[S-GL23] Geologic structure and tectonic history of East Asia and Japanese Islands

[SGL23-01] The Yamato tectonic line and tectonic framework of Far East Asia

*Yukio Isozaki¹, Yusuke Sawaki¹, Hideki Iwano², Takafumi Hirata³, Keitaro Kunugiza⁴ (1.Department of Earth Science and Astronomy, Graduate School of Arts and Sciences, The University of Tokyo, 2.Kyoto Fission-Track Co. Ltd. , 3.Geochemical Resaerch Center, The University of Tokyo, 4.Department of Human Development, Toyama University)

Keywords:Yamato tectonic line, CAOB, Nipponides, Greater South China block, Yamato Ridge, Hida belt

The traditional view on the South China block was recently revised owing to the recognition of its northeastern extension in Far East Asia. The Paleozoic South China block was much larger (almost 3-times longer) than previously imagined, which was renamed as Greater South China (GSC). Paleozoic GSC included the conterminous South China block (Yangtze and Cathaysia), East China Sea, Paleozoic SW-NE Japan, and the Khanka-Jiamusi-Bureya megablock mostly in Far East Russia. Along the Pacific margin of GSC ever since the Cambrian, the long-lasting subduction-related processes have formed a major Phanerozoic orogenic belt, which is called Nipponides (or Pacific-rim orogenic belt). On the western side of GSC, in contrast, two open oceans called the Paleo-Asian and Paleo-Tethys closed through multiple subduction/collisions, of which remnants were recognized currently along the Solonker and Dabie-Sulu collisional sutures in China, respectively. The contact between the Solonker suture and GSC/Nipponides is characterized by a unique domain with particular age combination of granitoids (250 and 180 Ma), e.g. the Hida belt (SW Japan), Yamato Ridge (Japan Sea), Laoelin-Grodekov belt (Russia/China/N. Korea), and the eastern Songliao block (NE China). The Yamato tectonic line defines the eastern margin of this unique granitoid domain to represent the major orogen-divide or geotectonic boundary in East Asia, which continues for >5000 km, i.e. the boundary between the Nipponides/GSC and the intra-continental orogenic belts (Solonker and Dabie-Sulu collisional sutures). The closure of the Paleo-Asian and Paleo-Tethys oceans and docking of GSC during the late Paleozoic-early Mesozoic finalized the consolidation of East Asia.

Reference: Isozaki et al. (2023) Island Arc, 32, e12475