A seawater throttle on H <sub>2</sub> production in Precambrian serpentinizing systems
Bibliographic record
Abstract
Significance Our current understanding of the redox state of Earth’s ancient atmosphere is heavily dependent on the assumption that ancient low-temperature serpentinizing systems produced abundant H 2 , as they do today. Here, we examine this assumption using data that constrain Fe partitioning in serpentine minerals. We find that H 2 production is linked to a Si deficiency in the serpentine structure, which itself is caused by low SiO 2 (aq) concentrations in fluids derived from modern seawater. Calculations accounting for this dependence of H 2 production on seawater SiO 2 (aq) imply that Precambrian serpentinizing systems would have produced up to about two orders of magnitude less H 2 than today, prompting a reexamination of atmospheric redox state and H 2 -dependent origins of life scenarios on early Earth.
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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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".