Arc environments are Au-endowed and it has been long hypothesized that Au mobilization during slab dehydration could affect mantle composition and arc Au-fertility. Here, we determine Au-mobility during prograde high pressure-low temperature metamorphism of both metavolcanic and metasedimentary rocks from the islands of Santorini, Ios, Naxos and Syros (Greece). These have sustained peak metamorphism from greenschist to upper-blueschist/eclogite facies, allowing determination of large-scale Au-mobility within the subduction zone. Gold is significantly mobilized by fluids at the blueschist-eclogite facies. Mélange zones at the slab-mantle interface provide a unique opportunity to understand the fate of Au in the mantle. In these zones Au shows heterogeneous concentration but is not enriched, implying only partial retention in the mélange and efficient Au mobilization across slab-mantle interface. Furthermore, mélange zones contribute to the slab component inherent to arc magmatism and their intrinsically complex lithology as well as heterogenous Au concentration appears to play a role on arc magmatism Au-fertility.

Copper (Cu) is essential for modern technologies, with demand expected to increase significantly due to the global transition towards green energy. Porphyry Cu deposits, which supply ~75% of the world’s Cu, are primarily associated with subduction-related magmatism in calc-alkaline arcs. Despite the widespread presence of such magmas, large porphyry Cu deposits are rare and increasingly challenging to discover. This study investigates the Permian–Triassic magmatic evolution of the Oyut Cu–Mo deposit in northern Mongolia through zircon U–Pb geochronology, lithogeochemistry, and mineral thermobarometry. The deposit is hosted in porphyritic andesite and basaltic andesite, intruded by (mostly) barren quartz-diorite and granodiorite, as well as mineralized granodiorite and dacite porphyries exhibiting intense K-feldspar and sericite alteration. Zircon U–Pb ages range from 254–246 Ma for the barren intrusions to 240–237 Ma for the mineralized porphyries. All magmatic rocks are high-K calc-alkaline and peraluminous to metaluminous, with Nb and Ta depletion indicating a continental arc setting. REE patterns distinguish two magmatic episodes: older barren intrusions show high overall REE contents and weak negative Eu anomalies, suggesting evolved melts. In contrast, mineralized intrusions (240–230 Ma) exhibit lower REE contents and positive Eu anomalies, indicating plagioclase accumulation or retention and a more oxidized, water-rich magma, favorable for Cu–Mo mineralization. Thermobarometric estimates (635–843 °C, 0.2–4.6 kbar) and trace element signatures suggest derivation from an enriched, volatile-rich mantle source and crystallization at mid-crustal depths. These findings highlight the importance of crustal differentiation, the role of plagioclase accumulation, and fluid evolution in forming Cu–Mo porphyry systems in continental arcs.

Novel petrographic, mineral chemical and microthermometric data combined with hydrothermal allanite U-Pb ages of the unusual high-grade Elizabeth Hill hydrothermal native Ag vein-type deposit in Western Australia reveal similarities to five element veins. Mineralized veins are hosted by fault-controlled quartz-carbonate breccias in Archean basement rocks of the West Pilbara Craton tied to basement contact with the layered ultramafic-mafic Munni Munni Complex hosting stratiform magmatic sulfides. Unconformity-based Fortescue Group siliciclastic-volcanic cover rocks are partly eroded. Host rocks close to the mineralization are silicified, calcified and chloritized. Pre-existing magmatic sulfides comprise chalcopyrite-pyrrhotite-pentlandite and are intersected by veins of stage I characterized by sphalerite-chalcopyrite-galena with minor pyrite, pyrrhotite and gersdorffite, and stage II Ag mineralization hosting argentopentlandite-acanthite-native Ag. Supergene remobilization of stage I and II minerals produced multiple generations of native Ag encompassing wires, veins and Ag-Hg amalgam ≤35.7 wt.% Hg. Chalcopyrite and acanthite allomorphs indicate high temperatures for stage I >557 °C and II >179 °C. Two phase (vapor-liquid) inclusions of stage I record the ternary CaCl₂-NaCl-H₂O system with salinities of 8.1–16.6 wt.% (CaCl₂+NaCl) and T_h of 107–147 °C, which are interpreted as a signature of retrograde re-equilibration. Two allanite age groups (2400–2370 and 2050–1990 Ma) coincide with episodes of craton-wide hydrothermal activity and orogenic and epithermal Au vein formation. Compared to most five-element veins, Ni, Co and As are rare; hence, Elizabeth Hill may represent an As-depleted, native Ag-dominated, Kongsberg-type five-element deposit. Repeated supergene Ag enrichment probably involved reactivation of the hosting fault system and long-term weathering.

