吉野川谷,美馬町中上の土柱層から見出された高度変成岩礫  [in Japanese] Gravels of high-grade metamorphic rocks from the Dochu Formation, Nakaue, Yoshinogawa Valley, East Shikoku, Japan  [in Japanese]

A condensed bed of the gravels derived from high-grade metamorphic rocks has firstly found in the lower Pleistocene Dochu Formation, from the Nakaue outcrop, Mima-cho in Tokushima Prefecture. The metamorphic gravels are garnet amphibolite, spotted amphibolite, serpentinite and coase grained piedmontite-quartz schist.The content of the metamorphic gravels is nearly 10 percent. Comparison with the modern original gravels, based on the mineral composition and rock texture on the slab, the metamorphic gravels were identified with the Sambagawa Metamorphic Rocks. Among them, garnet amphibolite and spotted amphibolite are high-grade metamorphic rocks that the modern distribution is restricted only in the Higashi Akaishi-yama district, central Shikoku, and the amphibolite gravels are rarely found in recent Yoshino-gawa riverbed around the Mima-choarea. The Nakaue outcrop and gravels of high-grade metamorphic rocks were described, and the provenance of the gravels was discussed with tectonic and geomorphological respects.