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Shearing mechanisms of MgSiO 3 at conditions of the Earth's D″ layer
Author(s) -
Zahn Dirk
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl048203
Subject(s) - perovskite (structure) , shearing (physics) , post perovskite , stacking , materials science , stacking fault , slip (aerodynamics) , geology , shear (geology) , mineralogy , crystallography , composite material , chemistry , thermodynamics , mantle (geology) , geophysics , physics , dislocation , organic chemistry
It is shown that the mechanic properties of MgSiO 3 at temperature and pressure conditions of the Earth's D″ layer are strongly affected by perovskite/post‐perovskite stacking faults and, more generally, perovskite → post‐perovskite → perovskite phase transitions. We employ molecular dynamics simulations to explore different shearing routes for {010} layers in the perovskite structure. While the yield strength was found as about 1 GPa for layer displacement along [100], [101] and [001], the underlying mechanisms differ considerably. Shear along [101] induces the formation of a perovskite/post‐perovskite stacking fault. Once such a stacking fault arrangement is formed, further shearing is facilitated and the yield strength is reduced to 0.25 GPa. Thus, perovskite/post‐perovskite stacking faults and/or perovskite/post‐perovskite phase interfaces are suggested as the preferential slip layers of MgSiO 3 in the Earth's D″ layer.