Biogeochemistry at the dawn of Carbonate deposition on Earth : elemental and isotopic chemostratigraphy of the Mesoarchean Red Lake carbonate platform, Canada
Bibliographic record
Abstract
The 2.87 Ga Ball Assemblage of the Red Lake Greenstone Belt, Canada preserves Earth’s oldest known thick carbonate platform.This study presents sedimentological, elemental, and isotopic (carbon, oxygen, and multiple sulfur isotope) analyses of five cored drill holes capturing a variety of chemical and siliciclastic rocks deposited in shallow-to-deep water settings.The rare earth element systematics of the diverse lithofacies reveal features similar to both Archean and modern oceans. The occasional presence of oxygen is inferred from both positive and negative Ce anomalies, and associated Mn and Cr enrichments in some iron formation and limestone samples, suggesting periodic oxygenation of the water column, at least locally. The mild but significant authigenicenrichment of Mo, V, U, and Cr in carbonates and iron formations suggest redox cycling under mildly oxic water column conditions.The isotopic composition of carbon and oxygen in carbonates are mineralogically and water-depth-controlled; dolostone shows evidence of meteoric water interaction during dolomitization, while limestone captured the isotopic signature of the open ocean DIC pool.Multiple sulfur isotope data indicate that the Red Lake sulfidic shales preserve a variety of sulfur sources and processing similar to other Mesoarchean rocks.
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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 | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.002 |
| 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".