The Mata Azul pegmatitic field, Tocantins/Goiás, central Brazil: geology, genesis and mineralization

Detalhes bibliográficos
Autor(a) principal: Queiroz,Hudson de Almeida
Data de Publicação: 2018
Outros Autores: Botelho,Nilson Francisquini
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Brazilian Journal of Geology
Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S2317-48892018000300435
Resumo: ABSTRACT: In Goiás and Tocantins States, Central Brazil, several granitic pegmatites were characterized and grouped for the first time. These pegmatites had been intensely explored by hand in the past, producing mainly gemstone varieties of tourmaline and beryl. Barren, beryl- and tourmaline-bearing pegmatites occur across an area of 2,000 km 2 where they intrude regional metasedimentary rocks and peraluminous granites. K-feldspar (mostly altered to kaolin), quartz and mica (mainly muscovite) are the major minerals. The main accessory minerals are beryl, tourmaline, garnet, albite, Fe-Mn phosphate aggregates, and trilithionite. The paragneiss surrounding the barren pegmatites was affected by thermal metamorphism and later hydrothermal alteration, producing Ca-silicates, Ti-Nb-Y oxides and sulfides. Leucogranites of the Mata Azul Suite are peraluminous and syn- to post-orogenic with geochemical characteristics of the LCT granite-pegmatite group. LA-ICP-MS U-Pb geochronology in monazite yields an age of 519 ± 2.8 Ma. ­Additionally, U-Th-Pb chemical dating of uraninite reveals a maximum age between 500 and 560 Ma. These ages, the field relationships, the mineralogy and the geochemical data suggest that the granites of the Mata Azul Suite are the probable sources of the studied pegmatites. The mineral associations and the mineral chemistry are used to define the degree of fractionation of the pegmatites. We propose that the group of studied pegmatites represents a pegmatitic field, called the Mata Azul Suite Pegmatitic Field.
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spelling The Mata Azul pegmatitic field, Tocantins/Goiás, central Brazil: geology, genesis and mineralizationPegmatitesMata Azul SuiteTocantinsLCT granite-pegmatite familyABSTRACT: In Goiás and Tocantins States, Central Brazil, several granitic pegmatites were characterized and grouped for the first time. These pegmatites had been intensely explored by hand in the past, producing mainly gemstone varieties of tourmaline and beryl. Barren, beryl- and tourmaline-bearing pegmatites occur across an area of 2,000 km 2 where they intrude regional metasedimentary rocks and peraluminous granites. K-feldspar (mostly altered to kaolin), quartz and mica (mainly muscovite) are the major minerals. The main accessory minerals are beryl, tourmaline, garnet, albite, Fe-Mn phosphate aggregates, and trilithionite. The paragneiss surrounding the barren pegmatites was affected by thermal metamorphism and later hydrothermal alteration, producing Ca-silicates, Ti-Nb-Y oxides and sulfides. Leucogranites of the Mata Azul Suite are peraluminous and syn- to post-orogenic with geochemical characteristics of the LCT granite-pegmatite group. LA-ICP-MS U-Pb geochronology in monazite yields an age of 519 ± 2.8 Ma. ­Additionally, U-Th-Pb chemical dating of uraninite reveals a maximum age between 500 and 560 Ma. These ages, the field relationships, the mineralogy and the geochemical data suggest that the granites of the Mata Azul Suite are the probable sources of the studied pegmatites. The mineral associations and the mineral chemistry are used to define the degree of fractionation of the pegmatites. We propose that the group of studied pegmatites represents a pegmatitic field, called the Mata Azul Suite Pegmatitic Field.Sociedade Brasileira de Geologia2018-07-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S2317-48892018000300435Brazilian Journal of Geology v.48 n.3 2018reponame:Brazilian Journal of Geologyinstname:Sociedade Brasileira de Geologia (SBGEO)instacron:SBGEO10.1590/2317-4889201820170048info:eu-repo/semantics/openAccessQueiroz,Hudson de AlmeidaBotelho,Nilson Francisquinieng2018-10-03T00:00:00Zoai:scielo:S2317-48892018000300435Revistahttp://bjg.siteoficial.ws/index.htmhttps://old.scielo.br/oai/scielo-oai.phpsbgsede@sbgeo.org.br||claudio.riccomini@gmail.com2317-46922317-4692opendoar:2018-10-03T00:00Brazilian Journal of Geology - Sociedade Brasileira de Geologia (SBGEO)false
