Glacier fluctuations in the western Alps during the Neoglacial, as indicated by the Miage morainic amphitheatre (Mont Blanc massif, Italy)

Abstract

Holocene glacier variations pre‐dating the Little Ice Age are poorly known in the western Alps. Studied for two centuries, the Miage morainic amphitheatre (MMA) is composed of three subconcentric sets of c. 25 moraines. Because of its location and of a dominant mode of morainic accretion, the MMA is a well‐preserved marker of the glacier dynamics during the Neoglacial. Radiocarbon dates were obtained by digging and coring in inter‐ morainic depressions of the MMA and through a deep core drilling in a dammed‐lake infill (Combal); complementary data for the inner MMA were obtained by lichenometry and dendrochronology. Radiocarbon chronology shows that (i) the MMA not only pre‐dates the Little Ice Age (LIA), but was built at least since 5029–4648 cal. yr BP (beginning of the Neoglacial); (ii) outer sets of moraines pre‐date 2748–2362 cal. yr BP; (iii) the MMA dammed the Lake Combal from 4.8 to 1.5 cal. kyr BP, while lakes/ponds formed inside the moraines (e.g. from 2147–1928 to 1506–1295 cal. yr BP). The ‘Neoglacial model’ proposed here considers that the MMA formed during the whole Neoglacial by a succession of glacier advances at 4.8–4.6 cal. ky BP (early Neoglacial), around 2.5 cal. ky BP (end of Göschener I), at AD 600–900 (end of Göschener II) and during the LIA, separated by raising phases of the right‐lateral moraine by active dumping because of the Miage debris cover.

Holocene and ‘Little Ice Age’ glacial activity in the Marboré Cirque, Monte Perdido Massif, Central Spanish Pyrenees

“…For instance, Mayewski et al (2004) stated that the most extensive of the socalled Holocene Rapid Climate Changes occurred from 6000 to 5000 yr BP. In the Alps, a generalized advance of the glaciers occurred during the period 5350-4900 yr BP in most regions (Denton and Karlén,1973;Haas et al, 1998;Deline and Orombelli, 2005;Joerin et al, 2006;Wanner et al, 2011) The 36 Cl age that we obtained for the outermost moraine appears to contradict the geomorphological evidence from other deposits and the dates obtained for polished bedrock using the same method. This is the case for the avalanche of grey limestone boulders (2.5 ± 0.05 ka and 4.4 ± 0.1 ka) located a bit further away from the Monte Perdido Wall, as well as the polished surfaces (3.4 ± 0.2 ka and 2.5 ± 0.1 ka), located in the Central Threshold.…”

“…The glaciation of this phase equaled (Haas et al, 1998;Ivy-Ochs et al, 2009a) and in some cases surpassed (Holzhauser et al, 2005;Deline and Orombelli, 2005) the LIA glacier advance in some areas of the Alps. Furthermore, glaciation reappeared on the northern slope of Mulhacén Peak (Sierra Nevada, southern Spain), between 1.4-1.2 ka BP (Oliva and Gómez Ortiz, 2012).…”

Los efectos geoecológicos del cambio global en el Pirineo Central español: una revisión a distintas escalas espaciales y temporales

“…Muchos de estos glaciares debieron de reactivarse durante el Neoglacial, aunque estos depósitos pueden haber quedado enmascarados por el impulso posterior de tales glaciares durante la Pequeña Edad del Hielo (PEH) (Deline & Orombelli, 2005). En el Pirineo se dispone de una datación en la morrena más externa del circo de Marboré, en la cara norte del Macizo de Monte Perdido, con una edad de 5100 ± 0.1 años cal.…”

Elemental (C/N ratios) and isotopic (δ15Norg, δ13Corg) compositions of sedimentary organic matter from a high-altitude mountain lake (Meidsee, 2661 m a.s.l., Switzerland): Implications for Lateglacial and Holocene Alpine landscape evolution

“…yr BP (Sub-Boreal period), probably linked to changes in summer and winter insolation (Heiri and Lotter, 2005;Ilyashuk et al, 2011). This period was characterized by a succession of glacier advances and timberline depressions, attributed to the development of cooler and wetter climate (Deline and Orombelli, 2005;Haas et al, 1998). During the second part of the Holocene, Meidsee recorded a smooth but continuous rise in P input (Figure 4) and in C/N ratios (Figure 4), suggesting the relative decline of aquatic OM source with regards to higher inputs of terrestrial OM (Schmidt et al, 2002).…”