Oxidation processes and their effects on the magnetic remanence of Early Cretaceous subaerial basalts from Sierra Chica de Córdoba, Argentina

Abstract We carried out magnetic analyses on a sequence of Cretaceous alkaline-transitional subaerial basalts of Córdoba Province, Argentina, which have high-Ti magnetite as the main opaque phase. Three different groups are identified based on the degree of high-temperature oxidation during the lava...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Geuna, Silvana Evangelina, Lagorio, Silvia Leonor, Vizan, Haroldo
Publicado:	2015
Materias:	basalt breccia Cretaceous lava flow magnetic field magnetic property magnetic susceptibility oxidation remanent magnetization titanomagnetite Argentina Cordoba [Argentina] Sierra Chica de Cordoba
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03058719_v396_n_p239_Geuna http://hdl.handle.net/20.500.12110/paper_03058719_v396_n_p239_Geuna
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_03058719_v396_n_p239_Geuna
record_format	dspace
spelling	paper:paper_03058719_v396_n_p239_Geuna2023-06-08T15:30:57Z Oxidation processes and their effects on the magnetic remanence of Early Cretaceous subaerial basalts from Sierra Chica de Córdoba, Argentina Geuna, Silvana Evangelina Lagorio, Silvia Leonor Vizan, Haroldo basalt breccia Cretaceous lava flow magnetic field magnetic property magnetic susceptibility oxidation remanent magnetization titanomagnetite Argentina Cordoba [Argentina] Sierra Chica de Cordoba Abstract We carried out magnetic analyses on a sequence of Cretaceous alkaline-transitional subaerial basalts of Córdoba Province, Argentina, which have high-Ti magnetite as the main opaque phase. Three different groups are identified based on the degree of high-temperature oxidation during the lava extrusion, combined with superimposed maghemitization and hematization. In the first group, titanomagnetites are optically homogeneous or exhibit coarse intergrowths with ilmenite. The magnetic susceptibility and its variation with temperature and magnetic field point to Ti-poorer compositions than those indicated by electron microprobe, which is interpreted as due to low-temperature oxidation with subsolvus microexsolution. The second group of basalts suffered moderate high-temperature oxidation, with crowded exsolved ilmenite laths within a Ti-poor magnetitess host, followed by maghemitization and hematite replacement. The third group shows a strongly advanced degree of low-temperature alteration, with the virtual disappearance of magnetite. Based on magnetic properties and field tests applied to the magnetic remanence, we interpret that maghemitization and hematization must have been responsible for the acquisition of a stable magnetic remanence, in the presence of hydrothermal fluids coeval with volcanism. The most advanced degree of alteration, typical of highly porous amygdaloidal lava flows and volcanic breccias, occurred later, probably due to weathering. © 2015 The Geological Society of London. Fil:Geuna, S.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Lagorio, S.L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Vizán, H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2015 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03058719_v396_n_p239_Geuna http://hdl.handle.net/20.500.12110/paper_03058719_v396_n_p239_Geuna
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	basalt breccia Cretaceous lava flow magnetic field magnetic property magnetic susceptibility oxidation remanent magnetization titanomagnetite Argentina Cordoba [Argentina] Sierra Chica de Cordoba
spellingShingle	basalt breccia Cretaceous lava flow magnetic field magnetic property magnetic susceptibility oxidation remanent magnetization titanomagnetite Argentina Cordoba [Argentina] Sierra Chica de Cordoba Geuna, Silvana Evangelina Lagorio, Silvia Leonor Vizan, Haroldo Oxidation processes and their effects on the magnetic remanence of Early Cretaceous subaerial basalts from Sierra Chica de Córdoba, Argentina
topic_facet	basalt breccia Cretaceous lava flow magnetic field magnetic property magnetic susceptibility oxidation remanent magnetization titanomagnetite Argentina Cordoba [Argentina] Sierra Chica de Cordoba
description	Abstract We carried out magnetic analyses on a sequence of Cretaceous alkaline-transitional subaerial basalts of Córdoba Province, Argentina, which have high-Ti magnetite as the main opaque phase. Three different groups are identified based on the degree of high-temperature oxidation during the lava extrusion, combined with superimposed maghemitization and hematization. In the first group, titanomagnetites are optically homogeneous or exhibit coarse intergrowths with ilmenite. The magnetic susceptibility and its variation with temperature and magnetic field point to Ti-poorer compositions than those indicated by electron microprobe, which is interpreted as due to low-temperature oxidation with subsolvus microexsolution. The second group of basalts suffered moderate high-temperature oxidation, with crowded exsolved ilmenite laths within a Ti-poor magnetitess host, followed by maghemitization and hematite replacement. The third group shows a strongly advanced degree of low-temperature alteration, with the virtual disappearance of magnetite. Based on magnetic properties and field tests applied to the magnetic remanence, we interpret that maghemitization and hematization must have been responsible for the acquisition of a stable magnetic remanence, in the presence of hydrothermal fluids coeval with volcanism. The most advanced degree of alteration, typical of highly porous amygdaloidal lava flows and volcanic breccias, occurred later, probably due to weathering. © 2015 The Geological Society of London.
author	Geuna, Silvana Evangelina Lagorio, Silvia Leonor Vizan, Haroldo
author_facet	Geuna, Silvana Evangelina Lagorio, Silvia Leonor Vizan, Haroldo
author_sort	Geuna, Silvana Evangelina
title	Oxidation processes and their effects on the magnetic remanence of Early Cretaceous subaerial basalts from Sierra Chica de Córdoba, Argentina
title_short	Oxidation processes and their effects on the magnetic remanence of Early Cretaceous subaerial basalts from Sierra Chica de Córdoba, Argentina
title_full	Oxidation processes and their effects on the magnetic remanence of Early Cretaceous subaerial basalts from Sierra Chica de Córdoba, Argentina
title_fullStr	Oxidation processes and their effects on the magnetic remanence of Early Cretaceous subaerial basalts from Sierra Chica de Córdoba, Argentina
title_full_unstemmed	Oxidation processes and their effects on the magnetic remanence of Early Cretaceous subaerial basalts from Sierra Chica de Córdoba, Argentina
title_sort	oxidation processes and their effects on the magnetic remanence of early cretaceous subaerial basalts from sierra chica de córdoba, argentina
publishDate	2015
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03058719_v396_n_p239_Geuna http://hdl.handle.net/20.500.12110/paper_03058719_v396_n_p239_Geuna
work_keys_str_mv	AT geunasilvanaevangelina oxidationprocessesandtheireffectsonthemagneticremanenceofearlycretaceoussubaerialbasaltsfromsierrachicadecordobaargentina AT lagoriosilvialeonor oxidationprocessesandtheireffectsonthemagneticremanenceofearlycretaceoussubaerialbasaltsfromsierrachicadecordobaargentina AT vizanharoldo oxidationprocessesandtheireffectsonthemagneticremanenceofearlycretaceoussubaerialbasaltsfromsierrachicadecordobaargentina
_version_	1768544866454732800

Oxidation processes and their effects on the magnetic remanence of Early Cretaceous subaerial basalts from Sierra Chica de Córdoba, Argentina

Ejemplares similares