Geochemical and reflectance spectroscopy data integration to characterize emerald deposits: the case of the Paraná deposit, Brazil
Autor(a) principal: | |
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Data de Publicação: | 2021 |
Outros Autores: | , , , |
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=S0001-37652021000101218 |
Resumo: | Abstract The Paraná emerald deposit is one of the few occurrences of emerald, a rare beryl variety, in Borborema Province, northeastern Brazil. We characterized the Paraná deposit by combining field geology, petrography, whole-rock geochemistry, mineral chemistry, and reflectance spectroscopy. The mineralization is associated with phlogopite-, actinolite-phlogopite-, and phlogopite-phengite schists, mylonitic gneisses, and several acidic rocks (e.g. granitic pegmatites/aplites, quartz ± feldspar veins) along the Portalegre Shear Zone. Emerald can be found in quartz-feldspar and aplite veins and veinlets interleaved with phlogopite- or actinolite-phlogopite schists, or within the foliation of the schists. The presence of albitites and the compositional variation of the schists suggest a metasomatic origin for emerald with variations of the metasomatic process. All these different lithotypes can be readily identified through reflectance spectroscopy especially in the range of 2,150-2,450 nm, where the main mafic minerals show absorption features related to Al-OH (phengite), and Fe-OH and Mg-OH bonds (phlogopite/actinolite). Our study shows that possible mineralized phlogopite schists can be distinguished from other sterile rocks, although point spectral analysis does not separate emerald-bearing phlogopite schists from schists without emerald due to the dominance of major phlogopite absorption features rather than emerald features. |
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Geochemical and reflectance spectroscopy data integration to characterize emerald deposits: the case of the Paraná deposit, BrazilGeochemistrymineral chemistryParaná emerald depositpetrographyreflectance spectroscopyAbstract The Paraná emerald deposit is one of the few occurrences of emerald, a rare beryl variety, in Borborema Province, northeastern Brazil. We characterized the Paraná deposit by combining field geology, petrography, whole-rock geochemistry, mineral chemistry, and reflectance spectroscopy. The mineralization is associated with phlogopite-, actinolite-phlogopite-, and phlogopite-phengite schists, mylonitic gneisses, and several acidic rocks (e.g. granitic pegmatites/aplites, quartz ± feldspar veins) along the Portalegre Shear Zone. Emerald can be found in quartz-feldspar and aplite veins and veinlets interleaved with phlogopite- or actinolite-phlogopite schists, or within the foliation of the schists. The presence of albitites and the compositional variation of the schists suggest a metasomatic origin for emerald with variations of the metasomatic process. All these different lithotypes can be readily identified through reflectance spectroscopy especially in the range of 2,150-2,450 nm, where the main mafic minerals show absorption features related to Al-OH (phengite), and Fe-OH and Mg-OH bonds (phlogopite/actinolite). Our study shows that possible mineralized phlogopite schists can be distinguished from other sterile rocks, although point spectral analysis does not separate emerald-bearing phlogopite schists from schists without emerald due to the dominance of major phlogopite absorption features rather than emerald features.Academia Brasileira de Ciências2021-01-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652021000101218Anais da Academia Brasileira de Ciências v.93 n.1 2021reponame:Anais da Academia Brasileira de Ciências (Online)instname:Academia Brasileira de Ciências (ABC)instacron:ABC10.1590/0001-3765202120200236info:eu-repo/semantics/openAccessARAÚJO NETO,JOSÉ F.BARRETO,SANDRA B.CARRINO,THAIS A.SOUZA,IGOR M.B.A.SANTOS,GLENDA L.eng2021-03-22T00:00:00Zoai:scielo:S0001-37652021000101218Revistahttp://www.scielo.br/aabchttps://old.scielo.br/oai/scielo-oai.php||aabc@abc.org.br1678-26900001-3765opendoar:2021-03-22T00:00Anais da Academia Brasileira de Ciências (Online) - Academia Brasileira de Ciências (ABC)false |
