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

• Published in: Quaternary Research
• Main Authors: Tomkins, Matt D., Dortch, Jason M., Hughes, Philip D., Huck, Jonny J., Stimson, Andrew G., Delmas, Magali, Calvet, Marc, Pallàs, Raimon
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2018
• Subjects: Ice Sheet
• Online Access: http://dx.doi.org/10.1017/qua.2018.12; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589418000121

Abstract Schmidt hammer (SH) sampling of 54 10 Be-dated granite surfaces from the Pyrenees reveals a clear relationship between exposure and weathering through time (n=52, R 2 =0.96, P <0.01) and permits the use of the SH as a numerical dating tool. To test this 10 Be-SH calibration curve, 100 surfaces were sampled from five ice-front positions in the Têt catchment, eastern Pyrenees, with results verified against independent 10 Be and 14 C 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 online ( http://shed.earth ) to enable wider application of this method throughout the Pyrenees.