[S-GL23] 日本列島および東アジアの地質と構造発達史

[SGL23-01] 大和構造線と極東アジアの地体構造

*磯崎 行雄¹、澤木 佑介¹、岩野 英樹²、平田 岳史³、椚座 圭太郎⁴ (1.東京大学大学院総合文化研究科広域科学専攻広域システム科学系、2.京都フィッショントラック（株）、3.東京大学地殻化学研究施設、4.富山大学人間発達科学部)

キーワード：大和構造線、中央アジア造山帯、ニッポニデス、大・南中国地塊、大和堆、飛騨帯

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