Widespread ancient anorthosites in the lower crust of Mars
Bibliographic record
Abstract
Understanding when and how evolved rocks formed on terrestrial planets remains a fundamental question in planetary geology. Mars preserves ancient surface rocks, providing unique opportunities to study early crustal formation. Here we report extensive detections of feldspathic, possibly anorthositic, rocks uplifted by the Argyre basin-forming impact using orbital remote sensing. The radial distribution of these feldspathic outcrops indicates they originated from the lower martian crust, positioned stratigraphically between olivine-bearing materials and low-calcium pyroxene-bearing upper crustal rocks. This stratigraphy resembles observations at the Hellas basin, suggesting feldspar-rich rocks are widespread in the lower crust. The spatial association of plagioclase-rich outcrops with pyroxene and olivine-bearing units resembles layered mafic intrusions on Earth, suggesting large-scale melting early in Mars’s history produced differentiated igneous complexes. These observations offer direct evidence to support and refine existing models of early crust formation, addressing key questions regarding crustal properties and formation that have lacked widespread observational constraints. Spectrally feldspathic lithologies, stratigraphically located in the lower crust above olivine-bearing material and below low-Ca pyroxene bearing rocks, are exposed in the Argyre impact basin and observed in data from the Mars Reconnaissance Orbiter.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.000 | 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 teacher head, 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".