Rapid age assessment of glacial landforms in the Pyrenees using Schmidt Hammer exposure dating (SHED)

• Published in: Quaternary Research
• Main Authors: Tomkins, Matthew, Dortch, Jason, Hughes, Philip, Huck, Jonathan, Stimson, Andrew, Delmas, Magali, Calvet, Marc, Pallas, Raimon
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2018
• Subjects: Ice Sheet
• Online Access: https://research.manchester.ac.uk/en/publications/b5b130eb-9273-4886-8bcb-0f8ea1ca523c; https://doi.org/10.1017/qua.2018.12; https://pure.manchester.ac.uk/ws/files/70315048/Tomkinsetal2018_QuaternaryResearch.pdf

Schmidt Hammer (SH) sampling of 54 10Be dated granite surfaces from the Pyrenees reveals a clear relationship between exposure and weathering through time (n = 52, R2 = 0.96, p < 0.01) and permits the use of the SH as a numerical dating tool. To test this 10Be-SH calibration curve, 100 surfaces were sampled from 5 ice-front positions in the Têt catchment, Eastern Pyrenees, with results verified against independent 10Be and 14C ages. Gaussian modelling differentiates Holocene (9.4 ± 0.6 ka), Younger Dryas (12.6 ± 0.9 ka), Oldest Dryas (16.1 ± 0.5 ka), Last Glacial Maximum (LGM: 24.8 ± 0.9 ka) and Würmian Maximum Ice Extent stages (MIE: 40.9 ± 1.1 ka). These data confirm comparable glacier lengths during the LGM and MIE (~300 m difference), in contrast to evidence from the Western Pyrenees (≥15 km), reflecting the relative influence of Atlantic and Mediterranean climates. Moreover, Pyrenean glaciers advanced significantly during the LGM, with a local maximum at ~25 ka, driven by growth of the Laurentide Ice Sheet, southward advection of the polar front and a solar radiation minimum in the Northern Hemisphere. This calibration curve is available at http://shed.earth to enable wider application of this method throughout the Pyrenees.