U-Series Ages for Solitary Coral Species from the Middle Pleistocene Kunosan Formation in the Udo Hills, Shizuoka, Central Japan

Abstract

The middle Pleistocene Kunosan Formation is distributed in the Udo Hills (Shizuoka, central Japan) that was tectonically uplifted about 300m during the late Quaternary. The formation consists of about 200-m-thick of coarse-grained fan-delta deposits. The thorium-230 age of a species of solitary coral from the Kunosan Formation in the eastern Udo Hills (Muramatsu Gravel-Silt Member) is 176.5+3.7-3.6ka (error is 1σ). This radiometric age means that the Kunosan Formation was deposited during marine isotope stage 6.5. This interpretation is consistent with previously published chronologic information for the middle and upper Pleistocene in the Udo Hills.