熊野層群基底部の放散虫化石年代 : 紀伊半島四万十累帯の研究(その14)

概要

論文の詳細を見る
The Kumano Group, occupying a wide area in the southeastern part of the Kii Peninsula, Southwest Japan, is a thick pile of terrigenous clastic sediments which was deposited in a large forearc basin. The geologic age of the Kumano Group is roughly estimated to be latest Early Miocene to early Middle Miocene based on foraminifers found in only the middle part of the Group. On the other hand, some workers have insisted that the lowermost horizon of the Kumano Group should be correlated to Oligocene based on molluscan fossils. To clarify the geologic age of the Group, radiolarian fossils were extracted from the basal part of the Group in the southern coastal area. Abundant occurrence of Cyrtocapsella tetrapera and C. japonica firmly indicates Miocene, not Oligocene, in age, and accompanying radiolarian species suggest an age of late Early Miocene.
地学団体研究会の論文
2008-01-25