Studies on the Neogene Tertiary strata distributed in the central part of Tottori prefecture

The Neogene Tertiary strata, distributed in the central part of Tottori Prefecture, are volcano-stratigraphically classified, as shown in Figure 3. The Miocene strata are divided into Ojika formation and Mitoku formation in ascending order. Ojika formation, composed of plagio-rhyolitic pyroclastics and lavas, abuts against the basement rocks. Furthermore, some breaccias derived from the talus basal conglomerate beds are found in Ojika formation. Mitoku formation abuts both against the basement rocks and Ojika formation, and sometimes overlaps on the basement rocks. From the investigation into the Miocene strata, it is clarified that the depression took place prior to the volcanic activities at the earliest stage of the present Miocene sedimentary basin. (author)