Geostandards and Geoanalytical Research最新文献

The certification protocol developed for the GeoPT proficiency testing programme was applied to the certification of Iceland Tholeiitic Basalt IAG BNA-1. Certified values for eight major element oxides and twenty-nine trace elements were reported together with fourteen indicative values. Metrological traceability was demonstrated in part by the excellent agreement between GeoPT assigned values and certified values for the established certified reference material BRP-1 (Basalt Ribeirão Preto), which was distributed for co-analysis with BNA-1 in Round 54 of the GeoPT programme. A comparison shows clear similarities, but some differences when the composition of BNA-1 was compared with values for USGS BIR-1 (Reykjavik Iceland Basalt), which originated from the same quarry near Reykjavik in Iceland. An assessment of quality factors for IAG BNA-1 shows that BNA-1 certified values are fully compatible with usage involving the assessment of data submitted by laboratories that routinely analyse silicate rocks to the GeoPT ‘research laboratory’ standard of performance.

Accurate measurements of Hf isotope ratios in zircon rely on adequate correction for isobaric interferences, which increase in complexity as the ratio of heavy rare earth elements (HREE) to Hf increases. Currently, synthetic high-HREE zircons are commonly used to bracket the highest naturally occurring HREE/Hf zircon grains during laser ablation-based measurement but these are in limited supply. We present results for Grey Hill zircon, a new high ¹⁷⁶Yb/¹⁷⁷Hf zircon with a weighted mean age of 482.97 ± 0.17 Ma (2s). We show that Hf is homogeneously distributed at the microscale in Grey Hill zircon, whereas Yb is heterogeneously distributed in oscillatory- and sector-zones following observed cathodoluminescence patterns. Atom probe tomography measurements show that Hf and Yb are homogeneously distributed at the nanoscale. Chemical abrasion solution multi-collector inductively coupled plasma-mass spectrometry (CA-S-MC-ICP-MS) yielded a mean ¹⁷⁶Hf/¹⁷⁷Hf of 0.282854 ± 0.000023 (2s, n = 15), with a correlation to ¹⁷⁶Lu/¹⁷⁷Hf that corresponds to radiogenic ingrowth since ca. 483 Ma. If analyses are back-calculated to the crystallisation age, the CA-S-MC-ICP-MS data yield a ¹⁷⁶Hf/¹⁷⁷Hf_(t) of 0.282805 ± 0.000010 (2s), which we recommend be used as the reference ratio for Grey Hill zircon. Non-abraded, in situ LA-MC-ICP-MS analyses yielded results consistent with the CA-S-MC-ICP-MS mean. Importantly, LA-MC-ICP-MS analyses do not show any correlation with HREE, and there is no apparent difference in measured ¹⁷⁶Hf/¹⁷⁷Hf between pristine and altered domains. The grains have ¹⁷⁶Yb/¹⁷⁷Hf (0.094–0.48) and ¹⁷⁶Lu/¹⁷⁷Hf (0.0028–0.014) ratios that are much higher than all commonly used natural reference materials. Thus, Grey Hill zircon is a useful natural reference material for LA-MC-ICP-MS Hf isotope measurement to guarantee accurate isobaric interference correction across the full spectrum of naturally occurring zircon grains. Grey Hill zircon concentrates can be requested from the authors.

Photo-induced Force Microscopy (PiFM) is a nanoanalytical, surface-sensitive new-frontier technique that provides in situ infrared spectroscopy at a spatial resolution of ~ 5 nm², which is approximately one billion times higher than traditional FTIR. These advantages led to significant discoveries in Earth and environmental sciences, as well as related disciplines. However, the high resolution and surface sensitivity of PiFM makes it highly susceptible to surface contamination. Factors such as sample preparation, handling and storage can introduce particulate and/or molecular layer contaminants, which may interfere with data analysis and lead to misinterpretation of results. In this study, we systematically investigated common laboratory materials, including gloves, mounting materials, polishing agents and storage solutions as potential sources of particulate and molecular contaminants and compiled a library of reference spectra available to all users of nano-scale molecular analyses. Further, we determined the contaminant signatures of human skin and gloves on AFM substrates and provided recommendations for sample preparation, handling and storage as well as strategies for contamination mitigation to ensure better-informed analysis of structurally and compositionally complex geological materials. We identified molecular and particulate contaminants through their specific IR absorption bands, and provide recommendations to selectively avoid or remove them, thereby improving the reliability of nanoscale molecular analyses by PiFM, ultimately increasing confidence in new discoveries.

