The thrust contact between the Canastra and Vazante groups in the Southern Brasília Belt: structural evolution, white mica crystallinity and implications for the Brasiliano orogeny
ABSTRACT: Two regional thrust-sheets of Neoproterozoic metasedimentary rocks occur in the Southern Brasília Belt, northwest Minas Gerais. The lower one comprises the Vazante Group, that is formed in the studied area, from base to top, by the Serra do Garrote (metapelites interlayered with carbonaceo...
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| Format: | Article |
| Language: | English |
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Sociedade Brasileira de Geologia
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| Series: | Brazilian Journal of Geology |
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| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S2317-48892016000400567&lng=en&tlng=en |
| _version_ | 1819148934329663488 |
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| author | Manuela de Oliveira Carvalho Claudio de Morisson Valeriano Pamela Alejandra Aparicio González Gustavo Diniz Oliveira Agnes Impiccini |
| author_facet | Manuela de Oliveira Carvalho Claudio de Morisson Valeriano Pamela Alejandra Aparicio González Gustavo Diniz Oliveira Agnes Impiccini |
| author_sort | Manuela de Oliveira Carvalho |
| collection | DOAJ |
| description | ABSTRACT: Two regional thrust-sheets of Neoproterozoic metasedimentary rocks occur in the Southern Brasília Belt, northwest Minas Gerais. The lower one comprises the Vazante Group, that is formed in the studied area, from base to top, by the Serra do Garrote (metapelites interlayered with carbonaceous phyllite), Serra do Poço Verde (beige to pink stromatolitic metadolomite with interlayered greenish slates), Morro do Calcário (gray stromatolitic metadolomite interlayered with gray slates) and Serra da Lapa (phyllite with dolarenitic lenses interlayered with slates) formations. The upper thrust sheet consists of the Canastra Group (Paracatu formation): laminated sericite phyllites and carbonaceous phyllites interlayered with quartzite. The Braziliano orogeny resulted in four phases of contractional deformation, associated with low-grade metamorphism. The first two (D1 and D2) are ductile, while the third and fourth ones (D3 and D4) are brittle-ductile. D1 developed a slaty S1 cleavage subparallel to the primary layering, with shallow to steep dips to NW. D2 developed a crenulation cleavage (S2) that dips moderately to NW and is associated with tight to isoclinal folds. D3 and D4 phases developed crenulations and open folds and kink bands. S3 dips steeply to NW, while S4 has moderate to steep dips to NE and SW. White mica crystallinity (Kübler index) measurements in metapelites indicate that both the Canastra and Vazante groups reached anchizone/epizone conditions, and metamorphic discontinuities along thrusts indicate that the peak of metamorphism is pre or syn-thrusting. |
| first_indexed | 2024-12-22T13:53:36Z |
| format | Article |
| id | doaj.art-fb5a0fcee909452db295d8c23d19ba1e |
| institution | Directory Open Access Journal |
| issn | 2317-4692 |
| language | English |
| last_indexed | 2024-12-22T13:53:36Z |
| publisher | Sociedade Brasileira de Geologia |
| record_format | Article |
| series | Brazilian Journal of Geology |
| spelling | doaj.art-fb5a0fcee909452db295d8c23d19ba1e2022-12-21T18:23:37ZengSociedade Brasileira de GeologiaBrazilian Journal of Geology2317-469246456758310.1590/2317-4889201620160052S2317-48892016000400567The thrust contact between the Canastra and Vazante groups in the Southern Brasília Belt: structural evolution, white mica crystallinity and implications for the Brasiliano orogenyManuela de Oliveira CarvalhoClaudio de Morisson ValerianoPamela Alejandra Aparicio GonzálezGustavo Diniz OliveiraAgnes ImpicciniABSTRACT: Two regional thrust-sheets of Neoproterozoic metasedimentary rocks occur in the Southern Brasília Belt, northwest Minas Gerais. The lower one comprises the Vazante Group, that is formed in the studied area, from base to top, by the Serra do Garrote (metapelites interlayered with carbonaceous phyllite), Serra do Poço Verde (beige to pink stromatolitic metadolomite with interlayered greenish slates), Morro do Calcário (gray stromatolitic metadolomite interlayered with gray slates) and Serra da Lapa (phyllite with dolarenitic lenses interlayered with slates) formations. The upper thrust sheet consists of the Canastra Group (Paracatu formation): laminated sericite phyllites and carbonaceous phyllites interlayered with quartzite. The Braziliano orogeny resulted in four phases of contractional deformation, associated with low-grade metamorphism. The first two (D1 and D2) are ductile, while the third and fourth ones (D3 and D4) are brittle-ductile. D1 developed a slaty S1 cleavage subparallel to the primary layering, with shallow to steep dips to NW. D2 developed a crenulation cleavage (S2) that dips moderately to NW and is associated with tight to isoclinal folds. D3 and D4 phases developed crenulations and open folds and kink bands. S3 dips steeply to NW, while S4 has moderate to steep dips to NE and SW. White mica crystallinity (Kübler index) measurements in metapelites indicate that both the Canastra and Vazante groups reached anchizone/epizone conditions, and metamorphic discontinuities along thrusts indicate that the peak of metamorphism is pre or syn-thrusting.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S2317-48892016000400567&lng=en&tlng=enNeoproterozoicoChumbo-zincoDifração de raios XCinturão de dobramentos e cavalgamentos |
| spellingShingle | Manuela de Oliveira Carvalho Claudio de Morisson Valeriano Pamela Alejandra Aparicio González Gustavo Diniz Oliveira Agnes Impiccini The thrust contact between the Canastra and Vazante groups in the Southern Brasília Belt: structural evolution, white mica crystallinity and implications for the Brasiliano orogeny Brazilian Journal of Geology Neoproterozoico Chumbo-zinco Difração de raios X Cinturão de dobramentos e cavalgamentos |
| title | The thrust contact between the Canastra and Vazante groups in the Southern Brasília Belt: structural evolution, white mica crystallinity and implications for the Brasiliano orogeny |
| title_full | The thrust contact between the Canastra and Vazante groups in the Southern Brasília Belt: structural evolution, white mica crystallinity and implications for the Brasiliano orogeny |
| title_fullStr | The thrust contact between the Canastra and Vazante groups in the Southern Brasília Belt: structural evolution, white mica crystallinity and implications for the Brasiliano orogeny |
| title_full_unstemmed | The thrust contact between the Canastra and Vazante groups in the Southern Brasília Belt: structural evolution, white mica crystallinity and implications for the Brasiliano orogeny |
| title_short | The thrust contact between the Canastra and Vazante groups in the Southern Brasília Belt: structural evolution, white mica crystallinity and implications for the Brasiliano orogeny |
| title_sort | thrust contact between the canastra and vazante groups in the southern brasilia belt structural evolution white mica crystallinity and implications for the brasiliano orogeny |
| topic | Neoproterozoico Chumbo-zinco Difração de raios X Cinturão de dobramentos e cavalgamentos |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S2317-48892016000400567&lng=en&tlng=en |
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