Abstract
In this report the writers intented to describe the zonation by the Benthonic Foraminifera. As an example, they have treated the Kazusa Group which is assigned to Plio-Pleistocene in age and 2500m in thickness.
A standard zonation must be established near the central part of the basin. The biofacies changes toward the marginal area owing to the basin architecture, the tectonic or/and eustatic movements in the basin and the difference of the amount of sediments brought in it. So the zonation is not always equal in each well. The aim of foraminiferal survey will be stressed more in recognition of depositional environment than the division of strata.
In the oil geology, the micropaleontological survey is one of the basical works for prospecting. It is able to presume the depositional environment and the depositional direction of mud or sand stone by recognition the change of litho and biofacies. Also foraminiferal data may be helpful to the judgment of the modes of sedimentation in sandstone which may have a relation to prospecting oil or gas.
