![]() ![]() Possibly the most important improvement was the introduction of the chemical abrasion pre-treatment of zircon prior to analysis. Precise U–Pb dates are crucial tools in the reconstruction of geological processes, therefore it is of paramount importance to know their accuracy, and to intercalibrate different mass spectrometry equipment and analytical protocols that are employed in different laboratories.Ī series of breakthroughs in chemical and mass spectrometric techniques, refined workflows, and new calibration and tracer solutions were at the origin of an improvement of the precision and accuracy in U–Pb geochronology to approximately 0.1% of single crystal 206Pb/ 238U ages. 16–18), and potential causal relationships between volcanic activity in large igneous provinces and global biotic and environmental deterioration ( e.g., ref. 15), timescales of global climate and biotic change ( e.g., ref. 11–14), dynamics of sedimentary systems ( e.g., ref. 9 and 10), the formation of ore deposits ( e.g., ref. 2–8), timescales of tectonic activity ( e.g., ref. As a result, it is commonly used to reconstruct the precise durations and rates of geological processes, including the duration and tempo of magmatism ( e.g., ref. Zircon (ZrSiO 4) is a particularly useful accessory mineral phase for this purpose, as it incorporates abundant U up to 1000's of ppm, with negligible initial Pb ( e.g., ref. Introduction Uranium–lead geochronology by isotope dilution thermal ionization mass spectrometry (ID-TIMS) applied to U-bearing minerals is considered to be the “gold standard” of geochronology. These data will allow U–Pb laboratories to evaluate their analytical performance and to independently calibrate non-EARTHTIME tracer solutions in use. This compilation demonstrates that (i) the choice of the thermal ionization mass spectrometer model has no influence on precision and accuracy of the data (ii) the often observed excess scatter of apparent ET100 solution 206Pb/ 238U dates can be mitigated by more careful tracer-sample equilibration and (iii) natural zircon reference materials are not suitable for evaluating intra-laboratory repeatability and inter-laboratory reproducibility, since they combine several phenomena of natural system complexities (especially domains of different age within the same zircon grain, and residual loss of radiogenic lead in domains of high decay damage after chemical abrasion pre-treatment). Here, we report ET100 and ET2000 solution data from the geochronology laboratory of University of Geneva obtained between 20 and compare the most recent data with results from the geochronology laboratories of Princeton University and ETH Zürich. A number of geochronology laboratories produce the highest precision U–Pb dates employing the EARTHTIME 202Pb– 205Pb– 233U– 235U tracer solution for isotope dilution, and the EARTHTIME ET100 and ET2000 solutions for system calibration and laboratory intercalibration. Age determination of minerals using the U–Pb technique is widely used to quantify time in Earth's history.
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