巻号一覧
29 巻, 1 号
選択された号の論文の6件中1～6を表示しています
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端山 好和, 山田 直利, 山田 哲雄, 沓掛 俊夫, 仲井 豊, 赤羽 久忠, 池田 極, 田辺 元祥原稿種別: 本文
1975 年 29 巻 1 号 p. 1-17
発行日: 1975/01/20
公開日: 2017/07/26
ジャーナル オープンアクセスIn the studies of the Ryoke metamorphic belt of central Japan, we classified the granitic rocks into two groups, the granitic rocks intruded into the Nohi rhyolite probably of the Late Cretaceous and the older ones, and clarified that the formation of the Ryoke metamorphic rocks is closely associated with the older granitic activities. However, we could not resolve the problem of the age relation between the Nohi rhyolite and the oldei granitic rocks. In the Osaki-shimojima Island, western Japan, it has been known that the metamorphosed Paleozoic sediments are unconformably covered by the rhyolitic pyroclastic rocks called the Kubi formation which roughly corresponds to the Nohi rhyolite in age. The main purpose of our present study is to make clear whether the metamorphosed Paleozoic sediments are truely the Ryoke metamorphic rocks or not. In this island, the Kubi formation consists of, in ascending order, the basal conglomerate member which unconformably overlies the Paleozoic rocks, the rhyolitic tuff member, the andesitic welded tuff member and the dacitic welded tuff member. Both the Paleozoic sediments and the Kubi formation are intruded by the granites in the northern and the southen parts of the island, and, consequently, they are thermally metamorphosed in the most part. The metamorphosed Paleozoic sediments of this island are, mainly, biotite hornfels and cordierite hornfels. They are not the Ryoke metamorphic rocks, at least, in their present metamorphic features. On the other hand, the development of schistose structure and ptygmatic quartz vein is frequently conspicuous in these hornfelses, and their distribution has no relationship to the form of granitic bodies. Moreover, in the basal conglomerate of the Kubi formation, the metamorphic rocks with schistose structure and ptygmatic quartz vein are contained as pebbles. These facts suggest that the regional metamorphism took place before the sedimentation of the Kubi formation. This regional metamorphism is considered to be the Ryoke metamorphism, judging from the geology of surrounding areas, especially of the Itsukishima Island, belonging to the Ryoke metamorphic belt, 4 km south of the Osaki-shimojima Island. The granitic rocks of the Osaki-shimojima Island are not a member of the Ryoke granites, judging from the conspicuous lattice structure of microcline, the common existence of fluorite and bluish color of hornblende in addition to their general rock feature. They may belong to the Hiroshima granites possibly younger than the Ryoke granites.抄録全体を表示PDF形式でダウンロード (3972K) -
濁川 明男, 西片 武原稿種別: 本文
1975 年 29 巻 1 号 p. 18-35
発行日: 1975/01/20
公開日: 2017/07/26
ジャーナル オープンアクセスWe have treated the result of the analysis of the diatom assemblages contained in the surface layers of the bottom sediments and those attached at aquatic plants, which were gathered in five lakes around Mikata Town, in Fukui Pref., two lakes around Kaga City in Ishikawa Pref., and Kahoku Lagoon. We studied chiefly about the relation between chlorine content, pH and the diatom assemblages. In our study the identified taxon were 44 genera, 135 species, 10 varieties and one form. In the chemical feature of water, the five lakes around Mikata are sea water to mesohaline water, Kahoku Lagoon is mesohaline water, and the two lakes around Kaga City are oligohaline water to fresh water. In the five lakes around Mikata, marine to brackish epiphytic forms are dominant and oceanic planktonic forms are not found at all. Characteristic species are Melosira moniliformis, Cocconeis scutellum, Navicula arenaria. In Kahoku Lagoon brackish epiphytic forms are also dominant, and especially Amphora robusta, Cyclotella striata, Cyclotella meneginiana, Navicula delta and Navicula arenaria are present. The two lakes around Kaga City are characterized by oligohaline species and mesohaline species. The difference between biocoenosis and thanatocoenosis could be recognized, but both of them may be controled by chlorine conditions in the water area.抄録全体を表示PDF形式でダウンロード (3496K) -
犬塚 則久, 長谷川 善和, 野苅家 宏原稿種別: 本文
1975 年 29 巻 1 号 p. 36-44c
発行日: 1975/01/20
公開日: 2017/07/26
ジャーナル オープンアクセスNumerous fossil bones of Naumann's elephant, Palaeoloxodon naumanni (MAKIYAMA) have been unearthed from the Latest Pleistocence sediments of the bottom of Lake Nojiri, northern central Japan (KAMEI & TARUNO, 1973). By the time of the excavation at Tategahana, Lake Nojiri in March of 1973, rather well-preserved stylohyoid bone of Naumann's elephant was newly found. As the occurrence of such proboscidean stylohyoid bone in fossil state is very rare and the first time in Japan, a description in details on that specimen and a comparative study with those of living Asiatic elephant, Elphas maximus and African elephant, Loxodonta africana are given in this paper. For convenience, the stylohyoid bone of the elephant is divided into three parts, and they are nominated as inferior-, superior- and posterior ramus. As a result of study, it has become clear that there are some remarkable morphological differences among those fossils and living materials. Namely, 1) The stylohyoid bone of Naumann's elephant is characteristic in having a distinct and stout process at the dorsal border of the base of the posterior ramus. 2) The stylohyoid bone of African elephant has distinct before and behind expansion at the proximal portion of the inferior ramus. 3) The twisting of the inferior ramus is represented to be the most in the case of the stylohyoid bone of Naumann's elephant.抄録全体を表示PDF形式でダウンロード (1859K) -
神谷 英利, 小林 巌雄原稿種別: 本文
1975 年 29 巻 1 号 p. 45-54c
発行日: 1975/01/20
公開日: 2017/07/26
ジャーナル オープンアクセスThe writers studied on the internal structure, mineral component, inorganic elemental composition and others of some tests of fossil Echinarachnius having various macroscopic characteristics from the Neogene and Quaternary sediments, mainly the Narita Formation, Pleistocene. They used for these investigations the optical microscopic observation, X-ray analysis, chemical analysis and EPMA method. Summary of the results obtained is described in the following. 1. Three types of the internal structure of optical microscopic level have been recognized in fossil echinoidean tests examined. The first one is that retain the network structure which is observed in the recent sample, the second is that partially preserved the network structure and the third is that completely lost the original structure. It does not always follow that these types of the structural pattern correspond to the external view of preservation of the fossil tests. 2. The tests which have clear network structure are mainly composed of high magnesian calcite, and the tests in which the network does not recongnized are composed of low magnesian calcite. Namely, the change of the morphological pattern of the internal structure well corresponds to that of the mineral component. 3. The internal structure and the mineral component of the brownish tests resemble to those of recent samples. It may be considered that the brownish color due to some iron compound, and the positive relation can be recognized between iron contents and magnesium contents.抄録全体を表示PDF形式でダウンロード (3953K) -
Bowen学説との闘い(その2)牛来 正夫原稿種別: 本文
1975 年 29 巻 1 号 p. 55-59
発行日: 1975/01/20
公開日: 2017/07/26
ジャーナル オープンアクセスPDF形式でダウンロード (877K) -
日本の第四紀層の14C年代(105)庄子 貞雄, 安藤 豊, 増井 淳一原稿種別: 本文
1975 年 29 巻 1 号 p. 60-iii
発行日: 1975/01/20
公開日: 2017/07/26
ジャーナル オープンアクセスPDF形式でダウンロード (266K)
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