Establishing a high-resolution late Pleistocene to Holocene tephrostratigraphic framework in central Japan using wetland deposit core records: An attempt to detect cryptotephra from terrestrial records in the productive volcanic arc

A high-resolution tephrostratigraphic framework focusing on cryptotephra provides a key isochron and the accurate ages of past explosive eruptions in remote regions. The Japanese archipelago has many Quaternary volcanoes, and the tephrochronology using visible tephras of this region has been extensively studied. Research on Lake Suigetsu and other repositories have provided the tephrostratigraphic framework. A detailed cryptotephra study in central Japan can provide correlation to Lake Suigetsu records and strengthens the tephrostratigraphic framework in and around central Japan, but has not been extensively conducted. In this study, we focused on wetland deposits formed in the mountainous regions in central Japan and conducted coring excavation, cryptotephra analysis, fingerprinting, and radiocarbon dating to establish a high-resolution tephrostratigraphic framework. We excavated the Aizu region with late Pleistocene records from the YNH-P1 core and Holocene records from the YNH-P2 core and the Sekita Mountain region with late Pleistocene records from the NNM-P1 core and Holocene records from the CYI-P1 core. Towada-Chuseri, Asama-YKU, Aira-Tn, and Daisen-Kurayoshi tephras were identified in multiple cores, which played an essential role in refining tephrostratigraphy. Tateyama-E tephra, which erupted from the Norikura volcanic chain, was identified for the first time in the Aizu region (YNH-P1 core); it provided important chronological constraints for the north Kanto tephrostratigraphy. Moreover, Myoko-Otagirigawa and Myoko-Akakura tephras from Myoko volcano were accurately dated as 4.4–4.2 and 5.9–5.7 cal ka, respectively, based on tephrostratigraphy and radiocarbon dating. Results showed a more detailed tephrostratigraphic framework in central Japan than those reported in previous studies. • A detailed tephrostratigraphy of central Japan was established. • Twenty visible tephras and twenty cryptotephras were detected across study sites. • Tateyama-E tephra distribution was extended 100 km beyond that of previous studies. • Two Holocene Myoko tephras were dated to 4.4–4.2 and 5.9–5.7 cal ka, respectively.