Mineralogical control on the magnetic anisotropy of lavas and ignimbrites : a case study in the caviahue-copahue field (Argentina)
Thiago R. Moncinhatto, Mauricio B. Haag, Gelvam A. Hartmann, Jairo F. Savian, Wilbor Poletti, Carlos A. Sommer, Alberto T. Caselli, Ricardo I. F. Trindade
ARTIGO
Inglês
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...
Ver mais
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 of magnetic anisotropy data in volcanic rocks and ignimbrites
Ver menos
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ
144580/2016-0; 454609/2014-0; 441766/2014-5; 303015/2015-2; 400724/2014-6
COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES
AUXPE 2043/2014
Aberto
DOI: https://doi.org/10.1093/gji/ggz483
Texto completo: https://academic.oup.com/gji/article/220/2/821/5603748
Mineralogical control on the magnetic anisotropy of lavas and ignimbrites : a case study in the caviahue-copahue field (Argentina)
Thiago R. Moncinhatto, Mauricio B. Haag, Gelvam A. Hartmann, Jairo F. Savian, Wilbor Poletti, Carlos A. Sommer, Alberto T. Caselli, Ricardo I. F. Trindade
Mineralogical control on the magnetic anisotropy of lavas and ignimbrites : a case study in the caviahue-copahue field (Argentina)
Thiago R. Moncinhatto, Mauricio B. Haag, Gelvam A. Hartmann, Jairo F. Savian, Wilbor Poletti, Carlos A. Sommer, Alberto T. Caselli, Ricardo I. F. Trindade
Fontes
|
Geophysical journal international (Fonte avulsa) |