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Selecting appropriate measurement points is crucial for apatite U–Pb dating of fossil teeth due to the impact of post-fossilization alterations. Previous studies have suggested that variations in yttrium (Y) concentrations within each sample can be qualitative indicators of such alterations (Y-screening method). To verify the validity of this method, ideal measurement areas for U–Pb dating were selected from Y mapping using a micro-focus X-ray fluorescence spectrometer (micro-XRF) on Late Cretaceous Tarbosaurus teeth with published apatite U–Pb ages, and trace element analysis and U–Pb dating of apatite was performed by laser ablation and inductively coupled plasma mass spectrometry (LA-ICP-MS). Two ages of 64.3 ± 3.4 Ma and 61.0 ± 11.0 Ma were obtained from two regions of relatively different Y concentrations in a sample that had been reported as 66.7 ± 2.5 Ma. Similarly, the sample with the reported age of approximately 30 Ma yielded ages of 51.5 ± 2.7 Ma and 57.3 ± 6.1 Ma in the areas with relatively low Y concentrations. These results show that Y concentration and an apatite U–Pb age are correlated, at least within the same sample, and support the usefulness of the Y-screening method. Although more measurements are needed to obtain conclusive proof, the Y micro-XRF mapping would be a helpful tool for non-destructive visualization of post-fossilization alteration in tooth fossils and could lead to the selection of suitable measuring points for LA-ICP-MS apatite U–Pb dating.
Research papers (academic journals)
