The Ilha Anchieta Quartz Monzonite: the southernmost expression of ca. 500 Ma post-collisional magmatism in the Ribeira Belt

Detalhes bibliográficos
Autor(a) principal: Sobrinho,José M. Azevedo
Data de Publicação: 2011
Outros Autores: Janas,Valdecir A., Simonetti,Antonio, Heaman,Larry M., santoro,Jair, Diniz,Hélio N.
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Anais da Academia Brasileira de Ciências (Online)
Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652011000300010
Resumo: The Ilha Anchieta Quartz Monzonite (IAQM) occupies most of the homonymous island in the coast of the state of São Paulo, and is intrusive into foliated rocks of the ~565 Ma Ubatuba Charnockite. The main petrographic variety is a porphyritic biotite-hornblende quartz monzonite with 2-4 cm tabular microcline megacrysts set in a medium-grained groundmass and magmatic foliation. Outcrop-scale structures indicate cumulative processes (modal and grain-size magmatic banding) and interaction with basic magmas (mafic microgranular enclaves). Lithogeochemical data indicates that the main variety is intermediate to acid (S1O2 = 63-67%), alkali-calcic, metaluminous and magnesian (mg# ~30), showing moderate Sr (300-400 ppm) and Ba (~1500 ppm) contents and relatively high HFSE (Nb = 40 ppm; Zr = 550-700 ppm). The older charnockites are more silicic (S1O2 = 71-78%), ferroan(mg# = 12-16), and have very low Sr (13-80 ppm) contents, resulting in Ba/Sr ratios remarkably higher than the IAQM (10 versus 4). LA-MC-ICPMS U-Pb zircon dating of the IAQM yielded 499.7 ± 5.9 Ma. This is the youngest magmatic age identified so far in the crystalline basement of the state of São Paulo, and indicates that the pluton is the southernmost expression of the post-collisional "G5" magmatism in the Ribeira Belt.
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spelling The Ilha Anchieta Quartz Monzonite: the southernmost expression of ca. 500 Ma post-collisional magmatism in the Ribeira BeltgranitelithogeochemistryLA-ICPMSzircon U-Pb datingRibeira BeltThe Ilha Anchieta Quartz Monzonite (IAQM) occupies most of the homonymous island in the coast of the state of São Paulo, and is intrusive into foliated rocks of the ~565 Ma Ubatuba Charnockite. The main petrographic variety is a porphyritic biotite-hornblende quartz monzonite with 2-4 cm tabular microcline megacrysts set in a medium-grained groundmass and magmatic foliation. Outcrop-scale structures indicate cumulative processes (modal and grain-size magmatic banding) and interaction with basic magmas (mafic microgranular enclaves). Lithogeochemical data indicates that the main variety is intermediate to acid (S1O2 = 63-67%), alkali-calcic, metaluminous and magnesian (mg# ~30), showing moderate Sr (300-400 ppm) and Ba (~1500 ppm) contents and relatively high HFSE (Nb = 40 ppm; Zr = 550-700 ppm). The older charnockites are more silicic (S1O2 = 71-78%), ferroan(mg# = 12-16), and have very low Sr (13-80 ppm) contents, resulting in Ba/Sr ratios remarkably higher than the IAQM (10 versus 4). LA-MC-ICPMS U-Pb zircon dating of the IAQM yielded 499.7 ± 5.9 Ma. This is the youngest magmatic age identified so far in the crystalline basement of the state of São Paulo, and indicates that the pluton is the southernmost expression of the post-collisional "G5" magmatism in the Ribeira Belt.Academia Brasileira de Ciências2011-09-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652011000300010Anais da Academia Brasileira de Ciências v.83 n.3 2011reponame:Anais da Academia Brasileira de Ciências (Online)instname:Academia Brasileira de Ciências (ABC)instacron:ABC10.1590/S0001-37652011000300010info:eu-repo/semantics/openAccessSobrinho,José M. AzevedoJanas,Valdecir A.Simonetti,AntonioHeaman,Larry M.santoro,JairDiniz,Hélio N.eng2011-08-15T00:00:00Zoai:scielo:S0001-37652011000300010Revistahttp://www.scielo.br/aabchttps://old.scielo.br/oai/scielo-oai.php||aabc@abc.org.br1678-26900001-3765opendoar:2011-08-15T00:00Anais da Academia Brasileira de Ciências (Online) - Academia Brasileira de Ciências (ABC)false
dc.title.none.fl_str_mv The Ilha Anchieta Quartz Monzonite: the southernmost expression of ca. 500 Ma post-collisional magmatism in the Ribeira Belt
