Experimental investigation of the stability of Fe‐rich carbonates in the lower mantle
Bibliographic record
Abstract
The fate of carbonates in the Earth's mantle plays a key role in the geodynamical carbon cycle. Although iron is a major component of the Earth's lower mantle, the stability of Fe‐bearing carbonates has rarely been studied. Here we present experimental results on the stability of Fe‐rich carbonates at pressures ranging from 40 to 105 GPa and temperatures of 1450–3600 K, corresponding to depths within the Earth's lower mantle of about 1000–2400 km. Samples of iron oxides and iron‐magnesium oxides were loaded into CO 2 gas and laser heated in a diamond‐anvil cell. The nature of crystalline run products was determined in situ by X‐ray diffraction, and the recovered samples were studied by analytical transmission electron microscopy and scanning transmission X‐ray microscopy. We show that Fe (II) is systematically involved in redox reactions with CO 2 yielding to Fe (III) ‐bearing phases and diamonds. We also report a new Fe (III) ‐bearing high‐pressure phase resulting from the transformation of FeCO 3 at pressures exceeding 40 GPa. The presence of both diamonds and an oxidized C‐bearing phase suggests that oxidized and reduced forms of carbon might coexist in the deep mantle. Finally, the observed reactions potentially provide a new mechanism for diamond formation at great depth.
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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 | 0.002 | 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 | 0.000 |
| 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".