INVESTIGATION OF LUNAR METEORITE NWA 3163 AND COMPARISONS WITH SHOCKED ANORTHOSITES FROM THE MISTASTIN LAKE IMPACT STRUCTURE, LABRADOR
Bibliographic record
Abstract
Lunar granulites are believed to be metamorphosed polymict impact breccias that have the potential to yield new information on the origin and evolution of the lunar crust and its impact history. A major challenge in studying these rocks is to elucidate the metamorphic environment and processes that gave rise to the enigmatic granulitic textures. Presented here is the first comparison of the metamorphic characteristics of lunar meteorite NWA 3163 with shock-metamorphosed and heated anorthosites at the Mistastin Lake impact structure of northern Labrador. The Mistastin Lake impact structure is a 36 ± 4 Ma, 28 km diameter feature situated at the north-eastern end of the Mesoproterozoic Mistastin Batholith composed of anorthosites, granites and lesser amounts of gabbro. Petrographic observations suggest that the majority of the feldspar within samples from the central uplift has been transformed to diaplectic glass (maskelynite). Samples from clasts within impact melt rock appear to have undergone some degree of devitrification, most likely because of thermal metamorphism due to the heat of the impact melt. A comparison of these shock features, maskelynite distribution and grain boundary characteristics as shown with Backscatter Imaging (BSE), colour Cathodoluminesence (CL) and Energy Dispersive X-Ray Spectrometry (EDS) spectra with those of NWA 3163 have determined that no samples retrieved from Mistastin exhibit textures similar to those found in lunar granulites. This result was unexpected and warrants additional studies of lunar granulites. Using CL to identify metamorphic textures, NWA 3163 has been found to be a poikiolitic granoblastic granulite.
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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 | 0.000 |
| 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 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".