Apatite Reference Materials for SIMS Microanalysis of Isotopes and Trace Elements
Bibliographic record
Abstract
Twelve apatite samples have been tested as secondary ion mass spectrometry (SIMS) reference materials. Laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) analysis shows that the SLAP, NUAN and GR40 apatite gems are internally homogeneous, with most trace element mass fractions having 2 standard deviations (2 s ) ≤ 2.0%. BR2, BR5, OL2, AFG2 and AFB1, which have U > 63 μg g ‐1 , 206 Pb/ 204 Pb > 283, and homogeneous SIMS U‐Pb data, have respective isotope dilution thermal ionisation mass spectrometry (ID‐TIMS) ages of 2053.83 ± 0.21 Ma, 2040.34 ± 0.09 Ma, 868.87 ± 0.25 Ma, 478.71 ± 0.22 Ma and 473.25 ± 0.09 Ma. Minor U‐Pb heterogeneity exists and accurate SIMS results require correction with the 3D Concordia‐constrained common Pb composition. Among the studied samples, AFG2 and BR5 are the most homogeneous U‐Pb reference materials. The SIMS sulfur isotopic compositions of eight of the apatites shows they are homogeneous, with 2 s for both 10 3 δ 34 S and 10 3 δ 33 S < 0.55‰. One apatite, BR96, has Δ 33 S = ‐0.36 ± 0.2‰. The apatite samples have ID‐TIMS 87 Sr/ 86 Sr between 0.704214 ± 0.000030 and 0.723134 ± 0.000035.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.017 | 0.000 |
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 teacher head, 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".