地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
105 巻 , 1 号
選択された号の論文の15件中1~15を表示しています
  • 鈴木 啓助
    1996 年 105 巻 1 号 p. 1-14
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
    Chemical studies of the stream water in a small forested watershed were conducted at Aidzu-Tajima, Fukushima prefecture. The experimental watershed is located under the snowy temperate climate, and has an area of 0.14 km2. The bedrock of the watershed consists of consolidated sediment formed in the Neogene. The watershed is entirely covered with forest vegetation. Maximum monthly precipitation is observed in summer however, maximum monthly runoff is recorded in snowmelt season. The HCO3- concentration of stream water is diluted by snow meltwater, and episodic increase of concentrations of Cl-, NO3- and SO24- is observed during the snowmelt season. The pH of stream water is lower during the snowmelt season than summer and autumn. The ionic composition of stream water is variable according to the seasons. Bicarbonate is the major anion in summer, and the ratio of Cl-+NO3-+SO24- increases in snowmelt season. The factor analysis is applied to the data matrix of chemistry of stream water. In the winter season, the explained variance of factor 1 which relates to acidity of stream water is 38.7 %, and the explained variance of factor 2 which relates to sea water origin is 28.4 %. Two thirds of variation of stream chemistry is explained by the chemical factor released from snowcover by melting.
  • 長岡 大輔, 西城 潔, 福田 正己, 中村 俊夫
    1996 年 105 巻 1 号 p. 15-30
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
    There exists large scale ground ice, which locally called “Edoma”, in plains along the Arctic coasts of eastern Siberia and the New Siberian Islands. The Edoma is mainly composed of massive ground ice with pillar-shaped frozen soil. The massive ice is considered as syngenetic ice-wedge origin, which develops alternative accumulations of ice-wedge and sedimentation on ground surface. The soil pillars are arranged in regular intervals of several meters in the massive ice, and contain a lot of ice lenses and several peat layers.
    A geological and geochemical survey was carried out in the Bykovsky Peninsula near the Lena Delta (Loc. 1), Bolshoi Lyakhovsky Island, the southern part of the New Siberian Islands (Loc. 2) and Oiyagosky Yar facing the Arctic Sea in middle of eastern Siberia (Loc. 3). Results of grain size analysis and determinations of radiocarbon datings of the Edoma in these surveyed sites were summarized as follows :
    1) Sediments of the Edoma in Loc. 1 are composed of dark gray silt to fine sand with a lot of organic matters. Compositional ratio of grain size varies vertically, and is characterized by bimodality in the grain size distribution. This suggests that the sediments were formed under two different transportation agents. Sediments of the Edoma both at Loc. 2 and Loc. 3 characterized by dark gray to brown silt, and also contains abundant organic matter. Grain-size distribution of these sediments is similar to the finer population in Loc. 1. Judging from the characteristics of grain size distribution, these sediments are considered as aeolian deposits.
    2) Radiocarbon ages at Loc. 1 scatter within a range from about 30, 000 to 20, 000 yr BP in upper part and about 11, 000 yr BP in uppermost. The ages at Loc. 2 are resulted in about 30, 000 to 40, 000 yr BP in case of the most parts and about 7, 000 yr BP at uppermost part in permafrost just under the active layer. At Loc. 3, most of the ages of the Edoma are determined over 40, 000 yr BP and that of uppermost is determined as about 22, 000 yr BP.
    Based on the results of radiocarbon dating mentioned above, it is suggested that the Edoma in eastern Siberia might have formed during Karginkiy Interstadial to Sartan Stadial in the Last Glacial stage, and especially main parts of the Edoma developed during Karginkiy Interstadial, in which period climate was more unstable than Sartan Stadial. Grain size distribution of sediments also suggest that the Edoma have accumulated under the sedimental condition at water flood plain or marsh, which were favorable locations to growth of syngenetic ice wedge as well as loess accumulation. Supply of sediments in Loc. 1 may have been stable because the main transport of sediments have been performed by fluvial activities of the Lena River and the wind action. On the other hand, since the sediments in Loc. 2 and Loc. 3 is probably derived from aeolian loess, the amounts of supplied sediments might have been less than Loc. 1. Therefore, flux of sedimentation, forming the Edoma in Loc. 1 maintained longer than those at Loc. 2 and Loc. 3.
