Abstract
Many landslides have been occurred in the Mikabu green rocks distributed in Shikoku Island. One of many factors of landslide occurrence is the formation of clay minerals by weathering and/or hydrothermal alteration process.
A lot of boring core specimens from the landslide areas where the Mikabu green rocks are distributed, Nuta/Youne and Kage landslide areas in Kohchi Prefecture, were collected. In this study, clay minerals formed in the boring cores were identified and their formation processes were discussed. As results, two different alteration zones were recognized by claymineral assemblage as follows;
Brownish zone: Chlorite, Chlorite/Smectite, Smectite, Vermiculite.
Greenish gray zone: Chlorite, Swelling chlorite, Chlorite/Smectite, Smectite.
