Incomplete oxidative sulfide weathering and low atmospheric oxygen levels during the Great Oxidation Event
Bibliographic record
Abstract
Abstract Multiple lines of evidence support permanent oxygenation of the Earth’s atmosphere during the early Paleoproterozoic (~2.5–2.1 billion years ago). Here, we report geochemical data, along with sulfide textures, for >2.31-bilion-year-old sedimentary rocks from the upper Espanola and Serpent formations that underlie the third glacial diamictite of the Huronian Supergroup, Canada. Redox-sensitive element contents and the isotopic compositions of molybdenum and sulfur are comparable to upper continental crust value. Subangular to rounded pyrite grains of detrital origin are observed in sandstones of the Serpent Formation. Our data indicate limited oxidative weathering of crustal sulfide prior to the third glaciation of the Huronian succession, consistent with low atmospheric oxygen levels (<5×10 −4 of the present atmospheric level). We suggest that such low atmospheric oxygen levels persisted for long periods prior to the final glaciation of the Huronian succession.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".