Record of Early Tonian mafic magmatism in the central Espinhaço (Brazil): New insights for break-up of the Neoproterozoic landmass ancestor of São Francisco-Congo paleocontinent
Petrological characterization, U–Pb geochronology, Lu–Hf analyses and major and trace element data from mafic intrusions in the Central Espinhaço (central portion of the Brazilian shield) are used here to investigate the geological significance of the Early Neoproterozoic magmatism in the context of...
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Elsevier
2020-11-01
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| Series: | Geoscience Frontiers |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S1674987120300499 |
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| author | Helen F. Moreira André Danderfer Alice F.O. Costa Samuel M. Bersan Cristiano C. Lana Gláucia N. Queiroga |
| author_facet | Helen F. Moreira André Danderfer Alice F.O. Costa Samuel M. Bersan Cristiano C. Lana Gláucia N. Queiroga |
| author_sort | Helen F. Moreira |
| collection | DOAJ |
| description | Petrological characterization, U–Pb geochronology, Lu–Hf analyses and major and trace element data from mafic intrusions in the Central Espinhaço (central portion of the Brazilian shield) are used here to investigate the geological significance of the Early Neoproterozoic magmatism in the context of the São Francisco-Congo paleocontinent. These mafic bodies are represented by medium to coarse-grained metagabbros with plagioclase, amphibole and clinopyroxene. Zircon U–Pb isotopic data from two samples yielded weighted mean 206Pb/238U ages of 895 ± 3.4 Ma (MSWD = 1.7) and 896 ± 2.4 Ma (MSWD = 0.64), regarded as the best estimates for the crystallization age of these mafic rocks. Major and trace element data (including REEs) show that the gabbros originated from a subalkaline tholeiitic magma, typical of intraplate magmatism. Such rocks are slightly enriched in LREEs and LILEs and depleted in HFSEs. Our new isotope and geochemical data, along with regional knowledge, indicate that these metagabbros mark the beginning of an important Tonian-age extensional tectonic event of the landmass of which the São Francisco-Congo paleocontinent was part (Rodinia supercontinent or Central African block?). We furthermore suggest that these rocks belong to a prominent suite of Tonian-age mafic rocks that mark a diachronic breakup attempt of this landmass which may have occurred from south to north along the Espinhaço mountain range. |
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| format | Article |
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| institution | Directory Open Access Journal |
| issn | 1674-9871 |
| language | English |
| last_indexed | 2024-03-12T05:46:28Z |
| publishDate | 2020-11-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Geoscience Frontiers |
| spelling | doaj.art-66e29e9af2a441b2882f4eec3f8603e82023-09-03T05:34:49ZengElsevierGeoscience Frontiers1674-98712020-11-0111623232337Record of Early Tonian mafic magmatism in the central Espinhaço (Brazil): New insights for break-up of the Neoproterozoic landmass ancestor of São Francisco-Congo paleocontinentHelen F. Moreira0André Danderfer1Alice F.O. Costa2Samuel M. Bersan3Cristiano C. Lana4Gláucia N. Queiroga5Post Graduate Program of Department of Geology, Mine School, Federal University of Ouro Preto, Brazil; Corresponding author. Department of Geology, Mine School, Federal University of Ouro Preto, Brazil, Campus Universitário, 35400-000, Ouro Preto, MG, Brazil.Department of Geology, Mine School, Federal University of Ouro Preto, BrazilDepartment of Geology, Mine School, Federal University of Ouro Preto, BrazilPost Graduate Program of Department of Geology, Mine School, Federal University of Ouro Preto, BrazilDepartment of Geology, Mine School, Federal University of Ouro Preto, BrazilDepartment of Geology, Mine School, Federal University of Ouro Preto, BrazilPetrological characterization, U–Pb geochronology, Lu–Hf analyses and major and trace element data from mafic intrusions in the Central Espinhaço (central portion of the Brazilian shield) are used here to investigate the geological significance of the Early Neoproterozoic magmatism in the context of the São Francisco-Congo paleocontinent. These mafic bodies are represented by medium to coarse-grained metagabbros with plagioclase, amphibole and clinopyroxene. Zircon U–Pb isotopic data from two samples yielded weighted mean 206Pb/238U ages of 895 ± 3.4 Ma (MSWD = 1.7) and 896 ± 2.4 Ma (MSWD = 0.64), regarded as the best estimates for the crystallization age of these mafic rocks. Major and trace element data (including REEs) show that the gabbros originated from a subalkaline tholeiitic magma, typical of intraplate magmatism. Such rocks are slightly enriched in LREEs and LILEs and depleted in HFSEs. Our new isotope and geochemical data, along with regional knowledge, indicate that these metagabbros mark the beginning of an important Tonian-age extensional tectonic event of the landmass of which the São Francisco-Congo paleocontinent was part (Rodinia supercontinent or Central African block?). We furthermore suggest that these rocks belong to a prominent suite of Tonian-age mafic rocks that mark a diachronic breakup attempt of this landmass which may have occurred from south to north along the Espinhaço mountain range.http://www.sciencedirect.com/science/article/pii/S1674987120300499Mafic rocksEspinhaço basinSão Francisco-Congo paleocontinentTonian riftingU–Pb geochronology |
| spellingShingle | Helen F. Moreira André Danderfer Alice F.O. Costa Samuel M. Bersan Cristiano C. Lana Gláucia N. Queiroga Record of Early Tonian mafic magmatism in the central Espinhaço (Brazil): New insights for break-up of the Neoproterozoic landmass ancestor of São Francisco-Congo paleocontinent Geoscience Frontiers Mafic rocks Espinhaço basin São Francisco-Congo paleocontinent Tonian rifting U–Pb geochronology |
| title | Record of Early Tonian mafic magmatism in the central Espinhaço (Brazil): New insights for break-up of the Neoproterozoic landmass ancestor of São Francisco-Congo paleocontinent |
| title_full | Record of Early Tonian mafic magmatism in the central Espinhaço (Brazil): New insights for break-up of the Neoproterozoic landmass ancestor of São Francisco-Congo paleocontinent |
| title_fullStr | Record of Early Tonian mafic magmatism in the central Espinhaço (Brazil): New insights for break-up of the Neoproterozoic landmass ancestor of São Francisco-Congo paleocontinent |
| title_full_unstemmed | Record of Early Tonian mafic magmatism in the central Espinhaço (Brazil): New insights for break-up of the Neoproterozoic landmass ancestor of São Francisco-Congo paleocontinent |
| title_short | Record of Early Tonian mafic magmatism in the central Espinhaço (Brazil): New insights for break-up of the Neoproterozoic landmass ancestor of São Francisco-Congo paleocontinent |
| title_sort | record of early tonian mafic magmatism in the central espinhaco brazil new insights for break up of the neoproterozoic landmass ancestor of sao francisco congo paleocontinent |
| topic | Mafic rocks Espinhaço basin São Francisco-Congo paleocontinent Tonian rifting U–Pb geochronology |
| url | http://www.sciencedirect.com/science/article/pii/S1674987120300499 |
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