Title: STRATIGRAPHY AND GEOLOGICAL AGE OF THE TAGA GROUP IN THE JOBAN COAL-FIELD OF FUKUSHIMA AND IBARAKI PREFECTURES
Abstract: Recently, an unconformity was recognized within the so-called Taga Group distributed widely in the Joban coal-field(Sugai and Matsui, 1957). The purpose of the present study is to make the stratigraphic correlation of the so-cal!ed Taga Group distributed in the separated sedimentary basins and to discuss the age of the Group。 The results of the present study can be summarized as 丘)110ws;(1)Thesocalled Taga Group should be subdivided into two formations (Table 2), each separated by an unconformity. (2) The geological age of the strata below the unconformity are Late Miocene and that above the‘unconformity Early Pliocene. Hence, the unconformity between the formations marks the Miocene°Pliocene boundary in the Joban coal-field. Introductioii The writerでs take great pleasure in dedicating this article to Dr. Kotora Hatai, Professor Emeritus of the Tohoku University in commemoration of his retirement fi・om the Tohoku University. The so-called Taga Group (Sugai and Matsui, 1957) is widely distributed in the Joban coal-field, extending from the southeastern part of Fukushima Prefecture southwards to the northeastern part of Ibaraki Prefecture (Fig. 1). The majority of the studies for the stratigraphic classification and geological age of the so°called Taga Group have been left in manuscript form, and the published articles show that the stratigraphic classification and formation names proposed for the group differ with the sedimentary basins and no unification had been proposed to‘date. Arid, the Taga Group had been considered to range in age fiヽomMiocene to Pliocene。 It had been the general thought that no unconformity existed within the Taga group・ However, recently, Mitsui and Ouchi investigation of the so-called Taga Group distributed i“ the Izumi-Ueda district (Mitsui and Ouchi, 1972), and Mitsui's study of thegroup in the Yotsukura Area (Mitsui, 1973),,・revealed the presence of an unconformity in the group and pointed that it marks the Miocene°Pliocene boundary in the Joban coal-field. Subsequently an unconformity ithin the Taga Group was discribed in the Hirakata-Otsu Area by Endo (1971 MS) and also in the Isohara and Takahagi areas by Hasegawa (1971 MS)。 The purpose of the present study is to correlate the so-called Taga Group distributed in the separated sedimentary basins, and to discuss the age of the Group・ 104 高知大学学術研究報告 第22巻 自然科学 第4号 To clarify these problems is important to determine the age of the fold and 亀ult structures developed in the formations in the Joban coal“field. Acknowledgements 。 The writers take this opportunity to express their deep gratitude to Prof. Nobu Kitamura, Associate Prof. Yokichi Takayanagi, and Dr. Hiroshi Noda, all of the Institute of Geology and Paleontology, Tohoku University and to Dr. Taro Kanaya of Tokyo。 Deep appreciation is due to Dr. Kotora I-Iatai,Professor Emeritus of the Tohoku University, for his kiりd guidance and criticalreading of the manuscript, and to Prof. Jiro Katto of the Institute of Geology, Faculty of Literature and Science, Kochi University,Prof. Yasuhiko Kamada of the Institute of Geology, Facu!ty of Education, Nagasaki un沁ersity,and to Dr. Kazuyoshi Okami, Department of Mining and Civil Engineering, Faculty of Technology, I ate University, for their suggestions on the stratigraphy, paleontology and problems on sedimentology l・elevant to the present study. The field works for this study were supported in part by th(きGrant in Aid for scientific Research from the Ministry of Education, Japan.
Publication Year: 1973
Publication Date: 1973-01-01
Language: en
Type: article
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