地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
86 巻 , 3 号
選択された号の論文の6件中1~6を表示しています
  • 前田 四郎
    1977 年 86 巻 3 号 p. 141-157
    発行日: 1977/06/25
    公開日: 2009/11/12
    ジャーナル フリー
    The Permian Copacabana Group consisting of limestone, grey shale, and sandstone, is exposed, being scattered over the districts of Escoma, Carabuco, Ancoraimes, Isla del Sol, Peninsula de Copacabana, Tiquina, Peninsula de Cumana, Peñas, Yaurichambi, Colquencha, Santiago Llallagua, Apillapampa, Torotoro and elsewhere, in the Altiplano, Cordillera Oriental and Subandes regions. General trend of the distribution is from NW to SE through Titicaca Lake. In the Altiplano region, the Copacabana Group covers conformably the alternation of sandstone and shale of the continental Carboniferous System, and is unconformably overlaid by the clastic reddish rocks of the Lower Cretaceous Puca Formation.
    The Copacabana Group is represented predominantly by limestone and indicates the uniform sedimentary environment in the region. The limestone, light grey or dark grey in colour, contains such fossils as fusulinids, brachiopods, corals and others. The Group shows that the region was under the shallow sea. Judging from the fusulinid species, the Group is presumed to be Wolfcampian to Leonardian in age.
    The Group was deposited during the southward transgression from Peru into Bolivia in early Permian Period. The sea might be a southern extension of the Tethys, and it transgressed from northwest to southeast, cutting obliquely the axis of Cordilleras Oriental to the north of Poopo Lake. It is thought that the Potosi and the Tarija regions, the southern part of Cordillera Oriental, were elevated before the Group was deposited.
    In the Titicaca Lake region, the Group, together with the Lower Cretaceous Puca Formation, forms a large syncline, which is the Tiquina syncline extending from NW to SE, the axis of which passes through Tiquina channel. The axes of some other anticlines and synclines in this region run parallel to that of the Tiquina syncline. In the Cordillera Oriental region, the Group was also folded with the axes running from NW to SE. These geologic structures were cut off by the thrusts trending NW to SE. The thrusts were formed before the Tertiary System was deposited.
    In Bolivia, there were two remarkable crustal deformations, one was after the deposition of the Devonian System and the other was between the latest Cretaceous Period and the earliest Tertiary Period. The Bolivia region was emerged and suffered the denudation from the late Permian to the end of the Jurassic, after the Copacabana Group was deposited.
  • 福原 正弘
    1977 年 86 巻 3 号 p. 158-173
    発行日: 1977/06/25
    公開日: 2009/11/12
    ジャーナル フリー
    (1) About thirty years have passed since the end of the World War II. The Japanese economy recovered from the war ruins with the Korean war as a momentum, and since 1955 has achieved a remarkable growth. In 1972, its GNP reached 298, 700 million in nominal terms, the third largest in the world. Per capita national income, too, increased to 2, 285 which ranked 14th or 15th. Thus Japan has come to be rated as a major economic power.
    (2) Such rapid economic growth caused a fierce movement of population from farm areas to big cities. As a result, a phenomenon of excessive density and scarcity has emerged in the nation's distribution of population. And, at the same time, difference in economic expansion has become conspicuous among cities, and in particular the Tokyo Metropolitan area has registered a notable growth.
    Also, an increase in the national income and a rise in consumption standards have stimulated development of suburban-central-cities and suburban residential areas. In the course of this development, cities centering around the suburbs have come into existence, In this fashion, the rapid economic growth have had considerable effects on the regional structure of metropolis.
    (3) Theories on regional Structure of metropolis were published by the following three Scholars :
    (a) The Concentric Zone Hypothesis by E. W. BURGESS
    (b) The Sector Theory by H. HOYT
    (c) The Multi Nuclei Theory by C. D. HARRIS and E. L. ULLMAN
    In the field of geography, R. E. DICKINSON published the Theory of Concentric Circular Zones. Among these, the E. W. BURGESS' Concentric Zone Hypothesis has stood high in the estimation of the academic world.
    (4) According to the Concentric Zone Hypothesis, along with growth of a city such phenomena as centralization, specialization and segregation present themselves, and unique zoning develops inside of the city. Then, invasion and succession among these zones bring the result of concentric expansion of a big city. The listed factors to distort the concentric Structure are configuration of the ground, railroads and industries. These factors, however, are considered to be of secondary importance in theory.
