![]() ![]() ![]() We believe the new tracers and standard solutions are essential for facilitating assessment and improvement of long-term accuracy of high-precision U/Pb dates. SRM U500 the IRMM 073/074 series) can be used for calibrating ion counting systems but they are not always appropriate for determining the response effect of other elements (e.g., Pb). Single detector (Daly/SEM) ion counting underpins the majority of high-precision U/Pb dates therefore detector linearity over a large dynamic range and long-term 'stability' require regular verification. This effect has been identified for different storage conditions for the spike. These solutions will provide a means of assessing agreement between different detection modes, long-term reproducibility and inter-laboratory agreement without the complexity of sample dissolution, ion exchange chemistry, etc. Micromass Sector 54 IR software employs Dodson (1978) 2nd-degree interpolation (release 3.977) Spike Parrish (1987) 205Pb233235U spike EARTHTIME 535. Earthtime tracer solution as a function of the residual volume in the bottle. The dashed green line represents the Talung-Daye formational boundary and the Permian-Triassic. These solutions are in sufficient quantities to permit use by all interested labs for many years. The horizontal gray band marks the interval of the Hg concentration spike (E2) and nadir of the negative 13 C excursion, and the vertical pink bands depict near-zero Hg isotope mass-independent fractionation (0 0.05, Thibodeau et al., 2016). 10, 100, 5 Ma) isotopic compositions and elemental ratios. Four synthetic U/Pb solutions have also been prepared with concordant (at ca. Interlab tracer U/Pb ratio calibration indicates agreement to better than 300 ppm. This tracer solution is calibrated against three mixed U/Pb gravimetric reference solutions (high purity NBS and CRM metal derivatives). As part of the EARTHTIME Initiative a quantity of mixed 205Pb-233U-235U tracer has been prepared, aiming to effectively eliminate interlaboratory bias due to tracer calibration. In an attempt to eliminate most to all of this bias we have prepared a community tracer solution and series of optimized solutions for monitoring long-term mass spectrometer performance. At present, interlaboratory biases exceed analytical uncertainties, and originate from spike calibration, detector characteristics, and ion- counting protocols. Double-spiked uranium measurements (as oxide) are often less challenging and measured on Faraday detectors, although low U, small and/or old samples often requires ion counting. This usually requires 'peak jumping' on an ion counting Daly or SEM, or at high 206Pb count rates exceeding the limit of the Daly/SEM, mixed ion counting - Faraday detection methods. Volume 1, September 2020, 100005 Research Paper New high precision U-Pb ages and Hf isotope data from the Karoo large igneous province implications for pulsed magmatism and early Toarcian environmental perturbations Nicolas D. High-precision U-Pb ID-TIMS geochronology presents several analytical challenges. ![]()
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