Artículo
Mineralogical control on the magnetic anisotropy of lavas and ignimbrites: a case study in the Caviahue-Copahue field (Argentina)
Moncinhatto, Thiago; Haag, Maurício Barcelos; Hartmann, Gelvam; Savian, Jairo; Poletti, Wilbor; Sommer, Carlos Augusto; Caselli, Alberto Tomás
; Ferreira Da Trindade, Ricardo Ivan
Fecha de publicación:
02/2020
Editorial:
Wiley Blackwell Publishing, Inc
Revista:
Geophysical Journal International
ISSN:
0956-540X
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
Anisotropy of magnetic susceptibility is a petrofabric tool used to estimate the alignment of minerals at the site-scale, the imbrication between the magnetic foliation and the emplacement surface being an indicator of flow direction. However, despite numerous studies examining the flow direction in pyroclastic deposits and lava flows, the effect of magnetic mineralogy and the domain state of ferromagnetic phases on the magnetic fabric remains poorly understood. This paper describes the magnetic mineralogy and its influence on the magnetic fabric of Plio-Pleistocene lava flows and ignimbrites of the Caviahue-Copahue Volcanic Complex in the Andean Southern Volcanic Zone, Argentina. Rock magnetism, anisotropy of magnetic susceptibility and anhysteretic remanent magnetization and petrographic observations were performed on 30 sites of the volcanic complex. Results revealed the extrusive and pyroclastic rocks present varied magnetic mineralogy, formed in different stages of the magmatic evolution. Magnetic mineralogy variations strongly affect the anisotropy of magnetic susceptibility data in volcanic rocks and associated ignimbrites, providing 'scattered' fabrics when late Tirich titanomagnetite phases dominate the fabric, and 'inverse' or 'intermediate' fabrics when single-domain grains are present. 'Normal' fabrics are typically found when early crystallized puremagnetite is present.Our results highlight the complexity in the interpretation ofmagnetic anisotropy data in volcanic rocks and ignimbrites.
Palabras clave:
AARM
,
AMS
,
CAVIAHUE-COPAHUE VOLCANIC COMPLEX
,
MAGNETIC MINERALOGY
Archivos asociados
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Identificadores
Colecciones
Articulos(IIPG)
Articulos de INSTITUTO DE INVESTIGACION EN PALEOBIOLOGIA Y GEOLOGIA
Articulos de INSTITUTO DE INVESTIGACION EN PALEOBIOLOGIA Y GEOLOGIA
Citación
Moncinhatto, Thiago; Haag, Maurício Barcelos; Hartmann, Gelvam; Savian, Jairo; Poletti, Wilbor; et al.; Mineralogical control on the magnetic anisotropy of lavas and ignimbrites: a case study in the Caviahue-Copahue field (Argentina); Wiley Blackwell Publishing, Inc; Geophysical Journal International; 220; 2; 2-2020; 821-838
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