피열 퇴적층 OSL 연대분석으로부터의 후기 플라이스토세 이후 용암층 수치연대 도출법 적용 가능성: 40Ar/39Ar 연대분석을 통한 확인

Precisely dating volcanic events since the Late Pleistocene is often difficult due to the lack of appropriate chronology. Such difficulty is encountered in the Jeju volcanics. In Jeju Island there are sedimentary deposits that are intercalated with volcanic units, as well as primary volcanic products. For the Kyorekyo Sediments that are sandwiched between two lava beds in the island, Ahn et al. (2018) estimated quantitatively paleotemperatures reached by heat of the upper lava emplacement by applying magnetic methods and explained that there were lava-heated sediments in which the OSL signal could be zeroed by the lava heat; thus, the estimated OSL ages indicate not the sedimentation age but the age of the lava emplacement resulting in 14.8 ± 0.8 ka. In this study the whole-rock-groundmass step-heating 40Ar/39Ar dating assigns a plateau age of 15 ± 5 ka to the upper lava, which shows relatively large uncertainty but is in good agreement with the lava-heated sediment OSL estimates thereby confirming the feasibility of the Ahn et al. (2018) dating approach. Future works by such lava-heated sediment OSL chronology with paleotemperature estimation have a potential to improve dating the Late Pleistocene- Holocene lavas related to the last volcanic history in Jeju Island.