Texture development during progressive deformation of hematite aggregates: Constraints from VPSC models and naturally deformed iron oxides from Minas Gerais,Brazil |
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| Institution: | 1. Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, Beijing 100083, PR China;2. Corrosion and Protection Center, Key Laboratory for Environmental Fracture (MOE), University of Science and Technology Beijing, Beijing 100083, PR China;3. Center for Advancing Materials Performance from the Nanoscale (CAMP-Nano), State Key Laboratory for Mechanical Behavior of Materials, Xi''an Jiaotong University, Xi''an, Shaanxi 710049, PR China;4. Department of Mechanical Engineering, University of South Florida, Tampa 33620, USA;5. National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan, ROC |
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| Abstract: | We show that naturally-deformed hematite from the Quadrilátero Ferrífero Province, Minas Gerais, Brazil, develops CPOs by dislocation creep, strongly influenced by basal plane parallel glide, even when this is not the favored slip system. Characterization of microstructure and texture, particularly intragranular misorientations, of naturally deformed hematite aggregates by EBSD allowed us to determine the importance of different slip systems, and confirm dislocation creep as the dominant deformation mechanism. Viscoplastic self-consistent (VPSC) models were constructed to constrain the slip systems required to operate for the observed CPO to develop, and its rheological implications. Changes in the CRSS ratio of hematite prism and basal slip systems and deformation regime lead to the development of distinct patterns of hematite crystallographic orientations. The basal slip-dominated simple shear model is the only one that can develop quasi-single-crystal CPO of the kind observed in highly deformed rocks from Quadrilátero Ferrífero. Comparison between naturally deformed hematite aggregates and VPSC models shows that CPO development of hematite is strongly influenced by a highly viscoplastic anisotropy through dislocation creep on hematite basal plane. Nonetheless, our results demonstrate that even the unfavorable slip systems should be regarded when the bulk rheology of mineral aggregates is evaluated. |
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| Keywords: | Hematite EBSD VPSC Quadrilátero Ferrífero |
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