九州西部八代地域の川口層から産した白亜紀古世放散虫化石

概要

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Radiolarian fossils were firstly extracted from the Kawaguchi Formation of the Chichibu Composite Terrane in the Yatsushiro area, western Kyushu. The Kawaguchi Formation is composed mainly of brackish strata, which yield abundant brackish conditional molluscus fossils, and intercalates shallow marine strata, which yield marine conditional molluscus fossils. In the western Kyushu, the Kawaguchi formation conformably overlies the Late Jurassic strata, and is overlain by Barremian strata. The radiolarian fossils obtained from the Kawaguchi formation are Hemicryptocapsa capita, Pseudoaulophacus (?) florealis, Sethocapsa uterculus, Suna cf. hybum and so on. This fauna indicates early to middle Hauterivian in age. The age assinged to the Kawaguchi Formation on the basis of radiolarian biochronology match well with the published stratigraphic data.
2002-05-25