島根県西部に分布する下部ジュラ系樋口層群の地質と北方系二枚貝化石群  [in Japanese] Geology and Boreal bivalve assemblages of the Lower Jurassic Higuchi Group, western Shimane Prefecture, Japan  [in Japanese]

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Abstract

島根県西部に分布する下部ジュラ系樋口層群の調査を行い,樋口層群を新たに下位より尾路地谷層と樋口谷層に区分した.尾路地谷層は,礫岩,砂岩,泥岩からなり,二枚貝化石の<i>Oxytoma</i> sp.や"<i>Pleuromya</i>" sp.を産出する.樋口谷層は,軟体動物化石を含む暗灰色泥岩を主体とする.樋口谷層からは,6属6種の二枚貝化石,<i>Kolymonectes staeschei</i>,<i>Palmoxytoma cygnipes</i>,<i>Ryderia texturata</i>,<i>Pseudomytiloides matsumotoi</i>,<i>Oxytoma</i> sp., "<i>Pleuromya</i>" sp.が産出する.本層群の二枚貝化石群は,ロシアやカナダ北部に分布する下部ジュラ系から産する北方系のフォーナである<i>K. staeschei</i>や<i>P. cygnipes</i>を含み,典型的なテチス系の種を含まない特徴がある.

The Lower Jurassic Higuchi Group, exposed in the western part of Shimane Prefecture, Japan, includes, in ascending order, the Orojidani and Higuchidani formations. The Orojidani Formation is composed of conglomerate, sandstone, and mudstone, the latter containing <i>Oxytoma</i> sp. and "<i>Pleuromya</i>" sp. The Higuchidani Formation consists mainly of dark gray mudstone, from which six genera and six species of bivalves were collected: <i>Kolymonectes staeschei</i>, <i>Palmoxytoma cygnipes</i>, <i>Ryderia texturata</i>, <i>Pseudomytiloides matsumotoi</i>,<i> Oxytoma</i> sp., and <i>Pleuromya</i> sp. This bivalve assemblage is characterized by Boreal elements such as <i>K. staeschei</i> and <i>P. cygnipes</i>, which are known exclusively from the Lower Jurassic of Russia and northern Canada; it contains no typical Tethyan species.

Journal

  • The Journal of the Geological Society of Japan

    The Journal of the Geological Society of Japan 121(2), 59-69, 2015

    The Geological Society of Japan

Codes

  • NII Article ID (NAID)
    130005070786
  • NII NACSIS-CAT ID (NCID)
    AN00141768
  • Text Lang
    JPN
  • ISSN
    0016-7630
  • NDL Article ID
    026196333
  • NDL Call No.
    Z15-174
  • Data Source
    NDL  J-STAGE 
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