Paleomagnetism of bedded cherts from southwest Japan

Abstract

Paleomagnetic and rock magnetic data from bedded cherts in southwest Japan have been analyzed to constrain the paleolatitude of the site of deposition of the cherts, the movement of the oceanic plate on which the cherts were deposited, and secondary magnetization events that occurred in southwest Japan. The primary remanent magnetization component of the cherts reveals that they were deposited near the equator during the Middle Triassic, and were accreted to the eastern margin of the South China Block. The cherts record three types of secondary magnetization: viscous remanent magnetization, thermoviscous remanent magnetization, and chemical remanent magnetization. The latter two magnetization events are recognized over a distance of ~ km across southwest Japan and are considered to reflect widespread secondary magnetization in the region.