    But, such concentric growth of a city is far from the actuality in cases of growth of Metropolis in the world. Especially in studying the regional structure of Japanese cities, in my opinion, configuration of the ground and railroads must be taken up as the prime factor. Also, the Sector Theory and the Multi Nuclei Theory should be combined, and the Concentric Zone Hypothesis be attached no more than secondary importance as the theory to valuate the yield of unit area from functions of location.
    (5) In this study, both the principle component analysis, a kind of the multivariate analysis, and the cluster analysis are employed. And, 162 cities, wards towns all villages which form the Tokyo metropolitan regions are covered.
    The subjects of this study are ever-five-year analyses and changes of the regional structure of the Tokyo Metropolitan Regions since 1955 based on 25 indicators.
    (6) A civic-center has been formed under historical and political conditions. Due to advantages of concentration, civic functions have been gathered in a very small area, and from time to time, parts of the functions have been transferred to zones in transition or sub-civic-centers. In this way, a civic center has continued to purify and enhance its civic functions by building of skyscrapers.
    On the other hand, the mainstay of civic centers has been shifted to a function of central supervision from the commercial and industrial function which was prominent for the period from 1955 to 1960.
    Judging by the component score of the principle component analysis, which indicates the degree of centralization of civic functions, in Tokyo, Chiyoda-ward surpassed Chuo-ward in 1960, and the difference in the degree between the two wards has tended to increase.
  • 白木 敬一, 黒田 直
    1977 年 86 巻 3 号 p. 174-190
    発行日: 1977/06/25
    公開日: 2009/11/12
    ジャーナル フリー
    Boninite occurring in Chichi-jima, Bonin Islands, is a rare rock, no exact equivalent known anywhere, and is a vesicular, feldspar-free glassy andesite according to SiO2 content (56-59%), consisting of phenocrysts of olivine (Fo90-85) and bronzite (En89-80), microphenocrysts and microlites of augite, and hydrous glass, with small quantities of Cr-rich spinel (Cr2O3 64-54%). Chemically it is characterized by high contents of MgO (12-6%) Cr (900-200 ppm), and Ni (300-100 ppm) similar to primitive basalts, apparently in ill accord with its intermediate SiO2 content. The boninite was first described in some detail by KIKUCHI (1890) and named by _PETERSEN (1891) after Bonin Islands coming from the Japanese “Bu-nin-sima” for no-man's islands. Surprisingly enough, this peculiar rock has since been touched upon only cursorily. We suggest that the boninite was formed by separation at shallow depths from hydrous mantle and rapid quenching from relatively high temperatures.
    The Bonin, or Ogasawara Islands, situated some 1000 km SSE of Tokyo, form the outer arc of the Idu-Marianas arc, and are composed of dominant volcanic rocks containing pillow lavas and subordinate sedimentary rocks with fossiliferous limestones, the age of which is Oligocene to early Miocene in Chichi-jima, the largest island, and Eocene in Haha-jima, the second largest one, lying 50 km south of Chichi-jima. The boninite, with subordinate bronzite-andesite, makes up the bulk of the pillow lavas in Chichi-jima, while in Haha-jima it has never been found. Volcanic breccias are composed mainly of hypersthene-andesite and-dacite,
    The magma of the boninite composition could exist in equilibrium with mantle peridotite at 10-5 kb, 1100-1050°C under water-saturated conditions, based on the experimental results of GREEN (1976) and NICHOLLS (1974). During its rise to the surface, olivine (and chromite) crystallized first from it, joined immediately later by bronzite, and augite was the last phase to crystallize. Before plagioclase is precipitated, the magma was erupted rapidly on sea floor to form the plagioclase-free glassy boninite pillow lavas. Available experimental data suggest that the boninite was quenched rapidly from a temperature of more than 900°C. The bronzite-andesite may represent a slowly cooled, relatively unfractionated part of the boninite magma. Low pressure fractionation involving removal of olivine, bronzite, augite, plagioclase, and magnetite could give rise to the hypersthene-andesite and -dacite from a parental boninite.
