To test the hypothesis that a Cretaceous hairpin turn is absent in the apparent polar wander path (APWP) of the inner arc of southwestern Japanese island (southwest Japan), we refined a mid-Cretaceous (100 Ma) paleomagnetic pole from southwest Japan. Red mudstone samples from the 100 Ma Hayama Formation were collected for paleomagnetic analysis from eight sites in the Hayama area in the central part of southwest Japan. A high-temperature remanent magnetization component carried by hematite was isolated from these sites and was found to be of primary mid-Cretaceous origin. The primary nature of the magnetization is supported by the detrital character of the magnetic carrier. The primary directions provided a paleomagnetic pole (35.0°N, 209.6°E, A95 = 6.1°, N = 8), which represented southwest Japan at 100 Ma. This pole falls into a cluster of Cretaceous poles in southwest Japan. An APWP for southwest Japan between 110 and 70 Ma was updated to ascertain the stationarity of the pole positions for this region. Therefore, it is unlikely that the APWP for southwest Japan experienced a hairpin turn during the Cretaceous.

中文翻译：

---

日本西南部明显的极地漂移路径中没有白垩纪发夹：古地磁极位置的一致性

为了检验日本西南部岛屿（日本西南部）内弧的表观极地漂移路径 (APWP) 中不存在白垩纪发夹转弯的假设，我们提炼了日本西南部的白垩纪中期 (100 Ma) 古地磁极。从日本西南部中部叶山地区的八个地点收集了 100 Ma Hayama 组的红色泥岩样品用于古地磁分析。从这些地点分离出一种由赤铁矿携带的高温剩磁成分，发现其起源于白垩纪中期。磁性载体的碎屑特性支持磁化的主要性质。主要方向提供了一个古地磁极（35.0°N，209.6°E，A95 = 6.1°，N = 8），代表日本西南部 100 Ma。该极点位于日本西南部的白垩纪极地群中。日本西南部 110 到 70 Ma 之间的 APWP 已更新，以确定该地区极点位置的稳定性。因此，日本西南部的 APWP 在白垩纪期间不太可能经历发夹形转弯。