1991 年 100 巻 4 号 p. 628-641
A brief review of paleomagnetic studies in the Philippine Sea and Izu-Bonin arc including the recent Ocean Drilling Program (ODP) results was made to clarify the present status and problems of the study on the tectonic evolution of the Philippine Sea plate. Paleomagnetic directions observed from the onland and marine areas on the Philippine Sea plate consistently show progressive increase of inclinations with time since the Eocene, and show large (30°-100°) clockwise deflections of declination in Eocene to middle Miocene rocks. These results suggest large clockwise rotation and northward drift of the whole Philippine Sea plate. This paper critically reviews all the models which have been proposed for the tectonic evolution of the Philippine Sea plate and proposes two possible reconstructions which can explain the paleomagnetic results.