新潟県三島郡塚山周辺の地質と珪藻化石について
スポンサーリンク
概要
- 論文の詳細を見る
The geology and micro-paleontology of the Tsukayama District in Santo-gun, Niigata Prefecture, known as the " Hachikoku oil-field," have been studied by the present writer. The geological map and stratigraphical classification of the Tertiary and the Pleistocene rock along Tsukanoyama〜Suganuma route in this district are shown in table 1 and figure 1. The columnar section, composition of the diatom assemblage of each horizon, change of sedimentary environments assumed from the former is shown in figure 2. From these works, The followings are concluded: 1) On the basis of the present stratigraphical survey the B Formation (≒Nishiyama Formation) composed of silt〜mudstone seems to be the deposit in the sublittoral zone, influenced by the fresh water. This formation is also distinguished from the underlying ones by the presence of some extinct species (Denticula hustedtii, Fragllariopsis pliocena, Thalassiosira cfr. nativa and T. zabelinae etc.). 2) The C Formation (≒Haizume Formation), divided into C: and C_2, is supposed to be the brackish water deposits of the inner bay, although the diatom valves are so rich. The lower part (C_1) consists of sandy siltstone, and the upper part (C_2) of fine〜medium sandstone. 3) The D Formation mainly composed of wellsorted fine sandstone bluish gray in colour may correspond to the lowest part of the Uonuma group of Pleistocene. The diatom assemblage is represented by the dominance of fresh water species, slightly accompanied by the brackish water ones. 4) The E Formation corresponding to the lower part of the Uonuma group is composed of the irregular alternation of sandstone, conglomerate and siltstone deposited in fresh water basin. In this route the middle and the upper parts of the E Formation are not recognized.
- 地学団体研究会の論文
- 1972-03-25