Abstract
1) This district is divided by E-W strike faults into nine narrow zones., Kobayashi and Iwaya reported "the imbricaed structure with low-angled thrust planes" in the Sakuradani area east of the present district, but the faults in the latter district are always vertical., Therefore, "Decke" structure as described by Kobayashi and Iwaya cannot be supported, so far as the present district is concerned., 2) The Paleozoic and Mesozoic formations differ remarkably from each other in rock facies and in distribution., The rocks of the former are more strongly disturbed than those of the latter., These facts suggest that the crustal movement before the deposition of the Middle Triassic Zohoin series might have been stronger than that hitherto been considered., 3) The differences between the upper Triassic Kochigatani series and the Middle Triassic Zohoin are rather slight compared with those between the Paleozoic and the Zohoin., And thus the two series form a group more or less sharply distinguished from the Paleozoic and Younger Mesozoic formations., 4) The younger Mesozoic formations from another group, covering the older formations clino-unconformably., They are roughly correlated with the so-called Torinosu-Ryoseki-Monobegawa series, ranging from the Upper Jurassic to Lower Cretaceous., The unconformity at their base shows that a folding movement occurred already in the Jurassic Period., 5) The Palezoic and Mesozoic formations were folded and faulted after the deposition of the so-called Monobegawa series., According to T., Kobayashi, the "imbricated structure of the Sakuradani area" may be a product of his "Sakawa Orogenesis of Sakawa Phase", that is Middle Cretaceous in age., But the present writer supposes from his study in the "Katsuragawa Basin" to the NEE of the present district that the Middle Cretaceous crustal movement was not so strong as thought by Kobayashi, and that the most important movement occurred after the deposition of the Upper Crertaceous formation of the Hanoura district., 6) Among three types of igneous rocks, the Takamarusan Igneous Body, gabbro and diorite, intruded into the Paleozoic formation., Serpentines occur as thin intrusives along some of the E-W faults., A granodiorite, seen along the northernmost fault, shows a cataclastic texture.,
