RELATION BETWEEN DISLOCATION DENSITY AND SUBGRAIN SIZE OF NATURALLY DEFORMED OLIVINE IN PERIDOTITES

The subgrain size and the dislocation density of subgrain interiors were measured by the oxidation-decoration method under the optical microscope on naturally deformed olivine from peridotite xenoliths and alpine-type peridotites. Relation of the subgrain size, d and the dislocation density, ρ{variant}, within subgrains is represented by the equation, d=15/√ρ{variant}. Combining with relations of the differential stress and the dislocation density proposed by Kohlstedt and Goetze (1974), relation between the stress (σ) and the subgrain size becomes d=45 Gb/σ, where G and b are the rigidity and the magnitude of the Burgers vector of olivine. This relation is in good agreement with those in a simple oxide (MgO), and alkali halides (NaCl, LiF) given by Hüther and Reppich (1973), Poirier (1972), and Streb and Reppich (1973), respectively. © 1979 Springer-Verlag.