Depositional controls on the preservation of ∆’17O signatures in sedimentary sulfate
Bibliographic record
Abstract
Triple oxygen isotope compositions of sedimentary sulfate (∆’17O) have been applied as a tracer of past primary productivity, pO2 and pCO2. However, large intraformational variability of ∆’17O signatures and debate surrounding how they are produced and eventually preserved has limited the understanding of this important geochemical record. Here we explore depositional controls on ∆’17O signatures of mid-Proterozoic (≈2.0-1.0 Ga) sulfates. We identify a clear depositional control on the magnitude of preserved ∆’17O sulfate signatures, with Proterozoic terrestrial environments preserving the most negative and variable signatures and marine environments displaying values near modern marine sulfate with less overall variability. Our results strongly suggest that local depositional settings influence the magnitude of the preserved signal, and the processes within those environments drive much of the observed intraformational variability. Finally, this analysis suggests that ∆’17O signatures may offer a powerful tool to identify basin restriction and non-marine settings throughout the geologic record.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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".