RT Journal Article
T1 Sulfide mineralogy of igneous basic rocks (ophites) from the external zone of the Betic Cordillera
A1 González Jiménez, José María
A1 Blanco Quintero, Idael Francisco
A1 Yesares Ortiz, María Dolores
A1 Marchesi, Claudio
A1 Ferreira García, Amira Rosa
A1 González Pérez, Igor
A1 Schettino, Erwin
A1 Jiménez Cantizano, Francisco Abel
A1 Gervilla, Fernando
AB The Triassic sedimentary rocks of the external zone of the Betic Cordillera in southern Spain host abundant igneous basic rocks (“ophites”) metamorphosed in the greenschist facies. Investigation based on high-resolution transmission electron microscopy (HRTEM) reveals magmatic sulfides intimately intergrown with primary silicates (pyroxene, plagioclase and olivine), consisting of pyrrhotite (FeS to Fe7S8; monoclinic C2/c polytype 4C) and pentlandite ((FeNi)9S8; cubic Fm3m), bounded by tetragonal I2d chalcopyrite (CuFeS2). Whole-rock and clinopyroxene geochemical data suggest that Fe–Ni–Cu sulfides crystallized from melt droplets segregated by immiscibility from transitional-alkaline magmas, after their fractional crystallization and volatile oversaturation within crustal conduits developed during intraplate rifting. In contrast, hydrothermal sulfides are pyrite (FeS2) and/or chalcopyrite associated with secondary silicates (chlorite, epidote, saussurite, prehnite, sericite and quartz). Porous pyrite (cubic Pa3) hosts nanodomains of pyrrhotite (monoclinic C2/c polytype 4C and orthorhombic Cmca polytype 11C) and orthorhombic Pnnm marcasite (FeS2), evidencing disulfide formation via coupled Fe loss and S addition in pyrrhotite due to reaction with high-fS2 and high-fO2 fluids at < 300 °C. Tetragonal I2d chalcopyrite replacing pyrite also preserves nanodomains of pyrrhotite as well as of pyrite  marcasite, suggesting reaction of pre-existing Fe sulfides with Cu transported by low-temperature (∼ 200–100 °C) acidic-to-neutral fluids. Additionally, inclusions of sphalerite (ZnS), galena (PbS) and vaesite (NiS2) in pyrite and chalcopyrite spotlight metal remobilization during hydrothermal alteration, which is further confirmed by the crystallization of cobaltite coronas (CoAsS) around pyrite. Our new results contribute to the current debate of the full sequence of processes operating in ore-forming mafic systems.
PB Copernicus Publications
SN 0935-1221
YR 2025
FD 2025-03-20
LK https://hdl.handle.net/20.500.14352/119222
UL https://hdl.handle.net/20.500.14352/119222
LA eng
NO González-Jiménez, J. M., Blanco-Quintero, I. F., Yesares, L., Marchesi, C., Ferreira, A. R., González-Pérez, I., Schettino, E., Jiménez Cantizano, F. A., & Gervilla, F. (2025). Sulfide mineralogy of igneous basic rocks (Ophites) from the external zone of the Betic Cordillera. European Journal of Mineralogy, 37(2), 191-220. https://doi.org/10.5194/ejm-37-191-2025
NO Junta de Andalucía
DS Docta Complutense
RD 17 dic 2025