Bibliographic record
Abstract
Secondary ion mass spectrometry (SIMS), an in situ micro-analytical technique, was used to date uraninite from the Huron Claim pegmatite in southeastern Manitoba. Detailed petrography shows that there are zones in the uraninite grains that have undergone varying degrees of alteration. Altered and relatively unaltered zones were analyzed on the scale of a few micrometers. In situ U–Pb isotopic analysis shows that the uraninite from the Huron Claim pegmatite is highly discordant (>5%) with an upper intercept of 2575 ± 38 Ma. Lead (207Pb/206Pb) isotope ages range from 2514 ± 3 to 2573 ± 18 Ma, with an average age of 2550 ± 17 Ma. Therefore, the crystallization age of the uraninite is interpreted to be 2575 ± 38 Ma. A comparison of this age with uraninite from other deposits suggests that the Huron Claim pegmatite uraninite is currently the oldest known example of primary uraninite. Evidence for the presence of very old primary uraninite is an important part of the global evolution of uranium minerals. Detrital accumulations such as the Witwatersrand and Elliot Lake deposits have inferred ages much greater than 2.2 Ga. However, no primary uraninite approaches the age of these deposits except for the Huron Claim uraninite.
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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 | 0.001 | 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".