Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, A...

Autores
Anzil, Patricia Andrea; Guereschi, Alina Beatriz; Martino, Roberto Donato
Año de publicación
2012
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
The La Cocha ultramafic body, in the Sierra Chica of Córdoba (Sierras Pampeanas, Argentina), is formed by serpentinized spinel harzburgites, with lenses of spinel pyroxenites and hornblendites. The associated metamorphic rocks are garnet sillimanite gneisses, intercalated with tabular bodies of pyroxene amphibolites and forsterite marbles.Mineral chemistry of relict primary phases (olivine, orthopyroxene and spinel) from samples of the spinel harzburgites and pyroxenites was determined, and several geothermometers were applied to estimate the temperature conditions under which these rocks may have been equilibrated.In the spinel harzburgites, the primary spinel is Al-chromite [Cr# = Cr/(Cr + Al) = 0.48-0.57], which is replaced by ferrichromite and chlinoclore by metamorphism. Orthopyroxene is enstatite (En92) and olivine is classified as forsterite (Fo92); this last one shows a homogeneous and constant composition along the ultramafic body. Using geothermometric calibrations of the pair olivine-spinel, the highest temperature of 1157 °C would correspond to the primary conditions of formation of the harzburgites.The spinel pyroxenites show a mineral composition defined by orthopyroxene (En85, enstatite), olivine (Fo86, chrysolite), spinel (s. s.) and magnetite. Serpentine and clinochlore were produced by metamorphism. Spinel has high concentrations in Al and very low in Cr, and is classified as spinel sensu stricto; magnetite replacement was produced by metamorphism. Orthopyroxene and olivine are depleted in MgO regarding these minerals in the harzburgites. Temperatures of 785-734 °C calculated using geothermometers with orthopyroxene are interpreted to be produced by metamorphism in amphibolite to granulite facies conditions.Cumular textures were not observed in outcrops and thin sections of the studied rocks. The narrow composicional range and high forsterite content in olivine, the high Cr# in spinel, and the low concentrations of Ni and Cr in whole rock analyses indicate a mantle residual origin for these peridotites, which would exclude a cumular origin.The association of peridotites with mafic bodies formed in an N-type MORB environment and a relict mantle fabric showed by the elongated crystals/aggregates of olivine (preserved in pseudomorphic replacements), indicating a high temperature flow, allow to interpret the La Cocha ultramafic body as a slice of oceanic mantle, belonging to basal tectonites of an ophiolite complex. This body shows similar petrological, geochemical and structural features than the other ultramafic bodies in the Sierras de Córdoba, therefore the origin proposed here could be applied to the other bodies.
Fil: Anzil, Patricia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina
Fil: Guereschi, Alina Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina
Fil: Martino, Roberto Donato. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina
Materia
Argentina
Geothermometry
Mineral Chemistry
Sierras Pampeanas
Ultramafic Rocks
Upper Mantle
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
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CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
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oai:ri.conicet.gov.ar:11336/52356
Acceder
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oai_identifier_str oai:ri.conicet.gov.ar:11336/52356
network_acronym_str CONICETDig
repository_id_str 3498
network_name_str CONICET Digital (CONICET)
spelling Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, ArgentinaAnzil, Patricia AndreaGuereschi, Alina BeatrizMartino, Roberto DonatoArgentinaGeothermometryMineral ChemistrySierras PampeanasUltramafic RocksUpper Mantlehttps://purl.org/becyt/ford/1.5https://purl.org/becyt/ford/1The La Cocha ultramafic body, in the Sierra Chica of Córdoba (Sierras Pampeanas, Argentina), is formed by serpentinized spinel harzburgites, with lenses of spinel pyroxenites and hornblendites. The associated metamorphic rocks are garnet sillimanite gneisses, intercalated with tabular bodies of pyroxene amphibolites and forsterite marbles.Mineral chemistry of relict primary phases (olivine, orthopyroxene and spinel) from samples of the spinel harzburgites and pyroxenites was determined, and several geothermometers were applied to estimate the temperature conditions under which these rocks may have been equilibrated.In the spinel harzburgites, the primary spinel is Al-chromite [Cr# = Cr/(Cr + Al) = 0.48-0.57], which is replaced by ferrichromite and chlinoclore by metamorphism. Orthopyroxene is enstatite (En92) and olivine is classified as forsterite (Fo92); this last one shows a homogeneous and constant composition along the ultramafic body. Using geothermometric calibrations of the pair olivine-spinel, the highest temperature of 1157 °C would correspond to the primary conditions of formation of the harzburgites.The spinel pyroxenites show a mineral composition defined by orthopyroxene (En85, enstatite), olivine (Fo86, chrysolite), spinel (s. s.) and magnetite. Serpentine and clinochlore were produced by metamorphism. Spinel has high concentrations in Al and very low in Cr, and is classified as spinel sensu stricto; magnetite replacement was produced by metamorphism. Orthopyroxene and olivine are depleted in MgO regarding these minerals in the harzburgites. Temperatures of 785-734 °C calculated using geothermometers with orthopyroxene are interpreted to be produced by metamorphism in amphibolite to granulite facies conditions.Cumular textures were not observed in outcrops and thin sections of the studied