Calcareous nannofossils and biostratigraphy of the Paleogene sequences of the northern Kyushu, Japan

Abstract

Calcareous nannofossil flora in the Paleogene marine sequences of five coalfields in the northern Kyushu, Japan is examined and its biostratigraphic correlation is studied. A total of 82 taxa and 18 datum events are identified and the deposit age is assigned to be spanned from the early middle Eocene to early late Oligocene. The age of Paleogene sequence of the Amakusa coalfield ranges between the early Middle Eocene (Subzone CP13a) and the Late Eocene (Zone CP15). The Yotsuyama formation of the Miike coalfield corresponds to the upper part of the Amakusa sequence (Zone CP14-15). The age of Nakado formation of Sakito-Matsushima coalfield. is the uppermost Eocene and the uppermost of Eocene/Oligocene boundary corresponds to the lower part of Matsusima formation. The age of Kijima formation of Karatsu coalfield is the lowest Oligocene and that of the Hatatsu shale member is possibly the upper Lower Oligocene (Zone CP18). The age of both Yamaga and Sakamizu formations in the Chikuho coalfield are early late Oligocene (Ca19a). 25 refs., 8 figs., 6 tabs.