第四紀研究
Online ISSN : 1881-8129
Print ISSN : 0418-2642
ISSN-L : 0418-2642
18 巻 , 2 号
選択された号の論文の5件中1~5を表示しています
  • 黒田 登美雄, 畑中 健一
    1979 年 18 巻 2 号 p. 53-68
    発行日: 1979/08/31
    公開日: 2009/08/21
    ジャーナル フリー
    黒田・太田 (1978) は, 福岡市天神地区から得られた堆積物の花粉分析結果から, 後期更新世 (約2万年前) に本地域に分布していた Fagus, Carpinus, Tilia, Quercusより成る冷温帯落葉広葉樹林が, 気候の温暖化により照葉樹林に移行した経過について報告した.
    今回は, 天神地区より西へ約2kmの荒戸 (Arato) 地区の試料につき花粉分析を行い, 後期更新世-完新世の気候変化 (寒冷→温暖) に対応した植生変遷史につき重要な知見を得た.
    分析試料は, 地下鉄工事現場の深度4.7m~10.2mの露頭から直接採取したが, 花粉分析の結果, 下部から上部にかけて, L, RI, RII, RIIIaの4花粉帯が区別された.
    L帯: Alnus, Betula, Carpinus, Artemisia.
    RI帯: Ulmus, Carpinus, Quercus, Celtis, Mallotus.
    RII帯{初期: Shiia, Cyclobalanopsis, Quercus, Carpinus, Ulmus, Celtis. 中期: Shiia, Cyclobalanopsis, Podocarpus, Myrica. 末期: Shiia, Cyclobalanopsis, Quercus.
    RIIIa帯: Shiia, Cyclobalanopsis, Quercus, Pinus, Abies, Gleichenia.
    以上の花粉分帯は, 中村 (1968, 1975a, 1975b) が提唱した後氷期の花粉分帯, 塚田 (1967, 1974a, 1974b) によって確立された晩氷期から後氷期にかけての花粉帯にそれぞれ対比することができる.
    本研究の総括として, 晩氷期以降の植生変遷に対応する古環境および絶対年代, 推定年代を検討し, Table 2 に示した.
  • 松下 勝秀
    1979 年 18 巻 2 号 p. 69-78
    発行日: 1979/08/31
    公開日: 2009/08/21
    ジャーナル フリー
    The Ishikari coastal plain is situated in the northwestern end of the so-called Sapporo-Tomakomai Lowland in Hokkaido, and bears such topographic features as coastal sand dunes, ridged beach plain, the older dunes and back marshes.
    The present report intends to clarify sea levels, stratigraphy and sedimentary process of deposits after the Würmian glacial maximum (20, 000-18, 000 years B.P.).
    At first buried landforms of the area in the Würmian glacial maximum are considered on the basis of many boring data. Consequently the shape and the depth of four buried terraces deposits (Bt1-Bt4), palaeo-delta and buried valleys have been discriminated. Among them Bt1 was formed before the eruption of Shikotsu volcano (caldera). Bt2-Bt4 and palaeo-delta deposits were formed after the Paudorf interglacial epoch untill the Würmian glacial maximum. Whereas gravel beds of buried valleys were flood plain deposits of old rivers in the Würmian glacial maximum. Estimation of sea level at that time of glacial age is difficult owing to that the Ishikari coastal plain was a land area then. However it is almost certain that the sea level was at least 65 meters below the present one.
    Then, the sea gradually invaded into the land, following transgression after the Würmian glacial maximum, and palaeotopographic relief was completely buried by later deposits, of which the upper part is characterized by the presence of black, soft clay. Later temporary regression caused a sand bar linking mountains southwest to the Ishikari hills in the northeast. Finally it developed to a sand-gravel barrier at the place of Momijiyama sand dune, and it created a big change in sedimentary environments of the area. Namely thereafter, swampy deposits were developed in the inland parts of the sand-gravel barrier, and rows of beach ridges were developed in seaward.
    The Bannaguro lowland formed by the development of continuous sedimentary processes when the sea level was 4-4.5 meters higher than the present one. From radiocarbon dating of marine shells contained in the deposits of beach ridges, it was clarified that the age of high sea level (4-4.5 meters) continued from 5, 800 to 2, 000 years B.P.
    Then followed a sudden lowering of sea level down to the present one and we see the present topography.
  • 川村 智子
    1979 年 18 巻 2 号 p. 79-88
    発行日: 1979/08/31
    公開日: 2009/08/21
    ジャーナル フリー
    In order to investigate the distributional history of Cryptomeria japonica in the Late Quaternary, the pollen analyses were made on six moors: Utonaito and Konuma moors in Hokkaido, and Narugo, Moniwa-Takada, Menuma and Hoshojiri moors in Tohoku district. The results show that Cryptomeria pollen increase around 2, 000y.B.P. in the investigated area except Hokkaido of the northern Japan. Cryptomeria japonica has never distributed in the Late Holocene, at least, in Hokkaido. Further, as a result of investigating many data of Tohoku district, the increasing ages of Cryptomeria pollen are 1, 500-4, 500y.B.P. in each region. From the fact, it is suggested that Cryptomeria japonica doesn't spread uniformly all over the place. Roughly speaking, from these facts and the previous many data, there is the tendency that the increasing ages of Cryptomeria pollen are newer in the north than in the south of Japan. So, it seems that Cryptomeria japonica spread from south to north after the Late Glacial Age.
  • 渡辺 一徳, 籾倉 克幹, 鶴田 孝三
    1979 年 18 巻 2 号 p. 89-101
    発行日: 1979/08/31
    公開日: 2009/08/21
    ジャーナル フリー
    This preliminary report gives the distribution of the active faults, their geomorphological features and the relationship between the parasitic eruption centers and the active faults found on the west flank of the Aso caldera.
    1) Many active faults are distributed on the west flank of the Aso caldera. NE trending faults dip north with right-lateral displacement. They are geomorphological manifestations of the Oita-Kumamoto tectonic line.
    2) Rate of vertical displacement of the Futagawa-fault, a principal fault in the studied area, is 1.7 to 0.6mm/y. for recent 350, 000 years as indicated by the displacement of the Aso pyroclastic flow deposits.
    3) The Hinagu-fault joins the Oita-Kumamoto tectonic line near the southern end of the Futagawa-fault.
    4) Lowland along Kiyama to Kashima formed by the active faulting is named Kiyama-Kashima graben. Narrow graben is also developed along the Hinagu-fault.
    5) It is noteworthy that the grabens are situated right outside of bending of Southwest Honshu arc from SW to SSW trend, the trend of the Ryukyu arc.
    6) Eruption centers of the parasitic volcanoes of the Aso caldera are situated at local tensional stress fields formed by right-lateral faulting of echelon arrangement active faults.
  • 太田 陽子, 岡田 篤正, 早川 唯弘
    1979 年 18 巻 2 号 p. 103-105
    発行日: 1979/08/31
    公開日: 2009/08/21
    ジャーナル フリー
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