Geological age of the Sashida Limestone in south Izu region, Japan based on microfossils

—New knowledge about the geohistory of the Izu Peninsula（Part 1）

Abstract

The late Cretaceous, Paleocene, late Middle to Late Eocene, Oligocene and early Early Miocene larger（benthonic）and planktonic foraminifera were confirmed for the first time, in addition to Early-Middle Miocene larger foraminifera, from the Sashida Limestone included basalt pebbles beside the outcrop, which was covered by river-construction, and near there, Sashida, Kamo-Gun, south Izu Peninsula, Japan. The Sashida Limestone consists of clastic carbonate rocks of various ages from the late Cretaceous through early Early Miocene to late Miocene or early Pliocene. From the research conclusion, the geology and geohistory of the Cretaceous-Paleogene Shimanto Group and Paleogene Setogawa Group along the Pacific Ocean as the pre-Yugashima Group, and the locus of lateral mobility of the Izu landmass of the antecedent of the Izu Peninsula were indicated as further research.