Methane, manganese, and helium‐3 in newly discovered hydrothermal plumes over the Central Indian Ridge, 18°–20°S
Bibliographic record
Abstract
We have investigated newly discovered submarine hydrothermal plumes over the Central Indian Ridge, 18°–20°S. Onshore chemical analyses of methane, its carbon isotope, manganese, and helium‐3 in seawater samples obtained from the plumes revealed their detailed geochemical characteristics. One of the newly discovered hydrothermal plumes located over the western wall of the axial valley at Segment 15B (19°33′S), called the Roger Plateau, showed constant CH 4 /Mn and CH 4 / 3 He ratios throughout the plume. The CH 4 / 3 He ratio (4 × 10 6 ) and δ 13 C (−17.5‰) are consistent with those of basalt‐hosted sediment‐free hydrothermal systems, although the CH 4 /Mn ratio (∼1) is moderately higher. These features are thought to indicate a metal‐depleted fluid chemistry. The other hydrothermal field is located within the axial valley at the northern part of the smooth lava plain at Segment 16 (18°20′S), called the Dodo Great Lava Plain, where several plumes were detected. The CH 4 /Mn and CH 4 / 3 He ratios showed large variation through the plumes while δ 13 C values were almost constant. Geochemical characteristics of venting fluid estimated from those of the plumes were apparently high CH 4 /Mn (>6) and CH 4 / 3 He (>60 × 10 6 ) ratios and low δ 13 C values (<−27.5‰), suggesting possible influences of several methane input processes to the fluid chemistry.
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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".