title The Ilha Anchieta Quartz Monzonite: the southernmost expression of ca. 500 Ma post-collisional magmatism in the Ribeira Belt
spellingShingle The Ilha Anchieta Quartz Monzonite: the southernmost expression of ca. 500 Ma post-collisional magmatism in the Ribeira Belt
Sobrinho,José M. Azevedo
granite
lithogeochemistry
LA-ICPMS
zircon U-Pb dating
Ribeira Belt
title_short The Ilha Anchieta Quartz Monzonite: the southernmost expression of ca. 500 Ma post-collisional magmatism in the Ribeira Belt
title_full The Ilha Anchieta Quartz Monzonite: the southernmost expression of ca. 500 Ma post-collisional magmatism in the Ribeira Belt
title_fullStr The Ilha Anchieta Quartz Monzonite: the southernmost expression of ca. 500 Ma post-collisional magmatism in the Ribeira Belt
title_full_unstemmed The Ilha Anchieta Quartz Monzonite: the southernmost expression of ca. 500 Ma post-collisional magmatism in the Ribeira Belt
title_sort The Ilha Anchieta Quartz Monzonite: the southernmost expression of ca. 500 Ma post-collisional magmatism in the Ribeira Belt
author Sobrinho,José M. Azevedo
author_facet Sobrinho,José M. Azevedo
Janas,Valdecir A.
Simonetti,Antonio
Heaman,Larry M.
santoro,Jair
Diniz,Hélio N.
author_role author
author2 Janas,Valdecir A.
Simonetti,Antonio
Heaman,Larry M.
santoro,Jair
Diniz,Hélio N.
author2_role author
author
author
author
author
dc.contributor.author.fl_str_mv Sobrinho,José M. Azevedo
Janas,Valdecir A.
Simonetti,Antonio
Heaman,Larry M.
santoro,Jair
Diniz,Hélio N.
dc.subject.por.fl_str_mv granite
lithogeochemistry
LA-ICPMS
zircon U-Pb dating
Ribeira Belt
topic granite
lithogeochemistry
LA-ICPMS
zircon U-Pb dating
Ribeira Belt
description The Ilha Anchieta Quartz Monzonite (IAQM) occupies most of the homonymous island in the coast of the state of São Paulo, and is intrusive into foliated rocks of the ~565 Ma Ubatuba Charnockite. The main petrographic variety is a porphyritic biotite-hornblende quartz monzonite with 2-4 cm tabular microcline megacrysts set in a medium-grained groundmass and magmatic foliation. Outcrop-scale structures indicate cumulative processes (modal and grain-size magmatic banding) and interaction with basic magmas (mafic microgranular enclaves). Lithogeochemical data indicates that the main variety is intermediate to acid (S1O2 = 63-67%), alkali-calcic, metaluminous and magnesian (mg# ~30), showing moderate Sr (300-400 ppm) and Ba (~1500 ppm) contents and relatively high HFSE (Nb = 40 ppm; Zr = 550-700 ppm). The older charnockites are more silicic (S1O2 = 71-78%), ferroan(mg# = 12-16), and have very low Sr (13-80 ppm) contents, resulting in Ba/Sr ratios remarkably higher than the IAQM (10 versus 4). LA-MC-ICPMS U-Pb zircon dating of the IAQM yielded 499.7 ± 5.9 Ma. This is the youngest magmatic age identified so far in the crystalline basement of the state of São Paulo, and indicates that the pluton is the southernmost expression of the post-collisional "G5" magmatism in the Ribeira Belt.
publishDate 2011
dc.date.none.fl_str_mv 2011-09-01
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
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status_str publishedVersion
dc.identifier.uri.fl_str_mv http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652011000300010
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dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv 10.1590/S0001-37652011000300010
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv text/html
dc.publisher.none.fl_str_mv Academia Brasileira de Ciências
publisher.none.fl_str_mv Academia Brasileira de Ciências
dc.source.none.fl_str_mv Anais da Academia Brasileira de Ciências v.83 n.3 2011
reponame:Anais da Academia Brasileira de Ciências (Online)
instname:Academia Brasileira de Ciências (ABC)
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instname_str Academia Brasileira de Ciências (ABC)
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reponame_str Anais da Academia Brasileira de Ciências (Online)
collection Anais da Academia Brasileira de Ciências (Online)
repository.name.fl_str_mv Anais da Academia Brasileira de Ciências (Online) - Academia Brasileira de Ciências (ABC)
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