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MS: Fachverband Massenspektrometrie

MS 7: Accelerator Mass Spectrometry

MS 7.6: Vortrag

Donnerstag, 5. März 2026, 16:00–16:15, N 6

Sample preparation of CaSO₄-containing sediments for exposure dating by ³⁶Cl — •Natasha Goaba Kalanke^1,2, Markus Schiffer^2,3, Stefan Heinze², Erik Strub⁴, Gregory Campbell¹, Michael Staubwasser⁵, Steven Binnie⁵, and Dennis Muecher² — ¹Department of Physics and Astronomy, Botswana International University of Science and Technology — ²Institute of Nuclear Physics, University of Cologne — ³Laboratory of Isotope Archaeology, Department of Prehistoric Archaeology, University of Cologne — ⁴Institute of Nuclear Chemistry, University of Cologne — ⁵Institute of Geology and Mineralogy, University of Cologne

The application of cosmogenic ³⁶Cl exposure dating to gypsum (CaSO₄· 2H₂O) is limited by pervasive sulfur isobaric interference and complex chemical purification requirements. A novel chemical protocol that effectively isolates chlorine from a sulfate-rich gypsum matrix has been developed. It was tested through procedural chemical blanks and natural gypsum deposits from the Atacama Desert with isotope dilution (ID-AMS). Chemical blanks were processed by the new protocol and revealed, on average, a ³⁶Cl/³⁵Cl ratio of (1.5± 3.48) × 10⁻¹⁴ with ³⁵Cl⁵⁺ currents ranging from 4-10 µA. The method will be used for exposure age determination of gypsum landforms including evaporite deposits, desert crusts and paleohydrological features, opening new avenues for Quaternary research in arid and sulfate-rich environments. First preliminary results of gypsum samples from the Atacama Desert will be reported and compared to their U-Th dating.

Keywords: 36Cl Exposure Dating; Gypsum Geochronology