概報徳島県北川地域の四万十帯付加コンプレックスから産出した白亜紀放散虫化石

概要

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Cretaceous radiolarians were recovered from three mudstone samples within the Shimanto accretionary complex in the Kitagawa district, Tokushima Prefecture, Southwest Japan. Two of them, red mudstone and gray mudstone, in the Osodani Unit yield radiolarian faunas indicating the ages of late Albian to Cenomanian and late Cenomanian, respectively. Black mudstone within the Taniyama Unit includes a representative radiolarian fauna presenting a Turonian age. Based on the age determination by our present data together with the radiolarian evidences reported from surrounding area, the accretionary age of the Osodani Unit is constrained to be Turonian to early Coniacian, and those of the Taniyama Unit is reinterpreted as the age of Turonian to Santonian. New findings of radiolarian fossils in the Kitagawa district help establish the age constraint for the Cretaceous Shimanto accretionary complex in eastern Shikoku.
産業技術総合研究所地質調査総合センターの論文