The Unconventional Peridotite-Related Mg-Fe-B Skarn of the El Robledal, SE Spain
Metadatos
Afficher la notice complèteAuteur
González Pérez, Igor; Gervilla Linares, Fernando; González Jiménez, José María; Acosta-Vigil, AntonioEditorial
MDPI
Materia
Boron Mg-skarn Ronda peridotites EBSD
Date
2023-02-21Referencia bibliográfica
González-Pérez, I.; Fanlo, I.; Ares, G.; Gervilla, F.; González-Jiménez, J.M.; Acosta-Vigil, A.; Arranz, E. The Unconventional Peridotite-Related Mg-Fe-B Skarn of the El Robledal, SE Spain. Minerals 2023, 13, 300. [https://doi.org/10.3390/min13030300]
Patrocinador
PRE2019-088262 “Ayudas para contratos predoctorales para la formación de doctores”, defrayed by the “Ministerio de Ciencia, Innovación y Universidades”; the MECRAS Project A-RNM-356-UGR20 “Proyectos de I+D+i en el marco del Programa Operativo FEDER Andalucía 2014-2020” defrayed by the “Junta de Andalucía”Résumé
The El Robledal deposit is a Mg-Fe-B skarn hosted in a dismembered block from the
footwall contact of the Ronda orogenic peridotites in the westernmost part of the Betic Cordillera.
The skarn is subdivided into two different zones according to the dominant ore mineral assemblage:
(1) the ludwigite–magnetite zone, hosted in a completely mineralized body along with
metasomatic forsterite, and (2) the magnetite–szaibelyite zone hosted in dolomitic marbles. In the
ludwigite–magnetite zone, the massive mineralization comprises ludwigite (Mg2Fe3+(BO3)O2), Mgrich
magnetite, and magnetite, with minor amounts of kotoite (Mg3(BO3)2), szaibelyite (MgBO2(OH)),
accessory schoenfliesite (MgSn4+(OH)6), and pentlandite. The ratio of ludwigite–magnetite decreases
downwards in the stratigraphy of this zone. In contrast, the mineralization in the magnetite–
szaibelyite zone is mainly composed of irregular and folded magnetite pods and bands with pull-apart
fractures, locally associated with a brucite-, szaibelyite-, and serpentine-rich groundmass. The set of
inclusions identified within these ore minerals, using a combination of a focused ion beam (FIB) and
high-resolution transmission electron microscope (HRTEM), supports the proposed evolution of the
system and reactions of the mineral formation of the skarn. The analysis of the microstructures of the
ores by means of electron backscatter diffraction (EBSD) allowed for the determination that the ores
experienced ductile deformation followed by variable degrees of recrystallization and annealing. We
propose a new classification of the deposit as well as a plausible genetic model in a deposit where the
heat source and the ore-fluid source are decoupled.