P-T evolution of metapelites from the Guarguaraz Complex, Argentina: evidence for Devonian crustal thickening close to the western Gondwana margin

In the Guarguaraz Complex of the Argentine Frontal Cordillera (latitude 33.3°S) serpentinite lenses, metabasites, and garnet-bearing metasedimentary rocks occur. The corresponding Devonian metamorphic event was assigned to the formation of an accretionary wedge by previous authors. We have tested th...

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Autores principales:	Massonne,Hans-Joachim, Calderón,Mauricio
Lenguaje:	English
Publicado:	Servicio Nacional de Geología y Minería (SERNAGEOMIN) 2008
Materias:	Metapelite Garnet Phengite High-Pressure Metamorphism Argentine Frontal Cordillera Devonian
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-02082008000200002
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spelling	oai:scielo:S0716-020820080002000022009-06-09P-T evolution of metapelites from the Guarguaraz Complex, Argentina: evidence for Devonian crustal thickening close to the western Gondwana marginMassonne,Hans-JoachimCalderón,Mauricio Metapelite Garnet Phengite High-Pressure Metamorphism Argentine Frontal Cordillera Devonian In the Guarguaraz Complex of the Argentine Frontal Cordillera (latitude 33.3°S) serpentinite lenses, metabasites, and garnet-bearing metasedimentary rocks occur. The corresponding Devonian metamorphic event was assigned to the formation of an accretionary wedge by previous authors. We have tested this hypothesis by investigating the metamorphic evolution of a pelite from this complex. Garnet in this rock shows a well evolved prograde zoning. Potassic white mica with Si contents between 3.38 (core) and 3.12 (rim) per formula unit, biotite, quartz and plagioclase, which have formed late blasts at the expense of amphibole, coexist with this phase. On the basis of P-T pseudosections and water-absent equilibria, we have estimated the subsequent P-T path for the studied metapelite. The garnet core formed at about 8 kbar and 470-500°C. After nearly isothermal burial to 45 km (13.5 kbar) where Si-rich phengites grew, temperatures increased followed by exhumation and an overprint stage at 8 kbar and 565°C. This P-T path is not compatible with the idea of an accretionary wedge complex. It is more likely that the high-pressure conditions were attained by thickening of continental crust when the hypothetical Chilenia terrane collided with the continental margin of western Gondwana in Devonian times.info:eu-repo/semantics/openAccessServicio Nacional de Geología y Minería (SERNAGEOMIN)Revista geológica de Chile v.35 n.2 20082008-07-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-02082008000200002en10.4067/S0716-02082008000200002
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Metapelite Garnet Phengite High-Pressure Metamorphism Argentine Frontal Cordillera Devonian
spellingShingle	Metapelite Garnet Phengite High-Pressure Metamorphism Argentine Frontal Cordillera Devonian Massonne,Hans-Joachim Calderón,Mauricio P-T evolution of metapelites from the Guarguaraz Complex, Argentina: evidence for Devonian crustal thickening close to the western Gondwana margin
description	In the Guarguaraz Complex of the Argentine Frontal Cordillera (latitude 33.3°S) serpentinite lenses, metabasites, and garnet-bearing metasedimentary rocks occur. The corresponding Devonian metamorphic event was assigned to the formation of an accretionary wedge by previous authors. We have tested this hypothesis by investigating the metamorphic evolution of a pelite from this complex. Garnet in this rock shows a well evolved prograde zoning. Potassic white mica with Si contents between 3.38 (core) and 3.12 (rim) per formula unit, biotite, quartz and plagioclase, which have formed late blasts at the expense of amphibole, coexist with this phase. On the basis of P-T pseudosections and water-absent equilibria, we have estimated the subsequent P-T path for the studied metapelite. The garnet core formed at about 8 kbar and 470-500°C. After nearly isothermal burial to 45 km (13.5 kbar) where Si-rich phengites grew, temperatures increased followed by exhumation and an overprint stage at 8 kbar and 565°C. This P-T path is not compatible with the idea of an accretionary wedge complex. It is more likely that the high-pressure conditions were attained by thickening of continental crust when the hypothetical Chilenia terrane collided with the continental margin of western Gondwana in Devonian times.
author	Massonne,Hans-Joachim Calderón,Mauricio
author_facet	Massonne,Hans-Joachim Calderón,Mauricio
author_sort	Massonne,Hans-Joachim
title	P-T evolution of metapelites from the Guarguaraz Complex, Argentina: evidence for Devonian crustal thickening close to the western Gondwana margin
title_short	P-T evolution of metapelites from the Guarguaraz Complex, Argentina: evidence for Devonian crustal thickening close to the western Gondwana margin
title_full	P-T evolution of metapelites from the Guarguaraz Complex, Argentina: evidence for Devonian crustal thickening close to the western Gondwana margin
title_fullStr	P-T evolution of metapelites from the Guarguaraz Complex, Argentina: evidence for Devonian crustal thickening close to the western Gondwana margin
title_full_unstemmed	P-T evolution of metapelites from the Guarguaraz Complex, Argentina: evidence for Devonian crustal thickening close to the western Gondwana margin
title_sort	p-t evolution of metapelites from the guarguaraz complex, argentina: evidence for devonian crustal thickening close to the western gondwana margin
publisher	Servicio Nacional de Geología y Minería (SERNAGEOMIN)
publishDate	2008
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-02082008000200002
work_keys_str_mv	AT massonnehansjoachim ptevolutionofmetapelitesfromtheguarguarazcomplexargentinaevidencefordevoniancrustalthickeningclosetothewesterngondwanamargin AT calderonmauricio ptevolutionofmetapelitesfromtheguarguarazcomplexargentinaevidencefordevoniancrustalthickeningclosetothewesterngondwanamargin
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P-T evolution of metapelites from the Guarguaraz Complex, Argentina: evidence for Devonian crustal thickening close to the western Gondwana margin

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