Timing of deglaciation and rock glacier origin in the southeastern Pyrenees: a review and new data

Andrés, Nuria; Gómez‐Ortiz, Antonio; Fernández‐Fernández, José M.; Tanarro, Luis M.; Franch, Ferran Salvador; Oliva, Marc; Palacios, David

doi:10.1111/bor.12324

Cited by 50 publications

(61 citation statements)

References 82 publications

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“…In any case, we have used the most advanced cosmogenic production rates at present for both isotopes, which are also the most used in the current scientific literature. In addition, the difference in results with the use of other widely used age calculation models is minimal and fits within the uncertainty range, as has been demonstrated in other Iberian mountain ranges (Palacios et al 2017;Andrés et al 2018). The 10 Be and 36 Cl ages are perfectly comparable to each other, as has been shown by the analysis of the two cosmogenic isotopes in the same samples conducted in other Iberian regions (Palacios et al 2017;Andrés et al 2018;Oliva et al 2019), although the rate of uncertainty that contributes to the 36 Cl ages is always greater than the from 10 Be.…”

Section: Surface Exposure Datingsupporting

confidence: 54%

“…In the latter case, CRE dating indicates that the highest cirques hosted glaciers until 11.5-10.5 ka (Table 1). As temperatures warmed during the Holocene Thermal Maximum (Renssen et al 2009), those glaciers disappeared and paraglacial dynamics occupied the formerly glaciated environments, favouring the development of rock glaciers (Gómez-Ortiz et al 2013b;Oliva et al 2016b;Andrés et al 2018).…”

Section: Discussionmentioning

confidence: 99%

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Multiproxy reconstruction of Holocene glaciers in Sierra Nevada (south Spain)

et al. 2019

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Pleistocene glaciers shaped the highest lands of the National Park of Sierra Nevada, South Spain. Alpine glaciers filled the western valleys of the massif with hundreds of meters of ice. Surface exposure dating shows evidence of glacial expansion during the Younger Dryas and the subsequent disappearance of glaciers of the massif during the Early Holocene. Since then, glacial records and lake sediments reveal that the massif has been ice-free for the most part of the Holocene, with the development of small glaciers during the coldest phases inside the highest northern cirques. This occurred at 2.8-2.7, 1.4-1.2 cal. ka BP and during the Little Ice Age (1300-1850 CE), when documentary sources confirm also the existence of some glaciers at the foot of the highest summits. This historical period was probably the coldest and wettest phase of the Holocene in the massif and recorded the largest glaciers of the current interglacial. Those glaciers finally melted away during the mid-20th century.

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Section: Surface Exposure Datingsupporting

confidence: 54%

Section: Discussionmentioning

confidence: 99%

Multiproxy reconstruction of Holocene glaciers in Sierra Nevada (south Spain)

et al. 2019

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“…As occurred during the post‐LIA phase in the rock glacier that exists in the Veleta cirque, the formation of permafrost‐related features – including rock glaciers and protalus lobes – must have been conditioned by highly active paraglacial processes, with very unstable rock walls that produced large quantities of sediment, which must have trapped ice that no longer featured glacial dynamics . This process has also been detected in other environments of the Iberian mountains, such as the Central and Eastern Pyrenees . Therefore, this probably means that these were glacier‐derived rock glaciers, suggesting that the elevation boundary for permafrost during the Late Glacial must have been located at ca.…”

Section: Discussionmentioning

confidence: 95%

Monitoring permafrost and periglacial processes in Sierra Nevada (Spain) from 2001 to 2016

