The Tokunoshima Belt: A New Geotectonic Unit in Central Ryukyus, Japan

Researchers have identified the Tokunoshima belt, a new geotectonic unit in central Ryukyus, Japan, characterized by its high-grade metamorphic rocks and distinct geological features. This discovery challenges existing models of the region's tectonic evolution. The study reveals that the Inokawadake metamorphic complex (IMC), part of this new belt, underwent amphibolite-facies metamorphism, a rarity in the Shimanto belt. Paleoproterozoic zircons suggest a complex history, while detrital zircon ages indicate metamorphism occurred in the Paleocene or later. The IMC structurally overlies Cretaceous accretionary complexes as a klippe, hinting at subhorizontal faulting and potential heat sources from either the San-in batholith belt to the north or an unknown collided island arc system to the south.

YAMAMOTO, H., ISOZAKI, Y., & OKAMOTO, K. (2024). 中琉球の新たな地体構造単元「徳之島帯」. Journal of Geography (Chigaku Zasshi), 133(6), 447–464. https://doi.org/10.5026/jgeography.133.447