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A multi-radionuclide approach for in-situ produced terrestrial cosmogenic nuclides: 10Be, 26Al, 36Cl and 41Ca from carbonate rocks
Merchel, S.; Benedetti, L.; Bourlès, D. L.; Braucher, R.; Dewald, A.; Faestermann, T.; Finkel, R. C.; Korschinek, G.; Masarik, J.; Poutivtsev, M.; Rochette, P.; Rugel, G.; Zell, K.-O.;
In contrast to siliceous environments, there is a severe lack of cosmogenic nuclides, which can be used for in-situ dating of calcareous environments. Thus, we have investigated other nuclides than 36Cl as possible dating tools by cross-calibration. Cosmogenic 10Be is highly contaminated with atmospheric 10Be and cannot be removed quantitatively, even by a very sophisticated chemical cleaning procedure. Only working on clay-free calcite provides correct 10Be data, giving a 2.7 times higher production rate of 10Be from CaCO3 than from SiO2. Though, the production rate of 26Al is only ~4.6% (CaCO3 relative to SiO2), 26Al can be easily determined in calcite, as the low intrinsic 27Al concentration yields to nearly as high 26Al/27Al as within corresponding quartz. The measurement of 41Ca, mainly produced via thermal-neutron-capture, is hindered by very low 41Ca/Ca: < 2.5x10-15.
Keywords: accelerator mass spectrometry, terrestrial cosmogenic nuclides (TCN), cosmogenic nuclide exposure dating

Publ.-Id: 11921 - Permalink