rocks. The narrow composicional range and high forsterite content in olivine, the high Cr# in spinel, and the low concentrations of Ni and Cr in whole rock analyses indicate a mantle residual origin for these peridotites, which would exclude a cumular origin.The association of peridotites with mafic bodies formed in an N-type MORB environment and a relict mantle fabric showed by the elongated crystals/aggregates of olivine (preserved in pseudomorphic replacements), indicating a high temperature flow, allow to interpret the La Cocha ultramafic body as a slice of oceanic mantle, belonging to basal tectonites of an ophiolite complex. This body shows similar petrological, geochemical and structural features than the other ultramafic bodies in the Sierras de Córdoba, therefore the origin proposed here could be applied to the other bodies.Fil: Anzil, Patricia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Guereschi, Alina Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Martino, Roberto Donato. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaPergamon-Elsevier Science Ltd2012-12info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/52356Anzil, Patricia Andrea; Guereschi, Alina Beatriz; Martino, Roberto Donato; Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, Argentina; Pergamon-Elsevier Science Ltd; Journal of South American Earth Sciences; 40; 12-2012; 38-520895-9811CONICET DigitalCONICETenginfo:eu-repo/semantics/altIdentifier/url/https://www.sciencedirect.com/science/article/pii/S089598111200137Xinfo:eu-repo/semantics/altIdentifier/doi/10.1016/j.jsames.2012.09.009info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-29T10:13:36Zoai:ri.conicet.gov.ar:11336/52356instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-09-29 10:13:37.078CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, Argentina
title Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, Argentina
spellingShingle Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, Argentina
Anzil, Patricia Andrea
Argentina
Geothermometry
Mineral Chemistry
Sierras Pampeanas
Ultramafic Rocks
Upper Mantle
title_short Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, Argentina
title_full Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, Argentina
title_fullStr Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, Argentina
title_full_unstemmed Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, Argentina
title_sort Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, Argentina
dc.creator.none.fl_str_mv Anzil, Patricia Andrea
Guereschi, Alina Beatriz
Martino, Roberto Donato
author Anzil, Patricia Andrea
author_facet Anzil, Patricia Andrea
Guereschi, Alina Beatriz
Martino, Roberto Donato
author_role author
author2 Guereschi, Alina Beatriz
Martino, Roberto Donato
author2_role author
author
dc.subject.none.fl_str_mv Argentina
Geothermometry
Mineral Chemistry
Sierras Pampeanas
Ultramafic Rocks
Upper Mantle
topic Argentina
Geothermometry
Mineral Chemistry
Sierras Pampeanas
Ultramafic Rocks
Upper Mantle
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.5
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv The La Cocha ultramafic body, in the Sierra Chica of Córdoba (Sierras Pampeanas, Argentina), is formed by serpentinized spinel harzburgites, with lenses of spinel pyroxenites and hornblendites. The associated metamorphic rocks are garnet sillimanite gneisses, intercalated with tabular bodies of pyroxene amphibolites and forsterite marbles.Mineral chemistry of relict primary phases (olivine, orthopyroxene and spinel) from samples of the spinel harzburgites and pyroxenites was determined, and several geothermometers were applied to estimate the temperature conditions under which these rocks may have been equilibrated.In the spinel harzburgites, the primary spinel is Al-chromite [Cr# = Cr/(Cr + Al) = 0.48-0.57], which is replaced by ferrichromite and chlinoclore by metamorphism. Orthopyroxene is enstatite (En92) and olivine is classified as forsterite (Fo92); this last one shows a homogeneous and constant composition along the ultramafic body. Using geothermometric calibrations of the pair olivine-spinel, the highest temperature of 1157 °C would correspond to the primary conditions of formation of the harzburgites.The spinel pyroxenites show a mineral composition defined by orthopyroxene (En85, enstatite), olivine (Fo86, chrysolite), spinel (s. s.) and magnetite. Serpentine and clinochlore were produced by metamorphism. Spinel has high concentrations in Al and very low in Cr, and is classified as spinel sensu stricto; magnetite replacement was produced by metamorphism. Orthopyroxene and olivine are depleted in MgO regarding these minerals in the harzburgites. Temperatures of 785-734 °C calculated using geothermometers with orthopyroxene are interpreted to be produced by metamorphism in amphibolite to granulite facies conditions.Cumular textures were not observed in outcrops and thin sections of the studied rocks. The narrow composicional range and high forsterite content in olivine, the high Cr# in spinel, and the low concentrations of Ni and Cr in whole rock analyses indicate a mantle residual origin for these peridotites, which would exclude a cumular origin.The association of peridotites with mafic bodies formed in an N-type MORB environment and a relict mantle fabric showed by the elongated crystals/aggregates of olivine (preserved in pseudomorphic replacements), indicating a high temperature flow, allow to interpret the La Cocha ultramafic body as a slice of oceanic mantle, belonging to basal tectonites of an ophiolite complex. This body shows similar petrological, geochemical and structural features than the other ultramafic bodies in the Sierras de Córdoba, therefore the origin proposed here could be applied to the other bodies.
