Quantification of shock in enstatite chondrites using micro-X-ray diffraction
Bibliographic record
Abstract
Enstatite chondrite meteorites are chemically and isotopically related to the precursors of inner Solar System planetesimals, and bear evidence of shock metamorphism which reflects events in enstatite chondrite evolution. Here, we build upon a micro-X-ray diffraction (micro-XRD)-based method to relate strain-related mosaicity (SRM) to petrographic shock stage. Making use of the peak pressure ranges estimated for the petrographic shock stages, we are able to provide quantitative constraints on the peak shock pressures recorded in enstatite (MgSiO3). Full-width at half-maximum measurement of X-ray diffraction maxima distributed along the Debye rings (ΣFWHMχ) are a proxy for SRM in enstatite grains. Eleven Antarctic enstatite chondrites spanning all documented shock stages (S1−S5), petrologic types, and metamorphic grades, are used to establish a linear correlation P (GPa) = 4.62 × ΣFWHMχ + 0.57; with R2 = 0.92 between estimated peak shock pressure and ΣFWHMχ. Enstatite lattice planes (020), (610) and (131) show similar ΣFWHMχ values where meaningful comparisons can be made, suggesting that enstatite has, within measurement error, an isotropic response to shock deformation along its three crystal axes. The (610) reflection is particularly productive at all shock stages and could be used exclusively for future peak pressure studies, under the assumption that enstatite is isotropic to shock deformation. This 2D XRD method enables the estimation of peak shock pressures up to at least 30 GPa in enstatite chondrites and for other enstatite-rich meteorites.
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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".