A new scenario of the Parece Vela Basin genesis

A new high density geophysical data set in the Parece Vela Basin north of 15 degrees N has been obtained through surveys conducted by the Hydrographic Department of Japan. The combined analyses of the swath bathymetry, magnetic and gravity anomalies from these surveys reveal a new scenario for the genesis of this basin. The evolutionary process is as follows: rifting and crust thinning (29-26 Ma), northward propagation of east-west opening (26-23 Ma), east-west opening together with the Shikoku Basin (23-21 Ma), and the northeast-southwest opening (20/19-15 Ma). The western part of the basin is complicated, displaying some traces of northward propagation of the spreading center. The change between early east-west opening and the final stage of northeast-southwest spreading is marked by a distinct north-south boundary in both structural and magnetic patterns. Deep and rough topography of the extinct Parece Vela Rift is due to magma starvation in the terminal phase of the spreading.