Characteristics of crustal structures in the <scp>Yamato Basin</scp>, sea of <scp>Japan</scp>, deduced from seismic explorations

Abstract Crustal structures around the Yamato Basin in southeastern Sea of Japan, inferred from recent ocean bottom seismography (OBS) and active‐source seismological studies, are reviewed to elucidate various stages crustal modification involved rifting crust surrounding continental arc production oceanic back‐arc basin. The northern, central, southern areas have thicknesses approximately 12–16 km, lowermost crusts with P‐wave velocities greater than 7.2 km/s. Very few units range 5.4–6.0 km/s, which corresponds upper crust. These findings, combined previous geochemical analysis basalt samples, interpreted indicate that a thick has been formed these basin, this underplated by mantle‐derived magma. In central Basin, original fully breached formed. Conversely, presence unit corresponding absence high‐velocity part lower implies southwestern edge rifted without significant intrusion. Oki Trough is 17–19 km formation resulted magmatic intrusion and/or underplating. We interpret variations characteristics area as reflecting instances thinning due extension, resulting