Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W Deposits

Detalhes bibliográficos
Autor(a) principal: Gaspar, Miguel
Data de Publicação: 2022
Outros Autores: Grácio, Nuno, Salgueiro, Rute, Costa, Mafalda
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10400.9/3965
Resumo: ABSTRACT: The Segura mining field, the easternmost segment of the Gois-Panasqueira-Segura tin-tungsten metallogenic belt (north-central Portugal), includes Sn-W quartz veins and Li-Sn aplite-pegmatites, which are believed to be genetically related to Variscan Granites. Sediment geochemistry indicates granite-related Ti-enrichments, locally disturbed by mineralization, suggesting magmatic and metamorphic/metasomatic titaniferous phases. Therefore, Segura alluvial samples and the geochemistry of their TiO2 polymorphs (rutile, anatase, and brookite) were investigated, and their potential as exploration tools for Sn and W deposits was evaluated. The heavy-mineral assemblages proved to be good proxies for bedrock geology, and TiO2 polymorph abundances were found to be suitable indicators of magmatic and/or metasomatic hydrothermal processes. The trace element geochemistry of Segura's alluvial rutile, anatase, and brookite is highly variable, implying multiple sources and a diversity of mineral-forming processes. The main compositional differences between TiO2 polymorphs are related to intrinsic (structural) factors, and to the P-T-X extrinsic parameters of their forming environments. Anomalous enrichments, up to 9% Nb, 6% Sn and W, 3% Fe, 2% Ta, and 1% V in rutile, and up to 1.8% Fe, 1.7% Ta, 1.2% Nb, 1.1% W 0.5% Sn and V in anatase, were registered. Brookite usually has low trace element content (<0.5%), except for Fe (similar to 1%). HFSE-rich and granitophile-rich rutile is most likely magmatic, forming in extremely differentiated melts, with Sn and W contents enabling the discrimination between Sn-dominant and W-dominant systems. Trace element geochemical distribution maps show pronounced negative Sn (rutile+anatase) and W (rutile) anomalies linked to hydrothermal cassiterite precipitation, as opposed to their hydrothermal alteration halos and to W-dominant cassiterite-free mineralized areas, where primary hydrothermal rutile shows enrichments similar to magmatic rutile. This contribution recognizes that trace element geochemistry of alluvial TiO2 polymorphs can be a robust, cost- and time-effective, exploration tool for Sn(W) and W(Sn) ore deposit systems.
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spelling Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W DepositsHeavy mineralsTitanium dioxidePolymorphsAlluvialGeochemistryGeochemical explorationABSTRACT: The Segura mining field, the easternmost segment of the Gois-Panasqueira-Segura tin-tungsten metallogenic belt (north-central Portugal), includes Sn-W quartz veins and Li-Sn aplite-pegmatites, which are believed to be genetically related to Variscan Granites. Sediment geochemistry indicates granite-related Ti-enrichments, locally disturbed by mineralization, suggesting magmatic and metamorphic/metasomatic titaniferous phases. Therefore, Segura alluvial samples and the geochemistry of their TiO2 polymorphs (rutile, anatase, and brookite) were investigated, and their potential as exploration tools for Sn and W deposits was evaluated. The heavy-mineral assemblages proved to be good proxies for bedrock geology, and TiO2 polymorph abundances were found to be suitable indicators of magmatic and/or metasomatic hydrothermal processes. The trace element geochemistry of Segura's alluvial rutile, anatase, and brookite is highly variable, implying multiple sources and a diversity of mineral-forming processes. The main compositional differences between TiO2 polymorphs are related to intrinsic (structural) factors, and to the P-T-X extrinsic parameters of their forming environments. Anomalous enrichments, up to 9% Nb, 6% Sn and W, 3% Fe, 2% Ta, and 1% V in rutile, and up to 1.8% Fe, 1.7% Ta, 1.2% Nb, 1.1% W 0.5% Sn and V in anatase, were registered. Brookite usually has low trace element content (<0.5%), except for Fe (similar to 1%). HFSE-rich and granitophile-rich rutile is most likely magmatic, forming in extremely differentiated melts, with Sn and W contents enabling the discrimination between Sn-dominant and W-dominant systems. Trace element geochemical distribution maps show pronounced negative Sn (rutile+anatase) and W (rutile) anomalies linked to hydrothermal cassiterite precipitation, as opposed to their hydrothermal alteration halos and to W-dominant cassiterite-free mineralized areas, where primary hydrothermal rutile shows enrichments similar to magmatic rutile. This contribution recognizes that trace element geochemistry of