Multiple stages of aqueous alteration along fractures in mudstone and sandstone strata in Gale Crater, Mars
Bibliographic record
Abstract
The Mars rover Curiosity in Gale crater conducted the first-ever direct chemical and mineralogical comparisons of samples that have clear parent (unaltered) and daughter (altered) relationships. The mineralogy and chemistry of samples within and adjacent to alteration halos in a sandstone formation were established by the Chemistry and Mineralogy (CheMin) X-ray diffraction (XRD) instrument and the Alpha Particle X-ray Spectrometer (APXS), respectively. The Stimson formation sandstones unconformably overlie the Murray mudstone formation and represent the youngest stratigraphic unit explored by Curiosity to date. Aqueous alteration of the parent sandstone resulted in a loss of half of the original crystalline mineral phases and a three-fold increase in X-ray amorphous material. Aqueous fluids extensively leached Mg, Al, Mn, Fe, Ni, Zn and other elements from the parent material, decreased the pyroxene to feldspar ratio by a factor of two, introduced Ca and mixed-cation sulfates, and both passively and actively enriched the silica content. Leaching of Mg, Al, Mn, Fe, Ni and Zn and enrichment of Si and S are also observed in alteration halos in the underlying mudstone. These observations are consistent with infiltration of subsurface fluids, initially acidic and then alkaline, propagating along fractures crosscutting the Stimson sandstone and Murray mudstone. The geochemistry and mineralogy suggest a complicated diagenetic history with multiple stages of aqueous alteration under a variety of environmental conditions (e.g. both low and moderate pH). The formation of these alteration halos post-dates lithification of the sandstones and mudstones and represents one of the youngest hydrogeologic events presently known to have occurred in Gale crater.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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 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".