Basamento paleoproterozoico del área de San Miguel, Sierras Septentrionales de la provincia de Buenos Aires: registro de una cuenca de retroarco en el margen sur del cratón del río...

Autores
Lajoinie, María Florencia; Lanfranchini, Mabel Elena; Etcheverry, Ricardo Oscar
Año de publicación
2017
Idioma
español castellano
Tipo de recurso
documento de conferencia
Estado
versión publicada
Descripción
New information obtained from the characterization of biotite gneises and migmatites from the San Miguel area allowed the interpretation of metamorphic processes that formed a portion of the Paleoproterozoic basement of the Tandilia Belt. Biotite gneiss shows a compositional Sj banding (N35°E/60°NW) and a mineral composition: microcline, (oligoclase-andesine), quartz and biotite. Migmatites occur as differentiated bodies with stromatic structure with Sj orientation and quartz, oligoclase, microcline leucosomes. Also almandine gamet appears in voluminous leucosomes. Chemical analyses indícate that the gneiss derived from a sedimentary protolith (wacke) while the migmatites would have formed from partial melting of the gneiss through decomposition of biotite in presence of quartz and plagioclase. This fact must have generated the gametiferous phase with potassic feldspar and a peraluminous granitic melt in imbalance: low ratio (La/Yb)N <55.85 and low Th and Zr contents. Migmatization must have started during the Transamazonian Cycle (~2200Ma) considering that most of the leucosomes are concordant with the banding gneiss orientation, formed during the mentioned Cycle. Thus, the pressure gradient favoured the migration and the intrusión of the melt (before to rebalance) into the gneiss and also in marbles generating metasomatism and skamification. This metamorphic evolution scheme matches with a tectonic context of back-arc basin associated with an oceanic-continental crust subduction that occu- rred during the Archaean-Paleoproterozoic period, and finished with the amalgamation of Tandilia Terrane to the Rio de la Plata Craton.
Instituto de Recursos Minerales
Materia
Geología
ciclo transamazónico
Tandilia (Buenos Aires, Argentina)
procesos metamórficos
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by-nc-nd/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/73586
Acceder
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spelling Basamento paleoproterozoico del área de San Miguel, Sierras Septentrionales de la provincia de Buenos Aires: registro de una cuenca de retroarco en el margen sur del cratón del río de la PlataPaleoproterozoic basement at the San Miguel area, Tandilia Belt: A record o f a back-arc basin in the Southern margin of the Rio de la Plata CratonLajoinie, María FlorenciaLanfranchini, Mabel ElenaEtcheverry, Ricardo OscarGeologíaciclo transamazónicoTandilia (Buenos Aires, Argentina)procesos metamórficosNew information obtained from the characterization of biotite gneises and migmatites from the San Miguel area allowed the interpretation of metamorphic processes that formed a portion of the Paleoproterozoic basement of the Tandilia Belt. Biotite gneiss shows a compositional Sj banding (N35°E/60°NW) and a mineral composition: microcline, (oligoclase-andesine), quartz and biotite. Migmatites occur as differentiated bodies with stromatic structure with Sj orientation and quartz, oligoclase, microcline leucosomes. Also almandine gamet appears in voluminous leucosomes. Chemical analyses indícate that the gneiss derived from a sedimentary protolith (wacke) while the migmatites would have formed from partial melting of the gneiss through decomposition of biotite in presence of quartz and plagioclase. This fact must have generated the gametiferous phase with potassic feldspar and a peraluminous granitic melt in imbalance: low ratio (La/Yb)N <55.85 and low Th and Zr contents. Migmatization must have started during the Transamazonian Cycle (~2200Ma) considering that most of the leucosomes are concordant with the banding gneiss orientation, formed during the mentioned Cycle. Thus, the pressure gradient favoured the migration and the intrusión of the melt (before to rebalance) into the gneiss and also in marbles generating metasomatism and skamification. This metamorphic evolution scheme matches with a tectonic context of back-arc basin associated with an oceanic-continental crust subduction that occu- rred during the Archaean-Paleoproterozoic period, and finished with the amalgamation of Tandilia Terrane to the Rio de la Plata Craton.Instituto de Recursos Minerales2017-08-07info:eu-repo/semantics/conferenceObjectinfo:eu-repo/semantics/publishedVersionObjeto de conferenciahttp://purl.org/coar/resource_type/c_5794info:ar-repo/semantics/documentoDeConferenciaapplication/pdf42-44http://sedici.unlp.edu.ar/handle/10915/73586spainfo:eu-repo/semantics/altIdentifier/hdl/11746/8096info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by-nc-nd/4.0/Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-09-03T10:44:34Zoai:sedici.unlp.edu.ar:10915/73586Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-03 10:44:34.522SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Basamento paleoproterozoico del área de San Miguel, Sierras Septentrionales de la provincia de Buenos Aires: registro de una cuenca de retroarco en el margen sur del cratón del río de la Plata
Paleoproterozoic basement at the San Miguel area, Tandilia Belt: A record o f a back-arc basin in the Southern margin of the Rio de la Plata Craton
title Basamento paleoproterozoico del área de San Miguel, Sierras Septentrionales de la provincia de Buenos Aires: registro de una cuenca de retroarco en el margen sur del cratón del río de la Plata
