR) that hosts mafic microgranular enclaves (MME) of monzonitic composition. Both lithologies contain quartz, microcline, plagioclase, biotite, secondary white mica, hornblende, and actinolite along with accessory minerals including titanite, epidote, allanite, apatite, zircon, and magnetite. Compared to the granite, the enclaves are richer in biotite, amphibole, and plagioclase but poorer in quartz and microcline. Mineral chemistry indicates a calc–alkaline affinity, consistent with the observed magmatic trends. Crystallization pressure, estimated at 3 kbar from Al in a hornblende barometer, suggests emplacement at mid-crustal levels. During the Alpine deformation, the pluton underwent low-grade greenschist to amphibolite-facies metamorphism, which partially overprinted the primary mineral assemblages. Magmatic titanite and allanite crystals are well preserved, showing only recrystallization features. Metamorphism produced tiny titanite needles and epidote replacing primary minerals (plagioclase, amphibole, and biotite). Later, hydrothermal alteration produced another generation of secondary epidote. Only a couple of epidote crystals preserve potential magmatic relict characteristics (euhedral habit, zircon inclusions, positive Eu anomaly, and sharp contact with primary minerals). These results provide insights into both the primary magmatic features and the subsequent metamorphic modification of the I-type Kastoria pluton within the Pelagonian domain. Full article

The Chaijiagou Mo deposit (0.11 Mt Mo @ 0.07%) is located along the northern margin of the North China Craton. This study integrates ore geology, S–Pb–He–Ar–H–O isotopes, and fluid inclusion (FI) analyses to constrain the sources of ore-forming fluids and metals, as well as mineralization mechanisms. Three principal inclusion types were identified: liquid-rich, vapor-rich, and saline FIs. Microthermometry documents a progressive decline in homogenization temperatures and salinities from early to late mineralization stages: Stage 1 (360–450 °C; 5.3–11.3 and 35.4–51.5 wt.% NaCl equation), Stages 2.1–2.2 (320–380 °C and 260–340 °C; 5.4–11.8 and 33.8–44.5 wt.% NaCl equation), and Stage 4 (140–200 °C; 0.4–3.9 wt.% NaCl equation). Noble gas and stable isotope data reveal that the ore-forming fluids were initially dominated by crustally derived magmatic–hydrothermal components with a minor mantle contribution, subsequently experiencing significant meteoric water input. S–Pb isotopic compositions demonstrate a genetic relationship between mineralization and the ore-bearing granite porphyry, indicating a magmatic origin for both sulfur and lead. Fluid–rock interactions and fluid boiling were the dominant controls on molybdenite and chalcopyrite deposition during Stage 2, whereas mixing with meteoric waters triggered galena and sphalerite precipitation in Stage 3. Full article

Quaternary lavas (ankaramite, basalt, basaltic andesite, andesite, dacite) from the Kamchatka, Kurile, Ecuador and Cascade volcanic arcs contain Cl-bearing mineral microinclusions in rock-forming minerals and groundmass volcanic glass. They are represented by chlorargyrite (with a variable amount of native Ag), Cu, Ag, Sn, and Zn compounds with Cl and S, Sn- and Pb-Sb oxychlorides compositionally similar to abhurite and nadorite, as well as bismoclite and Cl-F-apatite. The Cl-bearing compounds with chalcophile metals are best approximated by mixtures of chlorargyrite with Cu sulfides, malachite, or azurite. Some Cl-bearing solid microinclusions in magmatic rock-forming minerals could have formed from Cl-rich melts exsolved from arc magmas during differentiation. Alternatively, specific magmatic microinclusions may record the decomposition of primary sulfides in the presence of Cl-bearing magmatic volatiles. Post-magmatic Cl microminerals found in fractures, pores, grain contacts, and groundmass glass are most probably precipitated from hydrothermal fluids accompanying their emplacement at the surface and post-eruption transformations in active fumarole fields. Assemblages of Cl-bearing microminerals with native metal, alloy, sulfide, oxide, and sulfate microinclusions in arc lavas potentially record late-magmatic to post-magmatic stages of formation of the epithermal and possibly porphyry mineralization beneath arc volcanoes. Full article

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

There exists an east–west trending albitite (breccia) zone, approximately 400 km in length, closely related to gold mineralization, in Devonian strata in the South Qinling tectonic belt. The genesis and formation age of these albitite (breccia) are of great significance for understanding gold enrichment mechanisms and guiding future exploration. Past studies have mainly focused on the Fengxian–Taibai area in the western segment of the albitite (breccia) zone, whereas the eastern segment remains significantly understudied. In this study, a systematic field investigation, as well as petrology, geochemistry, and accessory-mineral geochronology studies were conducted on albitites and albitite breccias in the Shangnan area, the eastern segment of the albitite (breccia) zone. The results show that the albitites are interlayered with or occur as lenses within Devonian clastic rocks. The albitite breccias are mostly enclosed in albitite and Devonian strata, and the clasts within are subangular, uniform in type, and exhibit minimal displacement. Both albitites and albitite breccias exhibit similar trace-element characteristics and detrital zircon age spectra to those of Devonian clastic rocks. Abundant hydrothermal monazites with U–Pb ages ranging from 260 to 252 Ma are present in both albitites and albitite breccias but absent in Devonian clastic rocks. Collectively, these results indicate that the albitites in the Shangnan area are of hydrothermal metasomatic origin, while the albitite breccias record hydraulic fracturing and cementation, and both are products of the same fluid activity event in the Late Permian. We propose that albitite (breccia) zones in the South Qinling tectonic belt were formed under distinct tectonic settings during different evolution stages of the Late Paleozoic Mianlüe Ocean. Specifically, the albitites (breccias) in the Shangnan area are products of thorough metasomatism, local fracturing, and cementation of Devonian clastic rocks by mixed fluids, which ascended along the Fengzhen–Shanyang Fault coeval with the emplacement of magmatic rocks related to subduction of the Mianlüe Ocean. In contrast, the albitite breccias in the Fengxian–Taibai area are the result of fluid activity during the transition from regional compression to extension after the closure of the Mianlüe Ocean. Full article

