Pulsed volcanism and rapid oceanic deoxygenation during Oceanic Anoxic Event 1a
Bibliographic record
Abstract
Abstract Widespread oceanic anoxia, biological crises, and volcanic activity are associated with the onset of Early Aptian (ca. 120 Ma) Oceanic Anoxic Event 1a (OAE1a). Reconstructions of oceanic deoxygenation and its links to broadly contemporaneous volcanism, however, remain poorly resolved. We use geochemical data, including δ53Cr ratios and rare Earth element abundances, to define the timing and tempo of submarine volcanism and global oceanic deoxygenation across this event. Pacific Ocean sediments deposited in the run up to OAE1a record multiple phases of marine volcanism associated with the emplacement of Ontong Java Plateau lavas. Rapid oceanic deoxygenation followed the initial phases of volcanism and a biocalcification crisis. Large swaths of the oceans likely became anoxic from the Tethys to the Pacific Oceans in <30 k.y. Oceanic anoxia persisted for almost one million years after this and was likely sustained through intensified continental and submarine weathering. These results paint a new picture of OAE1a in which volcanism, biological crisis, and oceanic deoxygenation are separated in time and linked through Earth system responses that operate on time scales of tens of thousands of years.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| 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".