Studying the kinematics of magma emplacement in fabric-weak, epizonal plutons: The example of the Sauce Guacho and Santa Rosa plutons, eastern Sierras Pampeanas, Argentina

This work presents emplacement kinematics for two plutons emplaced in a crustal level dominated by brittle conditions as a useful methodology in the study of shallow, small intrusive bodies where the field evidence of deformation is scarce. The study was carried out in the Sauce Guacho and Santa Ros...

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Autores: Acosta Nagle, Ana Eugenia, Díaz Alvarado, Juan, Fernández Rodríguez, Carlos, Christiansen, Rodolfo, D'Eramo, Fernando Javier, Pinotti, Lucio Pedro, López, José Pablo, Bellos, Laura Iudith
Tipo de recurso: artículo
Fecha de publicación:2025
País:España
Institución:Universidad Complutense de Madrid (UCM)
Repositorio:Docta Complutense
Idioma:inglés
OAI Identifier:oai:docta.ucm.es:20.500.14352/112021
Acceso en línea:https://hdl.handle.net/20.500.14352/112021
Access Level:acceso abierto
Palabra clave:551.22(82)
Upper crustal plutons
Emplacement mechanism
Geophysical imaging
Structural analysis
Intracontinental magmatism
Eastern sierras pampeanas
Geodinámica
Petrología
2506.13 Petrología Ignea y Metamórfica
2506.20 Geología Estructural
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spelling Studying the kinematics of magma emplacement in fabric-weak, epizonal plutons: The example of the Sauce Guacho and Santa Rosa plutons, eastern Sierras Pampeanas, ArgentinaAcosta Nagle, Ana EugeniaDíaz Alvarado, JuanFernández Rodríguez, CarlosChristiansen, RodolfoD'Eramo, Fernando JavierPinotti, Lucio PedroLópez, José PabloBellos, Laura Iudith551.22(82)Upper crustal plutonsEmplacement mechanismGeophysical imagingStructural analysisIntracontinental magmatismEastern sierras pampeanasGeodinámicaPetrología2506.13 Petrología Ignea y Metamórfica2506.20 Geología EstructuralThis work presents emplacement kinematics for two plutons emplaced in a crustal level dominated by brittle conditions as a useful methodology in the study of shallow, small intrusive bodies where the field evidence of deformation is scarce. The study was carried out in the Sauce Guacho and Santa Rosa plutons, both located on NO sector of Sierra de Ancasti. They are zoned syeno-monzogranitic, strongly peraluminous intrusive bodies representing typical Carboniferous intracontinental magmatism in the Eastern Sierras Pampeanas of Argentina. Both plutons present ellipsoidal external shapes, and sharp and discordant contacts with the host rocks suggesting an emplacement with high rheological contrast between the intrusive magma and the metamorphic host rock. The geophysical study highlights an elongated, arcuate gravimetric low that coincides and is aligned with the long axis of both plutons and with a zone characterized by brittle structures. Regarding structural measurements, the main penetrative structure of the host rocks (Ancasti Formation) shows an averaged NNW-SSE orientation and presents a slight but significant variation close to the plutons. Magmatic fabrics were observed in the porphyritic units (K-feldspar megacrysts) that constitute part of the igneous bodies. All these pieces of evidence suggest a possible structural control during the emplacement of the igneous bodies and constitute the data used in the structural analysis that tests five different conceptual models simulating the shear zone influence for the emplacement of the plutons. According to our kinematic analysis, the distinct structural features and external shapes found in the Sauce Guacho and Santa Rosa plutons and their metamorphic envelope were imposed by the curved deformation zone. Thus, magma ascent and emplacement were probably assisted by the nucleation and growth of a dextral transtensional structure, with a predominance of simple shear (Wk ≫ 0.81) in its southern, NNE-SSW-striking segment (Santa Rosa pluton area), and with a