The characteristics of particle size and stable isotope compositions of smectite from the Hishikari gold deposit

Abstract

Smectites from veins and altered wall rocks of the Hishikari gold deposit were comparatively studied by means of the particle-size analysis and H- & O- stable isotope analysis to clarify the hydrothermal environment of smectite formation and the relationship with Au mineralization. Wall rock montmorillonite may be formed from hydrothermal water similar to present hot spring discharge originating from meteoric water. Vein montmorillonite may be a product of dissolution/reprecipitation in hydrothermal activity of low temperature, occurred at late stage or after vein formation. On the other hand vein saponite may be precipitate from high-temperature solution of different stage from montmorillonite formations.