Abstract
The reconstruction of palaeoclimate on a sub-annual scale requires the measurement of chemical proxies in fossil material at a high spatial resolution. While various methods for trace element analysis on the micrometre scale are available, they are usually destructive to the sample or not widely accessible. This study evaluates the performance of a table-top micro X-ray fluorescence scanner in obtaining reproducible trace element profiles on bivalve calcite. Standard calibration and repeatability tests demonstrate the robustness of results obtained with this new generation micro X-ray fluorescence device that uses a comparatively high excitation energy of 30 W. Results show that elemental abundances measured using this fast, readily accessible and non-destructive analytical set-up are reproducible on the μg g−1 level, and therefore suitable for the analysis of the abundance of commonly studied elements in bivalve calcite (for example, Sr, Mn and Fe). Spectra obtained in this study show considerable improvement in terms of signal to noise ratio compared to earlier table-top micro X-ray fluorescence studies. Reliability of the measurements is tested using a conservative detection and quantification limit. Count rates of Ca are used to check for point measurements disturbed by irregularities on the sample surface. Furthermore, the method allows semi-quantitative two-dimensional element mapping, which is a convenient tool for the detection of diagenetic alteration in fossil samples. The method reveals records of Sr/Ca, Fe/Ca and Mn/Ca ratios in a Late Campanian Vaccinites vesiculosus shell, with Sr/Ca ratios showing a trend opposite to Mn/Ca and Fe/Ca. Resulting trace element records are discussed in terms of seasonal cyclicity in the Late Cretaceous and diagenetic alteration of the fossil shell.
| Original language | English |
|---|---|
| Pages (from-to) | 231-251 |
| Number of pages | 21 |
| Journal | Sedimentology |
| Volume | 64 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1 Jan 2017 |
| Externally published | Yes |
Bibliographical note
Funding Information:The authors thank the valuable comments of Dr Peter Skelton and an anonymous reviewer that helped to improve this manuscript. We also thank the Associate Editor of this manuscript Dr Maria Rose Petrizzo for guiding the review process. The authors thank Dr René Fraaije from the Oertijdmuseum in Boxtel for supplying the fossil studied in this work, and Prof. Ir. Jean-Marc Baele of Université de Mons for help with the cathodoluminescence microscopy. We thank Dr Roald Tagle from Bruker Nano GmbH for his technical support and Christina Makarona from the Vrije Universiteit Brussel (VUB) for helpful discussions about measurement error and repeatability. We thank Prof. Frank Dehairs from VUB for offering his expertise in the interpretation of elemental abundance records in marine bivalves. We also thank Bart Lippens for help with sample preparation. This project was made possible by the strategic research funding of the Belgian Institute for Innovation through Research and Technology (IWT) and by the Hercules Foundation responsible for the funding of the X-ray analytical platform at the VUB. Ph Claeys also acknowledges the support of Research Foundation Flanders (grants: G.0C43.15; G0B8513, and G009113). The authors have no conflict of interest to declare regarding this work.
Publisher Copyright:
© 2016 The Authors. Sedimentology © 2016 International Association of Sedimentologists
Keywords
- Bivalve
- Cretaceous
- micro X-ray fluorescence (μXRF)
- rudist
- seasonality
- trace element