dc.title.none.fl_str_mv |
Geochemical and reflectance spectroscopy data integration to characterize emerald deposits: the case of the Paraná deposit, Brazil |
title |
Geochemical and reflectance spectroscopy data integration to characterize emerald deposits: the case of the Paraná deposit, Brazil |
spellingShingle |
Geochemical and reflectance spectroscopy data integration to characterize emerald deposits: the case of the Paraná deposit, Brazil ARAÚJO NETO,JOSÉ F. Geochemistry mineral chemistry Paraná emerald deposit petrography reflectance spectroscopy |
title_short |
Geochemical and reflectance spectroscopy data integration to characterize emerald deposits: the case of the Paraná deposit, Brazil |
title_full |
Geochemical and reflectance spectroscopy data integration to characterize emerald deposits: the case of the Paraná deposit, Brazil |
title_fullStr |
Geochemical and reflectance spectroscopy data integration to characterize emerald deposits: the case of the Paraná deposit, Brazil |
title_full_unstemmed |
Geochemical and reflectance spectroscopy data integration to characterize emerald deposits: the case of the Paraná deposit, Brazil |
title_sort |
Geochemical and reflectance spectroscopy data integration to characterize emerald deposits: the case of the Paraná deposit, Brazil |
author |
ARAÚJO NETO,JOSÉ F. |
author_facet |
ARAÚJO NETO,JOSÉ F. BARRETO,SANDRA B. CARRINO,THAIS A. SOUZA,IGOR M.B.A. SANTOS,GLENDA L. |
author_role |
author |
author2 |
BARRETO,SANDRA B. CARRINO,THAIS A. SOUZA,IGOR M.B.A. SANTOS,GLENDA L. |
author2_role |
author author author author |
dc.contributor.author.fl_str_mv |
ARAÚJO NETO,JOSÉ F. BARRETO,SANDRA B. CARRINO,THAIS A. SOUZA,IGOR M.B.A. SANTOS,GLENDA L. |
dc.subject.por.fl_str_mv |
Geochemistry mineral chemistry Paraná emerald deposit petrography reflectance spectroscopy |
topic |
Geochemistry mineral chemistry Paraná emerald deposit petrography reflectance spectroscopy |
description |
Abstract The Paraná emerald deposit is one of the few occurrences of emerald, a rare beryl variety, in Borborema Province, northeastern Brazil. We characterized the Paraná deposit by combining field geology, petrography, whole-rock geochemistry, mineral chemistry, and reflectance spectroscopy. The mineralization is associated with phlogopite-, actinolite-phlogopite-, and phlogopite-phengite schists, mylonitic gneisses, and several acidic rocks (e.g. granitic pegmatites/aplites, quartz ± feldspar veins) along the Portalegre Shear Zone. Emerald can be found in quartz-feldspar and aplite veins and veinlets interleaved with phlogopite- or actinolite-phlogopite schists, or within the foliation of the schists. The presence of albitites and the compositional variation of the schists suggest a metasomatic origin for emerald with variations of the metasomatic process. All these different lithotypes can be readily identified through reflectance spectroscopy especially in the range of 2,150-2,450 nm, where the main mafic minerals show absorption features related to Al-OH (phengite), and Fe-OH and Mg-OH bonds (phlogopite/actinolite). Our study shows that possible mineralized phlogopite schists can be distinguished from other sterile rocks, although point spectral analysis does not separate emerald-bearing phlogopite schists from schists without emerald due to the dominance of major phlogopite absorption features rather than emerald features. |
publishDate |
2021 |
dc.date.none.fl_str_mv |
2021-01-01 |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652021000101218 |
url |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652021000101218 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
10.1590/0001-3765202120200236 |
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.93 n.1 2021 reponame:Anais da Academia Brasileira de Ciências (Online) instname:Academia Brasileira de Ciências (ABC) instacron:ABC |
instname_str |
Academia Brasileira de Ciências (ABC) |
instacron_str |
ABC |
institution |
ABC |
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) |
repository.mail.fl_str_mv |
||aabc@abc.org.br |
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1754302869724463104 |