久世・鏡野地域における三郡変成岩とジュラ系智頭層との構造関係 <論文>

Based on the results of a field survey, we describe in this paper the structural relationship between the Sangun metamorphic rocks and the Jurassic Chizu Formation in Okayama Prefecture, southwest Japan. The Sangun metamorphic rocks are a high-pressure type and commonly display three generations of foliation. The Chizu Formation is a tectonic mélange and has suffered from low-grade metamorphism. We infer from the distribution of the Sangun metamorphic rocks and Chizu Formation in the southwestern part of the surveyed area that the Sangun metamorphic rocks underlie the Chizu Formation in fault contact. This result indicates that high-pressure-type metamorphic rocks do not always overlie the accretionary prism, such as in the relationship between the Sanbagawa metamorphic rocks and Shimanto Formation in Shikoku, Japan.