愛知県知多半島，中新統師崎層群に見られる小佐岩脈（砕屑岩脈）の浮遊性有孔虫化石

摘要

We investigated planktonic foraminifera obtained from a clastic dike (here we call it the Oza dike) that intrudes sedimentary rocks of the lower Miocene Morozaki Group on the Chita Peninsula, Aichi Prefecture. The Oza dike is an injection dike, and two different ideas have been proposed for the injection direction (i.e., upward and downward). In this paper, we show that the dike contains foraminiferal species correlated to the zone N.8， an early to middle Miocene planktonic foraminiferal zone at about 16 Ma, or upper zones. Because the N.8 and upper zones are younger than planktonic foraminiferal and diatom zones to which the host rocks are correlated, we conclude that the Oza dike is a downward injection dike. Our planktonic foraminiferal data suggest that the source sediments of the clastic dike were deposited under a marine environment influenced by the tropical to subtropical sea surface water.%愛知県知多半島に分布する中新統師崎層群（第1図）には砕屑岩脈が多数発達しており，その分布と産状は林（1957)とHayashi(1966)によって報告されている.そのうち最も規模の大きい岩脈は師崎層群下部の豊浜層中に見られる砂岩脈で，その分布地（知多郡南知多町豊浜の小佐漁港付近；第2図）の地名をとって本論文では小佐岩脈と呼ぶ（第3図).