Rapid deglaciation of the La Vega gorge (Sierra de Gredos, Iberian Peninsula) at the end of the global Last Glacial Maximum

Abstract

[Abstract] Previous studies from the Iberian Central System and other mountains of the Iberian Peninsula and Europe suggest that deglaciation in this area occurred at the end or immediately after the global Last Glacial Maximum (LGM, 26.5–19 ka). In this research, we investigate the timing and speed of deglaciation of the palaeoglacier in La Vega gorge (Iberian Central system) since the global LGM, dating the outer moraines, glacially polished bedrock and glaciofluvial deposits by means of in situ cosmogenic 10Be and optically stimulated luminescence. The results show that one intermediate arc located at the outer frontal moraine system has an age of ~21 ka, being consistent with the global LGM. Deglaciation began at ~21–19 ka, speeding up at ~19 ka. We estimate that around 4–5 km of the palaeoglacier receded in ~1–2 kyrs since ~19 ka, leaving La Vega gorge probably ice-free at ~18 ka. Therefore, our data confirm that deglaciation in Sierra de Gredos began at the end of the global LGM, characterised by a rapid and massive retreat of glaciers.