AN INTERSTRATIFIED ILLITE/SMECTITE MINERAL VEIN FOUND IN CHAOTIC ROCK FROM THE NIKORO GROUP IN THE ACCRETIONARY TOKORO BELT, NORTHEASTERN HOKKAIDO, JAPAN

Abstract

Interstratified illite/smectite mineral was found as a clay vein in the Toyomi landslide-prone area in Kitami City, northeastern Hokkaido, Japan. The white with a slight green tint drusy interstratified illite/smectite mineral vein was observed in chaotic rock of the Nikoro Group in the accretionary Tokoro Belt. The interstratified illite/smectite mineral is associated with calcite, quartz, and chlorite. The mode of occurrence and mineral assemblage indicate that the interstratified illite/smectite mineral precipitated directly from the hydrothermal solution having a near neutral pH.