Calcareous nannoplankton age and correlation of the Neogene Miura Group between the Miura and Boso Peninsulas, southern-central Japan

Abstract

Calcareous nannoplankton ages and description of pyroclastic key beds "Gomashio' intercalated in the Miura Group of the Miura and middle Boso Peninsulas are given. Three groups of marker tuffs are discriminated from each other on the basis of mafic mineral composition. Consequently, the nannoplankton age of the Miura Group in the Miura Peninsula can be summarized as follows. The Misaki Formation is correlated with CN5b (late Middle Miocene)-CN10c (Early Pliocene), the Zushi Formation with CN9 (late Late Miocene)-CN11 (Late Pliocene), the Ikego Formation with CN11-CN12 (Late Pliocene), and a part of the Hatsuse Formation with CN10c. The horizons of scoriaceous tuff beds occur in the calcareous nannoplankton zones of CN5b, CN9, CN10c and CN11-CN12. -from English summary