JpGU-AGU Joint Meeting 2020

Presentation information

[E] Poster

B (Biogeosciences ) » B-CG Complex & General

[B-CG07] Phanerozoic biodiversity change: radiation and extinction

convener:Yukio Isozaki(Department of Earth Science and Astronomy, Multi-disciplinary Sciences - General Systems Studies, Graduate School of Arts and Sciences, The University of Tokyo), Yusuke Sawaki(The University of Tokyo)

[BCG07-P04] Devonian ostracods from the Fukuji area, Takayama City, Gifu Prefecture, central Japan

*Mai Harashima1, Sachiko Agematsu1 (1.University of Tsukuba)

Keywords:Devonian, Hida-Gaien Belt, Fukuji Formation, ostracoda, palaeobiogeography

Ostracods are one of the most long-ranging group of crustaceans from the Ordovician to present day. Ostracods occur in every aquatic environment and their fossils are important indicator as a palaeoenvironment. In addition, most of the Palaeozoic ostracods are benthonic or nektobenthonic. Thus, Palaeozoic ostracods have been used for analysis of palaeogeography. In Japan, while Cenozoic ostracods are well known, much less work has been done on Paleozoic ostracods. This study focuses on ostracods from the Lower Carbonate Member of the Lower Devonian Fukuji Formation, and discusses their palaeobiogeogpahy.
The Fukuji Formation located in the Fukuji area, Takayama city, Gifu Prefecture, central Japan. Fossiliferous black bedded limestone and gray massive limestone are mainly distributed in this area. These limestones are divided into four lithofacies; coral rudstone, bioclastic pack/wackestone, micrite and peloidal grainstone. Quartz grains are also included in limestones, consequently the Fukuji Formation was deposited under sallow marine near coral reefs along a continental magin. Using the method called Hot-acetolysis, 11 ostracod species belonging to 15 genera are obtained from limestone of the Lower Carbonate Member. Most of the ostracods are classified into Palaeocopida or Podocopida, thus relevant to shallower-water ostracod assemblage. In addition, the ostracods from the Fukuji Formation share species-level links with those of South China and Russia, indicating palaeogeographical relationships with those areas.