Thermochemical oxidation of methane by manganese oxides in hydrothermal sediments
Bibliographic record
Abstract
Abstract Microbial anaerobic oxidation of methane coupled to the reduction of Mn(IV)-oxides, typically MnO 2 , derived from continental weathering and riverine transport has been proposed as a globally important sink of methane. However, the potential role of hydrothermal Mn(IV) oxide-rich sediments as a methane sink, and the mechanisms of underpinning methane oxidation at high-temperature hydrothermal fields remain poorly understood. Here, we report the occurrence of almost pure rhodochrosite with extremely negative δ 13 C PDB values (as low as –76.4‰) in direct association with hausmannite formed through hydrothermal activity in the Late Triassic Heqing Mn deposit in Southern China. Based on detailed petrography and geochemistry, this rhodochrosite is interpreted as the result of the thermochemical oxidation of methane by hausmannite during early diagenesis. Given high hydrothermal Mn 2+ and CH 4 release coupled to low sulfate concentration observed in the Archean oceans, we propose that hydrothermal Mn(IV) oxides may have been effective methane sinks in Earth’s ancient oceans.
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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 | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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; both teacher heads agree on what is shown here.
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".