Ice Sheet Changes and GIA‐Induced Surface Displacement of the Larsemann Hills During the Last 50 kyr

Abstract

AbstractThe Antarctic Ice Sheet (AIS) is the largest potential source for future global sea level rise. However, there are widely diverging estimates of its contribution, which emphasizes the need to improve our understanding of the long‐term behavior of the AIS and its impact on the solid Earth. This knowledge gap results from a shortage of records of glacial history, especially for the pre‐Holocene. Marine transgression and recession in the coastal areas of Antarctica are influenced by the mass of the overlying ice, providing crucial information about regional ice sheet dynamics. In this study, we determined a marine transgression from 53 kyr BP onward by diatom assemblages and a δ13C‐C/N biplot for the organic component in a sediment core (MCM2), from the Larsemann Hills in East Antarctica. Relative sea level (RSL) reached a maximum of ~12 m a.p.s.l. (above present sea level) during 38–29 kyr BP. Concurrent with the transgression, the regional crust experienced glacial‐isostatic‐adjustment (GIA)‐induced subsidence from ~75 to ~95 m beneath the present land level, suggesting an expansion trend of the East Antarctic ice sheet (EAIS), which may have outpaced global cooling. After the last deglaciation, the RSL rose to a highstand of ~8–10 m a.p.s.l. at ~8.5–7.1 kyr BP, when the bedrock uplifted to ~20 m below the present level. After 4.0 kyr BP, both regional and global deglaciation ceased, but an effect of ongoing relaxation caused the land to rebound continuously at a uniform rate of ~1.5 m/kyr, which can account for the sustained fall of RSL across Antarctica since mid‐Holocene.