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Texturing in Earth’s inner core due to preferential growth in its equatorial belt

2011; Elsevier BV; Volume: 188; Issue: 3-4 Linguagem: Inglês

10.1016/j.pepi.2011.08.008

1872-7395

Renaud Deguen, Philippe Cardin, Sébastien Merkel, Ricardo A. Lebensohn,

earthquake and tectonic studies

We propose an extension of the model by Yoshida et al. (1996), where deformation in the inner core is forced by preferential growth in the equatorial belt, by taking into account the presence of a stable compositional stratification.Stratification inhibits vertical motion, imposes a flow parallel to isodensity surfaces, and concentrates most deformation in a shallow shear layer of thickness ∼ B -1/5 , where B is the dimensionless buoyancy number.The localization of the flow results in large strain rates and enables the development of a strong alignment of iron crystals in the upper inner core.We couple our dynamical model with a numerical model of texture development and compute the time evolution of the lattice preferred orientation of different samples in the inner core.With sufficient stratification, texturing is significant in the uppermost inner core.In contrast, the deeper inner core