Abstract
The Triassic geosynclinal strata, the crystalline schists and the Cretaceous strata are distributed in the north of Yuasa. In this article, the structural relationship between the crystalline schists and the Triassic strata was investigated. The crystalline schists separately occur in two zones, south and middle parts of the present area. Detailed field investigation resulted in that the crystalline schists in the both zones are in fault contact with the Triassic strata. The low-angle thrust in the south part and both low-angle thrust and high-angle fault in the middle part are recognized. The low-angle thrusting prior to the high-angle faulting, similality of the original lithologic facies of the crystalline schists in the both zones, close association of the crystalline schists and the Cretaceous strata in their distribution and unconformity between the crystalline schists plus the Triassic strata and the overlying Cretaceous rocks are worthy of note in clarifying the history of structural relationship between the crystalline schists and the Triassic strata. It may be concluded that the crystalline schists in the both zones lay as a continuous body above the Triassic strata with the low-angle thrust during the early Jurassic period. The low-angle thrusting may be inferred to be a result of gravity gliding of the crystalline schists over the Triassic strata, which was probably related to marked uplifting of the members of the Kurosegawa Tectonic Zone.
