Time Trend Analysis of the Plio-Pleistocene Sequence in the Central Part of Kinki District, Japan

Abstract

A computer program has been designed to systematically process stratigraphical, time sequencial data for establishing the analytical methods of sedimentary environments. Using the program, a series of time trend analyses were performed on the fourteen sets of column data obtained from deep wells and outcrops of the Plio-Pleistocene sequence which is distributed in the Osaka Plain, the central part of Kinki district in Japan, and mainly consists of the Osaka Group. As the result, the time trends extracted from the columns show a definite pattern in common with each other. The pattern indicates that the Plio-Pleistocene sedimentary sequence in this region can be divided into four parts in terms of the history of sedimentary environments. Each boundary appears to be consistent with the stratigraphical boundary of the Osaka Group generally accepted by many authors (IKEBE, N., 1970; and others). It has been clarified that such a systematic time trend analysis as performed in the present study is very efficient for the understanding of the history of sedimentary environments. Furthermore, it has been also proved that the analysis can provide for processed data which are quite useful in the further comprehension of the history of sedimentary environments.