A study of generation process of " cleavable olivine" based on the microstructural observation

Abstract

Cleavable olivine shows the distinctive cleavage filled by antigorite. Such olivine has been reported at various serpentinized ultrabasic complexes and in the ultrabasic rocks collected from several serpentinite seamounts in the Izu-Ogasawara-Mariana forearc. However, the formation process of cleavable olivine has not been fully understood, so far. The purpose of this study is to clarify its formation process through microstructural observation. Our study suggests strongly that the subgrain boundary created by dislocation creep and the pipe diffusion of H₂O along the subgrain boundary are important to create the cleavable olivine.