Relationship between Oxygen Stable Isotope Ratios Recorded in a Cascade Tufa from Tokunoshima Island and Pacific Decadal Oscillation

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Other Title
  • 徳之島のカスケードトゥファに記録された酸素安定同位体比と太平洋十年規模振動の関係

Abstract

<p>Tufas are carbonate sediments that develop in freshwater environments in temperate to subtropical limestone regions. Tufas form annual laminations consisting of dense and porous layers, which can be used for dating. Conventional studies have mainly focused on fluvial tufas, but the problem is that a continuous deposition over 40 years is hardly expected due to changes in flow paths. However, longer records can be found in cascade tufas, which are deposited like stalagmites at waterfalls. In this study, we studied cascade tufas developed on the Obaru beach of Tokunoshima Island, Kagoshima Prefecture, Japan to obtain a longer climate record. A 50 cm long specimen of the cascade tufa has a depositional period of about 200 years, which was recognized by observation of thin-sections and CT scan. By comparing the results of oxygen and carbon isotope ratio measurements with meteorological records, we aim to reconstruct long-term quantitative paleoclimate using tufas. Our preliminary results show cyclicity of about 20 years in the oxygen isotopes, which can be correlated to the change in seawater temperature of the western Pacific. This suggested a close relationship between seawater temperature fluctuations and rainfall.</p>

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Details 詳細情報について

  • CRID
    1390290393638300416
  • NII Article ID
    130008129777
  • DOI
    10.14862/geochemproc.68.0_54
  • Text Lang
    ja
  • Data Source
    • JaLC
    • CiNii Articles
  • Abstract License Flag
    Disallowed

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