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Título
The Peña do Seo W-Sn deposit, NW Iberia: Petrology, fluid inclusions and O-H-S isotopes
Autor
Facultad/Centro
Área de conocimiento
Título de la revista
Ore Geology Reviews
Cita Bibliográfica
Caldevilla, P., González-Menéndez, L., Martín-Crespo, T., Vindel, E., Guedes, A., Berrezueta, E., Castañón, A. M., & Gómez-Fernández, F. (2023). The Peña do Seo W-Sn deposit, NW Iberia: Petrology, fluid inclusions and O-H-S isotopes. Ore Geology Reviews, 155, 105361. https://doi.org/10.1016/J.OREGEOREV.2023.105361
Editorial
Elsevier
Fecha
2023
ISSN
0169-1368
Resumen
[EN] The PeËœna do Seo W-Sn ore deposit in NW Iberia consists mainly of quartz veins hosted in schists. Vein mineralogy
comprises wolframite, cassiterite and minor molybdenite. Peraluminous S-type granites and minor metaluminous
granitoid breccias crop out in the same location. Whole rock geochemistry, mineral characterization, fluid inclusions
and stable isotope geochemistry have been combined to infer hydrothermal mineralization conditions.
A pre-ore stage (0) involving the alteration of host rocks, three stages of mineralization (I, II and III), and a
supergene stage (IV) have been identified. Stage I (oxide-halide-sulfide stage) consisted of a cassiterite-pyritefluorite
mineralization in granitoid breccias. Stage II (main oxide stage) involved wolframite-rich selvages and
wolframite-cassiterite-(molybdenite) quartz veins. Stage III (main sulfide stage) consisted of a sulfide mineralization
in quartz veins comprising pyrite and minor arsenopyrite and chalcopyrite.
Three types of fluid inclusions were found in vein quartz: (1) aqueous two-phase inclusions, with homogenization
temperatures (Th) between 445 â—¦C and 280 â—¦C and moderate salinities (9–14 wt% NaCl eq.), (2)
aqueous-carbonic three-phase fluid inclusions, with Th from 340 â—¦C to 260 â—¦C and low salinities (2–7 wt% NaCl
eq.), and (3) aqueous two-phase fluid inclusions, with Th from 270 â—¦C to 155 â—¦C and low salinities (0–6 wt% NaCl
eq.). δ18O values in quartz from mineralized veins range from +11.2‰ to +13.4‰, and between +15.0‰ and
+15.4% in quartz from mineralized granitoid breccias. δ34S values in sulfides (pyrite, arsenopyrite and chalcopyrite)
range between +13.0 ‰ and +37.1 ‰, thus suggesting a marine source of sulfate and possible
equilibration with host-rock sulfides. δD values in muscovite and chlorite from quartz veins range between
105.7 ‰ and 71.5 ‰ and between 69.4 ‰ and 67.1 ‰, respectively, indicating a transition from
magmatic to magmatic-metamorphic conditions.
An aqueous (H2O–NaCl) magmatic-hydrothermal fluid led to the W-Sn mineralization, as deduced from the
studied fluid inclusions and isotopic signatures. High W and Sn contents in the peraluminous granites indicate
that the W-Sn mineralization in PeËœna do Seo could partially be related to the granites and granitoid breccias.
Whereas the Sn (±W) likely derived from hydrothermal fluids exsolving from the crystallizing magmas, host
quartz schists would have supplied other elements required for wolframite deposition such as Fe and Mn. Sulfide
mineralization in stage III was probably driven by fluid dilution.
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