Sheared lherzolite xenoliths revisited

摘要: [1] The microstructures of sheared lherzolite xenoliths from South African kimberlites are investigated using new microstructural analysis techniques and rheological data. By applying electron backscatter diffraction (EBSD) methods the M-index technique for quantifying strength lattice preferred orientation (LPO), it is demonstrated that olivine orthopyroxene, after an initial stage dynamic recrystallization, deformed by different mechanisms: dislocation creep, while orthopyroxene a grain-size sensitive mechanism randomized preexisting LPO. New data, which incorporate effects pressure on deformation, applied to these xenoliths. The shown dramatically reduce inferred strain rates in comparison previous estimates. contrasting features analyzed Avrami theory coupled with observations experimental This suggests (1) difference recrystallized (2) completeness can be largely explained contrast grain boundary mobility between orthopyroxene.