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| Titel |
Were the MIS 11 and MIS 5e warmer and/or wetter than the Holocene? Test comparison of Interglacial intensities using stable isotope data from Northern France tufa deposits. |
| VerfasserIn |
Julie Dabkowski, N. Limondin-Lozouet, P. Antoine, A. Marca-Bell, J. Andrews |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250058607
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| Zusammenfassung |
| Many recent palaeoclimatic studies have focused on MIS 5 (Eemian) and 11 as they are
supposed to be the best analogues for our modern interglacial. As they are characteristic of
temperate periods and result of calcite precipitation from meteogene water, tufas are
key-deposits for palaeoclimatic reconstructions of these interglacials. Calcite oxygen and
carbon stable isotopes (δ18O and δ13C) are known since the 80s to be important
palaeoclimatic proxies for the Holocene and we recently have shown their suitability
in Pleistocene tufas. At decadal-scale sampling resolution, δ18O of tufa records
variations in δ18O of regional rainfall, and in this way reflects source or amount
effects (particularly continentality), and temperature depending on locality. δ13C of
tufa indicates moisture availability (linked to biomass type/abundance) and rainfall
intensity.
Using our new results from the tufa of Saint-Germain-le-Vasson (Normandy) dated to the
first half of the Holocene, and those from Caours (Somme) and La-Celle-sur-Seine
(Seine-et-Marne) respectively assigned to MIS 5e and MIS 11, we investigate similarities or
differences between these Pleistocene interglacials and the modern one. Comparison
between the sites is relevant as these tufas developed in a similar geological area (the
Paris Basin) and are nowadays in the same humid and temperate climatic area.
The Caours tufa presents carbon and oxygen isotopic compositions similar to the
Saint-Germain sequence. Comparable temperature and humidity conditions are
thus recorded during the Eemian and the Holocene. However, δ13C for the MIS 5e
optimum are more negative than those for the Atlantic optimum (Holocene), which
may indicate wetter conditions. In La Celle, slightly warmer conditions appear to
be recorded for MIS 11 compared to the Holocene by higher δ18O values than in
Saint-Germain. Moreover, two very humid episodes are observed in the La Celle δ13C profile
whereas such wet conditions are not observed during the first half of the Holocene at
Saint-Germain. One of the episodes is correlated to maximal temperatures and assigned to
the MIS 11 optimum. Stable isotope data for this period clearly indicate warmer
and wetter conditions compared to those during the Altantic optimum recorded at
Saint-Germain.
Tufa stable isotopes are thus suitable to compare MIS 11 and MIS 5e interglacials
palaeoclimatic conditions to those prevailing during the Holocene. New investigations on
recent and Pleistocene tufa deposits from France, Germany, England, etc. should lead to a
more complete record of differences and similarities between interglacials, and allow
including geographical parameters at European scale. |
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