Bibliographic record
Abstract
Julien Monteux, Mark Jellinek and Catherine L. Johnson, 1 Laboratoire de Planetologie et de Geodynamique de Nantes, U.M.R. CNRS, FRANCE, 2 Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, CANADA, 3 Planetary Science Institute, Tucson, AZ. (julien.monteux@univ-nantes.fr) Giant impacts may have played an important role in the late history of terrestrial planet accretion. A collision between the Earth and a Mars-sized impactor can, for example, explain the origin of the Earth-Moon system [1]. A large impact removing part of the silicate mantle is one hypothesis to explain Mercury’s unusually large core / mantle radius ratio [2]. A giant impact is also an increasingly popular explanation for why the northern hemisphere of Mars has a lower average elevation and a thinner crust than the southern hemisphere [3, 4, 5]. Cratering statistics indicate that the ages of both the northern lowlands and southern highlands on Mars are similar and that these features formed by 4.4 Gyr before present [6]. Hence, at the time of the giant impact, it is plausible that both Mars and the impactor were differentiated with silicate mantles and iron cores. Such a large impact event is, thus, likely to have been followed by a merging of the cores of both bodies, a process which will have implications for the early magnetic field history of the planet. Indeed, Mars records evidence for an early and short lived (i.e. < few hundred Myr) internally generated magnetic field that ceased by ∼ 4.0 Ga [7]. The timing of the initiation of the martian dynamo strongly depends on the differentiation processes that occurred during the first few million years of the Martian history [8]. Here, we explore a possible link between the impact that formed the northern lowlands and the initiation or modulation of a core dynamo. We first characterize the dynamics and thermodynamics of merging of a sinking metallic diapir with an existing planetary core on a Mars-size planet following a giant impact. Next, we investigate how this merging process might influence the likelihood and style of dynamo action.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".