  • 竹中 克行
    1996 年 105 巻 1 号 p. 31-52
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
    Most of the previous studies on the internal migration in Spain, although quantitatively important at regional and provincial level, have been largely centered in some limited aspects. Among the major trends that characterize the previous research, the followings are reconsidered in this study : 1) much importance given to net migration at regional and provincial level, rather than to migration flows themselves with great variety in spatial dimension and direction 2) frequent use of the regional demarcations, institutionalized as Comunidades Autónomas (Autonomous Communities), as a basic unit of analysis, which makes difficult to some extent the best use of the statistical data available on the theme.
    In this study, the internal migration in Spain from 1962 to 1993 is analyzed from the viewpoint of migration flows, with special emphasis on the spatial scale and direction of migration as well as the migration fields. The main source of data is the Estadistica de Variaciones Residenciales (EVR) published by the Instituto Nacional de Estadistica (INE) , which contains origin-destination tables disaggregated to provincial level, and data concerning the characteristics of emigrants and immigrants in each province. The EVR is complemented by the census data in some respects. The province is employed as the basic unit of analysis.
    The evolution of the spatial scale and direction of migration shows a radical change in the middle 1970's : migrations from 1962 to 1975 (first period) were unidirectional movements at great distance (interprovincial and interregional), whereas those from 1976 to 1993 (second period) are characterized by the weight of intraprovincial movements and the bidirectionality of interprovincial movements. Through the two periods, the major sector in which migrants are employed has shifted from the industry to the service sector. For the second period, the following groups are found to show high mobility : professional and technical workers, government officials and directors of companies and corporations, and workers with high educational level.
    The factor analysis was applied to the interprovincial migration in order to find the major migration fields in each of the two periods mentioned above, which in turn are divided in two sets of short periods. Again clear changes are observed between the two principal periods : in the second period, the migration fields are fragmenting, and none of the immigration center has strong power of attraction, in consequence of the bidirectionality of migratory movements. Special attention should be paid to the decline of the migration field of Barcelona and the expansion of that of Madrid, as well as the early reduction of the migration field of the Basque Country to intraregional scale. The migration fields extracted here do not coincide in many cases with the preestablished regional division, which confirms the effectiveness of the method of study by which no territorial aggregation of data is done prior to the analysis.
    The occupational structures of migrants are also examined to see characteristics of each migration field. The result of the analysis shows that the dominant occupations of migrants have evolved not only in response to the sectoral changes in Spanish economy as a whole, but in correspondence with the modifications of spatial patterns of migration. In this context, it is noticeable that there are increasing number of residential movements around the metropolitan areas that do not depend on the creation of new jobs, especially in the migration fields of Barcelona and the Basque Country.
    If most of the previous studies put emphasis on the net migration, it is because the migration balance between regions and provinces was supposed to represent the vertical movement from rural to urban area.
  • 植松 英行, 指田 勝男
    1996 年 105 巻 1 号 p. 53-66
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
    Well-preserved Late Jurassic radiolarians are recovered from allochtho-nous blocks of the Torinosu-type limestone embedded in the Early Cretaceous Hinodani Formation, northern Subbelt of the Shimanto Terrane, Shikoku. Based on the faunal composition, this radiolarian fauna is assigned to that of Late Jurassic Tithonian. The Torinosu-type limestone which contains this radiolarian fauna was deposited as marginal reef or shelf margin carbonates on the accreted Togano Group or its equivalents. The radiolarians were captured in ooid grainstone and bioclast wackestone and fossilized under the peculiarly suitable condition for preservation. Radiolarian-bearing limestones deposited on the reef or carbonate mound show certain sedimentary sequences and biofacies. These limestones intercalated in the Torinosu Group or its equivalents were deposited on the continental shelf or slope and emplaced as one of the constituents of olistostrome in the Hinodani Formation by submarine slidings in late Early Cretaceous time.
