Microfauna and its paleobiooceanography during Jurassic -Cretaceous in eastern margin of East Asia

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The purpose of this research is to reconstruct Jurassic to Cretaceous paleobiooceanography around the eastern margin of East Asia by using microfossils from the Jurassic-Cretaceous shallow marine starata in and around Japan. Research strata are listed as belows: Tetori Group in Hokuriku Region, Choshi Group and Nakaminato Group in Kanto Region, and Ikenoue Formation and Arida Formation in the Kii Peninsula. Calcareous concretions and ichnofossils have been processed by doluted hydrofluoric acid, hydrochloric acid, formic acid, and hydrogen peroxide water, and diversified microfauna has been extracted; radiolarians, foraminnifera, sponge spicules, molluscan prodissoconchs, and diatoms. The Jurassic radiolarian assemblages from the Tetori group demonstrate that the Hokuriku Region in the Jurassic age had been influenced by cold water surface currents from the Arctic Region.