dc.title.none.fl_str_mv The Mata Azul pegmatitic field, Tocantins/Goiás, central Brazil: geology, genesis and mineralization
title The Mata Azul pegmatitic field, Tocantins/Goiás, central Brazil: geology, genesis and mineralization
spellingShingle The Mata Azul pegmatitic field, Tocantins/Goiás, central Brazil: geology, genesis and mineralization
Queiroz,Hudson de Almeida
Pegmatites
Mata Azul Suite
Tocantins
LCT granite-pegmatite family
title_short The Mata Azul pegmatitic field, Tocantins/Goiás, central Brazil: geology, genesis and mineralization
title_full The Mata Azul pegmatitic field, Tocantins/Goiás, central Brazil: geology, genesis and mineralization
title_fullStr The Mata Azul pegmatitic field, Tocantins/Goiás, central Brazil: geology, genesis and mineralization
title_full_unstemmed The Mata Azul pegmatitic field, Tocantins/Goiás, central Brazil: geology, genesis and mineralization
title_sort The Mata Azul pegmatitic field, Tocantins/Goiás, central Brazil: geology, genesis and mineralization
author Queiroz,Hudson de Almeida
author_facet Queiroz,Hudson de Almeida
Botelho,Nilson Francisquini
author_role author
author2 Botelho,Nilson Francisquini
author2_role author
dc.contributor.author.fl_str_mv Queiroz,Hudson de Almeida
Botelho,Nilson Francisquini
dc.subject.por.fl_str_mv Pegmatites
Mata Azul Suite
Tocantins
LCT granite-pegmatite family
topic Pegmatites
Mata Azul Suite
Tocantins
LCT granite-pegmatite family
description ABSTRACT: In Goiás and Tocantins States, Central Brazil, several granitic pegmatites were characterized and grouped for the first time. These pegmatites had been intensely explored by hand in the past, producing mainly gemstone varieties of tourmaline and beryl. Barren, beryl- and tourmaline-bearing pegmatites occur across an area of 2,000 km 2 where they intrude regional metasedimentary rocks and peraluminous granites. K-feldspar (mostly altered to kaolin), quartz and mica (mainly muscovite) are the major minerals. The main accessory minerals are beryl, tourmaline, garnet, albite, Fe-Mn phosphate aggregates, and trilithionite. The paragneiss surrounding the barren pegmatites was affected by thermal metamorphism and later hydrothermal alteration, producing Ca-silicates, Ti-Nb-Y oxides and sulfides. Leucogranites of the Mata Azul Suite are peraluminous and syn- to post-orogenic with geochemical characteristics of the LCT granite-pegmatite group. LA-ICP-MS U-Pb geochronology in monazite yields an age of 519 ± 2.8 Ma. ­Additionally, U-Th-Pb chemical dating of uraninite reveals a maximum age between 500 and 560 Ma. These ages, the field relationships, the mineralogy and the geochemical data suggest that the granites of the Mata Azul Suite are the probable sources of the studied pegmatites. The mineral associations and the mineral chemistry are used to define the degree of fractionation of the pegmatites. We propose that the group of studied pegmatites represents a pegmatitic field, called the Mata Azul Suite Pegmatitic Field.
publishDate 2018
dc.date.none.fl_str_mv 2018-07-01
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
format article
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dc.identifier.uri.fl_str_mv http://old.scielo.br/scielo.php?script=sci_arttext&pid=S2317-48892018000300435
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dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv 10.1590/2317-4889201820170048
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 Sociedade Brasileira de Geologia
publisher.none.fl_str_mv Sociedade Brasileira de Geologia
dc.source.none.fl_str_mv Brazilian Journal of Geology v.48 n.3 2018
reponame:Brazilian Journal of Geology
instname:Sociedade Brasileira de Geologia (SBGEO)
instacron:SBGEO
instname_str Sociedade Brasileira de Geologia (SBGEO)
instacron_str SBGEO
institution SBGEO
reponame_str Brazilian Journal of Geology
collection Brazilian Journal of Geology
repository.name.fl_str_mv Brazilian Journal of Geology - Sociedade Brasileira de Geologia (SBGEO)
repository.mail.fl_str_mv sbgsede@sbgeo.org.br||claudio.riccomini@gmail.com
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