Scaling relationships for chemical lid convection with applications to cratonal lithosphere
Bibliographic record
Abstract
We obtain scaling relationships for convection beneath a chemically distinct conducting lid and compare this situation with isochemical stagnant lid convection. In both cases, the vigor of convection depends upon the small temperature contrast across the actively convecting rheological boundary layer, that is, ΔTrheo, the temperature difference between the base of the lid and the underlying half‐space. The laterally averaged convective heat flow beneath a chemical lid scales as q ∝ ΔTrheo4/3. Heat flow through a chemical lid approaches a stagnant lid value where the lid does not impact the rheological boundary layer. Such a condition is met when ΔTrheo/Tη ≈ 3.6, where Tη is the temperature change required to change viscosity by a factor of e. We apply our scaling relationships to the slow vertical tectonics of continental interiors: We find that whereas chemical lid convection governs the mantle heat flow to the base of cratons that are underlain by chemically buoyant lithosphere, classical stagnant lid convection governs heat flow into platforms. The laterally averaged heat flow supplied by isochemical stagnant lid convection to platforms has waned as the Earth's mantle cooled. Consequently, the thickness of platform lithosphere, in thermal equilibrium with isochemical stagnant lid convection, has increased over time. Thermal contraction of the thickening platform lithosphere is expected to produce ∼300 m subsidence relative to cratons beneath air. This prediction explains why cratons tend to outcrop and platforms tend to be sediment covered.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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; a candidate call from one source (direct Gemma or distilled Codex), 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".