Paleomagnetism of the Bonin Islands and its tectonic significance

Evolution of the boundary between the Philippine Sea Plate and Australia: palaeomagnetic evidence from eastern Indonesia

“…The results indicate about 10 ° of northward translation since the Early Miocene. This is similar to estimates from palaeomagnetic studies elsewhere in the Philippine Sea Plate (Louden, 1977;Keating and Herrero, 1980;Kinoshita, 1980;Bleil, 1981;Kodama et al, 1983;Hirooka et al, 1985;Haston and Fuller, 1991;Haston et al, 1992;Koyama et al, 1992).…”

“…Evidence for northward movement of about 15-20 ° of the Philippine Sea Plate has been widely accepted (see review by Haston and Fuller, 1991) but the suggestions of major rotation of the plate have proved more controversial. Interpretations of major (50-100 °) clockwise rotations of the entire plate have been based on the magnetic anomaly skewness in the West Philippine Basin (Louden, 1977;Shih, 1980) and palaeomagnetic data from the eastern margin of the plate (Kodama et al, 1983;Haston and Fuller, 1991;Koyama et al, 1992) but have been disputed for a number of reasons. These include the low resolution provided by anomaly skewness studies, conflict with interpretations based on Shikoku Basin seamount data (Vaquier and Uyeda, 1967) and possibility of local tectonic effects due to subduction at the eastem plate edge (Larson et al, 1975;McCabe and Uyeda, 1983).…”

Paleomagnetic Evidence for Northward Drift and Clockwise Rotation of the Izu-Bonin Forearc since the Early Oligocene

“…Systematically shallower paleomagnetic inclinations have been reported by many previous paleomagnetic studies on deep-sea cores drilled from the Philippine Sea (Louden, 1977;Bleil, 1980;Keating and Herrero, 1980;Kinoshita, 1980), and on terrestrial formations of the Izu-Bonin Arc Kodama et al, 1983;Koyama, 1983;Hirooka et al, 1985;Keating and Helsley, 1985;Hasten and Fuller, 1991). These studies attributed the shallower inclinations to northward latitudinal movements of the Philippine Sea (PHS) Plate.…”

“…Besides the paleomagnetic inclination, significant clockwise deflections of paleomagnetic declination were found in Eocene to middle Miocene formations in the Bonin, Mariana, and Palau islands (Larson et al, 1975;Fuller et al, 1980;Keating et al, 1983;Keating and Helsley, 1985;Kodama et al, 1983;McCabe and Uyeda, 1983;Adachi et al, 1987;Hasten et al, 1988;Hasten and Fuller, 1991). However, the interpretation of these declination anomalies is still debatable.…”

The determination of "paleolongitude" and its geophysical application to the Bonin islands.

“…It is very useful to detect the position of sharp positive anomalies in the south to determine the exact direction of the magnetization. KoDAMA et al (1983) carried out Chicijima. Our obtained inclination and declination are much different from these three directions, which suggests that the underground magnetized body has a different direction from that on the ground and/or may average out the various kinds of magnetizations.…”