Magmatic evolution of the Peñón Rosado granite: Petrogenesis of garnet-bearing granitoids

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dc.contributor.authorDahlquist, Juan A.
dc.contributor.authorGalindo Francisco, María Del Carmen
dc.contributor.authorPankhurst, R.J.
dc.contributor.authorRapela, Carlos W.
dc.contributor.authorAlasino, Pablo H.
dc.contributor.authorSaavedra, Julio
dc.contributor.authorFanning, C.M.
dc.date.accessioned2023-06-20T16:47:07Z
dc.date.available2023-06-20T16:47:07Z
dc.date.issued1995
dc.description.abstractGarnet is an uncommon accessory mineral in igneous rocks but is petrologically significant. The Peñón Rosado granite (469± 4Ma) at Cerro Asperecito is an S-type granite that contains an unusual amount of magmatic garnet. Combined petrology, chemistry/ mineralogy and whole-rock geochemistry indicates that the magma was produced by partial melting of the surrounding metasedimentary rocks and subsequent differentiation by fractional crystallization during emplacement, with garnet occurring throughout the crystallization sequence. Three facies are recognised: PRG1 (SiO2=65.70%) represents cumulates, PRG2 (SiO2=70.88%) represents a differentiated melt, and PRG3 (SiO2=74.59%) a residual melt. The fractionation of Mn in garnet and the proportion of garnet crystallizing are roughly controlled by the evolving composition of the different granitic facies.Geothermobaric calculations reveal an initial crystallization temperature of 764°–792 °Cand a pressure of 5.9–6.0 kb, indicating that the parental magma was emplaced atmiddle crustal depths (∼1920 km) in moderate–low magmatic temperature conditions.Major (CaO, Na2O,K2O) and trace element (Rb, Sr, Ba) contents in the Peñón Rosado granite strongly suggest anatexis was the outcome of H2O-fluxed melting of metagreywacke, with heat input from a major metaluminous suite. Our studies reveal that garnet formed by direct crystallization from peraluminous magma in equilibrium with solid phases such as biotite and white mica.We confirm previous suggestions that zoning in garnet is strongly temperature-dependent. Thus, magmatic garnets in granitic rocks crystallized above ∼ 700 °C have “spessartine inverse bell-shaped profile” or are unzoned, whereas garnet exhibiting “spessartine bell-shaped profile” must be considered of metamorphic origin (i.e., xenocrystic) or formed in very felsic magmas (SiO2=73–76%) crystallizing below ∼ 700 °C. © 2006 Elsevier B.V. All rights reserved.
dc.description.departmentDepto. de Mineralogía y Petrología
dc.description.facultyFac. de Ciencias Geológicas
dc.description.refereedTRUE
dc.description.statuspub
dc.eprint.idhttps://eprints.ucm.es/id/eprint/12023
dc.identifier.doi10.1016/j.lithos.2006.07.010
dc.identifier.issn0024-4937
dc.identifier.officialurlhttp://www.elsevier.com/locate/lithos
dc.identifier.urihttps://hdl.handle.net/20.500.14352/56987
dc.journal.titleLithos
dc.language.isoeng
dc.page.final207
dc.page.initial177
dc.publisherElsevier Science B.V., Amsterdam
dc.rights.accessRightsopen access
dc.subject.cdu552.3
dc.subject.keywordS-type granite
dc.subject.keywordPartial melting
dc.subject.keywordFractional crystallization
dc.subject.keywordGarnet zoning
dc.subject.ucmPetrología
dc.titleMagmatic evolution of the Peñón Rosado granite: Petrogenesis of garnet-bearing granitoids
dc.typejournal article
dc.volume.number95
dspace.entity.typePublication
relation.isAuthorOfPublicationf2fb71b6-b7fd-4fc6-bf39-d4de3ba5a67c
relation.isAuthorOfPublication.latestForDiscoveryf2fb71b6-b7fd-4fc6-bf39-d4de3ba5a67c
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