  • 小松 俊文, 安藤 寿男
    1996 年 105 巻 1 号 p. 67-76
    発行日: 1996/02/25
    公開日: 2010/02/25
    ジャーナル フリー
    Non-marine to marine deposits of the Lower Cretaceous Idaira Formation are exposed in north of the Lake Hamana, the western part of Shizuoka Prefecture. The Idaira Formation unconformably overlies the Chichibu Supergroup and is in fault contact with the supergroup. It is divided into three members, namely the lower, middle and upper members.
    The lower consists of the basal massive conglomerate and cross-bedded sandstone, and the upper black shale and intervening lenticular-or flaser-bedded sandstone. The latter part abundantly contains such brackish molluscan fauna as Protocardia ibukii, Costocyrena otsukai and Cassiope neumayri, and the Ryoseki-type flora. The two parts are interpreted to be alluvial fan and estuary/ lagoon deposits respectively.
    The middle member is composed of large-scale cross-bedded, conglomeratic sandstone with well-sorted sandstone and laminated shale, sometimes including the Ryoseki-type flora. Its sedimentary environment is thought to be braided river on fan delta.
    The upper is represented by outer shelf, laminated to massive black shale intercalated with cross-laminated sandstone layers. It yields Barremian ammonite (Shasticrioceras nipponicum), and offshore thin-shelled bivalves (Parvamussium kimurai) and echinoids.
  • 吉田 明夫, 伊藤 秀美, 細野 耕司
    1996 年 105 巻 1 号 p. 77-87
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
    Several examples are presented which seismic quiescence appeared in a wide area around the foci of intraplate earthquakes before their occurrence. A noteworthy feature is that the quiescence area extends along tectonic zones over more than several times of the focal region of the main shock. This phenomenon suggests that stress in a wide area along tectonic zones changes before the occurrence of major intraplate earthquake. We consider that the stress change is a manifestation of a significant physical process leading to earthquake occurrence. An apparently puzzling fact which earthquake precursors are sometimes observed at distant places from the focal region in the specific direction may be explained by such stress change. Further, it is expected that the precursory seismic quiescence provides us with a promising clue to the short-term prediction of intraplate earthquake.
  • 岸 清, 宮脇 理一郎
    1996 年 105 巻 1 号 p. 88-112
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
    From detailed stratigraphy including tephra, bio-and magneto-stratigraphy, we studied the process of folded structure development in Pliocene to early Pleistocene strata distributed in the Kashiwazaki plain and its vicinity, central Japan. Four folding phases are recognized; 1) from 2.8 to 2.4 Ma in the southern part and the southward of Chuo Hills, 2) from 2.0 to 1.5 Ma in Teradomari-Nishiyama Hills and its front area corresponding to continental shelf, 3) ca 1.0 Ma in the southern part of Chuo Hills, and 4) from 0.7 to 0.3 Ma in the northern part of Chuo and Hachikoku Hills. Besides them an active folding is observed in the eastern side of the Shinano River, the activity having commenced in latest Pleistocene.
    Each folding phase was relatively short lived from 0.4 to 0.5 Ma. In general, the intervals among these folding activities were geologically calm without any notable progress of folding activity. The culmination of folding activity had successively migrated eastward since last 3 Ma.
  • 村山 祐司, 尾野 久二
    1996 年 105 巻 1 号 p. 113-124
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 1996 年 105 巻 1 号 p. 125a
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 1996 年 105 巻 1 号 p. 125b
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 1996 年 105 巻 1 号 p. 125c
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 白尾 元理
    1996 年 105 巻 1 号 p. 125
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 鎌田 浩毅
    1996 年 105 巻 1 号 p. Plate1-Plate2
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 鎌田 浩毅
    1996 年 105 巻 1 号 p. Plate3
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 長岡 大輔, 西城 潔, 福田 正己, 中村 俊夫
    1996 年 105 巻 1 号 p. Plate4-Plate6
    発行日: 1996/02/25
    公開日: 2009/11/12
    ジャーナル フリー
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