近畿地方の新期新生代層の研究III : 大阪南方,和泉地域の大阪層群

概要

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The Osaka group which is composed of loose sediments such as gravels, sands, silts, clays and tuffs distributes in hills around the Osaka Plain and the Kyoto Basin. In this report the Osaka group in the Izumi Region locating to the south of the Osaka Plain is described with the detailed geological maps. The Osaka group overlies the basement rocks of the Ryoke Granites, the Sennan Acid-Rocks and the Izumi group of Cretaceous age, and underlies the Manchidani formation and the Higher-Terrace deposits. It is 170 to 210 m. in thickness and eight marine clay beds and eleven tuff-layers are inter-calated in it. These tuff-layers which are named T1, T2, and so on in ascending order are usefull for deciding the stratigraphical succession and the geological structures. The tuff-layers of T1, T2, T3, T4, T7, T9, and T11 are very continuous and are found in all areas where the Osaka group exists, and the Osaka group of this region can be well correlated by them with that of the Senriyama Hill as shown in Table 1. The Osaka group in this region is characterized by relatively thin sediments in comparison with that in the other areas, and the tuff-layers, however are rather thicker than in the other areas. The geological structure is shown precisely in Fig.10 which suggests that the structure of the Osaka group is strongly regulated by the shape of the basements below.
地学団体研究会の論文
1963-05-25