Discovery of Shimanto High-P/T Metamorphic Rocks from the Western Margin of Kyushu, Japan

U–Pb ages of detrital zircons from the Sanbagawa Belt in western Shikoku: Additional evidence for the prevalence of Late Cretaceous protoliths of the Sanbagawa Metamorphics

“…Otoh et al (2010) found zircons dated at 88 ± 10 and 91 ± 9 Ma at the base of the Minawa Formation in roughly the same area thus confirming the general conclusions of Kiminami (2010). Late Cretaceous Sanbagawa metamorphics also occur in the Kii Peninsular (Otoh et al, 2010), the Chubu part of the Sanbagawa Metamorphic Belt (Tsutsumi et al, 2012), in Kyushu (parts of the Nagasaki Metamorphics, Kouchi et al, 2011) and in north-western Shikoku (this study). Our study now extends the known exposure of Late Cretaceous Minawa Formation to north-western Shikoku.…”

“…Also, the maximum protolith age for the Nagasaki Metamorphics on Nishisonogi Peninsular of 89 ± 3 and 86 ± 2 Ma (Kouchi et al, 2011) combined with the Ar-Ar age of 93.2 ± 4.2 Ma for glaucophane reported by Faure et al (1988) suggest that the maximum age of the protolith and the age of peak metamorphism are indistinguishable with the methods used.…”

Evolution of the Sanbagawa and Shimanto high-pressure belts in SW Japan: Insights from K–Ar (Ar–Ar) geochronology

“…Recently Mori et al (2011) reported LA-ICPMS U-Pb age of 126 ± 6 Ma relict igneous zircons in jadeitite from Nishisonogi metamorphic rocks in Kyushu. Using the same facility of Mori et al (2011), Kouchi et al (2011) reported 86 ± 2 Ma detrital zircons from psammitic schist from Nishisonogi metamorphic rocks and correlated Nishisonogi metamorphic rocks to the Shimanto HP belt. However, Yui et al (2011) reported ionmicroprobe (SHRIMP RG) U-Pb ages of 136 ± 2 M from same jadeitite of Mori et al (2011).…”

Timescale of material circulation in subduction zone: U–Pb zircon and K–Ar phengite double‐dating of the Sanbagawa metamorphic complex in the Ikeda district, central Shikoku, southwest Japan

“…The Sanbagawa metamorphic complex comprises a complex of high‐ P metamorphic rocks distributed in the area stretching from the Kanto mountains near Tokyo to the Saganoseki Peninsula in eastern Kyushu, and it is possible that the Nagasaki metamorphic rocks in western Kyushu represent the western extension of these rocks (Kouchi et al, ; Miyazaki, Ozaki, Saito, & Toshimitsu, ; Nishimura, Hirota, Shiosaki, Nakahara, & Itaya, ). The Sanbagawa metamorphic complex extends, therefore, for more than 1 000 km within southwest Japan.…”