Microstructure of Neoarchean zircon from the Acasta gneiss complex, Northwest Territories; Radiogenic age and isotopic studies: Report 13
Bibliographic record
Abstract
The microstructure of zircon from a late Archean granite dyke from the Acasta gneiss complex was investigated using a number of microprobe techniques. Zircons from the study sample are composed of low-Ca, unaltered and high-Ca, altered domains. Transmission electron microscopy indicates that the unaltered areas have a distorted crystalline microstructure. The detailed microstructure of altered zircon is heterogeneous, composed of a mixture of low-Ca, crystalline domains and amorphous, high-Ca domains. Calculations show that radiation damage accumulated from the decay of U and Th over the entire life of the sample would have rendered the sample metamict. We conclude that the observed crystalline structure is the result of recrystallization late in the geological history of the sample. Sensitive high-resolution ion microprobe U-Pb ages from the low Ca, crystalline zircon are concordant, suggesting that Pb loss did not accompany the recrystallization process.
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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 | 0.001 | 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) | 0.001 | 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".