Major perturbation in sulfur cycling at the Triassic-Jurassic boundary
Bibliographic record
Abstract
Stable sulfur isotopes from the reduced sulfur fraction of Late Triassic–Early Jurassic marine sediments at Kennecott Point in British Columbia, Canada, show evidence for a major perturbation in sulfur cycling coincident with a major carbon cycle perturbation in the wake of a mass extinction event at the Triassic-Jurassic boundary. The δ34S of reduced sulfur shifts from values consistent with open system bacterial sulfate reduction (−30‰) to values higher than any previously reported for Early Jurassic sulfates (20‰) and consistent with complete utilization of sulfate and Rayleigh fractionation in a closed system. We suggest that this isotopic shift was initiated by declining seawater sulfate concentration due to evaporite deposition in nascent Atlantic rift zones and enhanced by a local mechanism, such as a decoupling of the zone of sulfate reduction from the sulfate supply due to a catastrophic increase in the flux of land-derived sediments reaching the sea in the wake of massive terrestrial plant die-off during the Triassic–Jurassic mass extinction.
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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 | 0.000 |
| 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 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".