Abstract
The Nedamo Complex is an accretionary complex constituting the Nedamo Terrane located at the boundary between the Jurassic North Kitakami Terrane and the Paleozoic South Kitakami Terrane. The accretion age of the complex is Early Carboniferous. Uchino and Kawamura (2006) identified tectonic blocks of high-P/T glaucophane-bearing mafic schist in the Nedamo Complex. In this study, step-heating method in 40Ar/39Ar chronometry was applied to muscovite from the high-P/T schists, yielding an age of ca. 380 Ma age (Middle-Late Devonian). This age is at least 30 myr older than the accretion age of the Nedamo Complex. Accordingly, the schists are considered not to be a metamorphosed part of the Nedamo Complex itself but rather a part of a pre-Carboniferous metamorphosed accretionary complex.
