Dépôt numérique

A 7000-year environmental history and soil erosion record inferred from the deep sediments of Lake Pavin (Massif Central, France).

Chassiot, Léo, Miras, Yannick, Chapron, Emmanuel, Develle, Anne-Lise, Arnaud, Fabien, Motelica-Heino, Mikaël et Di Giovanni, Christian (2018). A 7000-year environmental history and soil erosion record inferred from the deep sediments of Lake Pavin (Massif Central, France). Palaeogeography, Palaeoclimatology, Palaeoecology , vol. 497 . p. 218-233. DOI: 10.1016/j.palaeo.2018.02.024.

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A 14-m long sedimentary sequence (core PAV12) was collected in the deepest part of Lake Pavin, a maar lake located in the French Massif Central. The PAV12 sedimentary sequence documents the lake's environmental evolution since its formation 7000 years ago. The relationships between the catchment's vegetation cover, erosion processes and changes in trophic status were shown using a multi-proxy characterization of mineral and organic fractions supported by palynological data. The record shows a succession of lithological units starting at the base with volcanoclastic material corresponding to the early stage of Lake Pavin. The deposition of organic-rich and diatomaceous sedimentary units above volcanoclastic material indicates an evolution toward a pristine lacustrine state. The Late Holocene environmental history of this lake is marked by two tipping points reflecting major environmental disturbances at ca. 4000 cal BP and after the deposition of erosive mass-wasting deposits (MWDs) at 1350 cal BP (AD 600) and 650 cal BP (AD 1300). The upper unit of core PAV12, which corresponds to the past 700 years, indicates that one of these MWDs was likely the driving force behind a major limnological change marked by a shift in redox-sensitive elements (i.e., current meromictic lacustrine state). The palynological diagram indicates a forested catchment where woodland clearances and agro-pastoral activities have remained limited except over the last 700 years. These findings suggest restricted human impact within the watershed compared to other regional archives. The reconstruction of the Lake Pavin erosion record determined from titanium and red amorphous particle fluxes highlights phases of enhanced erosion at ca. 6.5–5.5, 4.1–3.8, 3.5, 2.8–2.6, 1.6–1.4 cal kyr BP and during the Little Ice Age (LIA). A comparison between this erosion record, palaeoenvironmental archives from Western Europe and palaeoclimatic data supports an Atlantic signal driving precipitation patterns over Lake Pavin at centennial to millennial timescales. The influence of local human activities, even on a small scale, cannot be completely discounted as their impact on erosional processes may be amplified in a steep catchment such as that found in Lake Pavin.

Type de document: Article
Mots-clés libres: maar lake; meromictic lake; paleolimnology; Holocene; NAO; human impact
Centre: Centre Eau Terre Environnement
Date de dépôt: 25 oct. 2018 19:10
Dernière modification: 25 oct. 2018 19:10
URI: https://espace.inrs.ca/id/eprint/7703

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