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The Fusaki Formation, located at the Ishigaki Island and [[Taketomi Island]] of the Yaeyama Islands in Southern Ryukyu,<ref name=":15" /> comprises weakly metamorphosed [[Olistostrome|olistromal rocks]]: [[allochthon|allochthonous blocks]] of chert, [[mudstone]], sandstone, and limestone are embedded in a muddy matrix.<ref name=":14" /> The metamorphic age of this formation ranges from 145–130 Ma (Early [[Cretaceous]]) and was determined by K-Ar phengitic micas dating.<ref name=":14" /> [[Radiolaria]] data show that the formation accreted in the [[Toarcian]] in the Early Jurassic.<ref name=":6" /> This formation is part of an accretionary complex of a Middle Jurassic subduction zone.<ref name=":14" />
On Ishigaki Island, this formation is thrusted beneath the Tomuru Formation along the Sokobaru [[Thrust fault|thrust]]
===Nakijin Formation===
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The Miyara Formation is a south-southwest-dipping succession of [[Conglomerate (geology)|conglomerate]], sandstone, [[shale]], and limestone deposited along the coast of Ishigaki Island.<ref name=":9" /> A large variety of marine fossils—e.g., calcareous algae, foraminifera, corals, [[Echinoderm|echinoderms]], [[Bryozoa|bryozoans]], and [[Gastropoda|gastropods]]— have been preserved in the limestones, and [[Mollusca|molluscs]] were also found in the conglomerate.<ref name=":9" /> Foraminifera and calcareous algae in the limestones suggest a late Eocene age.<ref name=":9" />
The Nosoko Formation is a 300m thick sequence of [[tuff]], volcanic sandstone and [[breccia]], and lavas with [[Dike (geology)|dykes]], [[Sill (geology)|sills]], and other small [[Igneous intrusion|intrusions]].<ref name=":9" /> This formation is widely exposed at the Nosoko peninsula in northern Ishigaki Island.<ref name=":9" /> It also lies conformably above the Miyara Formation.<ref name=":21" /> [[Paleomagnetism|Paleomagnetic]] data of the Nosoko Formation indicate a mean deflection of the magnetic direction at about 30˚ clockwise away from the expected pole.<ref name=":17">Miki, M. (1995). Two‐phase opening model for the Okinawa Trough inferred from paleomagnetic study of the Ryukyu arc. ''Journal of Geophysical Research: Solid Earth, 100''(B5), 8169–8184. https://doi.org/10.1029/95JB00034</ref> This data, coupled with [[Radiometric dating|radiometric]] ages, suggest that Southern Ryukyu might have rotated about 25˚ with respect to the Asian continent in the Miocene at 6–10 Ma.<ref name=":17" />
===Yaeyama Group===
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