Dislocation structure around fluid inclusions in olivine and orthopyroxene

Abstract

Dislocations provide a direct proof of plastic deformation of minerals. In olivine, dislocations surrounding fluid inclusions were observed to be greater along [100]. Dislocation density decreases with increasing distance from the fluid inclusion. This would be a result of plastic deformation of olivine engendered by excess pressure of the fluid inclusion. On the other hand, we can scarcely observe dislocation around fluid inclusions in orthopyroxene, indicating that yield strength of olivine is much weaker than that of orthopyroxene. More precise investigation of dislocation microstructure around the fluid inclusion tells us various rheological properties of a host mineral.