Neoproterozoic Anatexis of 2.9 Ga Old Granitoids in the Goiás-Crixás Archean Block, Central Brazil: Evidence From New SHRIMP U-Pb Data and Sm-Nd Isotopes
The first SHRIMP U-Pb ages for granitoid rocks from the southern part of the Goiás-Crixás Archean Block (Caiçara andUvá complexes) are presented and discussed in combination with Sm-Nd isotopic data in order to elucidate the main aspectsof the geological evolution of that part of the Brasília Belt i...
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| Format: | Article |
| Language: | English |
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Universidade de São Paulo
2003-08-01
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| Series: | Geologia USP. Série Científica |
| Subjects: | |
| Online Access: | http://ppegeo-local.igc.usp.br/pdf/guspsc/v3/01.pdf |
| _version_ | 1819224914386747392 |
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| author | Márcio Martins Pimentel Hardy Jost Reinhardt Adolfo Fuck Richard Austin Armstrong Elton Luiz Dantas Alain Potrel |
| author_facet | Márcio Martins Pimentel Hardy Jost Reinhardt Adolfo Fuck Richard Austin Armstrong Elton Luiz Dantas Alain Potrel |
| author_sort | Márcio Martins Pimentel |
| collection | DOAJ |
| description | The first SHRIMP U-Pb ages for granitoid rocks from the southern part of the Goiás-Crixás Archean Block (Caiçara andUvá complexes) are presented and discussed in combination with Sm-Nd isotopic data in order to elucidate the main aspectsof the geological evolution of that part of the Brasília Belt in central Brazil. Zircon grains from a tonalitic gneiss (GOV-4) inthe Uvá Complex show that the original tonalite crystallized at 2934 ± 5 Ma. One metamorphic zircon crystal is concordantand indicates an Archean age for the recrystallization episode (2793 ± 3 Ma) and one inherited grain with an age of 3092 ± 9suggests, together with negative values of eNd(T) (+0.4 and –4.6), that the magma was contaminated with older crust. Oneleucocratic granite (GOV-1) exposed north of the Goiás greenstone belt crystallized at 626 ± 7 Ma, as indicated by theigneous overgrowths surrounding older inherited cores. The latter indicate a crystallization age of 2893 ± 12 Ma. This rockis interpreted therefore as the product of Neoproterozoic anatexis of ca. 2.89 Ga-old rocks of the Caiçara Complex. This isreinforced by strongly negative eNd(T = 626) values of – 28.0 and –29.0. Its crystallization age is identical to the U-Pb agesof the Itapuranga granite and Uruana quartz syenite, which are exposed to the north of the investigated area and interpretedas syn-tectonic intrusions in relation to the main Brasiliano tectonic event. This represents, therefore, the first evidence ofNeoproterozoic magmatism within the Goiás Archean Block and raises the possibility that other leucogranite dykes andstocks identified regionally may also have been formed during the Brasiliano orogeny. |
| first_indexed | 2024-12-23T10:01:16Z |
| format | Article |
| id | doaj.art-94eaff123b994ce6ac43d84c87848303 |
| institution | Directory Open Access Journal |
| issn | 1519-874X |
| language | English |
| last_indexed | 2024-12-23T10:01:16Z |
| publishDate | 2003-08-01 |
| publisher | Universidade de São Paulo |
| record_format | Article |
| series | Geologia USP. Série Científica |
