Funding information Japan Society for the Promotion of Science, Grant/Award Numbers: JP16K21531, JP19K04043; Provate University Research Branding Project (OUS) Abstract Zircon U–Pb dating of the Tonaru metagabbro body in the Sanbagawa metamorphic belt, southwest Japan, suggests that igneous events at ca 200–180 Ma were involved in the protolith formation. The trace element compositions of the Tonaru zircons are enriched in U (a fluid-mobile element) and Sc (an amphibole-buffered element), and depleted in Nb (a fluid-immobile element), suggesting that the parental magmas related to the Tonaru metagabbros formed in an arc setting. Integration of our results with previous studies of the metasedimentary rocks in the Tonaru body clearly indicates that the protoliths of the Tonaru body were produced by oceanic-arc magmatism. With the previous geochronological and geological studies, the tectonomagmatic–metamorphic history of the Tonaru and other mafic bodies in the Sanbagawa metamorphic belt may be summarized as follows: (i) the protolith formation by the oceanic-arc magmatic event had occurred at 200–180 Ma; (ii) the protoliths were accreted in the trench at ca 130–120 Ma; and (iii) they were completely subducted into the depth of the eclogite-facies condition after 120 Ma.

中文翻译：

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日本西南三叶川变质带中 Tonaru 天体的起源

资助信息 日本科学振兴会，资助/奖励编号：JP16K21531、JP19K04043；Provate University Research Branding Project (OUS) 摘要 日本西南部三叶川变质带 Tonaru 变长岩体的锆石 U-Pb 定年表明，大约 200-180 Ma 的火成岩事件参与了原岩的形成。Tonaru 锆石的微量元素组成富含 U（一种流体流动元素）和 Sc（一种闪石缓冲元素），并缺乏 Nb（一种流体固定元素），表明与 Tonaru 相关的母岩浆在弧形环境中形成的metagabbros。将我们的结果与之前对 Tonaru 体变沉积岩的研究相结合，清楚地表明 Tonaru 体的原岩是由大洋弧岩浆作用产生的。结合前人的年代学和地质学研究，三叶川变质带托纳鲁等基性体的构造岩浆-变质历史可概括如下：(i) 大洋弧岩浆事件的原岩形成发生在200-180年嘛; (ii) 原岩在大约 130-120 Ma 时在海沟中增生；(iii) 它们在 120 Ma 之后完全俯冲到榴辉岩相条件的深处。