spellingShingle Basamento paleoproterozoico del área de San Miguel, Sierras Septentrionales de la provincia de Buenos Aires: registro de una cuenca de retroarco en el margen sur del cratón del río de la Plata
Lajoinie, María Florencia
Geología
ciclo transamazónico
Tandilia (Buenos Aires, Argentina)
procesos metamórficos
title_short Basamento paleoproterozoico del área de San Miguel, Sierras Septentrionales de la provincia de Buenos Aires: registro de una cuenca de retroarco en el margen sur del cratón del río de la Plata
title_full Basamento paleoproterozoico del área de San Miguel, Sierras Septentrionales de la provincia de Buenos Aires: registro de una cuenca de retroarco en el margen sur del cratón del río de la Plata
title_fullStr Basamento paleoproterozoico del área de San Miguel, Sierras Septentrionales de la provincia de Buenos Aires: registro de una cuenca de retroarco en el margen sur del cratón del río de la Plata
title_full_unstemmed Basamento paleoproterozoico del área de San Miguel, Sierras Septentrionales de la provincia de Buenos Aires: registro de una cuenca de retroarco en el margen sur del cratón del río de la Plata
title_sort Basamento paleoproterozoico del área de San Miguel, Sierras Septentrionales de la provincia de Buenos Aires: registro de una cuenca de retroarco en el margen sur del cratón del río de la Plata
dc.creator.none.fl_str_mv Lajoinie, María Florencia
Lanfranchini, Mabel Elena
Etcheverry, Ricardo Oscar
author Lajoinie, María Florencia
author_facet Lajoinie, María Florencia
Lanfranchini, Mabel Elena
Etcheverry, Ricardo Oscar
author_role author
author2 Lanfranchini, Mabel Elena
Etcheverry, Ricardo Oscar
author2_role author
author
dc.subject.none.fl_str_mv Geología
ciclo transamazónico
Tandilia (Buenos Aires, Argentina)
procesos metamórficos
topic Geología
ciclo transamazónico
Tandilia (Buenos Aires, Argentina)
procesos metamórficos
dc.description.none.fl_txt_mv New information obtained from the characterization of biotite gneises and migmatites from the San Miguel area allowed the interpretation of metamorphic processes that formed a portion of the Paleoproterozoic basement of the Tandilia Belt. Biotite gneiss shows a compositional Sj banding (N35°E/60°NW) and a mineral composition: microcline, (oligoclase-andesine), quartz and biotite. Migmatites occur as differentiated bodies with stromatic structure with Sj orientation and quartz, oligoclase, microcline leucosomes. Also almandine gamet appears in voluminous leucosomes. Chemical analyses indícate that the gneiss derived from a sedimentary protolith (wacke) while the migmatites would have formed from partial melting of the gneiss through decomposition of biotite in presence of quartz and plagioclase. This fact must have generated the gametiferous phase with potassic feldspar and a peraluminous granitic melt in imbalance: low ratio (La/Yb)N <55.85 and low Th and Zr contents. Migmatization must have started during the Transamazonian Cycle (~2200Ma) considering that most of the leucosomes are concordant with the banding gneiss orientation, formed during the mentioned Cycle. Thus, the pressure gradient favoured the migration and the intrusión of the melt (before to rebalance) into the gneiss and also in marbles generating metasomatism and skamification. This metamorphic evolution scheme matches with a tectonic context of back-arc basin associated with an oceanic-continental crust subduction that occu- rred during the Archaean-Paleoproterozoic period, and finished with the amalgamation of Tandilia Terrane to the Rio de la Plata Craton.
Instituto de Recursos Minerales
description New information obtained from the characterization of biotite gneises and migmatites from the San Miguel area allowed the interpretation of metamorphic processes that formed a portion of the Paleoproterozoic basement of the Tandilia Belt. Biotite gneiss shows a compositional Sj banding (N35°E/60°NW) and a mineral composition: microcline, (oligoclase-andesine), quartz and biotite. Migmatites occur as differentiated bodies with stromatic structure with Sj orientation and quartz, oligoclase, microcline leucosomes. Also almandine gamet appears in voluminous leucosomes. Chemical analyses indícate that the gneiss derived from a sedimentary protolith (wacke) while the migmatites would have formed from partial melting of the gneiss through decomposition of biotite in presence of quartz and plagioclase. This fact must have generated the gametiferous phase with potassic feldspar and a peraluminous granitic melt in imbalance: low ratio (La/Yb)N <55.85 and low Th and Zr contents. Migmatization must have started during the Transamazonian Cycle (~2200Ma) considering that most of the leucosomes are concordant with the banding gneiss orientation, formed during the mentioned Cycle. Thus, the pressure gradient favoured the migration and the intrusión of the melt (before to rebalance) into the gneiss and also in marbles generating metasomatism and skamification. This metamorphic evolution scheme matches with a tectonic context of back-arc basin associated with an oceanic-continental crust subduction that occu- rred during the Archaean-Paleoproterozoic period, and finished with the amalgamation of Tandilia Terrane to the Rio de la Plata Craton.
publishDate 2017
dc.date.none.fl_str_mv 2017-08-07
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rights_invalid_str_mv http://creativecommons.org/licenses/by-nc-nd/4.0/
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