Environmental and climate reconstruction of the late-glacial-Holocene transition from a lake sediment sequence in Aubrac, French Massif Central: Chironomid and diatom evidence

Abstract

International audienceThe analysis of fossil chironomid and diatom assemblages from a sedimentary record from Les Roustieres peat bog (Massif Central, France, 1196 m asl) allows the reconstruction of past environmental and climate changes during the late-glacial and early Holocene. Chironomid assemblages showed that the infilling of the palaeolake had commenced during the Oldest Dryas (GS-2b) as suggested by the rapid decrease in chironomid species associated with the cold and deep zone of lakes and by their replacement by littoral and eutrophic taxa. Quantitative July temperature reconstructions, based on the chironomid data, suggest that mean July air temperature (Tjul) ranged between 6 degrees C and 11 degrees C at the termination of the Oldest Dryas period (GS-2b). Climate began to warm at the start of the Bolling period (GI-1e), between 15,000 and 14,800 cal yr BP, with a rise in Tjul of about 4 degrees C. This climate warming is contemporaneous with lake eutrophication as suggested by diatoms and chironomids. Maximum temperatures of 13-14 degrees C were reached around 13,600 cal yr BP during the Allered period (GI-1c-GI-1a). The Younger Dryas period (GS-1) is marked by a return to cold conditions with Tjul of about 10 degrees C during a first phase, then 13 degrees C in its terminal part. A probable increase in the duration of the ice-cover may have favoured arctic and alpine diatom species. The early-Holocene climate improvement is marked by a rise in Tjul of about 3 degrees C. (C) 2016 Elsevier B.V. All rights reserved

Impact of human activities and vegetation changes on the tetraether sources in Lake St Front (Massif Central, France)

“…Data for longer periods were from the stations of Saint Julien Chapteuil (distance 9 km, altitude 810 m, period 1995-2017) and Le Puy en Velay (distance 22 km from Lake St Front to the northwest, altitude 833 m, period 1981-2010). Temperature values were corrected using an altitudinal gradient of 0.6°C/100 m (Gandouin et al, 2016).…”

Chironomid-inferred Holocene temperature reconstruction in Basa de la Mora Lake (Central Pyrenees)

“…Chironomid records in the Iberian Peninsula are scarce. The only temperature reconstructions available for the moment are focused on the Lateglacial period (Millet et al, 2012 (French Pyrenees); Gandouin et al, 2016 (French Massif Central); Sobrino et al, 2013 (NW Iberia)) or the last centuries (Granados and Toro, 2000), whereas other chironomid records covering the last centuries (Battarbee et al, 2002; Catalan et al, 2002) or millennia (Morellón et al, 2009a; Pérez-Sanz et al, 2013) are not linked to quantitative temperature reconstructions. Thus, chironomid records or chironomid-based temperature reconstructions covering large sections of the Holocene are not yet available for the Iberian Peninsula.…”

The usefulness of subfossil Cladocera remains in Younger Dryas climatic reconstructions in central Poland

“…This has had a strong influence on local ecosystems and the aquatic invertebrate fauna (Szeroczyńska 1985;Goslar et al 1998;Isarin and Bohncke 1999;Isarin and Rensen 1999;Milecka et al 2011;Feurdean et al 2014;Mirosław-Grabowska and Zawisza 2013;Gandouin et al 2016;Stivrins et al 2016). The river valleys of central Europe underwent significant geological and hydrological transformation (Starkel 1990(Starkel , 2002Macklin et al 2006;Starkel et al 2007;Notebaert and Verstraeten 2010;Kaiser et al 2012;Turner et al 2013).…”