A debris-covered glacier at Kerguelen (49°S, 69°E) over the past 15 000 years

Abstract

Debris-covered glaciers constitute a large part of the world's cryosphere. However, little is known about their long-term response to multi-millennial climate variability, in particular in the Southern Hemisphere. Here, we provide first insights into the response of a debris-covered glacier to multi-millennial climate variability in the sub-Antarctic Kerguelen Archipelago, which can be compared to that of recently investigated debris-free glaciers. We focus on the Gentil Glacier and present 13 new 36Cl cosmic-ray exposure ages from moraine boulders. The Gentil Glacier experienced at least two glacial advances: the first one during the Late Glacial (19.0–11.6 ka) at ~14.3 ka and the second one during the Late Holocene at ~2.6 ka. Both debris-covered and debris-free glaciers advanced broadly synchronously during the Late Glacial, most probably during the Antarctic Cold Reversal event (14.5–12.9 ka). This suggests that both glacier types at Kerguelen were sensitive to abrupt temperature changes recorded in Antarctic ice cores, associated with increased moisture. However, during the Late Holocene, the advance at ~2.6 ka was not observed in other glaciers and seems to be an original feature of the debris-covered Gentil Glacier, related to either distinct dynamics or to distinct sensitivity to precipitation changes.

Evolution of the Cook Ice Cap (Kerguelen Islands) between the last centuries and 2100 ce based on cosmogenic dating and glacio-climatic modelling

“…All detailed sample information is shown in Table I. The five new samples collected on the archipelago were shipped to the Centre de Recherche et d'Enseignement de Géosciences de l'Environnement (CEREGE) laboratory in Aix-en-Provence, France, where the basaltic whole-rock samples were prepared for in situ -produced 36 Cl CRE dating, following the same methods as those described in the online supplemental material of Charton et al (2020). The chemical compositions of the bulk rocks and the chemically treated sample fractions, which are needed to compute the exposure ages, are listed in Tables II and III.…”

Rapid deglaciation during the Bølling-Allerød Interstadial in the Central Pyrenees and associated glacial and periglacial landforms

“…However, recent research has also shown that debris-covered glaciers can be more sensitive to climate variability than initially thought, as some features may respond rapidly to changes in temperature and precipitation (Charton et al, 2020). Therefore, when interpreting past glacial oscillations both climate changes as well as paraglacial processes must be taken into account.…”