第四紀研究
Online ISSN : 1881-8129
Print ISSN : 0418-2642
ISSN-L : 0418-2642
22 巻 , 1 号
選択された号の論文の5件中1~5を表示しています
  • 松岡 数充, 西田 史朗, 金原 正明, 竹村 恵二
    1983 年 22 巻 1 号 p. 1-10
    発行日: 1983/04/30
    公開日: 2009/08/21
    ジャーナル フリー
    紀伊半島北部の倶留尊山東麓の池ノ原湿原から, 泥炭を主とする440cmの堆積物を採取し, それについて地質学的・花粉学的検討を行なった. その結果は以下のようである.
    1. 採取試料の地表から26cmと220~230cmに火山灰層が挾在し, 前者をA.D. 946に降灰記録のある白灰と推定し, 後者をアカホヤ火山灰層に同定した.
    2. 14C年代測定の結果は, 210~220cmが5,630±70y. B.P., 230~240cmが6,680±85y. B.P., 400~410cmが11,400±120y. B.P. であった.
    3. 採取試料中の花粉化石の出現状況から, 6つの花粉群集帯を認めた.
    4. 花粉群集の解析結果から, この地域では冷温帯落葉広葉樹林から照葉樹林への移行の間の8,400~6,300y. B.P. に温帯針葉樹林が成立していた可能性を指摘した.
    5. この地域での照葉樹林は, 4,300年前項に最盛期を迎えた. これは, 大阪湾沿岸にくらべ1,500年から2,000年, 深泥池にくらべると数100年の遅れを示している.
    6. 当地域での森林の二次林化の要因は, 農耕地や居住地の穫得によるものではなく, またその影響は, 奈良盆地や田原盆地に比べておよそ1,000年ほど遅れている.
  • 五十嵐 八枝子, 石井 次郎, 河内 晋平, 山崎 哲良, 宮坂 省吾
    1983 年 22 巻 1 号 p. 11-18
    発行日: 1983/04/30
    公開日: 2009/08/21
    ジャーナル フリー
    The Karurusu Clay Bed (13m in thickness) is deposited following the Noboribetsu Pumice Flow Deposit, from Kuttara Volcano, The 14C age of the Bed is older than 35, 500y.B.P. and is inferred to be a little older than that of the Shikotsu Pumice Flow Deposit (ca. 32, 000y.B.P.).
    The paleoclimatic condition deduced from the pollen assemblage, such as Betula, Picea, Corylus, Alnus and other several broad-leaved trees suggests a little cooler than present. Clay mineral compositions of the Bed are montmorillonite, randomly mixed-layer mineral of montmorillonite and illite, kaolinite, pyrophyllite and degrated illite. Gypsum is also found.
  • 大村 明雄
    1983 年 22 巻 1 号 p. 19-22
    発行日: 1983/04/30
    公開日: 2009/08/21
    ジャーナル フリー
  • 三好 真澄
    1983 年 22 巻 1 号 p. 23-41
    発行日: 1983/04/30
    公開日: 2009/08/21
    ジャーナル フリー
    The purpose of this paper is to review work on the about age and distribution of marine terraces since the last interglacial in 22 areas (excluding Japan) of the world (Fig. 1 and Table 1).
    The results are as follows. 1) Distribution and uplift rate: There are a number of marine terraces lower than the last interglacial terrace (S terrace) in 12 areas; where the height of the S terrace is over 30m and the uplift rate since the formation of the S terrace is 0.3m/1000yrs. This uplift rate is the minimum rate required to expose all terraces between the S terrace and 60KA terrace, assuming that (1) tectonic uplift continues at a constant rate, and (2) the sea-level curve of MACHIDA (1975) is correct. Especially, in the areas adjacent to the trenches of plate boundary, the height of the S terrace attains 300-400m, and the uplift rate since the formation of the S terrace range between 1.5 and 3.1m/1000yrs. The difference in the uplift rate of each area is perhaps due to differences in the character of the mobile belts (OTA and NARUSE, 1977). The marine terraces younger than the S terrace are found in the “zone of plate convergence” or “zone of plate transformation”. Especially, in the “zone of plate convergence” where the uplift rate is great, many marine terraces are developed.
    2) Age of terraces: The marine terraces dated ca. 100KA, 85KA and 60KA are recognized in many places of the world (Fig. 2). These ages agree well with relatively warmer episodes (Stages 3 and 5) in the oxygen-isotope stages founded in a tropical Pacific deep-sea core (SHACKELTON and OPDYKE, 1973). It is obvious that the formation of these terraces is essentially affected by sea-level fluctuations due to glacial eustasy, as has alreadly been proposed. Dates of samples mostly concentrate at 85KA then around 100KA and 60KA. This suggests the magnitude of transgressions.
    Marine terraces between 50KA and 30KA have been reported in California, New Guinea, New Hebrides, India, Mediterranean and South Africa. As a result of the combined effect of crustal movement and eustatic sea level change (BLOOM et al., 1974), the uplift rate since the formation of the S terrace requires more than 1.5m/1000yrs. mento expose the former shorelines above present sea level. In the former three areas tioned above, the uplift rate is higher than this value, but in other areas, it is less. Further studies concerning the acceleration of uplift rate towards the present, modification of the paleo sea level and cross checking of dates are necessary.
  • 1983 年 22 巻 1 号 p. 60
    発行日: 1983年
    公開日: 2009/08/21
    ジャーナル フリー
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