Spin transition-induced anomalies in the lower mantle: implications for mid-mantle partial layering
Bibliographic record
Abstract
Recent advances in high pressure mineral physics reveal that the thermoelastic properties of the lower mantle may significantly change as a consequence of the spin transition in ferric iron in the major lower mantle minerals, ferropericlase (Fp) and perovskite (Pv). The spin transition in iron introduces anomalies in the thermoelastic properties, like the bulk modulus, which influences the mixing and the style of mantle convection and the thermal history of the planet. Employing high resolution axi-symmetric spherical models, we explore the influence of the spin transition-induced anomalies in density and viscosity on mantle dynamics. Model results reveal that both a viscosity increase in the lower regions of the mantle and a negative spin transition-induced density anomaly can slow sinking slabs they approach mid-mantle depths; however, more profoundly, the density anomaly may halt slabs at mid-mantle depths for tens of millions of years, and up to ∼200 Myr before they finally penetrate to the lower depths. This phenomenon is consistent with the nature of sinking slabs inferred from high resolution tomographic images which show slab stagnations at mid-mantle depths (from 1200 to around 1600 km).
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".