    The boninite bears some resemblance to the clinoenstatite-bearing volcanic rocks from Cape Vogel, Papua, which have crystallized first protoenstatite but not olivine, generated at higher temperatures than the boninite. The boninite may well be closely connected in genesis with magnesian andesites found in some orogenic calc-alkalic suites, suggesting a major role of water rising from the subduction zone.
  • 小林 貞一
    1977 年 86 巻 3 号 p. 191-207
    発行日: 1977/06/25
    公開日: 2009/11/12
    ジャーナル フリー
    This article consists of ten chapters, viz. (1) two new publications on the geology of Korea, (2) development of Korean geology, (3) Pre-Cambrian stratigraphy, (4) the Joseon (i. e. Chosen) group, (5) the Pyeongan (Heian) group, (6) Mesozoic formations, (7) Cenozoic formations, (8) Palaeozoic and later intrusive rocks, (9) geotectonic development of Korea and (10) reminiscence of research in geologic history of Korea
    .Tateiwa published “History of Geological Research in Korea, ” 1956 and in 1976 a compilation of reviews of Korean geological publications before 1946. Prior to this the present author wrote “Geology of South Korea etc.” in 1953 and “A Contribution to the Geotectonics of Noth Korea and South Manchuria, ” in 1954, revised the former, 1967 and the latter, 1969 and printed in Geology and Mineral Resources of the Far East, vols. one and two. Among foreign publications are three on the similar subject as follows :
    V. L. Masaitis, : Geology of Korea, 1966.
    Kim Jongrai : The Geology and Useful Mineral Resources of Korea, 1967.
    A. J. Reedman and Um Sang Ho : The Geology of Korea, 1975.
    Carl Christian Gottsche (1855-1909), Bunjiro Koto (1856-1935) and Hisakatsu Yabe (18781969) are pioneers respectively of geology, geotectonics and palaeontology of Korea. The history of research in her geology may be divisible into the 1918 and older age of reconnaissance survey, the age of the Geological Survey of Chosen and the Fuel and Ore Dressing Research Center, 1918-1945, and the age since the two organizations have been unified in 1946.
    The Pre-Cambrian geology was greatly advanced in the third age with an aid of geochemical chronology. The stratigraphy of the Ogcheon (or Yokusen) metamorphic group is now a subject of moot discussion in South Korea. The Joseon group is the best zonated unit in Korean stratigraphy. The author's conclusion that the group of the Duwibong (Tsuibon) type is heteropic from but synchronous with the group of the Mungyeong-Yeongweol (Bunkei-Neietsu) type is now quite warranted by macro-as well as micro-palaeontology. (See fig. p. 60 (132) in part 1).
    In 1962 the Jeongseon (Seizen) limestone and a few other strata of the Taebaengsan region were presumed by certain geologists to be Middle Palaeozoic. but without fossil evidence. Subsequently this misunderstanding was, however, rectified by the discovery of Middle Ordovician conodonts in the limestone and other facts. Lately Carboniferous fusulinids were found in the limestone near Danyang whence the so-called Devonian type corals had been reported.
    Recently the Cretaceous stratigraphy of Southeast Korea was largely revised by K. H. Chang. In his new classification the Naktong series was bisected and its upper part was combined with the Silla series into the Hayang group, because the Naktong trough in which the Sindong group i.e. lower Naktong series was accumulated was closed and the Hayang group was deposited in the large Silla basin beside the new small Yeongyang basin where the former's basement was divided into two blocks at the entrance of the Hayang age. Furthermore, the Pulgogsa series by Tateiwa was spilitted into the Yucheon volanic group and the Pulgogsa granite series.
    Two extraordinarily important conclusions are that the Pulgogsa granites should be divided into the middle-upper Jurassic.Daebo granite series and the late Cretaceous-early Tertiary Pulgogsa granite series s. str. and that the Daebo granites are extensive to the north of the Sobaegsan-Taebaegsen region and elongated in the Sinian trend whereas the Pulgogsa granite series which is restsicted to the south of the Gyeonggi massif is less extensive in Southeast Korea and reveals no Sinian elongation.
  • 宮久 三千年
    1977 年 86 巻 3 号 p. 208-209
    発行日: 1977/06/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 小林 茂
    1977 年 86 巻 3 号 p. Plate1-Plate2
    発行日: 1977/06/25
    公開日: 2009/11/12
    ジャーナル フリー
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