Barite, Anhydrite and Gypsum Reference Materials for <i>In Situ</i> Oxygen and Sulfur Isotope Ratio Measurements
Bibliographic record
Abstract
Secondary ion mass spectrometry was used to test the δ 18 O and δ 34 S nanogram‐scale homogeneity of a suite of candidate sulfate minerals, ultimately selecting three barite, two anhydrite, and two gypsum samples from the Royal Ontario Museum that have repeatabilities for their SIMS measurements of better than ±0.39‰ and ±0.37‰ (1 s ) for oxygen and sulfur isotope ratios, respectively. Metrological splits of each of the seven materials were sent to multiple gas source isotope ratio mass spectrometry laboratories in order to establish their absolute 18 O/ 16 O and 34 S/ 32 S ratios. The inter‐laboratory results of GS‐IRMS analyses yielded reasonably narrow ranges in δ 18 O VSMOW , whereas larger variations in δ 34 S VCDT values were found between the results from the gas source laboratories. All samples have good reproducibility within laboratories of GS‐IRMS 10 3 δ 18 O values of between ±0.24‰ and ±0.44‰ (1 s ). The reproducibility within laboratories of GS‐IRMS 10 3 δ 34 S values range from ±0.07‰ to ±0.99‰ (1 s ). Here we also discuss some of the current analytical limitations affecting these isotope‐mineral systems. A total of 256 metrological splits have been prepared from each of these seven materials; these aliquots will be made available to the global geochemical community.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".