Chronology of glaciations in the Cantabrian Mountains (NW Iberia) during the Last Glacial Cycle based on in situ-produced 10 Be

• Published in: Quaternary Science Reviews
• Main Authors: Rodríguez-Rodríguez, Laura, Jiménez-Sánchez, Montserrat, Domínguez-Cuesta, María José, Rinterknecht, Vincent, Pallàs, Raimon, Bourlès, Didier
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: 10Be exposure dating; Glacier reconstruction; Paleoclimate; Last Glacial Cycle; Last deglaciation; Cantabrian Mountains; Iberian Peninsula; North Atlantic
• Online Access: https://research-portal.st-andrews.ac.uk/en/researchoutput/chronology-of-glaciations-in-the-cantabrian-mountains-nw-iberia-during-the-last-glacial-cycle-based-on-in-situproduced-10be(d15e69de-a93f-4950-929b-4cdd8fe3a254).html; https://doi.org/10.1016/j.quascirev.2016.02.027

The mountain ranges of the Iberian Peninsula preserve a valuable record of past glaciations that may help reconstruct past atmospheric circulation patterns in response to cooling events in the North Atlantic Ocean. Available chronologies for the glacial record of the Cantabrian Mountains, which are mainly based on radiocarbon and luminescence dating of glacial-related sediments, suggest that glaciers recorded their Glacial Maximum (GM) during MIS 3 and experienced a later Last Glacial Maximum (LGM) advance. This LGM extent is not established yet, preventing a fair correlation with available Cosmic Ray Exposure (CRE) based chronologies for the glacial record of the Pyrenees and the Sistema Central. We present a glacial reconstruction and a 10 Be CRE chronology for the Porma valley, in the southern slope of the central Cantabrian Mountains. Glacial evidence at the lowest altitudes correspond to erratic boulders and composite moraines whose minimum 10 Be CRE age of 113.9 ± 7.1 ka suggests that glaciers were at their maximum extent during MIS 5d, most likely in response to the minima in summertime insolation of the Last Glacial Cycle. Recessional moraines preserved within the glacial maximum limits allow the assessment of subsequent glacier advances or stagnations. The most remarkable advance took place prior to 55.7 ± 4.0 ka (probably at the end of MIS 4), consistently with minimum radiocarbon ages previously reported for lacustrine glacial-related deposits in the Cantabrian Mountains. A limited number of 10 Be CRE ages from a composite moraine suggest a possible advance of the Porma glacier coeval with the global LGM; the glacier front attributed to the LGM would be placed within the margins of the previous GM like in the western Pyrenees. Erratic boulders perched on an ice-moulded bedrock surface provided a mean 10 Be CRE age of 17.7 ± 1.0 ka, suggesting that part of the recessional moraine sequence corresponds to minor advances or stagnations of the glacier fronts during the Lateglacial period. This recessional ...