Origin of the Chichibu Sea, Japan: Middle Paleozoic to Early Mesozoic plate construction in the northern margin of the Gondwana continent

Pre‐Jurassic plate tectonic development of southwest Japan is discussed in the light of rifting tectonics using the symmetrical rock arrangement. In particular, a geodynamic model is presented of Middle Paleozoic to Early Mesozoic plate construction of the Chichibu Sea. The model involves five steps: (1) the deposition of Siluro‐Devonian rocks on the Gondwana continental margin; (2) incipient rifting into Hida + Hida Marginal continental block on the north and Kurosegawa continental block on the south, forming Chichibu Sea plate in Carboniferous time; (3) parts of the Chichibu Sea plate were subducted beneath the Kurosegawa continental block and newly formed Maizuru Island Arc in Permian time; (4) the rifting and subduction ceased in latest Permian time and the Chichibu Sea remained stable with the width of over 1000 km in Triassic time; and (5) the Kurosegawa continental block collided with the Hida + Hida Marginal continental block in Jurassic to earliest Cretaceous times. The geodynamic model is further discussed in the context of breakup and accretion tectonics.