Holocene Environmental Changes of Lake Geneva (Lac Léman) from Stable Isotopes (δ13C, δ18O) and Trace Element Records of Ostracod and Gastropod Carbonates |
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Authors: | Pere Anadón Andrea Moscariello Julio Rodríguez-Lázaro M L Filippi |
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Institution: | (1) Inst. Ciències de la Terra “J. Almera” CSIC, C. L. Solé Sabarís s/n, 08028 Barcelona, Spain;(2) Shell Int. Expl. Prod. B.V., Rijswijk, The Netherlands;(3) Dept. Estratigrafía y Paleontología, Universidad del País Vasco/EHU, 644 Apartado, Bilbao, Spain;(4) Museo Tridentino di Scienze Naturali, Via Calepina 14, 38100 Trento, Italy |
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Abstract: | Stable isotopes and trace-element contents of ostracod (Candona neglecta) valves mostly from the Holocene portion of two assembled cores from Petit Lac (Lake Geneva, Switzerland-France) were analysed
in order to depict the geochemical record of post-glacial environmental changes of this lake. Additional stable isotope and
trace element data from the gastropod Bithynia tentaculata (shells and opercula) from some intervals of these cores, as well as previous data from bulk carbonate from the lower part
of the studied intervals were also considered. Mg/Ca and Sr/Ca molar ratios for the Holocene lake water have been estimated
from evaluations of the partitioning coefficients for Mg and Sr for C. neglecta and B. tentaculata taking into account the modern-lake water composition. This study shows an overall gentle trend to higher δ18O values in C. neglecta valves from the Boreal interval (mean −8.44‰) to the upper part of the core (mean −8.11‰). This trend is superimposed to
higher frequency oscillations of stable isotope values and trace element ratios, especially through the upper Older Atlantic
and the Subboreal. The overall isotopic oxygen trend includes several shifts in δ18O of about 1‰. These shifts are interpreted as major regional-global climate changes that have also been observed in other
coeval δ18O and pollen records which reflect the Holocene climate variability in other European basins. Especially well-defined peaks
in some episodes like Older Atlantic (~8200 yr BP), Younger Atlantic – Subboreal transition (~5600 yr BP) and early Subatlantic
(~ 2500 yr BP) correspond to well-recognized events in globally-distributed records. Some of these shifts are correlated with
pulses in the lake-level curve of the Lake Geneva.
An erratum to this article is available at . |
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Keywords: | Gastropods Holocene Lake Geneva Ostracods Stable isotopes Trace-element Geochemistry |
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