Flexural Backstripping of the East Sea in Response to Quaternary Glaciation Mean Sea Level Fluctuations

The paleoceanographic evolution of the East Sea following large Quaternary glaciation mean sea level (MSL) fluctuations is reconstructed using three-dimensional flexural backstripping with spatially variable effective elastic thickness (Te) values. Post Pleistocene sediment loads are removed before quantifying the lithospheric response to water load variations and to calculate basement uplift and peripheral subsidence. Model results indicate that MSL fall of 1830- 1912 m could have produced flexural uplifts of 519-538 m in the Ulleung Basin, sufficient to generate shallow-marine to subaerial conditions. These sea-level reductions would have generated more than 130 m of flexural uplift in the Korea Strait, potentially leading to its temporary closure, with a minimum MSL fall of ~150 m required for this isolation. Such closure likely reduced water exchange, lowered surface salinity, inhibited deep-water ventilation, and created low-oxygen conditions, consistent with the regional fossil records in the area. These results demonstrate that MSL changes critically influenced basin evolution and highlight the sensitivity of semi-enclosed basins to sea-level fluctuations.