predominance of pure shear (0.6 > Wk > 0.1) in its northern, NE-SW striking segment (Sauce Guacho pluton area). In addition to a feasible emplacement model, our structural analysis shed light on the barely known Carboniferous tectonic scenario in this intracontinental setting of SW Gondwana. The common divergence angle estimated for both brittle-ductile shear zone segments is oriented 157°±9°. Therefore, this structure could have acted as a dextral transtensional structure with predominance of the coaxial component (extension) in NE-SW segments and dominated by simple shear in oblique NNE-SSW branches, interpreted as R-type fractures.ElsevierUniversidad Complutense de Madrid20252025-01-0120252025-01-01journal articlehttp://purl.org/coar/resource_type/c_6501VoRhttp://purl.org/coar/version/c_970fb48d4fbd8a85info:eu-repo/semantics/articleapplication/pdfhttps://hdl.handle.net/20.500.14352/112021reponame:Docta Complutenseinstname:Universidad Complutense de Madrid (UCM)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2Attribution-NonCommercial 4.0 Internationalhttp://creativecommons.org/licenses/by-nc/4.0/info:eu-repo/semantics/openAccessoai:docta.ucm.es:20.500.14352/1120212026-06-02T12:44:21Z
dc.title.none.fl_str_mv Studying the kinematics of magma emplacement in fabric-weak, epizonal plutons: The example of the Sauce Guacho and Santa Rosa plutons, eastern Sierras Pampeanas, Argentina
title Studying the kinematics of magma emplacement in fabric-weak, epizonal plutons: The example of the Sauce Guacho and Santa Rosa plutons, eastern Sierras Pampeanas, Argentina
spellingShingle Studying the kinematics of magma emplacement in fabric-weak, epizonal plutons: The example of the Sauce Guacho and Santa Rosa plutons, eastern Sierras Pampeanas, Argentina
Acosta Nagle, Ana Eugenia
551.22(82)
Upper crustal plutons
Emplacement mechanism
Geophysical imaging
Structural analysis
Intracontinental magmatism
Eastern sierras pampeanas
Geodinámica
Petrología
2506.13 Petrología Ignea y Metamórfica
2506.20 Geología Estructural
title_short Studying the kinematics of magma emplacement in fabric-weak, epizonal plutons: The example of the Sauce Guacho and Santa Rosa plutons, eastern Sierras Pampeanas, Argentina
title_full Studying the kinematics of magma emplacement in fabric-weak, epizonal plutons: The example of the Sauce Guacho and Santa Rosa plutons, eastern Sierras Pampeanas, Argentina
title_fullStr Studying the kinematics of magma emplacement in fabric-weak, epizonal plutons: The example of the Sauce Guacho and Santa Rosa plutons, eastern Sierras Pampeanas, Argentina
title_full_unstemmed Studying the kinematics of magma emplacement in fabric-weak, epizonal plutons: The example of the Sauce Guacho and Santa Rosa plutons, eastern Sierras Pampeanas, Argentina
title_sort Studying the kinematics of magma emplacement in fabric-weak, epizonal plutons: The example of the Sauce Guacho and Santa Rosa plutons, eastern Sierras Pampeanas, Argentina
dc.creator.none.fl_str_mv Acosta Nagle, Ana Eugenia
Díaz Alvarado, Juan
Fernández Rodríguez, Carlos
Christiansen, Rodolfo
D'Eramo, Fernando Javier
Pinotti, Lucio Pedro
López, José Pablo
Bellos, Laura Iudith
author Acosta Nagle, Ana Eugenia
author_facet Acosta Nagle, Ana Eugenia
Díaz Alvarado, Juan
Fernández Rodríguez, Carlos
Christiansen, Rodolfo
D'Eramo, Fernando Javier
Pinotti, Lucio Pedro
López, José Pablo
Bellos, Laura Iudith
author_role author
author2 Díaz Alvarado, Juan
Fernández Rodríguez, Carlos
Christiansen, Rodolfo
D'Eramo, Fernando Javier
Pinotti, Lucio Pedro
López, José Pablo
Bellos, Laura Iudith
author2_role author
author
author
author
author
author
author
dc.contributor.none.fl_str_mv Universidad Complutense de Madrid
dc.subject.none.fl_str_mv 551.22(82)
Upper crustal plutons
Emplacement mechanism
Geophysical imaging
Structural analysis
Intracontinental magmatism
Eastern sierras pampeanas
Geodinámica
Petrología
2506.13 Petrología Ignea y Metamórfica
2506.20 Geología Estructural
