Elemental (C/N ratios) and isotopic (δ 15 N org , δ 13 C org ) compositions of sedimentary organic matter from a high-altitude mountain lake (Meidsee, 2661 m a.s.l., Switzerland)

Implications for Lateglacial and Holocene Alpine landscape evolution

Bibliographic Data

ID19687217
AuthorsFlorian Thevenon (University of Geneva, corresponding author), Thierry Adatte (0000-0002-4319-2212, University of Lausanne), Jorge E Spangenberg (0000-0001-8636-6414, University of Lausanne), Flavio S Anselmetti (0000-0002-8785-3641, Swiss Federal Institute of Aquatic Science and Technology)
Year2012
Volume22
Issue10
Pages1135-1142
Publication date2012-04-17
Peer ReviewedYes
Open AccessYes
TypeARTICLE
VenueThe Holocene (JOURNAL)
Journal identifiersISSN: 0959-6836 • E-ISSN: 1477-0911
PublisherSAGE Publishing (PUBLISHER • US)
DOI10.1177/0959683612441841
OpenAlexW2046352629
LanguageEN
Citations received4
References cited32

The deposition of Late Pleistocene and Holocene sediments in the high-altitude lake Meidsee (located at an altitude of 2661 m a.s.l. in the Southwestern Alps) strikingly coincided with global ice-sheet and mountain-glacier decay in the Alpine forelands and the formation of perialpine lakes. Radiocarbon ages of bottom-core sediments point out (pre-) Holocene ice retreat below 2700 m a.s.l., at about 16, 13, 10, and 9 cal. kyr BP. The Meidsee sedimentary record therefore provides information about the high-altitude Alpine landscape evolution since the Late Pleistocene/Holocene deglaciation in the Swiss Southwestern Alps. Prior to 5 cal. kyr BP, the C/N ratio and the isotopic composition of sedimentary organic matter (δ 15 N org , δ 13 C org ) indicate the deposition of algal-derived organic matter with limited input of terrestrial organic matter. The early Holocene and the Holocene climatic optimum (between 7.0 and 5.5 cal. kyr BP) were characterized by low erosion (decreasing magnetic susceptibility, χ) and high content of organic matter (C org > 13 wt.%), enriched in 13 C org (> −18‰) with a low C/N (~10) ratio, typical of modern algal matter derived from in situ production. During the late Holocene, there was a long-term increasing contribution of terrestrial organic matter into the lake (C/N > 11), with maxima between 2.4 and 0.9 cal. kyr BP. A major environmental change took place 800 years ago, with an abrupt decrease in the relative contribution of terrestrial organic material into the lake compared with aquatic organic material which subsequently largely dominated (C/N drop from 16 to 10). Nonetheless, this event was marked by a rise in soil erosion (χ), in nutrients input (N and P contents) and in anthropogenic lead deposition, suggesting a human disturbance of Alpine ecosystems 800 years ago. Indeed, this time period coincided with the migration of the Walser Alemannic people in the region, who settled at relatively high altitude in the Southwestern Alps for farming and maintaining Alpine passes

Deglaciation · Glacier · Holocene · Holocene climatic optimum · Organic matter · Physical geography · Radiocarbon dating · Sediment · Sedimentary organic matter · Sedimentary rock · Total organic carbon · Chemistry · Geological formations and processes · Geology and Paleoclimatology Research · Isotope Analysis in Ecology · Ecology · Environmental Chemistry · Geology · Paleontology

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