Contact-Metamorphosed to Regionally-Metamorphosed Pelites: The Natural Record
Bibliographic record
Abstract
Abstract A large database of natural metapelites documenting patterns of mineral assemblages and mineral compositions as a function of bulk composition and relative depth (pressure) and temperature is presented. The settings range from low-pressure contact aureoles to intermediate/high-pressure (broadly ‘Barrovian’) sequences developed in continental collisional settings. The data are organized according to repeatedly observed prograde mineral assemblage sequences (MASs) that, for metapelites of average composition, vary consistently with pressure. The database comprises 365 metamorphic settings from 44 countries that span the Neoarchean to the Pliocene. Eleven MASs have been identified and further grouped into five broader categories. Of these, staurolite–kyanite (‘Barrovian’) sequences are especially difficult to classify, interpreted to be due in part to non-equilibrium processes involved in their formation. 140 settings (38%) have mineral compositions tied to mineral assemblages (3293 samples; 12 429 mineral analyses). Mineral compositions vary systematically as a function of bulk composition, grade and pressure within the MASs. Estimates of pressure and temperature from geothermobarometry are assessed against the relative constraints provided by the natural data and show broadly similar trends but with large uncertainties. Predicted phase equilibria and mineral compositions from thermodynamic modelling are assessed against the natural data. These reproduce some but not all of the natural patterns in mineral assemblages and intra- and inter-mineral compositions. The data in this paper provide constraints for future development of thermodynamic models. The paper concludes with suggestions for future research in metamorphic petrology to address some of the main problems that have been identified.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".