topic 551.22(82)
Upper crustal plutons
Emplacement mechanism
Geophysical imaging
Structural analysis
Intracontinental magmatism
Eastern sierras pampeanas
Geodinámica
Petrología
2506.13 Petrología Ignea y Metamórfica
2506.20 Geología Estructural
description This work presents emplacement kinematics for two plutons emplaced in a crustal level dominated by brittle conditions as a useful methodology in the study of shallow, small intrusive bodies where the field evidence of deformation is scarce. The study was carried out in the Sauce Guacho and Santa Rosa plutons, both located on NO sector of Sierra de Ancasti. They are zoned syeno-monzogranitic, strongly peraluminous intrusive bodies representing typical Carboniferous intracontinental magmatism in the Eastern Sierras Pampeanas of Argentina. Both plutons present ellipsoidal external shapes, and sharp and discordant contacts with the host rocks suggesting an emplacement with high rheological contrast between the intrusive magma and the metamorphic host rock. The geophysical study highlights an elongated, arcuate gravimetric low that coincides and is aligned with the long axis of both plutons and with a zone characterized by brittle structures. Regarding structural measurements, the main penetrative structure of the host rocks (Ancasti Formation) shows an averaged NNW-SSE orientation and presents a slight but significant variation close to the plutons. Magmatic fabrics were observed in the porphyritic units (K-feldspar megacrysts) that constitute part of the igneous bodies. All these pieces of evidence suggest a possible structural control during the emplacement of the igneous bodies and constitute the data used in the structural analysis that tests five different conceptual models simulating the shear zone influence for the emplacement of the plutons. According to our kinematic analysis, the distinct structural features and external shapes found in the Sauce Guacho and Santa Rosa plutons and their metamorphic envelope were imposed by the curved deformation zone. Thus, magma ascent and emplacement were probably assisted by the nucleation and growth of a dextral transtensional structure, with a predominance of simple shear (Wk ≫ 0.81) in its southern, NNE-SSW-striking segment (Santa Rosa pluton area), and with a predominance of pure shear (0.6 > Wk > 0.1) in its northern, NE-SW striking segment (Sauce Guacho pluton area). In addition to a feasible emplacement model, our structural analysis shed light on the barely known Carboniferous tectonic scenario in this intracontinental setting of SW Gondwana. The common divergence angle estimated for both brittle-ductile shear zone segments is oriented 157°±9°. Therefore, this structure could have acted as a dextral transtensional structure with predominance of the coaxial component (extension) in NE-SW segments and dominated by simple shear in oblique NNE-SSW branches, interpreted as R-type fractures.
publishDate 2025
dc.date.none.fl_str_mv 2025
2025-01-01
2025
2025-01-01
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
VoR
http://purl.org/coar/version/c_970fb48d4fbd8a85
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/20.500.14352/112021
url https://hdl.handle.net/20.500.14352/112021
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
Attribution-NonCommercial 4.0 International
http://creativecommons.org/licenses/by-nc/4.0/
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
Attribution-NonCommercial 4.0 International
http://creativecommons.org/licenses/by-nc/4.0/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Elsevier
publisher.none.fl_str_mv Elsevier
dc.source.none.fl_str_mv reponame:Docta Complutense
instname:Universidad Complutense de Madrid (UCM)
instname_str Universidad Complutense de Madrid (UCM)
reponame_str Docta Complutense
collection Docta Complutense
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,812429

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