Dating ice shelf edge marine sediments: A new approach using single-grain quartz luminescence

• Published in: Journal of Geophysical Research
• Main Authors: Berger, G.W., Murray, A.S., Thomsen, Kristina Jørkov, Domack, E.W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2010
• Subjects: Radiation research and nuclear technologies; Radiation physics; Strålingsfysik; Strålingsforskning og nukleare teknologier; /dk/atira/pure/sustainabledevelopmentgoals/life_below_water; SDG 14 - Life Below Water; Antarctic; The Antarctic; Antarctic Peninsula; Antarc*; Ice Shelf; Ice Shelves
• Online Access: https://orbit.dtu.dk/en/publications/78be8138-8927-4da4-bd91-54ec37ae7554; https://doi.org/10.1029/2009JF001415

To develop an alternative dating tool for the Antarctic Peninsula (where the 14C method requires large, spatially variable reservoir corrections), we tested the clock-zeroing assumption of photon-stimulated luminescence (PSL) dating using a variety of PSL procedures. At ice shelf edges around the Antarctic Peninsula, sediment-water-interface (“zero-age” analogs), silt-rich short cores were collected in 2001–2003, originally only for fine silt dating tests. Later access to suitable instrumentation also permitted testing the potential of single-grain quartz (SGQ) dating of sand grains from these cores. For the fine silt grains we employed multiple-aliquot and single-aliquot methods to obtain last daylight exposure age estimates from near-core-top material. With the sand fraction we employed automated SGQ PSL methods to isolate the youngest grains. Five of six fine silt samples gave unreasonably large age estimates (>20 ka), with the sixth sample yielding a multiple-aliquot short-bleach age estimate of 1.1 ± 0.6 ka. In contrast, five of seven sand samples yielded geologically reasonable last daylight exposure ages of 0.2–0.6 ka. These SGQ results are also remarkable when compared to published 14C ages of 1 ka to 9.7 ka from core top living calcite and acid-insoluble organic matter. These SGQ results establish the likely utility of this single-grain dating approach in such settings to provide chronologies for calving line histories of ice shelves. To take advantage of this utility, core collection should employ large-diameter coring devices (e.g., Kasten and multicorers). A caveat is that large numbers (e.g., ∼10,000) of quartz grains may need analysis to provide acceptable statistics for useful age calculations.