三浦半島中・北部の新生界の微化石生層序年代と古環境

概要

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The geologic age is clarified for the Neogene to Pleistocene systems; the Hayama, Miura and Kazusa Groups distributed in the middle and northern parts of the Miura Peninsula, on the basis of the biostratigraphy of radiolaria, planktonic foraminifera and calcareous nannoplanktons. The age of the Hayama Group ranges from early Early Miocene to late Middle Miocene based upon radiolarians. The Miura Group is from Late Miocene to early Late Pliocene, the Kazusa Group ranges from late Late Pliocene to Early Pleistocene in age respectively, on the basis of both the planktonic foraminifera and the nannoplanktons. The age of each formation of the respective groups assigned in details in the present paper. The authors point out that the boundary between Miocene and Pliocene can be laid at the upper horizon of the Zushi Formation of the Miura Group distributed in the northern part of the peninsula, and the boundary between Pliocene and Pleistocene may be laid at the middle to lower horizon of the Nojima Formation of the Kazusa Group. Sedimentary environment of their groups is preliminarily discussed based upon the benthic foraminiferal assemblages.
横浜国立大学の論文
1987-10-31