Classification of Ordinary Chondrite NWA 6514 and Pb-Pb Chondrule Chronology
Bibliographic record
Abstract
This study presents a petrographic description and a classification of ordinary chondrite NWA 6514 and aims to establish the first high-precision Pb-Pb age of a single ordinary chondrite chondrule. Furthermore, the distribution of different isotopic Pb signatures among chondritic components will be investigated by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). This study shows that NWA 6514 can be classified as a highly unequilibrated (subtype 3.10) L or LL chondrite that has experienced moderate terrestrial weathering (W2) and a low degree of shock (S2). The LA-ICP-MS measurements suggest that radiogenic Pb signatures have been locally preserved in chondrules. However, the Pb isotopic compositions of leaches from a large chondrule obtained by thermal ionization mass spectrometry show an anomalous distribution that indicates the presence of an exotic Pb component. The best estimate for the chondrule formation age is a model age of the last leach (4566.8 ± 2.6 Myr).
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".