Microstructural observation on naturally deformed olivine: verification of ultra-low strain rate effect

Abstract

The purpose of this research is to confirm whether Fe concentration on dislocation core occurs in deformed mantle olivine, due to Cottrell atmosphere. The samples we observed are alpine type peridotites and mantle xenoliths in basalt. The present result is that Fe concentration is observed in the former, not in the latter samples. The microstructural observations suggest that the result of the mantle xenoliths is caused by static annealing or higher additional stress applied to the sample after steady state creep, or that the Cottrell atmosphere does not occur in the upper mantle.