Preliminary reports of strontium isotopic ages of molluscs from the locality of the “Paleoparadoxiid Mizunami-Kamado specimen” in Mizunami City, central Japan

Abstract

Paleoparadoxiid fossils were discovered in the Shukunohora Formation of the Mizunami Group exposed in the Toki River bed in Shimogiri-ku, Kamado-cho, Mizunami City, in 2022. In order to clarify the age of the Shukunohora Formation in this locality, we determined strontium isotopic ages using shell fossil samples that were cooccurred with paleoparadoxiid fossils. The strontium isotopic ages suggest that the depositional age of the paleoparadoxiid-bearing horizon is ca. 16.5 Ma.