Penetrative Convection in Super‐Earth Planets: Consequences of MgSiO<sub>3</sub> Postperovskite Dissociation Transition and Implications for Super‐Earth GJ 876 d
Bibliographic record
Abstract
Abstract Theoretical studies suggest that MgSiO 3 postperovskite dissociates into MgO and MgSi 2 O 5 at 0.9 TPa, and MgSi 2 O 5 dissociates into MgO and SiO 2 at 2.1 TPa, both with negative Clapeyron slopes. In addition, unlike a conventional view, the viscosity in super‐Earth planets is proposed to decrease with pressure when pressure exceeds ~0.1 TPa. Employing 2‐D‐axisymmtric and 3‐D‐spherical control volume compressible models, we perform an investigation on the impact of deep mantle dissociation of postperovskite into oxides, in conjunction with variations of the mantle viscosity, on the degree of the deep mantle layering, and the consequences of this layering on cooling of the rocky planets similar to super‐Earth GJ 876 d. Small‐scale convection in a layer of thickness ~500 km from which penetrative plumes originate, develops above the core‐mantle boundary (CMB) in the models for which the viscosity at the dissociation transition depth and below is less than ~10 23 Pa·s. Due to the buffering effect of this deep mantle layering, while the mean mantle temperature above the layer decreases, resulting in a viscosity increase above the layer, it increases in the layered region above the CMB. This leads to a further reduction in viscosity at the bottom of the mantle. The effect is enhanced with increasing the CMB temperature and the contrast in thermal expansivity. The cooling rate of the planet decreases in the layered models due to the buffering effect of this deep mantle transition, as well as the influence of the viscosity increase above transition 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 | 0.001 | 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) | 0.000 | 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".