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

• Published in: Quaternary Science Advances
• Main Authors: Behrens, Bethany C., Jiménez Espejo, Francisco J., Escutia Dotti, Carlota
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2022
• Subjects: Holocene; East Antarctica; Cosmogenic nuclides; Beryllium isotopes; Scavenging; Antarctic; East Antarctic Ice Sheet; New Zealand; Wilkes Subglacial Basin; Antarc*; Antarctica; Ice Sheet; Ice Shelf
• Online Access: https://hdl.handle.net/10481/79749; https://doi.org/10.1016/j.qsa.2022.100054

The Ad´elie Basin is a relatively small (~1600 km2), 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 ~3–4 m sea level equivalent of ice. Located within the Ad´elie Basin is a ~184 m thick laminated sediment deposit, the Ad´elie 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 ((10Be/9Be)reac) in a marine sediment core obtained from the Ad´elie Drift to assess these changes during the Holocene epoch (11.7 ka BP to present). The (10Be/9Be)reac record provides insight into changes in freshwater input, primary productivity, and scavenging efficiency, while removing the influence of particle size on 10Be concentration. During the early Holocene, (10Be/9Be)reac ratios indicate increased meltwater discharge from ca. 11.7 to 10 ka BP, as grounded ice retreated from the Ad´elie Basin and adjacent bathymetric highs. After ~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 (10Be/9Be)reac as a proxy for ice shelf cover and glacial dynamics. Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research (KAKENHI) 20H00193 Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science 20J21145 PE17712 P18791 New Zealand Ministry of Business, Innovation and Employment (MBIE) ANTA1801 Ministry of Science and Innovation, Spain (MICINN) Spanish Government CTM2017-89711-C2-1-P European Union through FEDER funds