Early Carboniferous radiolarians discovered from the Hayachine Terrane, Northeast Japan: the oldest fossil age for clastic rocks of accretionary complex in Japan

Abstract

Early Carboniferous radiolarians were newly discovered from siltstone of the Nedamo Complex in the Hayachine Terrane, Northeast Japan. This siltstone and other clastic rocks along with greenstone and chert are the components of an accretionary complex. Radiolarian fauna contains Palaeoscenidium cladophorum Deflan-dre that ranges in age from Early or Middle Devonian to Early Carboniferous. Since the Fe-Mn chert intercalated in a MORB-type basalt of the Nedamo Complex was assigned an age of Late Devonian Hamano et al., , the accretionary age of the Hayachine Terrane is no older than Late Devonian, most probable Early Car-boniferous. This is the first report of an Early Carboni-ferous accretionary complex recognized by biostrati-graphic data in Japan.