Secondary precipitation of Fe–Ti oxides as a source for strongly changing magnetic properties in ancient volcanic rocks (Cadí Basin, Pyrenees)
Simón-Muzás, Ana ; Casas-Sainz, Antonio M. (Universidad de Zaragoza) ; Soto, Ruth ; Oliva-Urcia, Belén (Universidad de Zaragoza)
Resumen: Abstract
Strong changes of magnetic properties (magnetic susceptibility and natural magnetic remanence) affecting large volumes of rocks can be conditioned by a series of factors, including circulation of hydrothermal fluids or meteoric waters, often favored by the primary porosity of the rock or pervasive fracturing. In the Late Carboniferous-Permian Cadí Basin, in the Eastern Pyrenees, there are volcanic rocks that show a unique pattern of magnetic anomalies up to 200 nT in amplitude revealing a heterogeneous distribution of their magnetic properties. To unravel the origin of these anomalies, we performed a detailed study of the magnetic properties of the volcanic and volcaniclastic rocks, combined with magnetic surveying and analysis of brittle structures. The results indicate that the origin of the strong variations in the magnetic properties is linked to: (i) lithological changes within the volcanic series, and (ii) the inhomogeneous secondary precipitation of ferromagnetic minerals. As a result of these secondary processes, magnetic fabrics do not reliably record either the volcanic paleoflow or the deformation imprint. The mineralogical composition can be interpreted as the result of a strong hydrothermal alteration that took place during early diagenetic stages, which was also responsible for the neoformation of magnetite crystals with variable titanium content. Random fluid circulation during the Late-Variscan stage could be the origin of these strong variations in magnetic properties.
Graphical Abstract
Idioma: Inglés
DOI: 10.1007/s00531-025-02530-1
Año: 2025
Publicado en: International Journal of Earth Sciences 114, 5 (2025), 959-978
ISSN: 1437-3254
Financiación: info:eu-repo/grantAgreement/ES/AEI/PID2019-108753GB-C22
Financiación: info:eu-repo/grantAgreement/ES/MICINN/FPU19-02353
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PID2020-114273GB-C22
Financiación: info:eu-repo/grantAgreement/ES/MICIU /PID2023-148256NB-I00
Tipo y forma: Article (Published version)
Área (Departamento): Área Geodinámica Interna (Dpto. Ciencias de la Tierra)
You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
Exportado de SIDERAL (2025-10-08-12:59:46)
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Strong changes of magnetic properties (magnetic susceptibility and natural magnetic remanence) affecting large volumes of rocks can be conditioned by a series of factors, including circulation of hydrothermal fluids or meteoric waters, often favored by the primary porosity of the rock or pervasive fracturing. In the Late Carboniferous-Permian Cadí Basin, in the Eastern Pyrenees, there are volcanic rocks that show a unique pattern of magnetic anomalies up to 200 nT in amplitude revealing a heterogeneous distribution of their magnetic properties. To unravel the origin of these anomalies, we performed a detailed study of the magnetic properties of the volcanic and volcaniclastic rocks, combined with magnetic surveying and analysis of brittle structures. The results indicate that the origin of the strong variations in the magnetic properties is linked to: (i) lithological changes within the volcanic series, and (ii) the inhomogeneous secondary precipitation of ferromagnetic minerals. As a result of these secondary processes, magnetic fabrics do not reliably record either the volcanic paleoflow or the deformation imprint. The mineralogical composition can be interpreted as the result of a strong hydrothermal alteration that took place during early diagenetic stages, which was also responsible for the neoformation of magnetite crystals with variable titanium content. Random fluid circulation during the Late-Variscan stage could be the origin of these strong variations in magnetic properties.
Graphical Abstract
Idioma: Inglés
DOI: 10.1007/s00531-025-02530-1
Año: 2025
Publicado en: International Journal of Earth Sciences 114, 5 (2025), 959-978
ISSN: 1437-3254
Financiación: info:eu-repo/grantAgreement/ES/AEI/PID2019-108753GB-C22
Financiación: info:eu-repo/grantAgreement/ES/MICINN/FPU19-02353
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PID2020-114273GB-C22
Financiación: info:eu-repo/grantAgreement/ES/MICIU /PID2023-148256NB-I00
Tipo y forma: Article (Published version)
Área (Departamento): Área Geodinámica Interna (Dpto. Ciencias de la Tierra)
You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. Exportado de SIDERAL (2025-10-08-12:59:46)
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Record created 2025-10-09, last modified 2025-10-09