@article{oai:kanazawa-u.repo.nii.ac.jp:00055338,
 author = {Maeda, Haruyoshi and Ueda, Naoto and Nishimura,  Tomohiro and Tanaka, Gengo and Nomura, Shin'ichi and Matsuoka, Hiroshige and 前田, 晴良 and 上田, 直人 and 西村, 智弘 and 田中, 源吾 and 野村, 真一 and 松岡, 廣繁},
 issue = {11},
 journal = {地質学雑誌, The journal of the Geological Society of Japan},
 month = {},
 note = {高知県佐川地域に分布する七良谷層の模式層序周辺の泥質砂岩中から，最上部ジュラ系を示す2種類のアンモノイド化石を発見した．そのうちAspidoceras属は，テチス海地域の最上部ジュラ系から多産し，Hybonoticeras属は同地域のキンメリッジアン−チトニアン階境界付近を示準するタクサである．これらの化石の産出により，七良谷層は最上部ジュラ系（キンメリッジアン−チトニアン階）に対比される可能性が高い．この結論は放散虫化石層序とおおむね調和的である．これまで七良谷層は，上部ジュラ系−下部白亜系鳥巣層群の層序的下位にあたる地層と考えられてきた．しかし七良谷層から産出したアンモノイドの示す時代は，鳥巣層群産アンモノイドのレンジと明らかに重複し，アンモノイド化石からは両岩相層序ユニットの時代差は識別できない．したがって，今後，七良谷層と鳥巣層群の層序関係を再検討する必要がある．, The Naradani Formation is located to the south of the Torinosu Group in the Sakawa district of Kochi, southwest Japan, and consists of a linear, narrowly distributed series of marine clastic deposits that contain allochthonous limestone blocks. This formation was previously correlated to the Bajocian–Bathonian Middle Jurassic using brachiopods extracted from the limestone blocks, with later radiolarian correlations suggesting an Oxfordian–Kimmeridgian Upper Jurassic age. The formation has also been interpreted to underlie the Upper Jurassic–Lower Cretaceous Torinosu Group. However, the discovery of two stage-diagnostic aspidoceratid ammonoids, Aspidoceras sp. and Hybonoticeras sp., from muddy sandstones in the stratotype area of the Naradani Formation casts doubt on these previous interpretations. Aspidoceras was widespread during the latest Jurassic, and the presence of Hybonoticeras limits this short stratigraphic interval to the Kimmeridgian–Tithonian boundary in various Tethyan sections. This clearly suggests a latest Jurassic age for the Naradani Formation and generally supports the radiolarian biostratigraphy age-assignment. However, the ranges of ammonoids from the Naradani Formation overlap those from the Torinosu Group, meaning that it is not possible to determine an age-difference between these two lithostratigraphic units. Further research is needed to test other hypotheses, for example to determine whether heterotopic facies relationships exist between the Naradani Formation and the Torinosu Group., 金沢大学国際基幹教育院GS教育系},
 pages = {741--747},
 title = {高知県佐川地域の奈良谷層から最上部ジュラ系アンモノイドの産出},
 volume = {118},
 year = {2012}
}