Mars is a mirror – Understanding the Pahrump Hills mudstones from a perspective of Earth analogues
Bibliographic record
Abstract
ABSTRACT Mudstone‐dominated lacustrine strata in the Pahrump Hills area of Gale Crater, Mars, have the most extensive data set of physical and geochemical observations yet collected. Although sparse by Earth standards, a source‐to‐sink portrayal of the sedimentary system that differs substantially from previous work has been extracted by integrating sedimentology, stratigraphy, mineral and elemental analyses, geochemical modelling, laboratory experiments and Earth analogues in a sequence‐stratigraphic and palaeogeographical framework. Approximately 3.5 Ga, these 15 m thick strata contain five facies that range from fine to coarse detrital mudstone with abundant sediment‐incorporative evaporite pseudomorphs. The section is dominated by first‐cycle grains of minimally weathered primary igneous minerals but with four distinct compositions. Bedding in the mudstones comprises planar‐parallel beds, current ripples and wave‐induced structures, with common and widespread truncation. The absence of primary desiccation and synaeresis cracks is probably due to minimal clay‐mineral content, as supported by laboratory experiments. Evaporite minerals formed on and within detrital muds shortly after accumulation by evapoconcentration and cooling. The succession contains 16 parasequences in five depositional sequences with all the sequence‐stratigraphic elements known from terrestrial strata. Two of the sequence boundaries are unconformities that record significant shifts in the behaviour and palaeogeographical configuration of the fluvio‐lacustrine system. This contrasts with the previous view that all facies are genetically related. Most of the variability in rock composition can be attributed to stratigraphic changes in provenance that integrate changing drainage basin configurations, type of exposed bedrock and changes in weathering regime. These strata are interpreted as evaporative lake deposits that accumulated in an underfilled lake basin with closed surface hydrography but through‐flowing groundwater. Lake waters were saline to hypersaline, and lake levels, shorelines and salinities fluctuated greatly at various temporal scales.
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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 | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".