Iron isotopes are increasingly applied in Earth science fields, including cosmochemistry, geochemistry and environmental sciences. Refining non-traditional stable isotope systematics requires well-characterised isotopic reference materials to ensure accuracy and precision. Consequently, the direct comparison of data obtained from different laboratories is a key prerequisite for establishing reliable isotopic systematics. Here, we describe a new Fe isotope measurement method using multi-collector-ICP-MS. The Fe isotope ratios of widely used geological reference materials (JB-2, BHVO-2, BE-N, AGV-1 and RGM-1) were measured and new Fe isotope values for IAEA-B5 (basalt from Mount Etna, Italy) are recommended. Anion exchange chromatography was used to separate Fe from the rest of the matrix. Mass bias was corrected using a standard-sample-standard bracketing method combined with Ni-doping. Iron isotope ratios of JB-2, BHVO-2, BE-N, AGV-1 and RGM-1 show strong agreement with published values and fall within reported analytical uncertainties. Based on these results, we validate and propose δ⁵⁶Fe = 0.103 ± 0.064 (2s) and δ⁵⁷Fe = 0.141 ± 0.068 (2s) as recommended values for IAEA-B5. We further advocate the IAEA-B5 as a robust and complementary reference material for analytical validation and quality control in Fe isotope studies, providing both a supplement to and an alternative for established iron isotope reference materials.

Apatite supergroup minerals are common in diverse lithologies and rich in strontium and neodymium making them optimal minerals for in situ Sr-Nd isotopic tracing in geological studies. We present detailed spectroscopy, major and trace element compositional determinations, and Sr-Nd isotopic measurement results for two natural apatite samples (MAP-1 and MAP-4) to assess their chemical homogeneity and suitability as Sr and Sm-Nd reference materials (RMs). The results reveal that both samples display remarkably uniform trace element distributions, and nearly consistent major element chemistry and Sr-Nd isotope ratios. They are particularly characterised by high Sr mass fractions (> 8000 μg g^-1) and relatively high Nd mass fractions (~ 3000 μg g^-1). For MAP-1, the ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd values determined by (ID-)TIMS are 0.704340 ± 0.000029 (2s, n = 3) and 0.511978 ± 0.000008 (2s, n = 3). MAP-4 yielded ⁸⁷Sr/⁸⁶Sr of 0.704354 ± 0.000010 (2s, n = 4) and ¹⁴³Nd/¹⁴⁴Nd of 0.511956 ± 0.000005 (2s, n = 7). Reproducibility tests using LA-MC-ICP-MS were consistent or nearly consistent with the results of (ID-)TIMS measurements, demonstrating that both fluorapatites are suitable new RMs for in situ ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd isotopic measurements, providing new benchmarks of apatite RMs for laser-based Sr-Nd isotopic measurements.

A single-column extraction chromatographic purification method for tungsten using the N-benzoyl-N-phenylhydroxylamine (BPHA) resin was investigated in this study. This method greatly simplifies the W purification procedure, and only 10 ml of acid (5 ml 3 mol l^-1 HCl-0.1 mol l^-1 HF and 5 ml 1 mol l^-1 HF) is required to separate W from Ti, Zr, Hf, Ta and other matrix elements. The blank in the separation step was less than 0.1 ng, and the recovery of W was ~ 99%. Six independent digestion measurements of reference materials BHVO-2, BCR-2, RGM-2 and JB-2 yielded μ¹⁸²W values (mean value with intermediate precision, 95% confidence level) of -10.3 ± 4.0 (n = 6, 2s)，-1.2 ± 5.3 (n = 6, 2s)，-1.4 ± 4.4 (n = 6, 2s) and 0.6 ± 3.8 (n = 6, 2s), respectively, which are in good agreement with the previously reported values.