Igneous rocks associated with the Cretaceous to Paleogene volcanic arc in SW Japan show ages that young from west to east in a direction parallel to the Median Tectonic Line suggesting corresponding translation of a heat source traditionally interpreted in terms of oblique subduction of a spreading ridge. However, recent oceanic plate reconstructions suggest ridge subduction may be younger than the main arc activity. Age compilations of 1227 points of felsic to intermediate Cretaceous and Cenozoic igneous rocks from the Japan arc show arc magmatism that can be separated into an early active period 130–60 Ma (stage 1), a subsequent period of quiescence 60–46 Ma (stage 2), which is followed by a resumption of igneous activity from 46 Ma onward (stage 3). In southwest Japan, the orientations of the magmatic arcs of stages 1 and 3 show and angular discordance of about 20°. The lack of active arc magmatism and the occurrence patterns of adakitic and high-Mg andesitic magmas indicate that ridge subduction occurred during stage 2. The arc age distribution pattern of stage 1 is explained by the slab shallowing related to a younging of the subducting slab as the ridge approaches. Furthermore, the obliquity of the arcs formed at stages 1 and 3 is explained by a 20° clockwise rotation of the inner zone of southwest Japan during the ridge-subduction phase. Oceanic plate reconstructions show counterclockwise rotation in the subduction direction after the ridge subduction phase, and coupling of the subducting oceanic plate with the upper plate would support microplate rotation in the inner zone. The new proposed tectonic reconstructions provide a framework to related Paleogene subduction of an active spreading ridge along the east Asia margin not only to the distribution of granitic bodies but also to rift-related basin formation on the eastern margin of the Eurasian continent and to rotation of crustal blocks indicated by paleomagnetic data of Cretaceous terranes.

与日本西南部白垩纪至古近纪火山弧相关的火成岩显示出年龄从西向东沿平行于中位构造线的方向年轻，这表明传统上用扩张脊的倾斜俯冲来解释的热源的相应转换。然而，最近的海洋板块重建表明洋脊俯冲可能比主要弧活动更晚。日本岛弧长英质至中白垩纪和新生代火成岩的 1227 个点的年龄汇编显示，岛弧岩浆作用可分为早期活动期 130-60 Ma（第 1 阶段）和随后的静止期 60-46 Ma（第 1 阶段）。 2），随后从 46 Ma 开始火岩活动恢复（第 3 阶段）。在日本西南部，第一阶段和第三阶段岩浆弧的方向显示出约20°的角度不一致。缺乏活跃的弧岩浆活动以及埃达克质和高镁安山质岩浆的赋存模式表明脊俯冲发生在第 2 阶段。第 1 阶段的弧龄分布模式可以通过与俯冲板片年轻化相关的板片变浅来解释：山脊逼近。此外，第1阶段和第3阶段形成的弧的倾斜度可以通过山脊俯冲阶段日本西南部内部区域顺时针旋转20°来解释。大洋板块重建显示，在洋脊俯冲阶段之后，大洋板块沿俯冲方向逆时针旋转，俯冲大洋板块与上部板块的耦合将支持内部区域的微板块旋转。新提出的构造重建为沿东亚边缘的活动扩张脊的古近纪俯冲提供了一个框架，不仅与花岗岩体的分布有关，而且还与欧亚大陆东缘裂谷相关的盆地形成以及地球的旋转有关。白垩纪地体的古地磁数据表明的地壳块。