Beryllium isotope variations recorded in the Adelie Basin, East Antarctica reflect Holocene changes in ice dynamics, productivity, and scavenging efficiency

The Adelie Basin is a relatively small (similar to 1600 km(2)), semi-enclosed continental shelf bathymetric depression located adjacent to the Wilkes Subglacial Basin, a basin underlying a sector of the East Antarctic Ice Sheet that contains similar to 3-4 m sea level equivalent of ice. Located within the Adelie Basin is a similar to 184 m thick laminated sediment deposit, the Adelie Drift, ideal for examining regional changes in ice sheet and ocean dynamics. Here, we examine the ratio of reactive beryllium-10 to reactive beryllium-9 ((Be-10/Be-9)(reac)) in a marine sediment core obtained from the Adelie Drift to assess these changes during the Holocene epoch (11.7 ka BP to present). The (Be-10/Be-9)(reac) record provides insight into changes in freshwater input, primary productivity, and scavenging efficiency, while removing the influence of particle size on Be-10 concentration. During the early Holocene, (Be-10/Be-9)(reac) ratios indicate increased meltwater discharge from ca. 11.7 to 10 ka BP, as grounded ice retreated from the Adelie Basin and adjacent bathymetric highs. After similar to 10 ka BP, beryllium isotopes are influenced by scavenging efficiency and dilution controlled by ocean currents and accumulation rate, operating alongside meltwater input, suggesting there are additional factors to consider when using (Be-10/Be-9)(reac) as a proxy for ice shelf cover and glacial dynamics.

Automated summary

The Adelie Basin provides an ideal location to study regional changes in ice sheet and ocean dynamics through examination of sediment deposits. The (Be-10/Be-9)(reac) ratio can provide insights into changes in freshwater input, primary productivity, and scavenging efficiency, but additional factors need to be considered when using it as a proxy for ice shelf cover and glacial dynamics.