Abstract
Deformation and recrystallization of hematite in iron formations and high-grade ore bodies of the Cauê Formation from the Quadrilátero Ferrı́fero District, Minas Gerais, Brazil, resulted in several types of fabrics, depending on the tectonic and metamorphic imprint. The fabrics vary from randomly oriented granoblastic to strongly oriented lepidoblastic/mylonitic with local development of cataclastic features.Complete pole figures of the crystallographic planes (003)-basal plane; {110}-prism and {104}-rhombohedron were measured on several samples from different areas by means of neutron diffraction revealing a typical crystallographic preferred orientation for the different fabric types. The configuration and intensity of the maxima are directly related to the magnitude of the deformation and the type of response of the ore.The analysis of the textures and microstructures of the iron ores and comparison with experimental deformation data lead us to the conclusion that three main mechanisms are active: basal slip, diffusion processes and anisotropic grain growth. Post-tectonic recrystallization and secondary grain growth did not affect the textures developed during deformation.
Published Version
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