Dynamic recrystallization of garnet and related diffusion processes

摘要: Abstract Electron backscatter diffraction and compositional data of Permian metapegmatite garnet from the Koralpe basement (Eastern Alps, Austria) show evolution distinct intracrystalline shear zones in c. 10 mm sized almandine–spessartine garnet. Orientation maps reveal continuous distortion crystal lattice. New grains (grain size 20–30 μm) within intragranular deformation zones, oriented subparallel to main foliation metapegmatite, have similar orientations host garnet, whereas recrystallized along fractures or growth heterogeneities a much weaker crystallographic preferred orientation (CPO). Needles kyanite as well inclusions apatite, xenotime rutile occur zones. Together with Ca variation across these give evidence material diffusion related plastic The individual porphyroclasts record recrystallization microfabrics. grains, once formed by subgrain rotation recrystallization, are able deform partly accommodated grain boundary sliding resulting weakening CPO. Whereas magmatic had taken place at LP conditions equilibrium andalusite, occurrence some triggered localized plasticity indicates that was Cretaceous HP metamorphic event.