Holocene palaeohydrological changes in the northern Mediterranean borderlands as reflected by the lake-level record of Lake Ledro, northeastern Italy

Abstract : A lake-level record of Lake Ledro (northern Italy) spans the entire Holocenewith a chronology derived from51 radiocarbon dates. It is based on a specific sedimentological approach that combines data fromfive sediment profiles sampled in distinct locations in the littoral zone. On a millennial scale, the lake-level record shows two successive periods from 11,700 to 4500 cal yr BP and from 4500 cal yr BP to the present, characterized by lower and higher average lake levels, respectively. In addition to key seasonal and inter-hemispherical changes in insolation, the major hydrological change around 4500 cal yr BP may be related to a non-linear response of the climate system to orbitally-driven gradual decrease in insolation. The Ledro record questions the notion of an accentuated summer rain regime in the northern Mediterranean borderlands during the boreal insolation maximum. Moreover, the Ledro record highlights that the Holocenewas punctuated by successive centennial-scale highstands. Correlations with the Preboreal oscillation and the 8.2 ka event, and comparisonwith the atmospheric 14C residual record, suggest that short-lived lake-level fluctuations developed at Ledro in response to (1) final steps of the deglaciation in the North Atlantic area and (2) variations in solar activity.
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Quaternary Research, Elsevier, 2012, 77 (3), pp.382-396. <10.1016/j.yqres.2012.01.005>
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Michel Magny, Sébastien Joannin, Didier Galop, Boris Vannière, Jean Nicolas Haas, et al.. Holocene palaeohydrological changes in the northern Mediterranean borderlands as reflected by the lake-level record of Lake Ledro, northeastern Italy. Quaternary Research, Elsevier, 2012, 77 (3), pp.382-396. <10.1016/j.yqres.2012.01.005>. <hal-00669616>

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