Last interglacial sea-level proxies in the Korean Peninsula

Abstract

Like most of the world's coastlines, the Korean Peninsula experienced higher-than-present sea levels during the last interglacial (LIG), otherwise known as Marine Isotope Stage (MIS) 5e. However, the expression of that highstand in the geological record differs across the eastern and western Korean Peninsula. The tectonically active east coast of the Korean Peninsula is characterized by broad uplifted marine terraces, while the stable west coast is characterized by tidal flats and rias. In this study, we used a standardized database template to review and extract the existing constraints on LIG sea levels along both the east and west coasts of the Korean Peninsula. A total of 62 LIG constraining data points were compiled including 34 sea-level indicators, 22 marine limiting records, and 6 terrestrial limiting records. The ages from these data points are based on 61 optically stimulated luminescence (OSL) measurements and 1 paleomagnetic-based age. Along the uplifted east coast, LIG sea-level indicators based on marine terraces are at elevations ranging from +9 to +32 m. The uplifted marine terraces are cut or otherwise deformed by faults developed under a compressional regime due to back-arc closing of the East Sea since the early Pliocene. As a result, tectonic uplift likely has affected the elevations of the east coast LIG shorelines. In contrast, LIG sea-level records on the west coast of the Korean Peninsula are found at heights of between +3 and +6 m and include marine and terrestrial elevation limiting records as well as true sea-level indicators. The LIG sea-level constraints along the west coast of the Korean Peninsula are likely unaffected by vertical movement or experienced minor subsidence during the Quaternary. The database is available open access at https://doi.org/10.5281/zenodo.4974826 (Ryang and Simms, 2021).