Linear magnetic anomalies in the Shikoku Basin, northeastern Philippine Sea.

Abstract

A linear magnetic pattern, offset along fracture zones was found in the Shikoku Basin, which lies between the Izu-Bonin and northern Kyushu-Palau Ridges. This lineation, nearly parallel to the trend of the Kyushu-Palau Ridge, seems to indicate that this basin originated from a type of seafloor spreading. A possible spreading center was suggested on the basis of symmetry of magnetic anomaly profiles and distribution of sediment cover in the basin. The anomaly profiles were tentatively correlated to the synthetic profile calculated from the reversal history of the earth's magnetic field during a period in Early to Middle Miocene, which gives a good fit of age to the result of the DSDP hole 297.