The Mianhuakeng deposit, located within the Zhuguangshan batholith in the Nanling area, is currently recognized as the largest granite-related uranium deposit in China. A portion of the uranium ore bodies is spatially associated with NE-trending mafic veins within the granite. In this study, the field investigation, zircon U-Pb dating, S and Pb isotope analysis, and whole-rock geochemical analysis were conducted on these mafic veins to explore their crystallization age, petrogenesis, tectonic setting, and relationships with uranium mineralization. The weighted mean result of zircon U-Pb is 189 ± 3 Ma, suggesting that the mafic dyke was crystallized during the Early Jurassic. The whole-rock geochemistry and isotopes exhibit characteristics of intraplate basalts, suggesting that the mafic dykes originate from an enriched mantle source consisting of garnet–spinel lherzolite, with an estimated partial melting of 1%–5%. Mafic magmas underwent low-degree contamination from the lower crust during upwelling, induced by the extension of the lithosphere during the Early Jurassic. The analyses of pyrite sulfur isotopes in mafic samples vary between −2.9‰ and 1.8‰, significantly different from that of pyrite (−14.4‰ to −7.8‰) formed during the uranium mineralization. Furthermore, the ages of the pitchblende of 127–54 Ma are much younger than the crystallization ages of mafic dykes, indicating that the mafic magmas did not contribute to the uranium mineralization of Mianhuakeng deposit during magmatism. However, the abundant reducing minerals (e.g., pyrite, hornblende, and Fe²⁺-bearing minerals) in the mafic dykes can act as a redox barrier, reducing mobile U⁶⁺ to immobile U⁴⁺ during fluid–rock interaction, thereby facilitating uranium precipitation from the hydrothermal ore-forming fluids. The secondary fractures created by the intrusion of mafic magma probably provided favorable pathways for the movement of hydrothermal fluids. Full article

The Sanjiang Tethys orogenic belt in Southwest China is a globally important polymetallic metallogenic domain, hosting numerous world-class Cu-Pb-Zn deposits. Among these, the Lanping Basin is a typical ore concentration area, characterized by complex tectonic evolution and extensive hydrothermal mineralization. Although numerous vein-type Cu deposits occur in the northern and western parts of the basin, research in the north region remains less comprehensive. This study investigates three typical vein-type Cu deposits (Hetaoqing, Hemeigou, and Songpingzi) in the northern Lanping Basin using rare-earth element (REE) analysis, S-Pb-Sr isotope determinations, and tectonic stress inversion. Results show that ²⁰⁶Pb/²⁰⁴Pb ratios range from 18.374 to 18.691, and δ³⁴S_V-CDT values vary from –11.7‰ to +9.4‰, indicating mixed sources of ore-forming materials dominated by deep magmatic sources, particularly related to alkaline rocks around the basin. Sulfur sources are closely associated with thermochemical sulfate reduction (TSR). Additionally, ⁸⁷Sr/⁸⁶Sr ratios range from 0.710949 to 0.711864, ΣREE values range from 85.87 × 10^–6 to 111.86 × 10^–6, Ce/Ce* ratios range from 0.86 to 0.92, and Eu/Eu* ratios range from 1.06 to 2.99. Fluid inclusion microthermometry yields temperatures of 217–252 °C (average 238 °C), indicating that ore-forming fluids experienced water–rock interaction during migration and ultimately exhibited mixed properties. Tectonic stress field inversion reveals that the structures formed by NE–SW compressive stress field before mineralization stage provided ore-hosting spaces and fluid migration pathways, while a late Cenozoic abrupt stress field change promoted the precipitation of ore-forming materials. Full article

The Tuzla area, located in the Ayvacık district of Çanakkale (Biga Peninsula, northwestern Türkiye), hosts a Oligocene-Miocene volcanic system comprising andesitic, dacitic, rhyolitic lavas, trachyandesite, pyroclastics, and ignimbrites, and the Kestanbol Pluton. Petrographic and X-ray diffraction (XRD) analyses indicate that the altered volcanic units are dominated by porphyritic dacitic/rhyodacitic and trachyandesitic rocks, with silicification, iron oxide formation, and opacification. XRD results reveal smectite, smectite–illite/mica, illite–mica, kaolinite, cristobalite–opal, K-feldspar, plagioclase, dolomite, hematite, and quartz as the principal mineral phases. Geochemical data, including rare earth elements (REEs), suggest that fractional crystallization of primary mineral phases played a major role in controlling magmatic evolution. Chondrite-normalized REE patterns display enrichment in light REEs relative to heavy REEs, indicating derivation from a common magma source. K₂O–Na₂O and (Na₂O + K₂O)–FeOᵗ–MgO (AFM) diagrams show high-K calc-alkaline, calc-alkaline, and tholeiitic affinities, with most rhyodacite/dacite and all trachyandesite samples plotting in the tholeiitic field. Tectonic discrimination diagrams indicate formation in both volcanic arc and intraplate tectonic settings. Moderate enrichments in Ba and Sr reflect magmatic evolution and source characteristics, whereas the highest concentrations are attributed to post-magmatic fluid–rock interaction. Overall, the Tuzla volcanic rocks originated from a collision-related enriched lithospheric mantle source and subsequently evolved through fractional crystallization and assimilation processes, accompanied by crustal contamination and variable hydrothermal overprint. Full article