Ca-metasomatism of the Mantle Wedge: an Example from the Khantaishir Ophiolite in the Chandman area, Western Mongolia

Abstract

Hydration and metasomatism of mantle wedge are thought to cause drastic changes of mechanical properties of plate interfaces. In this study, we report outstanding alteration textures of orthopyroxene as an evidence for significant Ca-metasomatism from the ultramafic bodies in the Khantaishir ophiolite, the Chandman area, western Mongolia. Microstructures and mass-balance calculation suggest (1) Ca and water are gained, and (2) Ca could be derived from the external sources. We will discuss the relationship between the eclogite bodies and the mantle wedge in the Chandman area.