alluvial TiO2 polymorphs can be a robust, cost- and time-effective, exploration tool for Sn(W) and W(Sn) ore deposit systems.MDPIRepositório do LNEGGaspar, MiguelGrácio, NunoSalgueiro, RuteCosta, Mafalda2022-11-30T12:42:13Z2022-102022-10-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/10400.9/3965engGaspar, Miguel... [et.al.] - Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W Deposits. In: Minerals, 2022, vol. 12(10), article nº 124810.3390/min121012482075-163Xinfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2022-12-04T04:45:15Zoai:repositorio.lneg.pt:10400.9/3965Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T16:15:26.675353Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W Deposits
title Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W Deposits
spellingShingle Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W Deposits
Gaspar, Miguel
Heavy minerals
Titanium dioxide
Polymorphs
Alluvial
Geochemistry
Geochemical exploration
title_short Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W Deposits
title_full Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W Deposits
title_fullStr Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W Deposits
title_full_unstemmed Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W Deposits
title_sort Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W Deposits
author Gaspar, Miguel
author_facet Gaspar, Miguel
Grácio, Nuno
Salgueiro, Rute
Costa, Mafalda
author_role author
author2 Grácio, Nuno
Salgueiro, Rute
Costa, Mafalda
author2_role author
author
author
dc.contributor.none.fl_str_mv Repositório do LNEG
dc.contributor.author.fl_str_mv Gaspar, Miguel
Grácio, Nuno
Salgueiro, Rute
Costa, Mafalda
dc.subject.por.fl_str_mv Heavy minerals
Titanium dioxide
Polymorphs
Alluvial
Geochemistry
Geochemical exploration
topic Heavy minerals
Titanium dioxide
Polymorphs
Alluvial
Geochemistry
Geochemical exploration
description ABSTRACT: The Segura mining field, the easternmost segment of the Gois-Panasqueira-Segura tin-tungsten metallogenic belt (north-central Portugal), includes Sn-W quartz veins and Li-Sn aplite-pegmatites, which are believed to be genetically related to Variscan Granites. Sediment geochemistry indicates granite-related Ti-enrichments, locally disturbed by mineralization, suggesting magmatic and metamorphic/metasomatic titaniferous phases. Therefore, Segura alluvial samples and the geochemistry of their TiO2 polymorphs (rutile, anatase, and brookite) were investigated, and their potential as exploration tools for Sn and W deposits was evaluated. The heavy-mineral assemblages proved to be good proxies for bedrock geology, and TiO2 polymorph abundances were found to be suitable indicators of magmatic and/or metasomatic hydrothermal processes. The trace element geochemistry of Segura's alluvial rutile, anatase, and brookite is highly variable, implying multiple sources and a diversity of mineral-forming processes. The main compositional differences between TiO2 polymorphs are related to intrinsic (structural) factors, and to the P-T-X extrinsic parameters of their forming environments. Anomalous enrichments, up to 9% Nb, 6% Sn and W, 3% Fe, 2% Ta, and 1% V in rutile, and up to 1.8% Fe, 1.7% Ta, 1.2% Nb, 1.1% W 0.5% Sn and V in anatase, were registered. Brookite usually has low trace element content (<0.5%), except for Fe (similar to 1%). HFSE-rich and granitophile-rich rutile is most likely magmatic, forming in extremely differentiated melts, with Sn and W contents enabling the discrimination between Sn-dominant and W-dominant systems. Trace element geochemical distribution maps show pronounced negative Sn (rutile+anatase) and W (rutile) anomalies linked to hydrothermal cassiterite precipitation, as opposed to their hydrothermal alteration halos and to W-dominant cassiterite-free mineralized areas, where primary hydrothermal rutile shows enrichments similar to magmatic rutile. This contribution recognizes that trace element geochemistry of alluvial TiO2 polymorphs can be a robust, cost- and time-effective, exploration tool for Sn(W) and W(Sn) ore deposit systems.
publishDate 2022
dc.date.none.fl_str_mv 2022-11-30T12:42:13Z
2022-10
2022-10-01T00:00:00Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10400.9/3965
url http://hdl.handle.net/10400.9/3965
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv Gaspar, Miguel... [et.al.] - Trace Element Geochemistry of Alluvial TiO2 Polymorphs as a Proxy for Sn and W Deposits. In: Minerals, 2022, vol. 12(10), article nº 1248
10.3390/min12101248
2075-163X
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv MDPI
publisher.none.fl_str_mv MDPI
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
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