40Ar/39Ar ages (600-570 Ma) of the Serra do Azeite transtensional shear zone: evidence for syncontractional extension in the Cajati area, southern Ribeira belt
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| Formato: | Artículo científico |
| Lenguaje: | en |
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Academia Brasileira de Ciências
2007
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| _version_ | 1876449984811892736 |
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| author | Rômulo Machado |
| author_facet | Rômulo Machado |
| contents | 40Ar/39Ar ages (600-570 Ma) of the Serra do Azeite transtensional shear zone: evidence for syncontractional extension in the Cajati area, southern Ribeira belt Rômulo Machado Nolan M. Dehler Paulo Vasconcelos Multidisciplinaria (Ciencias Naturales y Exactas) 40Ar 39Ar ages Ribeira belt syncontractional extension This paper presents 40Ar/39Ar ages of the rocks from the Serra do Azeite transtensional shear zone in the southern part ofthe Ribeira belt, between the States of São Paulo and Paraná, and also discusses the regional correlations and the tectonicimplications for other parts of the belt. The geochronological data suggest that transtensional deformation was activebetween 600 and 580 Ma (hornblende and muscovite apparent ages, respectively). This time span is considerably olderthan previous proposals for the period of activity of these structures (520-480 Ma) in the northern segment of this belt andin the Araçuaí belt. Kinematic analysis of the datedmylonites shows extensional structures with top-down movement toESE compatible with structures found in other tectonic segments in the eastern portion of the Quadrilátero Ferrífero andin the Rio Doce Valley region. Our ages are situated in the same time interval defined for the alkaline magmatism of theSerra do Mar suite. We suggest that the regional tectonic framework was developed during continental-scale extension.This process has been coeval with convergent strain in the adjacent Neoproterozoic shear zones of the Apiaí/Ribeiraand Araçuaí belts, which make up significant segments of these belts. The available data show that these structuresmay not be simply related to post-orogenic gravitational collapse, but must involve a more complex process probablyrelated to dynamic balance between crustal thickening and thinning during tectonic convergence, basin formation andexhumation processes. 2007 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32779411 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.4 Vol.79 |
| format | Artículo científico |
| id | redalyc_32779411 |
| institution | Redalyc |
| language | en |
| publishDate | 2007 |
| publisher | Academia Brasileira de Ciências |
| spellingShingle | 40Ar/39Ar ages (600-570 Ma) of the Serra do Azeite transtensional shear zone: evidence for syncontractional extension in the Cajati area, southern Ribeira belt Rômulo Machado Multidisciplinaria (Ciencias Naturales y Exactas) 40Ar 39Ar ages Ribeira belt syncontractional extension 40Ar/39Ar ages (600-570 Ma) of the Serra do Azeite transtensional shear zone: evidence for syncontractional extension in the Cajati area, southern Ribeira belt Rômulo Machado Nolan M. Dehler Paulo Vasconcelos Multidisciplinaria (Ciencias Naturales y Exactas) 40Ar 39Ar ages Ribeira belt syncontractional extension This paper presents 40Ar/39Ar ages of the rocks from the Serra do Azeite transtensional shear zone in the southern part ofthe Ribeira belt, between the States of São Paulo and Paraná, and also discusses the regional correlations and the tectonicimplications for other parts of the belt. The geochronological data suggest that transtensional deformation was activebetween 600 and 580 Ma (hornblende and muscovite apparent ages, respectively). This time span is considerably olderthan previous proposals for the period of activity of these structures (520-480 Ma) in the northern segment of this belt andin the Araçuaí belt. Kinematic analysis of the datedmylonites shows extensional structures with top-down movement toESE compatible with structures found in other tectonic segments in the eastern portion of the Quadrilátero Ferrífero andin the Rio Doce Valley region. Our ages are situated in the same time interval defined for the alkaline magmatism of theSerra do Mar suite. We suggest that the regional tectonic framework was developed during continental-scale extension.This process has been coeval with convergent strain in the adjacent Neoproterozoic shear zones of the Apiaí/Ribeiraand Araçuaí belts, which make up significant segments of these belts. The available data show that these structuresmay not be simply related to post-orogenic gravitational collapse, but must involve a more complex process probablyrelated to dynamic balance between crustal thickening and thinning during tectonic convergence, basin formation andexhumation processes. 2007 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32779411 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.4 Vol.79 |
| title | 40Ar/39Ar ages (600-570 Ma) of the Serra do Azeite transtensional shear zone: evidence for syncontractional extension in the Cajati area, southern Ribeira belt |
| topic | Multidisciplinaria (Ciencias Naturales y Exactas) 40Ar 39Ar ages Ribeira belt syncontractional extension |
| url | https://www.redalyc.org/articulo.oa?id=32779411 |