Gómez‐Ortiz

Oliva

Franch

et al. 2019

Permafrost & Periglacial

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Outside the Alps, the Sierra Nevada is probably the best studied European massif with respect to its past and current environmental dynamics. A multi‐approach research program started in the early 2000s focused on the monitoring of frozen ground conditions in this National Park. Here, we present data on the thermal state and distribution of permafrost and seasonal frozen ground in different sites across the highest areas of the massif. New results confirm the absence of widespread permafrost conditions, with seasonal frost prevailing above 2500 m. Small permafrost patches have been only detected in glaciated areas of the Veleta and Mulhacén cirques during the Little Ice Age at elevations of 3000–3100 m. The remnants of those glaciers are still preserved under the thick debris layer covering the cirque floors. Geomatic and geophysical surveying of a rock glacier existing in the Veleta cirque, together with the monitoring of soil temperature at different depths, have revealed permanently frozen conditions undergoing a process of degradation. In the rest of the massif, a seasonal frost regime prevails, even at the highest plateaus at 3300–3400 m, where annual soil temperatures average 2.5°C. The monitoring of soil temperatures in other different periglacial features has also revealed positive average values ranging between 2°C (inactive sorted‐circles) and 3–4°C (inactive and weakly active solifluction lobes). Consequently, we conclude that the present‐day climatic regime does not allow the existence of permafrost in the Sierra Nevada, and environmental dynamics is controlled by the intensity and duration of seasonal frost in the ground.

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“…However, there are still many unsolved issues concerning the application of surface exposure dating on rock glaciers, mainly related to: (i) the timing between boulders (i.e. rock glacier) stabilization and permafrost disappearance, (ii) the paleoclimatic significance of rock glacier activity in very active geomorphological settings experiencing paraglacial readjustment (Ballantyne et al, 2009;Palacios et al, 2016Palacios et al, , 2017bAndrés et al, 2018), (iii) the problem of excessive inherited nuclides yielding too old ages (Ivy-Ochs et al, 2009; contrary to the moraines where glacial carving removes the cosmogenic inheritance, and last but not least (iv) the problem related to toppling and/or erosion of boulders that result in too young ages (e.g. Moran et al, 2016).…”

Section: Methodsmentioning

confidence: 99%

Permafrost conditions in the Mediterranean region since the Last Glaciation

Oliva

Žebre

Guglielmin

et al. 2018

Earth-Science Reviews

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The relatively warm climate conditions prevailing today in the Mediterranean region limit cold geomorphological processes only to the highest mountain environments. However, climate variability during the Late Pleistocene and Holocene has led to significant spatio-temporal variations of the glacial and periglacial domain in these mountains, including permafrost conditions. Here, we examine the distribution and evolution of permafrost in the Mediterranean region considering five time periods: Last Glaciation, deglaciation, Holocene, Little Ice Age (LIA) and present-day. The distribution of inactive permafrost-derived features as well as sedimentary records indicates that the elevation limit of permafrost during the Last Glaciation was between 1000 m and even 2000 m lower than present. Permafrost was also widespread in non-glaciated slopes above the snowline forming rock glaciers and block streams, as well as meter-sized stone circles in relatively flat summit areas. As in most of the Northern Hemisphere, the onset of deglaciation in the Mediterranean region started around 19-20 ka. The ice-free terrain left by retreating glaciers was subject to paraglacial activity and intense periglacial processes under permafrost conditions. Many rock glaciers, protalus lobes and block streams formed in these recently deglaciated environments, though most of them became gradually inactive as temperatures kept rising, especially those at lower altitudes. Following the Younger Dryas glacial advance, the Early Holocene saw the last massive deglaciation in Mediterranean mountains accompanied by a progressive shift of permafrost conditions to higher elevations. It is unlikely that air temperatures recorded in Mediterranean mountains during the Holocene favoured the existence of widespread permafrost regimes, with the only exception of the highest massifs exceeding 2500-3000 m. LIA colder climate promoted a minor glacial advance and the spatial expansion of permafrost, with the development of new protalus lobes and rock glaciers in the highest massifs. Finally, post-LIA warming has led to glacial retreat/disappearance, enhanced paraglacial activity, shift of periglacial processes to higher elevations, degradation of alpine permafrost along with geoecological changes.

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Timing of deglaciation and rock glacier origin in the southeastern Pyrenees: a review and new data

Cited by 50 publications

References 82 publications

Multiproxy reconstruction of Holocene glaciers in Sierra Nevada (south Spain)

Multiproxy reconstruction of Holocene glaciers in Sierra Nevada (south Spain)

Monitoring permafrost and periglacial processes in Sierra Nevada (Spain) from 2001 to 2016

Permafrost conditions in the Mediterranean region since the Last Glaciation

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