四国海盆と西南日本沈み込み帯の温度構造について

概要

論文の詳細を見る
The existing heat flow data in the Shikoku Basin are highly scattered and the average is lower than the value expected from the heat flow versus age relation for normal ocean basins, probably because hydrothermal circulations in the upper crustal layer are not well sealed by sediments. In the Nankai Trough, where the Shikoku Basin lithosphere subducts beneath the southwest Japan arc, the heat flow is too high for its age in the western part, possibly due to heat transfer by fluid flow associated with accretion process, while it appears to be normal in the eastern part. We carried out heat flow measurements in two areas with thick sediment covers at the northeastern end of the Shikoku Basin. The values obtained are quite uniform and agree with the standard heat flow-age relation after correcting for the sedimentation effect. As the crustal structures of the two areas may not be typical of the basin, similar heat flow surveys in the central part of the basin are necessary to know if the thermal structure of the Shikoku Basin lithosphere is normal.