A multi-radionuclide approach for in situ produced terrestrial cosmogenic nuclides: 10 Be, 26 Al, 36 Cl and 41 Ca from carbonate rocks S. Merchel a,b, * , L. Benedetti a , D.L. Bourlès a , R. Braucher a , A. Dewald c , T. Faestermann d , R.C. Finkel a,e,f , G. Korschinek d , J. Masarik g , M. Poutivtsev d , P. Rochette a , G. Rugel d , K.-O. Zell c a CEREGE, CNRS-IRD-Université Aix-Marseille, F-13545 Aix-en-Provence, France b Forschungszentrum Dresden-Rossendorf, D-01314 Dresden, Germany c Institut für Kernphysik, Universität zu Köln, D-50937 Köln, Germany d Technische Universität München, D-85748 Garching, Germany e CAMS, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA f University of California, Berkeley, CA 94720, USA g Department of Nuclear Physics, Komensky University, SK-84215 Bratislava, Slovakia article info Article history: Available online 12 October 2009 Keywords: Accelerator mass spectrometry Terrestrial cosmogenic nuclides (TCN) Cosmogenic nuclide exposure dating abstract In contrary to siliceous environments, there is a severe lack of cosmogenic nuclides, that can be used for in situ dating of calcareous environments. Thus, we have investigated other nuclides than 36 Cl as possible dating tools by cross-calibration. Cosmogenic 10 Be is highly contaminated with atmospheric 10 Be and cannot be removed quantitatively, even by a very sophisticated chemical cleaning procedure. Only work- ing on clay-free calcite provides correct 10 Be data, giving a 2.7 times higher production rate of 10 Be from CaCO 3 than from SiO 2 . Though, the production rate of 26 Al is only 4.6% (CaCO 3 relative to SiO 2 ), 26 Al can be easily determined in calcite, as the low intrinsic 27 Al concentration yields to nearly as high 26 Al/ 27 Al as within corresponding quartz. The measurement of 41 Ca, mainly produced via thermal-neutron-capture, is hindered by very low 41 Ca/Ca:<5  10 15 . Ó 2009 Elsevier B.V. All rights reserved. 1. Introduction In situ produced cosmogenic nuclides have proved to be valu- able tools for quantifying Earth’s surface processes. Here, the work-horses are 10 Be and 26 Al in quartz-rich minerals, and 36 Cl in Ca- or K-rich minerals. Several attempts to find new matrix-prod- uct-pairs have been yet performed, especially with respect to broaden the time-scale to both more ancient [1] and more recent (historic) times. The ability to analyse 10 Be in carbonate rocks would have sev- eral advantages: extending the timescale and allowing burial dat- ing in calcareous environments, and as the 10 Be production rate from C is higher than from O [2], better analytical precision, re- duced sample mass, enlarged resolution, and investigation of sam- ples with shorter exposure. Beryllium-10 determinations from calcite samples had been proven to be quite challenging [3], be- cause atmosphere-produced 10 Be is absorbed on ubiquitous clay minerals and cannot be removed by simple leaching techniques. We have tested new 10 Be and clay decontamination schemes, but we are also focussing on other cosmogenic nuclides from this envi- ronment, namely 26 Al and 41 Ca. Of course, we are aware that both nuclides have some disadvantages over 10 Be or 36 Cl, i.e. lower 26 Al production rate or being a pure (n,c)-product yielding low 41 Ca/Ca ratios. Measuring at least two nuclides from the same sample allows us to better constrain the thermal neutron field, perform burial dating and/or reconstruct more precisely erosion rates and irradi- ation histories. We have, thus, determined 10 Be, 26 Al, 36 Cl, and 41 Ca in accompanied calcite- and quartz-rich samples from Antarc- tica and Southern France. Ratios between different nuclides from the same matrix (CaCO 3 ) and ratios of 10 Be or 26 Al from CaCO 3 and SiO 2 can be compared with pure physical model calculations giving us experimental terrestrial production rates for 10 Be, 26 Al, and 41 Ca from Ca and CaCO 3 . 2. Experimental 2.1. Samples As our work is more like a feasibility study, we have looked for samples with high radionuclide concentrations and coexisting calcite- and quartz-rich lithologies. Due to generally low erosion 0168-583X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2009.10.128 * Corresponding author. Address: Forschungszentrum Dresden-Rossendorf, D-01314 Dresden, Germany. Tel.: +49 351 260 2802; fax: +49 351 260 12802. E-mail address: s.merchel@fzd.de (S. Merchel). Nuclear Instruments and Methods in Physics Research B 268 (2010) 1179–1184 Contents lists available at ScienceDirect Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb