Petrogenetic constraints on the felsic vein magmatism in northern Portugal based on petrological and geochemical data
Three of the largest granite porphyries of northern Portugal were studied to improve current knowledge on the regional felsic vein hypabyssal magmatism. All porphyries exhibit microcrystalline groundmasses of variable granularity (composed of quartz, K-feldspar, and muscovite), quartz, K-feldspar, p...
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| Format: | Article |
| Language: | English |
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Académie des sciences
2021-12-01
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| Series: | Comptes Rendus. Géoscience |
| Subjects: | |
| Online Access: | https://comptes-rendus.academie-sciences.fr/geoscience/articles/10.5802/crgeos.100/ |
| _version_ | 1797651300223025152 |
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| author | Oliveira, António João Teixeira Martins, Helena Cristina Brites da Silva, Helena Maria Sant’Ovaia Mendes |
| author_facet | Oliveira, António João Teixeira Martins, Helena Cristina Brites da Silva, Helena Maria Sant’Ovaia Mendes |
| author_sort | Oliveira, António João Teixeira |
| collection | DOAJ |
| description | Three of the largest granite porphyries of northern Portugal were studied to improve current knowledge on the regional felsic vein hypabyssal magmatism. All porphyries exhibit microcrystalline groundmasses of variable granularity (composed of quartz, K-feldspar, and muscovite), quartz, K-feldspar, plagioclase, biotite, and cordierite phenocrysts, antirapakivi and rapakivi feldspars, embayments in quartz, and enrichments in rare metal incompatible elements. The veins were emplaced along fractures generated during the last phase of the Variscan orogeny. Textural features were presumably conditioned by fast cooling, volatile loss, subsolidus annealing, and the magnitude of thermal contrasts at the time of emplacement. All veins were altered by subsolidus hydrothermal fluids, as suggested by several petrographic and geochemical evidence. The generation of mantled feldspars is probably related to isothermal decompression and magma mixing, which is compatible with the $\varepsilon \mathrm{Nd}_{i}$ signatures (${-}3.76$ to ${-}4.40$). Based on this research, both processes have contributed to the petrogenesis of the studied porphyries. |
| first_indexed | 2024-03-11T16:14:02Z |
| format | Article |
| id | doaj.art-31370e0498e2485f954372293de32863 |
| institution | Directory Open Access Journal |
| issn | 1778-7025 |
| language | English |
| last_indexed | 2024-03-11T16:14:02Z |
| publishDate | 2021-12-01 |
| publisher | Académie des sciences |
| record_format | Article |
| series | Comptes Rendus. Géoscience |
| spelling | doaj.art-31370e0498e2485f954372293de328632023-10-24T14:24:05ZengAcadémie des sciencesComptes Rendus. Géoscience1778-70252021-12-01353137739810.5802/crgeos.10010.5802/crgeos.100Petrogenetic constraints on the felsic vein magmatism in northern Portugal based on petrological and geochemical dataOliveira, António João Teixeira0https://orcid.org/0000-0003-1445-1681Martins, Helena Cristina Brites1https://orcid.org/0000-0002-5668-470Xda Silva, Helena Maria Sant’Ovaia Mendes2https://orcid.org/0000-0002-1884-7440Faculdade de Ciências da Universidade do Porto, Departamento de Geociências, Ambiente e Ordenamento do Território, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal; Instituto de Ciências da Terra, Polo do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, PortugalFaculdade de Ciências da Universidade do Porto, Departamento de Geociências, Ambiente e Ordenamento do Território, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal; Instituto de Ciências da Terra, Polo do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, PortugalFaculdade de Ciências da Universidade do Porto, Departamento de Geociências, Ambiente e Ordenamento do Território, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal; Instituto de Ciências da Terra, Polo do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, PortugalThree of the largest granite porphyries of northern Portugal were studied to improve current knowledge on the regional felsic vein hypabyssal magmatism. All porphyries exhibit microcrystalline groundmasses of variable granularity (composed of quartz, K-feldspar, and muscovite), quartz, K-feldspar, plagioclase, biotite, and cordierite phenocrysts, antirapakivi and rapakivi feldspars, embayments in quartz, and enrichments in rare metal incompatible elements. The veins were emplaced along fractures generated during the last phase of the Variscan orogeny. Textural features were presumably conditioned by fast cooling, volatile loss, subsolidus annealing, and the magnitude of thermal contrasts at the time of emplacement. All veins were altered by subsolidus hydrothermal fluids, as suggested by several petrographic and geochemical evidence. The generation of mantled feldspars is probably related to isothermal decompression and magma mixing, which is compatible with the $\varepsilon \mathrm{Nd}_{i}$ signatures (${-}3.76$ to ${-}4.40$). Based on this research, both processes have contributed to the petrogenesis of the studied porphyries.https://comptes-rendus.academie-sciences.fr/geoscience/articles/10.5802/crgeos.100/Whole-rock geochemistryGranite porphyriesSubvolcanic magmatismCentral Iberian zoneAntirapakivi and rapakivi texturesMicrostructuresWhole-rock geochemistry |
| spellingShingle | Oliveira, António João Teixeira Martins, Helena Cristina Brites da Silva, Helena Maria Sant’Ovaia Mendes Petrogenetic constraints on the felsic vein magmatism in northern Portugal based on petrological and geochemical data Comptes Rendus. Géoscience Whole-rock geochemistry Granite porphyries Subvolcanic magmatism Central Iberian zone Antirapakivi and rapakivi textures Microstructures Whole-rock geochemistry |
| title | Petrogenetic constraints on the felsic vein magmatism in northern Portugal based on petrological and geochemical data |
| title_full | Petrogenetic constraints on the felsic vein magmatism in northern Portugal based on petrological and geochemical data |
| title_fullStr | Petrogenetic constraints on the felsic vein magmatism in northern Portugal based on petrological and geochemical data |
| title_full_unstemmed | Petrogenetic constraints on the felsic vein magmatism in northern Portugal based on petrological and geochemical data |
| title_short | Petrogenetic constraints on the felsic vein magmatism in northern Portugal based on petrological and geochemical data |
| title_sort | petrogenetic constraints on the felsic vein magmatism in northern portugal based on petrological and geochemical data |
| topic | Whole-rock geochemistry Granite porphyries Subvolcanic magmatism Central Iberian zone Antirapakivi and rapakivi textures Microstructures Whole-rock geochemistry |
| url | https://comptes-rendus.academie-sciences.fr/geoscience/articles/10.5802/crgeos.100/ |
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