琉球列島久米島に分布する新第三系海成島尻層群の石灰質ナンノ化石年代に関する新事実

概要

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Calcareous nannofossil biostratigraphy was studied for the Neogene marine Shimajiri Group distributed in Kume-jima Island, Ryukyu Islands, southwestern Japan. Out of 21 samples examined in this study, 14 samples yielded calcareous nannofossils. As was reported in a previous study, Zones CN9 and CN12 of Okada and Bukry (1980) were recognized in this study. In addition, Subzone CN11b (early Pliocene) was newly identified in the lower parts of the sequence where the ages were previously assigned to the late Miocene (upper part of Zone CN9 or older). This result shows the difficulty of establishing the stratigraphy of the subjected group based mainly upon lithotratigraphy, particularly in the lower part. Additional biostratigraphic data are needed to establish the reliable stratigraphy of the marine Shimajiri Group in Kume-jima Island.
日本地質学会の論文
2002-08-15