Pleistocene glacial morphology and timing of last glacial cycle in cantabrian mountains (Northern Spain): new chronological data from the Asón area

Abstract

Abstract:The timing of the local last glacial maximum in the mountains of the Northern Iberian Peninsula is not synchronous with the global Last Glacial Maximum (LGM) probably due to the marginal position of the Northern Iberian Peninsula within the European continent. The study of a Cantabrian massif, the Asón platform and summits, provides new data on the extent and timing of the local last glaciation. Here we can place the last maximal extent of glaciers during Early Würm, according to OSL dating on till samples. The main glaciers developed at least between 78-65 ka BP, well centred on MIS 4 and even the transition to MIS 5. The erosive efficacy of these glaciers decreased later, ca. 45-40 ka BP, until they abruptly disappeared from the edges of the massif. A new ice advance left welldefined moraines at the edges of the massif's internal depressions, indicating a tongue disjunction phase with two glacier sub-stages, probably one at the beginning of the cooling ca. 27-25 ka BP, followed by a retreat and another glacial advance ca. 21-18 ka BP. After these episodes the glaciers disappeared from the Asón Mountains and only some residual glaciers were formed that may be related to the LGM.

Glaciokarst landforms in the Siera de los Grajos, Babia and Luna natural park (Cantabrian Mountains, NW Spain)

“…The moraines in the Sierra de los Grajos show the occurrence of many glacial stages that should be correlated with previous researches on glacial chronology in the Cantabrian Mountains (Jalut et al 2010;Frochoso et al 2013;Jiménez-Sánchez et al 2013;Serrano et al 2013;Rodríguez-Rodríguez et al 2016;Ruiz-Fernández et al 2016), that show a local glacial maximum previous to the global Last Glacial Maximum.…”

“…The infiltration of the subglacial water into the karst network reduces overland flow, which modifies the discharges of the pro-glacial streams and the sediments they carry. Therefore, when glacier dynamics converge with a subglacial karst (Žebre & Stepišnik 2015), a type of landscape that combines the reliefs derived from both processes, named glaciokarst, is generated (Ford 1979;Smart 2004;Žebre & Stepišnik 2015).During cold stages of the Pleistocene, these dynamics has been common in the calcareous mountains at middle latitudes (Johnson & Stieglizt 1990;Bodgdan & Leszek 1999;Goldie 2006;Lepirica 2008;Hughes et al 2010;Telbisz et al 2011;Adamson et al 2014;Stepišnik 2014;Žebre & Stepišnik 2015;Žebre et al 2016), and also in limestone outcrops of the Cantabrian Mountains were the glacial processes were intense (Jalut et al 2010;Serrano et al 2012Serrano et al , 2013Frochoso et al 2013;Jiménez-Sánchez et al 2013;Santos-González et al 2013a;Gómez-Villar et al 2015;Rodríguez-Rodríguez et al 2016;Ruiz-Fernández et al 2016). However, in lower zones where this association does not occur, karst processes are dominant.…”

Influencia de la glaciación en la red de drenaje: el ejemplo de los valles de Respina y Rebueno (Alto Porma, Cordillera Cantábrica, noroeste de España)

“…Entre los trabajos más recientes, se pueden destacar, entre otros, algunos análisis sobre circos (Ruiz-Fernández et al, 2009;Gómez-Villar et al, 2015), sobre depósitos glaciares (Santos-González et al, 2013b), la altitud de la línea de equilibro glaciar (Serrano Cañadas y González Trueba, 2004;Santos-González et al, 2013a) o sobre la cronología glaciar (García-Ruiz et al, 2010;Jalut et al, 2010;Frochoso et al, 2013;Jiménez-Sánchez et al, 2013;Moreno et al, 2010;Serrano et al, 2013;Rodríguez-Rodríguez et al, 2015;Ruiz-Fernández et al, 2016). A pesar de esos esfuerzos, lo cierto es que aún quedan muchos valles que apenas han sido analizados en detalle y en otros muchos no se conocen con precisión los límites que alcanzó la glaciación.…”

Deglaciación en la Cordillera Cantábrica: modelo y evolución

“…In the Picos de Europa the maximum glacial extent has been dated as previous to 40 kyr in Enol ), 40,480 ± 820 BP in Comeya (Jiménez-Sánchezand Farias, 2002, 35,700-34,850 cal yr BP in the Duje valley and 37.2 kyr cal BP in the Belbin basin (Nieuwendam et al, 2015). The minimum age obtained for the glacial maximum in the Fuentes Carrionas massifs is 36,028 ± 2350 yr BP (Pellitero, 2011(Pellitero, , 2014Serrano et al, 2012) and in the TruebaValley (Pas Mountains) the age is prior to 29,149-28,572 cal yr BP (Serrano et al, , 2013 and 44,980 ± 2300 yr BP (Frochoso et al, 2013) on the north side. The western massif shows the same chronologies: 28,990 ± 230 yr BP in Redes (Jiménez et al, , 2013 and around 44 kyr in the Sil Valley (Jalut et al, 2010).…”

“…Recent studies on distinct Cantabrian Mountain massifs have provided radiocarbon dates ( 14 C, AMS) in Redes, Sil Valley, Picos de Europa and Pas Mountains Jiménez-Sánchez et al, 2013;Jalut et al, 2010;Moreno et al, 2010;Serrano et al, 2011, Niewendam et al, 2015, and U/Th and optically stimulated luminescence (OSL) dates from the Fuentes Carrionas and Pas Mountains (Pellitero, 2011(Pellitero, , 2014Serrano et al, 2012;Frochoso et al, 2013). The glacial morphosequences analysed and available dates have facilitated a first approximation to the Late Pleistocene glacial chronology and deglaciation pattern in the Cantabrian Mountains, where three main Pleistocene glacial phases have been detected (Jiménez-Sánchez et al, 2013;Serrano et al, 2013a,b;Rodríguez-Rodríguez et al, 2014).…”