地質学雑誌
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
短報
上部白亜系御船層群の凝灰岩層のフィッション・トラック年代
池上 直樹岩野 英樹檀原 徹酒井 治孝
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ジャーナル フリー

2007 年 113 巻 3 号 p. 127-130

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抄録
Fission-track (FT) dating was carried out on zircon crystals from four vitric tuff beds in the Mifune Group, middle Kyushu. FT ages of 93.1±4.4 Ma, 89.8±4.0 Ma for the lower part of the Lower formation, 83.6±3.1 Ma for the lower part of the Upper formation and 82.1±11.1 Ma for the upper part of the Upper formation were obtained. These data suggest that the Mifune Group ranges in age from Late Cenomanian to Early Campanian, though the upper age limit remains uncertain. The age of the vertebrate fauna from the middle part of the Upper formation is assigned to Coniacian to Campanian. This age is younger than previously estimated age obtained from paleontological studies. The Mifune Group is possibly correlated with the Onogawa Group on the basis of the present FT ages.
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© 2007 日本地質学会
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