Mercury's global evolution : elucidating the tectonic, volcanic, and early magnetic field history through observations and numerical modeling
Bibliographic record
Abstract
The MESSENGER mission from 2008-2015 yielded a wealth of information about our innermost planet, Mercury. For the first time, visible images of the entire planet, measurements of topography, global characterization of the gravity and magnetic fields as well as surface composition, were all acquired. From these observations, multiple enigmatic aspects regarding the geological evolution of Mercury emerged: The early evolution was dominated by crustal production and creation of the Intercrater Plains by extensive effusive volcanism covering the planet until ~4.0 billion years ago (Ga). This was followed by spatially localized effusive volcanism until ~3.5 Ga that created the Smooth Plains, by global contraction that resulted in a unique global distribution of thrust-fault related landforms called shortening structures, and an early internally-driven magnetic field at ~4.0-3.5 Ga producing crustal magnetization detectable from orbit. In this thesis, I focus on the origin and driving mechanism(s) of each these observations. First, I constrain and investigate the formation of shortening structures in the Smooth Plains. I compile a new comprehensive database that characterizes the morphology of shortening structures and provide the first statistical analysis of variations in morphological characteristics across the entire planet (Chapter 2). Second, areal strain estimates (Chapter 2), and numerical modelling of the surface morphology of Smooth Plain’s shortening structures to constrain the subsurface fault structure (Chapter 3), both require large compressional stresses. These stresses are attributed mainly to 5-10 km of global contraction due to secular cooling of the planet, rather than to bending stresses from volcanic loading by ~1-4 km of basalt as previously assumed. Lastly, I revisit the thermal evolution of Mercury (Chapter 4) and propose the first self-consistent model that matches the newly-constrained geologic record. I focus on a novel way to incorporate the thermal consequences of magmatism and crustal production to form the Intercrater and Smooth Plains. Here, I show that voluminous crustal production can drive a period of strong mantle cooling that both favors an ancient thermally driven dynamo, 5-10 km of radial contraction of the planet, and crustal production.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".