Various features of tectogenesis are analyzed and a physicochemical model of tectogenesis is presented. From thermodynamical considerations the energy source of tectogenesis is concluded as an abnormal heat flow from the mantle toward the crust. The heat flow is inferred to be directly related with a generation and upward transfer of basaltic magmas within the mantle. The model is a kind of heat engine in which a coupling among tectonic process, magma transfer, and metamorphism is existed. The efficiency of engine becomes an order of 0.1. Two varieties of hypotheses of tectogenesis, where the horizontal deformation and vertical movement of the crust are considered to have a primary significance respectively, are critically tested with respect to their efficiency. It is shown that the latter hypothesis can not be disregarded if only the crust is subjected to vertical movements. Numerical experiments are carried out to drive the model engine of tectogenesis. A thickening and vertical movement of the crust are assumed to be caused either by a plastic buckling or by a phase transition at the Moho. Variations in thickness and temperature of respective layers within the earth are computed using the high-speed computer. A sequence of sinking (geosyncline formation) and uplifting (mountain building) stages is deduced from the model of which time scales are 10^8 and 10^7 years respectively. Igneous activities accompanying by tectogenesis are also derived.

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The Quaternary deposits of Koriyama City and its environs from stratigraphical and topographical studies are divided into several formations and terraces, respectively. The stratigraphic units recognized are the Pleistocene Koriyama formation, the Iwashiro-atami terrace deposits, the Nishino-uchi terrace deposits, the Ogibukuro terrace deposits, the Arayashiki terrace deposits, the Tamagawa terrace deposits, the Holocene lower terrace deposits and the river deposits. The depositional plane of the Koriyama formation is preserved and represented by the flat surface and the depositional planes of each of the mentioned terrace deposits are preserved and represented by the suceessive terrace surfaces. No volcanic ash covering on the depositional plane of each of the formation and the terrace deposits is found in this area. From stratigraphical and geomorphological features correlation of the deposits and the terraces is undertaken with the result shown in Table 2. Especially, the KOriyama formation intercalates the peat beds at the three horizons, and contains the many plant fossils. The plant fossil assemblages from each of the three peat beds are somewhat varied in the floral composition,

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In the so-called unknown Mesozoic formations (Shimanto-gawa complex) around Takakuma-yama, phyllitec rocks are regionally developed. They are derived mainly from the pelitic and the alternations of pelitic and psammitic rocks, and also the basic tuffaceous rocks, through intense flattening with or without differential movement. This zone of phyllites is probably the southward extension of the phyllite zone along Nobeoka-Shibisan Tectonic Line in Central Kyushu. From the modes of occurrence of the phyllites, especially from its regional extent, these are not the products of mere faulting but are thought to represent the regional metamorphism through Alpine orogenic movement in the outermost terrain of the Outer Zone of Southwestern Japan as recently suggested by N, YAMASHITA (1960). I propose the name "Takakuma-yama regional metamorphic zone" for this zone of phyllites. Among several characteristic features reckoned in this zone, intimate distributional relation of the post-kinematic granitic stocks with this zone is stressed.

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The Okoku line from Yokote and Kitakami via Kawashiri provides a section of the Tertiary beds of Miocene. The beds dominantly consist of lapillituff, tuff, tuffaceous sandstone, tuffaceous silt stone and lava. The powdered samples of these rocks were X-rayed for an identification of the constituent minerals. The results were summarized in Fig.2 in relation to the stratigraphy of each rock specimen. From the mineralogical characters, it is suggested that the Miocene formations are classified into the two mineral zones for alteration as described below. The upper mineral zone : Middle to late Miocene (Nishikurosawa, Onnagawa and Funakawa stage). Characteristic minerals are clinoptilolite, analcite, montmorillonite minerals, cristobalite and calcite associating with a minor amount of chlorite and mica mineral (may be illite). The lower mineral zone : Early Miocene (Nishioga and Daijima stage). Characteristic minerals are chlorite, sericite (or illite) and epidote. Although felspar and quartz occur in the both zones, they are considered to have the two origins, i.e. detrital and authigenic, from a microscopical observation. The boundary between the two zones can be drawn in the Kawashiri tuff member correlated to Nishikurosawa formation in the Oga Peninsula, Akita. In order to make the identification of clinoptilolite more precisely, differential thermal analyses and high temperature X-ray diffraction studies of the rock specimen containing clinoptilolite as a main constituent have been done. From the results ,zeolite under investigation has been confirmed to belong to a clinoptilolite species redefined by F. A. MUMPTON. The mineral zone for alteration in this area has been tentatively correlated to that of Miocene beds in other several areas in Japan. From the data mentioned above and obtained from the supplementary microscopical observation, it is considered that alteration of the Tertiary beds under investigation is that of regional scale- a kind of diagenesis or metamorphism including two different mineral zones of the upper and the lower. The upper zone is almost equivalent to heulandite-analcite assemblages of the zeolite facies presented by COOMBS, et al., and the lower zone may be corresponding to the lower part of the zeolite facies or the upper part of the green schist facies (the muscovite-chlorite subfacies).

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