Early Holocene relative sea-level changes on the central east coast of the Yellow Sea

Paleo-relative sea level (paleo-RSL) records in the far-field are essential for constraining models for global sea level change. We compared the early Holocene RSL history on the central east coast of the Yellow Sea with those of Bohai Bay, the northernmost point, and Gunsan Bay, south of the study area. A multi-proxy approach, including lithostratigraphy, biostratigraphy, combined with radiocarbon and OSL dating, facilitated the generation of 28 sea level index points (SLIPs) using 11 borehole samples. Excavation of basal peat of the 10.3 ka in the study area established that the observed RSL of the transgression in the early Holocene was −14.88 m, which was much shallower than −27.9 m in Gunsan Bay at 9.8 ka and was similar to −17.3 m in Bohai Bay at 9.7 ka. The observed RSL and the prediction curves of the study area were compared with those of other areas. In Gunsan Bay, the early Holocene GIA prediction curves are consistent with those observed, which seems to be the result of a “low setting” of the crust thickness and mantle viscosity. Therefore, it is presumed that the significant difference in the elevations observed between the study area and Gunsan Bay is caused by the levering effect owing to the difference in the tectonic characteristics. Conversely, other observed groups during 7.6–6 ka have a similar slope to the prediction curve of the Early Holocene in the study site, and it is thought that the sediments of the early Holocene were eroded and re-deposited along the channel. These results are of great importance as data of sea level variability in the far field due to glacial collapse and as data for the GIA modeling process. •The RSL in the early Holocene is 13 m shallower than Gunsan on the west coast.•During the 8.2 ka event, the RSL difference between the two sites is 5 m.•GIA models suggest the different costal levering effects between two sites.•Different GIA responses of Gyeonggi Massif and Ockcheon Belt to IESL.