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dc.contributor.author
Fortunatti, Natalia Beatriz
dc.contributor.author
Delpino, Sergio Hugo
dc.contributor.author
Dimieri, Luis Vicente
dc.date.available
2019-08-09T13:55:38Z
dc.date.issued
2001-12
dc.identifier.citation
Fortunatti, Natalia Beatriz; Delpino, Sergio Hugo; Dimieri, Luis Vicente; Análisis preliminar de la deformación interna en cuarcitas de la Formación Napostá, Grupo Ventana, Sierras Australes de Buenos Aires; Asociación Geológica Argentina; Revista de la Asociación Geológica Argentina. Serie D. Publicación especial; 5; 12-2001; 89-95
dc.identifier.issn
0328-2767
dc.identifier.uri
http://hdl.handle.net/11336/81301
dc.description.abstract
The Sierras Australes fold-and-thrust-belt is located southwest of the Buenos Aires province, Argentina. The chain is composed of a precambrian basement overlied by a middle to upper palaeozoic metasedimentary sequence, and surrounded by tertiary and quaternary deposits. A preliminary microestructural analysis was carried on rocks of the Napostá Formation (orthoquartzites, Ventana Group). A systematic sampling on a section located south to the Abra de la Ventana locality, was performed. Samples were collected in several positions within a key bed that shows the typical style of folding in the sierras: extended normal limbs (SW) and refolded short limbs (NE). The main observations are: 1) In function of the sample locations within the folded bed, the rock shows different rheologic behaviour: normal extended limbs are less deformed showing protomylonitic textures with preservation of a great proportion of relictic grains, scarce recrystallized matrix and neoformed sericite; intensely deformed refolded short limbs show mylonitic textures with flattened and strongly recrystallized relict grains, surrounded by a matrix composed of fine recrystallized quartz grains and sericite. Samples cióse to fold hinges, show more intense mylonitization than those of theneighbouring limbs; 2) Evidences of dynamic recrystallization, involving both grain boundary migration and subgrain rotation mechanisms, have been observed. Grain size reduction took place in a transition between régimen 2 and 3, in the temperature range 250° to 300°C. Presence of fluids during mylonitization is documented by textura] evidences of pressure solution and associated mass transfer mechanisms (straight quartz crystal faces parallel to foliation and new-crystallization of sericite-muscovite in folias and pressure shadows).
dc.format
application/pdf
dc.language.iso
spa
dc.publisher
Asociación Geológica Argentina
dc.rights
info:eu-repo/semantics/openAccess
dc.rights.uri
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.subject
Sierras Australes
dc.subject
Microestructuras
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Deformacion
dc.subject
Grupo Ventana
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Geología
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Ciencias de la Tierra y relacionadas con el Medio Ambiente
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CIENCIAS NATURALES Y EXACTAS
dc.title
Análisis preliminar de la deformación interna en cuarcitas de la Formación Napostá, Grupo Ventana, Sierras Australes de Buenos Aires
dc.title
Preliminary análisis of infernal deformation on Napostá Formation quartzites, Ventana Group, Sierras Australes of Buenos Aires
dc.type
info:eu-repo/semantics/article
dc.type
info:ar-repo/semantics/artículo
dc.type
info:eu-repo/semantics/publishedVersion
dc.date.updated
2019-06-03T14:25:51Z
dc.journal.number
5
dc.journal.pagination
89-95
dc.journal.pais
Argentina
dc.journal.ciudad
Buenos Aires
dc.description.fil
Fil: Fortunatti, Natalia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina
dc.description.fil
Fil: Delpino, Sergio Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina
dc.description.fil
Fil: Dimieri, Luis Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Geológico del Sur. Universidad Nacional del Sur. Departamento de Geología. Instituto Geológico del Sur; Argentina
dc.journal.title
Revista de la Asociación Geológica Argentina. Serie D. Publicación especial


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