| spelling | doaj.art-94eaff123b994ce6ac43d84c878483032022-12-21T17:51:12ZengUniversidade de São PauloGeologia USP. Série Científica1519-874X2003-08-013112Neoproterozoic Anatexis of 2.9 Ga Old Granitoids in the Goiás-Crixás Archean Block, Central Brazil: Evidence From New SHRIMP U-Pb Data and Sm-Nd IsotopesMárcio Martins PimentelHardy JostReinhardt Adolfo FuckRichard Austin ArmstrongElton Luiz DantasAlain PotrelThe first SHRIMP U-Pb ages for granitoid rocks from the southern part of the Goiás-Crixás Archean Block (Caiçara andUvá complexes) are presented and discussed in combination with Sm-Nd isotopic data in order to elucidate the main aspectsof the geological evolution of that part of the Brasília Belt in central Brazil. Zircon grains from a tonalitic gneiss (GOV-4) inthe Uvá Complex show that the original tonalite crystallized at 2934 ± 5 Ma. One metamorphic zircon crystal is concordantand indicates an Archean age for the recrystallization episode (2793 ± 3 Ma) and one inherited grain with an age of 3092 ± 9suggests, together with negative values of eNd(T) (+0.4 and –4.6), that the magma was contaminated with older crust. Oneleucocratic granite (GOV-1) exposed north of the Goiás greenstone belt crystallized at 626 ± 7 Ma, as indicated by theigneous overgrowths surrounding older inherited cores. The latter indicate a crystallization age of 2893 ± 12 Ma. This rockis interpreted therefore as the product of Neoproterozoic anatexis of ca. 2.89 Ga-old rocks of the Caiçara Complex. This isreinforced by strongly negative eNd(T = 626) values of – 28.0 and –29.0. Its crystallization age is identical to the U-Pb agesof the Itapuranga granite and Uruana quartz syenite, which are exposed to the north of the investigated area and interpretedas syn-tectonic intrusions in relation to the main Brasiliano tectonic event. This represents, therefore, the first evidence ofNeoproterozoic magmatism within the Goiás Archean Block and raises the possibility that other leucogranite dykes andstocks identified regionally may also have been formed during the Brasiliano orogeny.http://ppegeo-local.igc.usp.br/pdf/guspsc/v3/01.pdfArcheanGoiásSHRIMP U-PbBrasilianoanatexis |
| spellingShingle | Márcio Martins Pimentel Hardy Jost Reinhardt Adolfo Fuck Richard Austin Armstrong Elton Luiz Dantas Alain Potrel Neoproterozoic Anatexis of 2.9 Ga Old Granitoids in the Goiás-Crixás Archean Block, Central Brazil: Evidence From New SHRIMP U-Pb Data and Sm-Nd Isotopes Geologia USP. Série Científica Archean Goiás SHRIMP U-Pb Brasiliano anatexis |
| title | Neoproterozoic Anatexis of 2.9 Ga Old Granitoids in the Goiás-Crixás Archean Block, Central Brazil: Evidence From New SHRIMP U-Pb Data and Sm-Nd Isotopes |
| title_full | Neoproterozoic Anatexis of 2.9 Ga Old Granitoids in the Goiás-Crixás Archean Block, Central Brazil: Evidence From New SHRIMP U-Pb Data and Sm-Nd Isotopes |
| title_fullStr | Neoproterozoic Anatexis of 2.9 Ga Old Granitoids in the Goiás-Crixás Archean Block, Central Brazil: Evidence From New SHRIMP U-Pb Data and Sm-Nd Isotopes |
| title_full_unstemmed | Neoproterozoic Anatexis of 2.9 Ga Old Granitoids in the Goiás-Crixás Archean Block, Central Brazil: Evidence From New SHRIMP U-Pb Data and Sm-Nd Isotopes |
| title_short | Neoproterozoic Anatexis of 2.9 Ga Old Granitoids in the Goiás-Crixás Archean Block, Central Brazil: Evidence From New SHRIMP U-Pb Data and Sm-Nd Isotopes |
| title_sort | neoproterozoic anatexis of 2 9 ga old granitoids in the goias crixas archean block central brazil evidence from new shrimp u pb data and sm nd isotopes |
| topic | Archean Goiás SHRIMP U-Pb Brasiliano anatexis |
| url | http://ppegeo-local.igc.usp.br/pdf/guspsc/v3/01.pdf |
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