The Freiberg district represents a key example of a Late Paleozoic epithermal precious and base metal deposit in Europe. Despite extensive research focusing on the ore-bearing vein infill, the nature and extent of hydrothermal alteration in the surrounding wall rocks remain poorly understood. This study presents new petrographic and mineral chemical data from altered host rocks adjacent to mineralized veins across different parts of the Freiberg district. The data are supplemented by Ar-Ar geochronology of muscovite (sericite), which has been identified in both the alteration halos and as part of vein assemblages. Our results reveal a complex alteration pattern involving sericitic, chloritic, and silicic overprints associated with the epithermal mineralization. The Ar-Ar dating of the coarse-grained muscovite within veins and fine-grained sericite in altered host rocks yielded ages between 316.7±3.2 Ma and 306.8±3.1 Ma. These values are older than the previously reported Rb-Sr age of 276±16 Ma on sphalerite but align well with field-based cross-cutting relationships and recent evidence for multiple rhyolitic magmatic pulses in the area (326–297 Ma). Some samples returned anomalously old ages, likely due to excess argon. The data support a multi-stage mineralization history and demonstrate the complex interplay between regional geodynamics, felsic magmatism, and hydrothermal processes in the Erzgebirge Metallogenic province.

The mid-Proterozoic McArthur Basin (Australia) hosts exceptionally well-preserved sedimentary rocks and giant clastic-dominant (CD-type) Zn deposits. Previous δ³⁴S-based studies aimed to reconstruct sulfide precipitation pathways; however, interpretations of δ³⁴S values are challenging due to overlapping signatures from organoclastic sulfate reduction (OSR), anaerobic oxidation of methane coupled with sulfate reduction (AOM-SR), and thermochemical sulfate reduction (TSR).

Here, we present new multiple sulfur isotope data from mineralized and unmineralized bulk rock samples of the Barney Creek Formation, host to the Teena Zn deposit, to resolve different diagenetic and hydrothermal sulfate reduction pathways. The sulfide paragenesis includes early diagenetic fine-grained pyrite, overgrown and partially replaced by coarser pyrite and sphalerite. Sulfur was extracted as chromous-reducible sulfur (CRS; n=40) from pyrite, and as acid-volatile sulfur (AVS; n=13) from sphalerite. CRS and AVS show broadly overlapping sulfur isotope compositions, with a wide range of δ³⁴S (–2.8 to 35.7‰), Δ³³S (–0.08 to 0.05‰), and Δ³⁶S (–0.40 to 0.67‰). The multiple sulfur isotope data will be integrated with redox-sensitive trace element data to reconstruct the local depositional redox environment (anoxic, euxinic conditions) in the Teena sub-basin.

Microbial fractionation models and Rayleigh distillation trends suggest sulfides formed mainly via OSR, as the data plot on a convex array in δ³⁴S–Δ³³S space. No evidence of mixing with AOM-SR, which would result in a concave trajectory; nor for TSR, which would produce lower Δ³³S values. Importantly, the results suggest that hydrothermal sulfides most likely precipitated from sulfur that was derived from the replacement of pre-existing diagenetic pyrite.