Natural Allanite Reference Materials for<i>In Situ</i>U‐Th‐Pb and Sm‐Nd Isotopic Measurements by LA‐(MC)‐ICP‐MS
Bibliographic record
Abstract
Allanite is a common accessory mineral that generally incorporates considerable amounts of Th, U and light rare Earth elements in its structure, making it a useful mineral forin situU‐Th‐Pb geochronology and Sm‐Nd isotope measurements. Here, we presentin situU‐Th‐Pb ages and Sm‐Nd isotopic compositions for nine allanite samples considered as potential reference materials (CAPb, Tara, Daibosatsu, LE40010, LE2808, A007, A011, A012 and SQ‐51), with ages ranging from ~ 2650 Ma to ~ 12 Ma. Our study indicates that Daibosatsu and LE40010 have relatively homogeneous147Sm/144Nd and143Nd/144Nd isotopic compositions (147Sm/144Nd ratio variation is less than 2%) and, thus, can serve as primary reference materials for Sm‐Nd microanalysis. In contrast, CAPb, Tara, LE2808, A007, A011 and A012 all show homogeneous calculated initial143Nd/144Nd isotopic compositions, but with variable147Sm/144Nd compositions, and thus can be used only as secondary reference materials for Sm‐Nd microanalysis. Of these materials, LE40010 allanite can serve as a suitable primary reference material forin situU‐Pb dating, CAPballanite can serve as a suitable primary reference material forin situTh‐Pb dating, and LE2808, LE40010, A007, A011 and A012 can serve as suitable secondary reference materials forin situU‐Pb geochronology. In addition, Daibosatsu is suitable as a secondary reference material for Cenozoic Th‐Pb dating to monitor data reproducibility.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.002 |
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".