西南日本外帯の下部白亜系の堆積環境と古地理 : アンモナイトなど軟体動物化石と恐竜に基づく古生物地理からのアプローチ

概要

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In Southwest Japan, Lower Cretaceous sediments are distributed in three terranes: Hida-Chugoku, Chichibu and Shimanto, from inner to outer, with a WNW-ESE trend. These terranes are characterized mainly by nonmarine, alternation of nonmarine and marine and marine deposits, respectively, which are interpreted to have accumulated in fluvio-lacustrine through shallow marine shelf to shelf slope environments. Additionally, the occurrence of ammonites, which were distributed in the Tethyan, NW European, northern Pacific and Boreal provinces, in southwest Japan, provides important evidence for the influence of both cold and warm water currents originating in the Arctic and near the Equator, respectively. The latitude of Southwest Japan in Early Cretaceous, therefore, is inferred from the currents generated by the coriolis force. Lower Cretaceous dinosaurs from both the inner and outer sides of Southwest Japan show that the Japanese islands in Early Cretaceous time were a part of the Asian continent.
日本地質学会の論文
1993-04-30