フィッション・トラック熱年代に基づいた六甲地域の冷却・削剥史 Cooling and Denudation History of the Rokko Area, Southwest Japan, Based on Fission-track Thermochronology

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著者

    • 末岡 茂 SUEOKA Shigeru
    • 京都大学大学院理学研究科地球惑星科学専攻 Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University
    • 田上 高広 TAGAMI Takahiro
    • 京都大学大学院理学研究科地球惑星科学専攻 Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University
    • 堤 浩之 [他] TSUTSUMI Hiroyuki
    • 京都大学大学院理学研究科地球惑星科学専攻 Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University
    • 荒井 章司 ARAI Shoji
    • 金沢大学理工学域自然システム学類 School of Natural System, College of Science and Engineering, Kanazawa University
    • 山田 隆二 YAMADA Ryuji
    • 独立行政法人防災科学技術研究所地震研究部 Earthquake Research Department, National Research Institute for Earth Science and Disaster Prevention
    • 松田 達生 MATSUDA Tatsuo
    • 独立行政法人防災科学技術研究所地震研究部 Earthquake Research Department, National Research Institute for Earth Science and Disaster Prevention
    • 小村 健太朗 OMURA Kentaro
    • 独立行政法人防災科学技術研究所地震研究部 Earthquake Research Department, National Research Institute for Earth Science and Disaster Prevention

抄録

 Quantitatively estimating denudation is generally difficult because it essentially involves the removal and loss of materials in situ. The denudation rate of mountainous areas in Japan has commonly been studied from the volume of sediment in a basin or catchment. Nonetheless, the availability of these methods is constrained spatially by upstream area and temporally by depositional age. In the last few decades, thermochronometric methods that evaluate thermal history using radiometric-dating methods have been used to evaluate the denudation and tectonic history of orogenic belts around the world. The advantages of thermochronometric methods are that we can calculate the denudation rate at each sampling point and that combining multiple methods and/or target minerals enables us to calculate denudation rates in multiple periods. However, thermochronometric methods have been applied to areas with extraordinarily high denudation rates in island arc areas such as Japan. Thus, the effectiveness of thermochronometric methods for estimating denudation rates in island arc areas has not been demonstrated. We applied apatite and zircon fission-track thermochronometry to granitic rock samples collected from outcrops and a borehole to estimate the tectonic history of the Rokko area, southwest Japan. Previous studies suggested that the Rokko Mountains have been uplifted by active faulting along their northern and southern margins during the Rokko movements, a Quaternary tectonic movement in the Kinki district. However, the tectonic history of the Rokko area prior to 1 Ma has not been revealed due to a lack of prevalent geologic markers. We estimated average denudation rates in various periods based on apatite and zircon FT ages and previously reported radiometric ages. We obtained denudation rates at about 0.04-0.10 mm/yr after about 30 Ma, 0.05-0.7 mm/yr during 50-30 Ma, 0.7-4.0 mm/yr during 70-50 Ma. The denudation rate after the deposition of the Kobe Group (36.9-30.4 Ma) is estimated to be in the 0.01-0.1 mm/yr order, while bedrock uplift rate after about 1 Ma is estimated to be about 0.5 mm/yr. Thus, the tectonic activity of the Rokko Mountains area prior to 1 Ma has been relatively low.

収録刊行物

  • 地學雜誌

    地學雜誌 119(1), 84-101, 2010-02-25

    公益社団法人 東京地学協会

参考文献:  62件中 1-62件 を表示

被引用文献:  1件中 1-1件 を表示

各種コード

  • NII論文ID(NAID)
    10030368061
  • NII書誌ID(NCID)
    AN00322536
  • 本文言語コード
    JPN
  • 資料種別
    ART
  • ISSN
    0022135X
  • NDL 記事登録ID
    10597342
  • NDL 雑誌分類
    ZM41(科学技術--地球科学)
  • NDL 請求記号
    Z15-169
  • データ提供元
    CJP書誌  CJP引用  NDL  J-STAGE 
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