Testing Nano-Powder and Fused-Glass Mineral Reference Materials for In Situ Rb-Sr Dating of Glauconite,Phlogopite, Biotite and Feldspar via LA-ICP-MS/MS |
| |
| Authors: | Ahmad Redaa Juraj Farka? Sarah Gilbert Alan S Collins Stefan Löhr Davood Vasegh Marnie Forster Morgan Blades Thomas Zack Andrea Giuliani Roland Maas Andre Baldermann Martin Dietzel Dieter Garbe-Schönberg |
| |
| Institution: | 1. Department of Earth Sciences, Metal Isotope Group (MIG), University of Adelaide, Adelaide, Australia;2. Adelaide Microscopy, University of Adelaide, Adelaide, Australia;3. Research School of Earth Sciences, Australian National University, Canberra, Australia;4. MinEx Cooperative Research Centre (CRC), University of Adelaide, Adelaide, Australia;5. Department of Earth Sciences, Metal Isotope Group (MIG), University of Adelaide, Adelaide, Australia
MinEx Cooperative Research Centre (CRC), University of Adelaide, Adelaide, Australia;6. Institute of Geochemistry and Petrology, Department of Earth Sciences, Zürich, ETH, Switzerland;7. School of Earth Sciences, Faculty of Science, University of Melbourne, Australia;8. Institute of Applied Geosciences, Graz University of Technology and NAWI Graz Geocentre, Graz, Austria;9. Institute of Geosciences, Kiel University, Kiel, Germany |
| |
| Abstract: | Reference materials (RMs) with well-characterised composition are necessary for reliable quantification and quality control of isotopic analyses of geological samples. For in situ Rb-Sr analysis of silicate minerals via laser ablation inductively coupled plasma tandem mass spectrometry (LA-ICP-MS/MS) with a collision/reaction cell, there is a general lack of mineral-specific and matrix-matched RMs, which limits wider application of this new laser-based dating technique to certain minerals. In this work, pressed nano-powder pellets (NP) of four RMs, GL-O (glauconite), Mica-Mg (phlogopite), Mica-Fe (biotite) and FK-N (K-feldspar), were analysed and tested for in situ Rb-Sr dating, complemented by isotope dilution (ID) MC-ICP-MS Rb-Sr analyses of GL-O and Mica-Mg. In addition, we attempted to develop alternative flux-free and fused ‘mineral glasses’ from the above RMs for in situ Rb-Sr dating applications. Overall, the results of this study showed that among the above RMs only two NP (Mica-Mg-NP and GL-O-NP) were suitable and robust for in situ dating applications. These two nano-powder reference materials, Mica-Mg-NP and GL-O-NP, were thus used as primary RMs to normalise and determine Rb-Sr ages for three natural minerals: MDC phlogopite and GL-O glauconite grains, and also Mica-Fe-NP (biotite). Our in situ analyses of the above RMs yielded Rb-Sr ages that are in good agreement (within 8%) of published ages, which suggests that both Mica-Mg-NP and GL-O-NP are suitable RMs for in situ Rb-Sr dating of phlogopite, glauconite and biotite. However, using secondary RMs is recommended to monitor the quality of the obtained ages. |
| |
| Keywords: | in situ Rb-Sr dating LA-ICP-MS/MS reference materials nano-powders |
|
|
