AbstractThe results of SHRIMP U‐Pb zircon dating are presented for igneous and metamorphic rocks of enigmatic age in northern Japan. The SHRIMP analyses for the Tsubonosawa metamorphic rocks included in the Hikami Granite reveals (1) Ordovician sedimentation of the original rocks, including Archaean‐Proterozoic detrital zircons, and (2) thermal metamorphism with partial melting or assimilation followed by intrusion of the Hikami Granite at ca. 440 Ma (end of Ordovician). This study allows the reconstruction of Siluro‐Ordovician palaeogeography and magmatism‐associated metamorphism in East Asia. The SHRIMP results are compared with those of CHIME (chemical U‐Pb total Th isochron method) chronology, which is evaluated as providing significant reconnaissance ages in some