Kinematics and geometry of structures in the southern limb of the Paraíba do Sul divergent structural fan, SE Brazil: a true transtensional shear
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| Sprache: | en |
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Academia Brasileira de Ciências
2006
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| author | Heloisa R.S. Dehler |
| author_facet | Heloisa R.S. Dehler |
| contents | Kinematics and geometry of structures in the southern limb of the Paraíba do Sul divergent structural fan, SE Brazil: a true transtensional shear Heloisa R.S. Dehler Ian McReath Nolan M. Dehler Rômulo Machado Alexis R. Nummer Multidisciplinaria (Ciencias Naturales y Exactas) extrusion transpression divergent fan transtensional deformation Shear zones geometry in the Paraíba do Sul belt, southeastern Brazil, delineates a NE-trending fan-like structure.Shear zones dip towards SE in the northern limb, and towards NW in the southern one. This geometryhas been interpreted either due to transpression or to late folding of flat-lying thrust surfaces. Stretchinglineation plunges to ENE-ESE in the northern limb and towards NNE-NE in the southern one. Structural datain the southern limb of the divergent fan suggest a two stage kinematic evolution in high-temperature conditions:an earlier stage with top-to-SSW/SW sinistral thrusting and orogenic-parallel tangential motion, and alater stage with top-down to NNE/NE transtensional deformation. We propose a heterogeneous deformationmodel to explain the observed shear reversal, and suggest that the imposed transpressional displacementgradient may change during progressive deformation due to transient rheological inhomogeneities in bulkpure shear strain. In the earlier stage, the partially molten material could easily accommodate the imposedstrain rates, giving rise firstly to the SW-directed shearing. As the thermal disturbance tended to vanishand the convergence increased, the NNE-directed transtensional shearing developed. We propose that thetranstensional deformation characterized in this paper could be related to extrusion processes during regionaltranspressional strain. 2006 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32778214 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.2 Vol.78 |
| format | Artículo científico |
| id | redalyc_32778214 |
| institution | Redalyc |
| language | en |
| publishDate | 2006 |
| publisher | Academia Brasileira de Ciências |
| spellingShingle | Kinematics and geometry of structures in the southern limb of the Paraíba do Sul divergent structural fan, SE Brazil: a true transtensional shear Heloisa R.S. Dehler Multidisciplinaria (Ciencias Naturales y Exactas) extrusion transpression divergent fan transtensional deformation Kinematics and geometry of structures in the southern limb of the Paraíba do Sul divergent structural fan, SE Brazil: a true transtensional shear Heloisa R.S. Dehler Ian McReath Nolan M. Dehler Rômulo Machado Alexis R. Nummer Multidisciplinaria (Ciencias Naturales y Exactas) extrusion transpression divergent fan transtensional deformation Shear zones geometry in the Paraíba do Sul belt, southeastern Brazil, delineates a NE-trending fan-like structure.Shear zones dip towards SE in the northern limb, and towards NW in the southern one. This geometryhas been interpreted either due to transpression or to late folding of flat-lying thrust surfaces. Stretchinglineation plunges to ENE-ESE in the northern limb and towards NNE-NE in the southern one. Structural datain the southern limb of the divergent fan suggest a two stage kinematic evolution in high-temperature conditions:an earlier stage with top-to-SSW/SW sinistral thrusting and orogenic-parallel tangential motion, and alater stage with top-down to NNE/NE transtensional deformation. We propose a heterogeneous deformationmodel to explain the observed shear reversal, and suggest that the imposed transpressional displacementgradient may change during progressive deformation due to transient rheological inhomogeneities in bulkpure shear strain. In the earlier stage, the partially molten material could easily accommodate the imposedstrain rates, giving rise firstly to the SW-directed shearing. As the thermal disturbance tended to vanishand the convergence increased, the NNE-directed transtensional shearing developed. We propose that thetranstensional deformation characterized in this paper could be related to extrusion processes during regionaltranspressional strain. 2006 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32778214 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.2 Vol.78 |
| title | Kinematics and geometry of structures in the southern limb of the Paraíba do Sul divergent structural fan, SE Brazil: a true transtensional shear |
| topic | Multidisciplinaria (Ciencias Naturales y Exactas) extrusion transpression divergent fan transtensional deformation |
| url | https://www.redalyc.org/articulo.oa?id=32778214 |