Triassic marine Os isotope record from a pelagic chert succession, Sakahogi section, Mino Belt, southwest Japan

•Pelagic cherts in accretionary rocks preserve pre-Cretaceous marine Os isotope data.•Os isotope data from cherts of the Sakahogi section represent 40 Myr of the Triassic.•Triassic marine Os and Sr isotopic records show similar paleoceanographic histories.•The Os isotopic record reflects impacts, igneous episodes, and paleoclimatic events.•Accreted cherts may preserve a marine Os isotope record for the whole Phanerozoic.