青森地域上部新生界の層序と古地理 (古日本海東縁の新第3系--層序・古地理・古環境) -- (古地理・古環境の復元)  [in Japanese] Stratigraphy and paleogeographic reconstruction of the Upper Cenozoic in the Aomori district, northern Japan  [in Japanese]

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Abstract

東北本州弧最北部を占める青森地域の上部新生界に関する層序学的および微化石・放射年代学的検討により,当地域の構造発達史が明らかとなった。泥質岩類を主とし膨大な苦鉄質~珪長質火砕岩類が挟在する新第三系は,東西性の構造作用に支配された半閉塞的な堆積場で集積したものと判断できる。これを傾斜不整合におおう第四系は主に安山岩~流紋岩質の火砕岩類により構成される。地質年代および構造解析結果によれば,当地域の新第三紀堆積盆の発達史は,17~16 Maの急激な沈降期,15~13 Maの緩慢かつ局所的な沈降期,および5~3 Maの分化期に大別される。東西性の伸張応力下における沈降期の堆積盆には周囲の高まりから大量の砕屑物が集積し,厚い海成層を形成した。後期鮮新世から更新世には,代わって東西性の圧縮応力場が当地域を,支配した。この構造作用により堆積盆は分化・離水し,さらに南北に軸を有する背斜(白神,津軽および奥羽山地など)と向斜(津軽平野,むつ・野辺地凹地など)が形成された。後期更新世以降,これら向斜部の堆積盆は背斜軸部あるいは第四紀火山からの砕屑物により埋積されつつある。

Thick sedimentary rocks, ranging from the early Miocene to the late Pleisteene, is extensively distributed in the Aomori district, northernmost part of Honshu. A considerable portion of the Neogene sequence is marine in origin, with subordinate amounts of intercalated mafic, intermediate and felsic lavas and pyroclastic rocks. Andesitic to rhyolitic volcanic lastic deposits are predominant in the Quaternary. The Upper Cenozoic rocks are interpreted to have been developed in a semiclosed basin under east-west tectonic controls. Based on the geotectonic consideration, the evolutional history of the Neogene basin can be described in three stages: rapid subsidence (from 17 to 16 Ma), slow subsidence (from 15 to 13 Ma) and differentiation (from 5 to 3 Ma). The subsiding basin received huge amounts of clastic materials from ambient emerged lands, leading to completion of thick marine sequence. The Plio-Pleistocene basin was in turn controlled by east-west compressional tectonics, which resulted information of anticlinal mountains (Ou backbone range, Shiragami highlands) and synclinal valleys (Tsugaru plain, Mutsu-Nohegi depression). The synclinal troughs were filled with clastic materials derived from anticlinal arches as well as Quaternary volcanoes.

Journal

  • The Memoirs of the Geological Society of Japan.

    The Memoirs of the Geological Society of Japan. (37), p25-37, 1992-03

    日本地質学会

Cited by:  5

Codes

  • NII Article ID (NAID)
    110003025348
  • NII NACSIS-CAT ID (NCID)
    AN00141779
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    03858545
  • NDL Article ID
    3767273
  • NDL Source Classification
    ZM49(科学技術--地球科学--地質)
  • NDL Call No.
    Z15-322
  • Data Source
    CJPref  NDL  NII-ELS  NDL-Digital 
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