北海道北部猿払村の沖積層コアの珪藻分析:-塩分指数と電気伝導度の検討-  [in Japanese] Diatom analysis of the uppermost Pleistocene to Holocene drilled core at Sarufutsu, northern Hokkaido, Japan::Investigation of salinity index and electrical conductivity  [in Japanese]

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<p>北海道北部の猿払川流域の沖積層から,中湿原コア(全長33 m,HU-SRN-1)とアカエゾ松林コア(全長9 m,AEM-1)を採取し, 堆積環境を明らかにするために放射性炭素年代や電気伝導度(EC)の測定,珪藻分析を行った.コアは層相に基づき下位より頁岩相,砂礫相,泥炭質シルト相,砂質シルト相またはシルト相,泥炭質砂質シルト相および泥炭相に区分される.本地域の完新世の堆積環境は下位より淡水域,汽水域,淡水域へと変化し,汽水化した原因は縄文海進によるものと考えられる.中湿原コアの海水流入開始は深度27 m(標高 -15.2 m)付近で,その年代は約8,990 cal BP と推定される.珪藻群集から求めた塩分指数とEC 値の相関係数は0.38 前後で,塩分指数の曲線は猿払湿原と北海道中央部の石狩平野の沖積層の対比の可能性を示唆している.</p>

<p>In order to clarify sedimentary environment of the latest Pleistocene to Holocene sediments, Chuseki-so, geologic core of 33 m (HU-SRN-1) and 9 m core (AEM-1) in length were obtained at the Sarufutsu, northern Hokkaido. Radiocarbon dating, electrical conductivity measurement, diatom analysis and lithofacies division were carried out on the cores. Results of diatom analysis of the HU-SRN-1 core show the sedimentary environment changed fresh waters, brackish waters and fresh waters in ascending order, and seawater inundation during Holocene transgression occurred at 27 m in depth (15.2 m below sea level) at ca. 8,990 cal BP. Correlation coefficient in the HU-SRN-1, ca. 0.38, is computed by electrical conductivity and salinity index, determined from diatom assemblages. Distinctive features in curved lines of salinity index infer possibility of stratigraphic correlation of Chuseki-so in two different areas, Ishikari, central Hokkaido, and Sarufutsu.</p>

Journal

  • Earth Science (Chikyu Kagaku)

    Earth Science (Chikyu Kagaku) 72(1), 1-10, 2018

    The Association for the Geological Collaboration in Japan

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