Preprints
https://doi.org/10.5194/esurf-2017-30
https://doi.org/10.5194/esurf-2017-30
30 May 2017
 | 30 May 2017
Status: this preprint has been withdrawn by the authors.

Determination limits for cosmogenic 10Be and their importance for geomorphic applications

Sara Savi, Stefanie Tofelde, Hella Wittmann, Fabiana Castino, and Taylor Schildgen

Abstract. When using cosmogenic nuclides to determine exposure ages or denudation rates in rapidly evolving landscapes, challenges arise related to the small number of nuclides that have accumulated in surface materials. Improvements in accelerator mass spectrometry have enabled analysis of samples with low 10Be content (< 105 atoms), such that it is timely to discuss how technical limits of nuclide determination, effects of laboratory cleanliness, and overall sample preparation quality affect lower blank limits. Here we describe an approach that defines a lower threshold above which samples with low 10Be content can be statistically distinguished from laboratory blanks. In general, this threshold depends on the chosen confidence interval. In detail, however, we show that depending on which ensemble of blank values and which approach is chosen for the calculation of this threshold, significant differences can arise with respect to when a sample can be distinguished from a blank. This in turn dictates whether the sample can be used to determine an exposure age or a denudation rate, or when it only constrains a maximum age or a minimum denudation rate. Based on a dataset of 57 samples and 61 blank measurements obtained in one laboratory, we demonstrate how these different approaches may influence the interpretation of the data.

This preprint has been withdrawn.

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Sara Savi, Stefanie Tofelde, Hella Wittmann, Fabiana Castino, and Taylor Schildgen

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Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Sara Savi, Stefanie Tofelde, Hella Wittmann, Fabiana Castino, and Taylor Schildgen
Sara Savi, Stefanie Tofelde, Hella Wittmann, Fabiana Castino, and Taylor Schildgen

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Short summary
When using cosmogenic nuclides to determine exposure ages or denudation rates in rapidly evolving landscapes, challenges arise related to the small number of nuclides that have accumulated in surface materials. Here we describe an approach that defines a lower threshold above which samples with low 10Be content can be statistically distinguished from laboratory blanks. This in turn dictates the meaning and reliability of the samples and their possible use.