Clim. Past Discuss., 8, 5963-6009, 2012
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This discussion paper has been under review for the journal Climate of the Past (CP). Please refer to the corresponding final paper in CP.
An optimized multi-proxy, multi-site Antarctic ice and gas orbital chronology (AICC2012): 120–800 ka
L. Bazin1, A. Landais1, B. Lemieux-Dudon2, H. Toyé Mahamadou Kele2, D. Veres3,4, F. Parrenin3, P. Martinerie3, C. Ritz3, E. Capron5, V. Lipenkov6, M.-F. Loutre7, D. Raynaud3, B. Vinther8, A. Svensson8, S. O. Rasmussen8, M. Severi9, T. Blunier8, M. Leuenberger10, H. Fischer10, V. Masson-Delmotte1, J. Chappellaz3, and E. Wolff5
1Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Gif-sur-Yvette, France
2Laboratoire Jean Kuntzmann, Grenoble, France
3Laboratoire de Glaciologie et Geophysique de l'Environnement, CNRS-UJF, St. Martin d'Heres, France
4Institute of Speleology, Romanian Academy, Cluj-Napoca, Romania
5British Antarctic Survey, Cambridge, UK
6Arctic and Antarctic Research Institute, St. Petersburg, Russia
7Université catholique de Louvain, Georges Lemaître Center for Earth and Climate Research, Belgium
8Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
9Department of Chemistry Ugo Schiff, University of Florence, Florence, Italy
10Climate and Environmental Physics, Physics Institute and Oeschger Center for Climate Change Research, University of Bern, Bern, Switzerland

Abstract. An accurate and coherent chronological framework is essential for the interpretation of climatic and environmental records obtained from deep polar ice cores. Until now, one common ice core age scale has been developed based on an inverse dating method (Datice) combining glaciological modelling with absolute and stratigraphic markers between 4 ice cores covering the last 50 ka (thousand of years before present) (Lemieux-Dudon et al., 2010). In this paper, together with the companion paper of Veres et al. (2012), we present an extension of this work back to 800 ka for the NGRIP, TALDICE, EDML, Vostok and EDC ice cores using an improved version of the Datice tool. The AICC2012 (Antarctic Ice Core Chronology 2012) chronology includes numerous new gas and ice stratigraphic links as well as improved evaluation of background and associated variance scenarios. This paper concentrates on the long timescales between 120–800 ka. In this frame, new measurements of δ18Oatm over Marine Isotope Stage (MIS) 11–12 on EDC and a complete δ18Oatm record of the TALDICE ice cores permit us to derive new orbital gas age constraints. The coherency of the different orbitally deduced ages (from δ18Oatm, δO2/N2 and air content) has been verified before implementation in AICC2012. The new chronology shows only small differences, well within the original uncertainty range, when compared with the previous ice core reference age scale EDC3. For instance, the duration of the last four interglacial periods is not affected by more than 5%. The largest deviation between AICC2012 and EDC3 (4.4 ka) is obtained around MIS 12. Despite significant modifications of the chronological constraints around MIS 5, now independent of speleothem records in AICC2012, the date of Termination II is very close to the EDC3 one.

Citation: Bazin, L., Landais, A., Lemieux-Dudon, B., Toyé Mahamadou Kele, H., Veres, D., Parrenin, F., Martinerie, P., Ritz, C., Capron, E., Lipenkov, V., Loutre, M.-F., Raynaud, D., Vinther, B., Svensson, A., Rasmussen, S. O., Severi, M., Blunier, T., Leuenberger, M., Fischer, H., Masson-Delmotte, V., Chappellaz, J., and Wolff, E.: An optimized multi-proxy, multi-site Antarctic ice and gas orbital chronology (AICC2012): 120–800 ka, Clim. Past Discuss., 8, 5963-6009, doi:10.5194/cpd-8-5963-2012, 2012.
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