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Quantification and spatial distribution of dose rate relevant elements in silex used for luminescence dating

Title data

Schmidt, Christoph ; Pettke, Thomas ; Preusser, Frank ; Rufer, Daniel ; Kasper, Haino U. ; Hilgers, Alexandra:
Quantification and spatial distribution of dose rate relevant elements in silex used for luminescence dating.
In: Quaternary Geochronology. Vol. 12 (2012) . - pp. 65-73.
ISSN 1871-1014
DOI: https://doi.org/10.1016/j.quageo.2012.05.006

Project information

Project title:
Project's official titleProject's id
SFB 806 'Our Way To Europe'SFB806

Project financing: Deutsche Forschungsgemeinschaft

Abstract in another language

Thermoluminescence (TL) is routinely used to date heated lithic artefacts which mostly consist of silex (a mixture of amorphous opal and microcrystalline chalcedony). Analytical investigations of bulk samples confirmed that these materials contain considerable concentrations of radioactive elements, generating an internal dose rate contribution. Common dosimetric models assume the latter to be homogeneous throughout the sample. If this assumption would prove invalid, this will result in systematic errors in the calculated age, especially in the course of so called 'hot spots' of α-emitters (and associated local changes in α-sensitivity) and the dose response characteristics of α-radiation. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of 22 silex samples are presented here, quantifying element concentrations at several tens analytical spots per sample. Along with radioactive elements (K, Rb, U, Th), another 21 major, minor and trace elements were measured in order to allow characterization of the impurities present in most of the samples. The dataset provides a detailed picture of the spatial distribution of radionuclides and hence of the uniformity of the internal α- and β-dose rate. It is shown that the silex itself mostly contains low amounts of K (<0.1 wt.%), U (<1.0 μg g−1) and Th (<0.4 μg g−1), and dosimetrically negligible Rb concentrations. Systematically higher concentrations are obtained by ICP-MS measurements of the bulk samples. This matches with the finding that impurities (veins, inclusions) often yield significantly elevated radionuclide concentrations, up to two orders of magnitude higher than the silex values. These veins and inclusions, for example Ca or Mg carbonates and Fe–Mn- xy-hydroxides, lead to steep gradients mainly in the internal α-radiation field. Alternative approaches are required to account for the non-uniform internal dose rate and improve the reliability of TL dates of problematic samples.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: Silex; Flint; Thermoluminescence; TL; Microdosimetry; ICP-MS; LA-ICP-MS
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Former Professors > Chair Geomorphology - Univ.-Prof. Dr. Ludwig Zöller
Profile Fields > Advanced Fields > Ecology and the Environmental Sciences
Profile Fields > Advanced Fields > Nonlinear Dynamics
Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Geomorphology
Profile Fields
Profile Fields > Advanced Fields
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: No
DDC Subjects: 500 Science > 550 Earth sciences, geology
Date Deposited: 21 Dec 2015 13:03
Last Modified: 23 Mar 2016 11:00
URI: https://eref.uni-bayreuth.de/id/eprint/29061