Constraints on the elastic thickness, heat flow, and melt production at early Tharsis from topography and magnetic field observations
Bibliographic record
Abstract
The southern half of the Tharsis region of Mars displays enigmatic variations in the crustal magnetic field that are correlated with topography and the distribution of volcanism. Radial magnetic field anomaly values (Br) at 400 km altitude are greater than 25 nT over areas at elevations less than about 6 km, Br = 0 over areas at higher elevations where volcanism is also concentrated. Assuming that much of the uplift and magmatism of Tharsis postdates the crustal magnetic field, we hypothesize that the absence of radial field in the central part of the rise is related to enhanced heat flow from an underlying mantle plume. A parameterized mantle convection model, combined with a heat transfer requirement for crustal demagnetization and analysis of the dynamic topography provides restrictive and self‐consistent constraints on the plume structure, excess temperature ΔTex and heat flux qp as well as the average elastic thickness de at Tharsis at the time of uplift. These results lead, in turn, to bounds on the long‐term average magma supply from the mantle. ΔTex is found to be in the range 205–240°C and upper bounds for de are 29–40 km, depending on the magnitude of the dynamic topography. Assuming magnetite is the dominant magnetic carrier, these results imply also that the lower 50–60% of the crustal column is raised above the Curie temperature and thermally demagnetized. The plume heat flux qp ≈ 60–100 mW m2 and corresponds to melt production rate Q ≈ 0.01–0.03 km3 a−1, comparable to minimum estimates determined from geological data for the rate of Noachian‐Hesperian volcanism.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| 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".