Fulltext

The last 1300years of environmental history recorded in the sediments of Lake Sils (Engadine, Switzerland)

Blass, Alex ; Anselmetti, Flavio ; Grosjean, Martin ; Sturm, Michael

In: Eclogae Geologicae Helvetiae, 2005, vol. 98, no. 3, p. 319-332

Ajouter à la liste personnelle
    Titre
    • The last 1300years of environmental history recorded in the sediments of Lake Sils (Engadine, Switzerland)
    Auteur
    • Blass, Alex. Institute of Geography, University of Berne, Hallerstr. 12, 3012, Bern, Switzerland
    • Anselmetti, Flavio. Geological Institute, ETH Zürich, Sonneggstr. 5, 8092, Zürich, Switzerland
    • Grosjean, Martin. Institute of Geography, University of Berne, Hallerstr. 12, 3012, Bern, Switzerland
    • Sturm, Michael. Surface Waters, EAWAG, Überlandstr. 133, 8600, Dübendorf, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Eclogae Geologicae Helvetiae, 2005, vol. 98, no. 3, p. 319-332. Birkhäuser-Verlag; www.birkhauser.ch
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:316196
    Summary
    Abstract.: Proglacial Lake Sils is located in the Upper Engadine (south-eastern Swiss Alps) at 1800 m a.s.l. and is the uppermost of four lakes in the valley. A highresolution seismic survey combined with geophysical and chemical data of 22 short sediment cores, and 137Cs, 210Pb, and 14C AMS dating provide insight into the sedimentological development of the lake during the last 1300years. The deposits consist of diffusely laminated clayey silts. In contrast to nearby Lake Silvaplana, no varves could be detected. Sedimentation rates are on average 1.1mm per year (40mg cm−2a−1) which is much lower than in the adjacent Engadine lakes. The most prominent sediment feature is a turbidite that was deposited around cal AD 700, has a thickness of up to more than 6 metres and a total estimated volume of 6.5*106 m3, which is more than the total cumulated sediment mass deposited since that time (4.5 * 106 m3). The sediments deposited after around AD 1880 show higher contents of organic carbon (Corg) and biogenic silica (bSi), which suggests enhanced primary production due to increasing tourism in the area and subsequent higher nutrient supply to the lake. Sediments with distinctly lower Corg and bSi concentrations, but with larger grain-size medians and higher mica concentrations were accumulated between AD 1500 and 1880. These features are related to a late period of the ‘Little Ice Age' when major regional glacier advances occurred