Fil: Anzil, Patricia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina
Fil: Guereschi, Alina Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina
Fil: Martino, Roberto Donato. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina
description The La Cocha ultramafic body, in the Sierra Chica of Córdoba (Sierras Pampeanas, Argentina), is formed by serpentinized spinel harzburgites, with lenses of spinel pyroxenites and hornblendites. The associated metamorphic rocks are garnet sillimanite gneisses, intercalated with tabular bodies of pyroxene amphibolites and forsterite marbles.Mineral chemistry of relict primary phases (olivine, orthopyroxene and spinel) from samples of the spinel harzburgites and pyroxenites was determined, and several geothermometers were applied to estimate the temperature conditions under which these rocks may have been equilibrated.In the spinel harzburgites, the primary spinel is Al-chromite [Cr# = Cr/(Cr + Al) = 0.48-0.57], which is replaced by ferrichromite and chlinoclore by metamorphism. Orthopyroxene is enstatite (En92) and olivine is classified as forsterite (Fo92); this last one shows a homogeneous and constant composition along the ultramafic body. Using geothermometric calibrations of the pair olivine-spinel, the highest temperature of 1157 °C would correspond to the primary conditions of formation of the harzburgites.The spinel pyroxenites show a mineral composition defined by orthopyroxene (En85, enstatite), olivine (Fo86, chrysolite), spinel (s. s.) and magnetite. Serpentine and clinochlore were produced by metamorphism. Spinel has high concentrations in Al and very low in Cr, and is classified as spinel sensu stricto; magnetite replacement was produced by metamorphism. Orthopyroxene and olivine are depleted in MgO regarding these minerals in the harzburgites. Temperatures of 785-734 °C calculated using geothermometers with orthopyroxene are interpreted to be produced by metamorphism in amphibolite to granulite facies conditions.Cumular textures were not observed in outcrops and thin sections of the studied rocks. The narrow composicional range and high forsterite content in olivine, the high Cr# in spinel, and the low concentrations of Ni and Cr in whole rock analyses indicate a mantle residual origin for these peridotites, which would exclude a cumular origin.The association of peridotites with mafic bodies formed in an N-type MORB environment and a relict mantle fabric showed by the elongated crystals/aggregates of olivine (preserved in pseudomorphic replacements), indicating a high temperature flow, allow to interpret the La Cocha ultramafic body as a slice of oceanic mantle, belonging to basal tectonites of an ophiolite complex. This body shows similar petrological, geochemical and structural features than the other ultramafic bodies in the Sierras de Córdoba, therefore the origin proposed here could be applied to the other bodies.
publishDate 2012
dc.date.none.fl_str_mv 2012-12
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/52356
Anzil, Patricia Andrea; Guereschi, Alina Beatriz; Martino, Roberto Donato; Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, Argentina; Pergamon-Elsevier Science Ltd; Journal of South American Earth Sciences; 40; 12-2012; 38-52
0895-9811
CONICET Digital
CONICET
url http://hdl.handle.net/11336/52356
identifier_str_mv Anzil, Patricia Andrea; Guereschi, Alina Beatriz; Martino, Roberto Donato; Mineral chemistry and geothermometry using relict primary minerals in the La Cocha ultramafic body: A slice of the upper mantle in the Sierra Chica of Córdoba, Sierras Pampeanas, Argentina; Pergamon-Elsevier Science Ltd; Journal of South American Earth Sciences; 40; 12-2012; 38-52
0895-9811
CONICET Digital
CONICET
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/url/https://www.sciencedirect.com/science/article/pii/S089598111200137X
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.jsames.2012.09.009
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.format.none.fl_str_mv application/pdf
application/pdf
application/pdf
dc.publisher.none.fl_str_mv Pergamon-Elsevier Science Ltd
publisher.none.fl_str_mv Pergamon-Elsevier Science Ltd
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
collection CONICET Digital (CONICET)
instname_str Consejo Nacional de Investigaciones Científicas y Técnicas
repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
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score 13.070432

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