Paleomagnetism of three seamounts northwest of the Marshall Islands from magnetic inversion

Abstract

Total magnetic field measurements were performed to study paleomagnetism of three seamounts (OSM7, OSM8-1, and OSM8-2) to the northwest of the Marshall Islands in the western Pacific. The study area is located at the Ogasawara Fracture Zone which is a boundary between the Pigafetta and East Mariana basins. The magnetic parameters and paleopoles of three seamounts were derived from inversion of the measured magnetic field. The goodness-of-fit ratio of OSM7 is too low to be included to the estimation of parameters. The complex magnetic anomalies of center, scarcity of flank rift zones and steep slope at OSM7 suggest that the multiple intrusions of magma converge into the center of volcanic edifice. Inclination calculated from the magnetic anomalies of OSM8-1 and OSMS-2 is -41.2°, and the paleolatitude calculated from the inclination is 23.6°S. The corresponding paleopoles for OSM8-1 and OSM8-2 are (24° 42′W, 48° 54′N) and (18° 18′W, 48° 30′N), respectively. In comparison with the apparent polar wander path (APWP) of the Pacific plate, the paleopoles are close to 129-Ma pole. The paleopoles and paleolatitudes of OSM8-1 and OSM8-2 suggest that they were formed at similar time and location. The seamounts have drifted northward about 41° from the paleolatitude to present latitude of seamounts.