Postglacial landscape changes and cryogenic processes in the Picos de Europa (Northern Spain): reconstructed from geomorphological mapping and microstructures on quartz grains

Abstract

A 5.4m long sediment core was collected from Belbín, a karstic depression dammed by a moraine in a mid-altitude environment in the Western Massif of the Picos de Europa of the Cantabrian Mountains, northern Spain. 14C AMS dating of the basal sediments in the core suggests that the maximum glacier advance during the last glacial cycle preceded the global Last Glacial Maximum and occurred prior to 37.2 ka cal BP. Four environmental stages are reconstructed from analysis of the sediment core and in particular the surface microstructures on quartz sand grains: (1) 37.2–29.4 ka was characterised by intense periglacial activity with deposition of slope deposits; (2) 29.4–22.6 ka saw the gradual infilling of the depression with sediment; (3) 22.6–8.1 ka was associated with a palaeolake; and (4) since 8.1 ka, terrestrialisation of the palaeolake commenced, and human impact related to fire activity started around 4.9 ka. Microstructures on the surface of quartz grains suggest different intensity patterns of frost weathering processes in response to Late Quaternary climate oscillations.