ボーリングコア中の貝形虫化石群集から推定した大阪湾における完新世海水準変動.地質雑 Holocene sea-level changes in Osaka Bay, western Japan : ostracode evidence in a drilling core from the southern Osaka Plain

Access this Article

Search this Article

Author(s)

Abstract

大阪平野南部の堺市で掘削されたボーリングコアから採取した33試料中から少なくとも72種群の貝形虫化石が産出した.クラスター分析の結果これらの試料は大きく6個のbiofaciesに区分された(PS,SBm,LS,PL,CL,LC).本研究では完新世における堆積環境と相対的海水準の変化を貝形虫群集に基づいて復元した.大阪平野南部では,約9,000-6,000年前(暦年)に急激に海水準が上昇し,その後,現在の海水準まで下降した.最高海水準期は約6,000-5,600年前(暦年)であった.この海水準変動の傾向は大阪平野中央部や大阪湾海域での海水準変動によく類似しているため,これらの傾向は大阪堆積盆地で高い普遍性を持つと考えられる.また,塩分濃度,海岸線からの距離,沿岸流や波浪による影響は相対的海水準変動と良く対応して変化する.

Seventy two species groups of Ostracoda were identified from 33 samples obtained from the drilling core 'A', excavated in the southern Osaka Plain, southwest Japan. Q-mode cluster analysis of ostracode faunas in this core reveals six biofacies (PS, SBm, LS, PL, CL and LC). This study provided ostracode evidence revealing temporal variation in depositional environment and relative sea level throughout the Holocene. In the southern Osaka Plain, the sea level rose rapidly from the period between ca. 9, 000 and ca. 6, 000 cal yr BP. The maximum sea-level highstand was at ca. 6, 000-5, 600 cal yr BP, after which the sea level has gradually fallen to its present one. This trend in sea-level change is well correlated to those of central Osaka Plain and Osaka Bay, suggesting that the relative sea-level changes were widespread throughout the Osaka sedimentary basin. Changes of salinity, distance from shoreline and influence by coastal current and waves are well correlated with the observed relative sea-level changes.

Journal

  • The Journal of the Geological Society of Japan

    The Journal of the Geological Society of Japan 108(10), 633-643, 2002-10-15

    The Geological Society of Japan

References:  28

Cited by:  5

Codes

  • NII Article ID (NAID)
    110003024579
  • NII NACSIS-CAT ID (NCID)
    AN00141768
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    00167630
  • NDL Article ID
    6343676
  • NDL Source Classification
    ZM49(科学技術--地球科学--地質)
  • NDL Call No.
    Z15-174
  • Data Source
    CJP  CJPref  NDL  NII-ELS  J-STAGE 
Page Top