第四紀研究
Online ISSN : 1881-8129
Print ISSN : 0418-2642
ISSN-L : 0418-2642
22 巻 , 4 号
選択された号の論文の4件中1~4を表示しています
  • 辻 誠一郎, 南木 睦彦, 大沢 進
    1984 年 22 巻 4 号 p. 279-296
    発行日: 1984/02/29
    公開日: 2009/08/21
    ジャーナル フリー
    相模地域の後期更新世の大型植物化石・花粉化石群集を記載し, 植物群と植生, および古環境を論じた.
    植物分類・地理学上注目すべきイワヒバ・カラマツ・トウヒ各属の大型植物化石の形態を記載した. このうちトウヒ属は, トウヒ, ヒメバラモミの2種とトウヒ属A・B・Cの3型に分けられた.
    主に, スギおよびヒメバラモミからなる冷温帯針葉樹林が約9万-6万年前に優勢であった. これは上部冷温帯の年降水量の多い湿潤な気候を示す. 約6万-5.5万年前の三崎海進を通じての植生は, 冷温帯のナラ類林の拡大によって区別される. これは年降水量の少ない比較的温暖な気候を示す. 約5.5万-5万年前の主にヒメバラモミとカラマツ属からなる亜寒帯ないし冷温帯針葉樹林は, 関東地方で従来知るかぎり後期更新世における最初の寒冷気候を示す. この時代は立山で確認された室堂氷期にあたる. 亜寒帯針葉樹林と冷温帯落葉広葉樹林の間の移行的な混交林が約1.6万-1.3万年前に優勢であった. このような森林は更新世末期の南関東に分布拡大していたと思われる. この時代の富士山東麓における亜寒帯針葉樹林の下降は1,000m以上であった.
    (地名)
    Eda 荏田
    Ekoda, Egota 江古田
    Iseyamabe 伊勢山辺
    Kyuden 給田
    Nippa 新羽
    Rengeji 蓮花寺
    Shijuhasse River 四十八瀬川
    (地層名)
    Kissawa L. 吉沢ローム層
    Younger L. 新期ローム層
    Anjin Pumice 安針軽石
  • 竹村 利夫, 藤井 昭二
    1984 年 22 巻 4 号 p. 297-312
    発行日: 1984/02/29
    公開日: 2009/08/21
    ジャーナル フリー
    There are many active faults in central Japan. Several active faults distributed in the northern part of the Hida mountains are described in detail in this paper.
    The Atotsugawa, Mozumi and Ushikubi faults, 40-80km in length, are NE-ENE in trend and displaced to the right side. The amounts of horizontal displacement as revealed in the offsets of the streams crossing the fault lines are about 1-3km, and the amounts of vertical displacement are 100-300m with the northwest side upthrown.
    The Kazura fault, 30km long, is NNW in trend and displaced to the left side. The amount of horizontal displacement is 1km as recognized from the stream offset, and the amount of vertical displacement is 100-200m with the west side upthrown.
    The Atotsugawa fault has displaced the Pleistocene terraces and lake deposits (20, 000- 40, 000y.B.P.) as much as 50-60m vertically at the outcrops of the Magawa River area located up the Jyoganjigawa River. Also the Holocene terraces (about 500y.B.P.) have been displaced 1-4m vertically. The average vertical displacement rate of the Atotsugawa fault is 1-4m/1000y., and the average lateral displacement rate is 1-5.7m/1000y. as judged from the pitch θ of striation on the fault planes.
    Several outcrops are found along the Mozumi, Ushikubi and Kazura faults. Late Pleistocene and Holocene terraces have been cut and displaced by faults. The average rate of displacement was 0.4-1.5m/1000y. in vertical displacement. The lateral component of displacements are usually larger than or nearly the same as the vertical components.
    These faults can be ranked as A class or the upper half of B class in degree of activities.
  • 近藤 務, 五十嵐 八枝子, 吉田 充夫, 赤松 守雄
    1984 年 22 巻 4 号 p. 313-325
    発行日: 1984/02/29
    公開日: 2009/08/21
    ジャーナル フリー
    A stratigraphic study was made on the Quaternary deposits in the borehole at Shizukawa, situated in the southeastern marginal part of the Sapporo-Tomakomai Lowland in Hokkaido. The core of the borehole is divided lithostratigraphically into 8 formations, namely SZ-I to SZ-VIII Formation in ascending order.
    Each formation is characterized, apart from its lithology, by molluscan fossils, pollen assemblage, palaeomagnetic property and tephra identification (Fig. 3, Table 3).
    The results of the study are summarized as follows:
    1) SZ-I Formation is possibly correlated with the Lower Pleistocene, because the horizons of reversed magnetic polarities are dominant in the Formation. Pollen assemblage indicates that the sedimentation occurred under a cooler climatic condition than that of the present age in this area.
    2) SZ-II and SZ-III Formations, deposited during the Brunhes Normal Epoch, are probably correlated with the Middle Pleistocene. SZ-II Formation, mainly consisting of marine sediments, deposited during the time range when it was somewhat warmer and more humid than today. The Formation is reasonably correlated with the Hayakita Formation distributed in the Atsuma area, on the basis of common pollen assemblages in both formations. The geologic age of the Formation is provisionally correlated with the M/R Interglacial Age.
    SZ-III Formation intercalates peaty beds which indicate the existence of a boreal forest. The authors will call the age of the deposition of the beds “Shizukawa Cold Age”. The age may be correlated with the Riss Glacial Age.
    3) SZ-IV Formation, having some marine deposits in the lower part, may have been deposited under a similar climatic condition to that of the present age. The Formation is possibly correlated with the Atsuma Formation on the basis of the features of its pollen assemblages. The range of the Formation may be correlated with the early Late Pleistocene, namely the R/W (Last) Interglacial Age.
    4) The time range of the three formations, namely SZ-V, SZ-VI and SZ-VII, is probably correlated to the Würm (Last) Glacial Age. SZ-VI Formation, including the same key tephras, namely the Azuma ash fall deposits (>43, 200+4, 300-2, 700y.B.P.), is reasonably correlated to the Hongo Formation which has been considered as the deposits during the early Würmian Glacial Age. SZ-VII Formation intercalates the Shikotsu pumice fall deposits (from about 35, 750±1, 350y.B.P. to 32, 200+4, 700-3, 100y.B.P.). The time range of the SZ-V Formation is presumed to be almost the same as that of SZ-VI Formation on the basis of its stratigraphic position.
    5) SZ-VIII Formation is the Holocene.
  • 成瀬 敏郎, 小野間 正巳
    1984 年 22 巻 4 号 p. 327-331
    発行日: 1984/02/29
    公開日: 2009/08/21
    ジャーナル フリー
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