European Geosciences Union General Assembly 2012 Vienna Austria 22 27 April 2012 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. Dabkowski Julie 1&2, Limondin-Lozouet Nicole 1, Antoine Pierre 1, Marca-Bell Alina 3, Andrews Julian 3. 1 2 3
Why work on tufa? In terrace systems, interglacial optima are only recorded in calcareous tufa deposits. Fluvial sequences: substratum Full Interglacial (calcareous tufa) Lateglacial / Interglacial (calcareous fluvial silts and sands overlaid by organic soils) Pleniglacial (fluvial gravels with sand lenses) Early Glacial (slope deposits with under bedded fluvial silt levels) Calcareous tufas are common : during interglacial, in areas with carbonated bedrock under temperate climate. Calcareous tufas fossilise (in situ): palaeontological remains (mollusc shells, ostracods, mammals, insects and leaf prints, wood charcoal...), archaeological levels. Calcareous tufas are often >90% of calcite, suitable for: direct U-Th dating on calcite, O and C stable isotope analyses (palaeoclimate reconstructions).
Studied sites and methodology La Celle-sur-Seine MIS 11 Caours MIS 5e Saint-Germain Caours La Celle Saint-Germain-le Vasson HOLOCENE Geological map and profile of the Paris Basin (modified after Pomerol, 1964). Pluridisciplinary studies Strong chronological assignment both by relative and absolute datations Clear climatic optimum recorded
Studied sites and methodology Calcite stable isotopes (δ 18 O c et δ 13 C c ) Known since the 80 s as palaeoclimatic proxies in Holocene tufas. Suitability for Pleistocene interglacial climate reconstructions recently demonstrate (Dabkowski et al., 2011, Quaternaire) δ 18 O c (oxygen) Depends on: - water temperature - Water isotopic composition => depending on Atmospheric temperature δ 13 C c (carbon) Depends on 3 sources of DIC: - soil CO 2 (very negative δ 13 C) - atmospheric CO 2 (slightly negative δ 13 C) - aquifer dissolved CaCO3 (slightly negative to positive δ 13 C) Cooler Warmer Wetter (and warmer) Drier (and cooler) δ 18 O c δ 13 C c
Studied sites and methodology Continuous sampling each 5 cm of all stratigraphical units including climatic optimum if known by palaeoenvironmental data. Stable isotope analyses at the Stable Isotope Laboratory of the UEA (Norwich, UK) OM destruction (oxygen plasma) Inorganic carbonate: 100 (± 10) µg Europa SIRA mass spectrometer online with automated preparation system (common acid bath of H 3 PO 4 at 90 C)
Results: climatic records of past interglacials La Celle-sur-Seine MIS 11 Caours MIS 5e Position of the climatic optimum strictly define: - Malacological succession - Geochemical data Saint-Germain-le Vasson HOLOCENE Atlantic optimum define by palynological data
Results: MIS 11 compared to the Holocene La Celle vs. Saint Germain-le-Vasson Cooler Warmer Drier MIS 11 optimum vs. Atlantic Saint-Germain-le-Vasson Humid episod La Celle-sur-Seine Wetter MIS 11 slighly warmer than the first half of the Holocene, Very humid episodes during the MIS 11 (compared to the first half of the Holocene), MIS 11 optimum warmer and wetter than the Atlantic.
Results: MIS 5e compared to the Holocene Caours vs. Saint Germain-le-Vasson Cooler Warmer Drier Saint-Germain-le-Vasson MIS 5e optimum vs. Atlantic Caours Wetter Similar temperature conditions. Similar humidity conditions but: Smaller amplitudes during the MIS 5e than during the first half of the Holocene, Eemian optimum wetter than the Atlantic.
Conclusion and perspectives Tufa stable isotopes suitable to compare MIS 11 and MIS 5e interglacials to Holocene palaeoclimates: MIS 11: slighly warmer, with wetter episodes (especially the optimum). MIS 5e: as temperate and wet as the first half of the Holocene (optimum wetter than the Atlantic). New investigations on recent and Pleistocene tufa deposits: at local to regional scale, at European scale (data base, GIS). At Condat (SW France): Tuf actif dans le cours du Coly Tuf fossile Holocène (SIM 1) Tuf fossile SIM 5 England France Germany Croatia Hongria Holocène SIM 5 SIM 11 Italy (Toscana)
European Geosciences Union General Assembly 2012 Vienna Austria 22 27 April 2012 ANY QUESTION?? Please visit our poster! (ref. XY 127 / abstract: EGU2012-376) Thanks for your attention. Active and Holocene tufa from the Ru Blanc, Bourgundy (France) MIS 5 tufa from Burgtonna, Thuringia (Germany)