Calendar-dated glacier variations in the Western European Alps during the Neoglacial: the Mer de Glace record, Mont Blanc massif

Abstract : Holocene glacier records from the western European Alps are still sparse, although a number of sites are well suited to constraining pre- and early- Little Ice Age (LIA) glacier advances. The present study provides the first dendrochronologically-based and calendar-dated Neoglacial glacier chronology for the Mont Blanc massif, French Alps. It is based on the analysis of over 240 glacially buried Pinus cembra subfossil logs and wood remains found either embedded-in-till or as detrital material in the Mer de Glace right lateral moraine. Only a few of the samples were found to be ‘formally in situ’ but we show that some logs were ‘virtually in situ’ (not rooted but showing little or no evidence of reworking) and could be used to accurately reconstruct past glacier margin behavior in space and time. Uncertainties regarding the other samples may relate to original growth location and/or to outer wood decay. The resulting dates (followed by a ‘+’) were therefore considered maximum-limiting ages for glacier advances. The main burial events – interpreted as glacier advances – occurred between ca 1655+ and 1544+ BC, between ca 1230+ and 1105+ BC, between ca 1013+ and 962+/937+ BC, at ca 802–777 BC, after 608+ BC, between 312 and 337 AD, between ca 485+ AD and 606+ AD, between 1120 and 1178 AD, between ca 1248 and 1278+/1296 AD, and after 1352+ AD. These advances predate the late LIA maxima known from historical sources. The magnitude of the advances gradually increased to culminate in three near-Neoglacial maxima during the 7th, 12th and 13th centuries AD, followed by a first LIA/Neoglacial maximum in the second half of the 14th century AD. The pattern of Neoglacial events described here is coherent with Central and Eastern Alpine glacier chronologies. This indicates marked synchronicity of late Holocene glacier variability and forcing at a regional scale, although occasional differences could be detected between ‘Western’ and ‘Eastern’ records. The Mer de Glace record also confirms the link between the timing of sediment erosion in a high-elevation glaciated Alpine catchment and subsequent deposition in the sub-alpine Lake Bourget.
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https://hal-sde.archives-ouvertes.fr/hal-01313197
Contributeur : Christine Maury Referent Hal Edytem <>
Soumis le : lundi 9 mai 2016 - 16:13:33
Dernière modification le : jeudi 8 novembre 2018 - 15:46:05

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Melaine Le Roy, Kurt Nicolussi, Philip Deline, Laurent Astrade, Jean-Louis Edouard, et al.. Calendar-dated glacier variations in the Western European Alps during the Neoglacial: the Mer de Glace record, Mont Blanc massif. Quaternary Science Reviews, Elsevier, 2014, 〈10.1016/j.quascirev.2014.10.033〉. 〈hal-01313197〉

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