Composite magnetic fabrics and S-C structure in granitic gneiss of Cerro de los Viejos, La Pampa province, Argentina

The Cerro los Viejos gneiss, in La Pampa Province, Argentina, is a mylonitized granite which lies along the late Paleozoic deformed boundary zone between the Patagonia block and 'mainland' Gondwana to the north. Petrofabric and anisotropy of magnetic susceptibility (AMS) analyses were comp...

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Detalles Bibliográficos
Autor principal: Tomezzoli, Renata Nela
Publicado: 2002
Materias:
Anisotropy of magnetic susceptibility
Argentina
Gondwana
Granitic gneiss
Petrofabric
S-C structure
Superimposed fabrics
Anisotropy
Composite materials
Magnetic susceptibility
Magnetite
Structural geology
gneiss
magnetic anisotropy
magnetic susceptibility
petrofabric
tectonic evolution
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01918141_v25_n2_p159_Tomezzoli
http://hdl.handle.net/20.500.12110/paper_01918141_v25_n2_p159_Tomezzoli
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling paper:paper_01918141_v25_n2_p159_Tomezzoli2023-06-08T15:19:53Z Composite magnetic fabrics and S-C structure in granitic gneiss of Cerro de los Viejos, La Pampa province, Argentina Tomezzoli, Renata Nela Anisotropy of magnetic susceptibility Argentina Gondwana Granitic gneiss Petrofabric S-C structure Superimposed fabrics Anisotropy Composite materials Magnetic susceptibility Magnetite Structural geology gneiss Gondwana magnetic anisotropy magnetic susceptibility petrofabric tectonic evolution Argentina The Cerro los Viejos gneiss, in La Pampa Province, Argentina, is a mylonitized granite which lies along the late Paleozoic deformed boundary zone between the Patagonia block and 'mainland' Gondwana to the north. Petrofabric and anisotropy of magnetic susceptibility (AMS) analyses were compared for this body. Unexpectedly, it was found that the Kmin poles deviate from the poles of the main foliation s1 by about 25°. Similarly, but not so noticeably, the Kmax poles trend NE/SW, with a near-horizontal plunge, whereas the principal lineation l1 plunges gently SW. This unusual situation is attributed to the existence of superimposed fabrics arising from S-C structures. Examination of oriented cores in a modified universal stage and of oriented thin-sections revealed that the Kmin poles are clearly associated with a younger but less obvious metamorphic 'C' foliation (s2). Biotite and magnetite, the main contributors to the AMS response, are distributed along both s1 and s2. The dominance of s2 in the AMS anisotropy suggests that magnetite is preferentially distributed on s2. © 2002 Elsevier Science Ltd. All rights reserved. Fil:Tomezzoli, R.N. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2002 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01918141_v25_n2_p159_Tomezzoli http://hdl.handle.net/20.500.12110/paper_01918141_v25_n2_p159_Tomezzoli
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Anisotropy of magnetic susceptibility
Argentina
Gondwana
Granitic gneiss
Petrofabric
S-C structure
Superimposed fabrics
Anisotropy
Composite materials
Magnetic susceptibility
Magnetite
Structural geology
gneiss
Gondwana
magnetic anisotropy
magnetic susceptibility
petrofabric
tectonic evolution
Argentina
spellingShingle Anisotropy of magnetic susceptibility
Argentina
Gondwana
Granitic gneiss
Petrofabric
S-C structure
Superimposed fabrics
Anisotropy
Composite materials
Magnetic susceptibility
Magnetite
Structural geology
gneiss
Gondwana
magnetic anisotropy
magnetic susceptibility
petrofabric
tectonic evolution
Argentina
Tomezzoli, Renata Nela
Composite magnetic fabrics and S-C structure in granitic gneiss of Cerro de los Viejos, La Pampa province, Argentina
topic_facet Anisotropy of magnetic susceptibility
Argentina
Gondwana
Granitic gneiss
Petrofabric
S-C structure
Superimposed fabrics
Anisotropy
Composite materials
Magnetic susceptibility
Magnetite
Structural geology
gneiss
Gondwana
magnetic anisotropy
magnetic susceptibility
petrofabric
tectonic evolution
Argentina
description The Cerro los Viejos gneiss, in La Pampa Province, Argentina, is a mylonitized granite which lies along the late Paleozoic deformed boundary zone between the Patagonia block and 'mainland' Gondwana to the north. Petrofabric and anisotropy of magnetic susceptibility (AMS) analyses were compared for this body. Unexpectedly, it was found that the Kmin poles deviate from the poles of the main foliation s1 by about 25°. Similarly, but not so noticeably, the Kmax poles trend NE/SW, with a near-horizontal plunge, whereas the principal lineation l1 plunges gently SW. This unusual situation is attributed to the existence of superimposed fabrics arising from S-C structures. Examination of oriented cores in a modified universal stage and of oriented thin-sections revealed that the Kmin poles are clearly associated with a younger but less obvious metamorphic 'C' foliation (s2). Biotite and magnetite, the main contributors to the AMS response, are distributed along both s1 and s2. The dominance of s2 in the AMS anisotropy suggests that magnetite is preferentially distributed on s2. © 2002 Elsevier Science Ltd. All rights reserved.
author Tomezzoli, Renata Nela
author_facet Tomezzoli, Renata Nela
author_sort Tomezzoli, Renata Nela
title Composite magnetic fabrics and S-C structure in granitic gneiss of Cerro de los Viejos, La Pampa province, Argentina
title_short Composite magnetic fabrics and S-C structure in granitic gneiss of Cerro de los Viejos, La Pampa province, Argentina
title_full Composite magnetic fabrics and S-C structure in granitic gneiss of Cerro de los Viejos, La Pampa province, Argentina
title_fullStr Composite magnetic fabrics and S-C structure in granitic gneiss of Cerro de los Viejos, La Pampa province, Argentina
title_full_unstemmed Composite magnetic fabrics and S-C structure in granitic gneiss of Cerro de los Viejos, La Pampa province, Argentina
title_sort composite magnetic fabrics and s-c structure in granitic gneiss of cerro de los viejos, la pampa province, argentina
publishDate 2002
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01918141_v25_n2_p159_Tomezzoli
http://hdl.handle.net/20.500.12110/paper_01918141_v25_n2_p159_Tomezzoli
work_keys_str_mv AT tomezzolirenatanela compositemagneticfabricsandscstructureingraniticgneissofcerrodelosviejoslapampaprovinceargentina
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