Impact-generated magnetite in Chang’e-5 soil as a potential recorder of lunar magnetism
Bibliographic record
Abstract
Abstract Magnetite is a principal paleomagnetic recorder on Earth, but lunar magnetism is thought to be dominated by metallic iron and Fe-Ni alloys, with magnetite rare and typically sub-micrometer within troilite. We identify nanometer- to micrometer-scale magnetite in pentlandite-troilite assemblages from a Chang’e-5 regolith breccia. Magnetite occurs at and within pentlandite, locally enclosing pentlandite nanoinclusions, implying a formation pathway distinct from troilite-hosted occurrences. Textures and compositions indicate sequential crystallization from an impact-generated Fe-Ni-S-O melt: rapid pentlandite growth along troilite margins followed by magnetite nucleation at sulfide-silicate interfaces. The lunar low oxygen fugacity stabilizes Fe 2+ -enriched magnetite, unlike terrestrial analogues. High crystallinity and single-domain to single-vortex states indicate strong remanence stability, making these grains reliable recorders of the contemporaneous lunar magnetic fields. These results broaden the inventory of lunar magnetic carriers, demonstrate impact-driven magnetite formation under lunar redox conditions, and motivate use of magnetite to refine the Moon’s magnetic history.
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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 | 0.000 |
| 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 | 0.000 | 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".