三重県津市の東海層群亀山層から得られた海生珪藻化石と高海水準期イベント

抄録

Diatom assemblages in the Kameyama Formation of the Mid-Pliocene Tokai Group and distributed in Tsu City, Mie Prefecture, central Japan are investigated. They consist of 109 taxa in 49 genera, and are characterized by an mixture of both freshwater and marine diatoms. Among them, freshwater planktonic species Aulacoseira praeislandica (including A. praeislandica f. curvata) is predominant, and the marine species Schuettia annulata is subordinate. The mixed flora may suggest that the Kameyama Formation was deposited in a lake-like condition, which was invaded intermittently by seawater in the Mid-Pliocene. This marine invasion may be caused by both local and global settings: this area was located at the southernmost end of the Tokai Group sedimentary basin, and the global climate at this time was warm and the sea level was high.