Effects of mantle flow law stress exponent on postglacial induced surface motion and gravity in Laurentia
Bibliographic record
Abstract
Recent studies show that power-law rheology with stress exponent n = 3 in the lower mantle or in a thin zone just beneath the lithosphere are consistent with the sea level observations in and around Laurentia. In this study, the stress exponent n is varied from 2 to 4, and for each value of n, a range of creep parameter A* is searched to find the earth model that gives the best fit to the sea level observations in and around Laurentia. The effects of stress exponent on other geophysical observables—namely present day uplift rate, horizontal velocity, free-air gravity and the rate of change in gravity are also studied. The model used to calculate the postglacial readjustment of the Earth is a 3-D finite element model that includes realistic ice histories and eustatic water loads on stratified incompressible viscoelastic Maxwell flat-earths. Three types of earth rheology models are considered—the first one has nonlinear rheology throughout the mantle and the second has a nonlinear zone at the top of the mantle below the elastic lithosphere and a linear mantle. The third one has nonlinear rheology restricted to lie in the lower mantle. It is found that the models with nonlinear rheology in the lower mantle give better fits to the sea level data in and around Laurentia than the first two types. However, sea level data, when taken as a whole, cannot clearly discriminate between the stress exponents 2, 3 or 4. Present day uplift rate, horizontal velocity and rate of gravity change however may be useful in further discriminating mantle rheology.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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 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".