Magnetic fabric of Araguainha complex impact structure (Central Brazil) : implications for deformation mechanisms and central uplift formation.

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dc.contributor.authorYokoyama, Elder
dc.contributor.authorTrindade, Ricardo Ivan Ferreira da
dc.contributor.authorLana, Cristiano de Carvalho
dc.contributor.authorSouza Filho, Carlos Roberto de
dc.contributor.authorBaratoux, D.
dc.contributor.authorMarangoni, Yára Regina
dc.contributor.authorTohver, Eric
dc.date.accessioned2012-10-22T12:50:19Z
dc.date.available2012-10-22T12:50:19Z
dc.date.issued2012
dc.description.abstractThe weakening mechanisms involved in the collapse of compleximpact craters are controversial. The Araguainhaimpact crater, in Brazil, exposes a complexstructure of 40 km in diameter, and is an excellent object to address this issue. Its core is dominated by granite. In addition to microstructural observations, magnetic studies reveal its internal fabric acquired during the collapse phase. All granite samples exhibit impact-related planar deformation features (PDFs) and planar fractures (PFs), which were overprinted by cataclasis. Cataclastic deformation has evolved from incipient brittle fracturing to the development of discrete shear bands in the center of the structure. Fracture planes are systematically decorated by tiny grains (< 10 μm) of magnetite and hematite, and the orientation of magnetic lineation and magnetic foliation obtained by the anisotropies of magnetic susceptibility (AMS) and anhysteretic remanence (AAR) are perfectly coaxial in all studied sites. Therefore, we could track the orientation of deformation features which are decorated by iron oxides using the AMS and AAR. The magneticfabrics show a regular pattern at the borders of the central peak, with orientations consistent with the fabric of sediments at the crater's inner collar and complex in the center of the structure. Both the cataclastic flow revealed from microstructural observations and the structural pattern of the magnetic anisotropy match the predictions from numerical models of compleximpactstructures. The widespread occurrence of cataclasis in the central peak, and its orientations revealed by magnetic studies indicate that acoustic fluidization likely operates at all scales, including the mineral scales. The cataclastic flow made possible by acoustic fluidization results in an apparent plastic deformation at the macroscopic scale in the core.pt_BR
dc.identifier.citationYOKOYAMA, E. et al. Magnetic fabric of Araguainha complex impact structure (Central Brazil): implications for deformation mechanisms and central uplift formation. Earth and Planetary Science Letters, v. 331-332, p. 347-359, maio 2012. Disponível em: <https://www.sciencedirect.com/science/article/pii/S0012821X12000155>. Acesso em: 22 out. 2012.pt_BR
dc.identifier.issn0012821X
dc.identifier.urihttp://www.repositorio.ufop.br/handle/123456789/1708
dc.language.isoen_USpt_BR
dc.rights.licenseO periódico Earth and Planetary Science Letters concede permissão para depósito deste artigo no Repositório Institucional da UFOP. Número da licença: 3315440555391.
dc.subjectMicrostructurespt_BR
dc.subjectAraguainhapt_BR
dc.subjectMagnetic anisotropypt_BR
dc.subjectCompleximpact craterpt_BR
dc.subjectWeakening mechanismpt_BR
dc.titleMagnetic fabric of Araguainha complex impact structure (Central Brazil) : implications for deformation mechanisms and central uplift formation.pt_BR
dc.typeArtigo publicado em periodicopt_BR
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