ウェーブリップルの遷移過程  [in Japanese] A brief review of transition processes of wave ripples  [in Japanese]

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Abstract

ウェーブリップルは,与えられた振動流条件と堆積物特性の下で,安定的に持続する特定の形状,サイズ,波峰線オリエンテーションを有する.振動流条件が変わるとウェーブリップルはその条件下での定常状態の獲得をめざして遷移する.新たな振動流方向が初期リップルの波峰線と直交する場合,遷移過程は(1)初期リップルと定常リップルの波長の大小関係,(2)振動流の非対称性,(3)堆積物粒径に依存する.とくに,初期リップルの波長が定常リップルのそれよりも大きいと,初期リップルの形状の一部をとどめる遷移リップルが一時的に現れる.地層に見られる遷移リップルは,地層形成時の振動流条件を推測する重要な手がかりとなりうる.

Wave ripples forming under stable oscillatory-flow conditions have a particular set of morphologies, dimensions, and crest orientations. With any significant change in the hydraulic conditions, the wave ripples lose their original equilibrium configuration, take transient forms, and eventually attain a new equilibrium state. This transition process depends on (1) the ratio of the wavelengths of the original ripples to the renewed equilibrium ripples (λ<sub>e</sub>/λ<sub>i</sub>), (2) the degree of asymmetry in oscillatory flow, and (3) sediment grain size when a new oscillatory flow is perpendicular to the crest lines of pre-existing ripples. Distinctive transient ripples, which tentatively appear (and then disappear) during the period of modification, are likely to be preserved in the geological record when λ<sub>e</sub>/λ<sub>i</sub> < 1. The analysis of such ripples can benefit estimations of paleohydraulic conditions.

Journal

  • The Journal of the Geological Society of Japan

    The Journal of the Geological Society of Japan 117(3), 141-147, 2011

    The Geological Society of Japan

Codes

  • NII Article ID (NAID)
    130000758394
  • NII NACSIS-CAT ID (NCID)
    AN00141768
  • Text Lang
    JPN
  • Article Type
    特集
  • ISSN
    0016-7630
  • NDL Article ID
    11069327
  • NDL Source Classification
    ZM49(科学技術--地球科学--地質)
  • NDL Call No.
    Z15-174
  • Data Source
    NDL  J-STAGE 
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