Frequent Millennial‐Scale Oceanic Redox Oscillations Recorded by Negative Pyrite Δ<sup>33</sup>S: Implications for Phanerozoic Extinctions
Bibliographic record
Abstract
Abstract Phanerozoic extinctions may have been influenced by oceanic redox oscillations, as indicated by mixing‐induced negative pyrite Δ 33 S (Δ 33 S py ). However, the frequencies, intensities, and timescales of these oscillations remain elusive. Here, we measured stratigraphic Δ 33 S py from the currently anoxic Cariaco Basin, spanning ∼0.6 million years. Our results reveal two distinct patterns of negative Δ 33 S py that are linked to specific redox oscillations, potentially analogous to patterns recorded during Phanerozoic extinctions. During Marine Isotope Stage 1–2 and 9–10, bottom water experienced redox oscillations on a timescale of 10,000 years, resulting in slightly negative Δ 33 S py (−0.03‰). In contrast, during the period of 160–200 kyr BP, bottom water underwent frequent redox oscillations on millennial‐ and centennial‐timescales, leading to significantly more negative Δ 33 S py values (−0.09‰). We highlight that similarly frequent oceanic redox fluctuations may have contributed to the end‐Guadalupian extinction, when notably negative Δ 33 S py values akin to those observed in our study were prevalent.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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".