Continental weathering and recovery from ocean nutrient stress during the Early Triassic Biotic Crisis
Bibliographic record
Abstract
Abstract Following the latest Permian extinction ∼252 million years ago, normal marine and terrestrial ecosystems did not recover for another 5-9 million years. The driver(s) for the Early Triassic biotic crisis, marked by high atmospheric CO 2 concentration, extreme ocean warming, and marine anoxia, remains unclear. Here we constrain the timing of authigenic K-bearing mineral formation extracted from supergene weathering profiles of NW-Pangea by Argon geochronology, to demonstrate that an accelerated hydrological cycle causing intense chemical alteration of the continents occurred between ∼254 and 248 Ma, and continued throughout the Triassic period. We show that enhanced ocean nutrient supply from this intense continental weathering did not trigger increased ocean productivity during the Early Triassic biotic crisis, due to strong thermal ocean stratification off NW Pangea. Nitrogen isotope constraints suggest, instead, that full recovery from ocean nutrient stress, despite some brief amelioration ∼1.5 million years after the latest Permian extinction, did not commence until climate cooling revitalized the global upwelling systems and ocean mixing ∼10 million years after the mass extinction.
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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 | 0.001 |
| 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".