POLYMETAMORPHIC AMPHIBOLE VEINS IN METABASALTS FROM THE BETIC OPHIOLITIC ASSOCIATION AT COBDAR, SOUTHEASTERN SPAIN: RELICS OF OCEAN-FLOOR METAMORPHISM PRESERVED THROUGH THE ALPINE OROGENY
Bibliographic record
Abstract
Our aim in this work is (1) to characterize mineralogically and geochemically the brown amphibole and other minerals filling millimetric veins in the Cóbdar metabasalts of the Betic ophiolites in southern Spain, and (2) to deduce their genetic conditions, mainly with the aid of the optical microscopy and analytical electron-microprobe analysis, complemented by transmission and analytical electron microscopy. The vein-filling minerals can be grouped into two assemblages according to their textural relationships. The first assemblage comprises brown amphibole (titanian pargasite and kaersutite) and sodic–calcic plagioclase, and the second one comprises green amphibole (mainly katophorite, barroisite, taramite and tremolite), sodic plagioclase, rutile, clinozoisite and calcite. Brown and green amphiboles present similar, unusually high chlorine contents, up to 0.8 wt.%. Halite micro-inclusions are present in the brown amphiboles, whereas chlorine is incorporated in the structure of the green sodic–calcic amphiboles. Differences in Ti, IVAl, VIAl and BNa values between the brown and green amphiboles clearly indicate different genetic conditions, which are, in turn, similar to those corresponding to amphiboles developed in ocean-floor and orogenic metamorphic conditions, respectively. P–T estimates yield temperatures ranging from 660 ° to 880°C at very low pressure for the first assemblage, and conditions lower than 550°C and 8 kbar for the second assemblage. These data suggest that the minerals filled the Cóbdar veins during the pre-Alpine ocean-floor metamorphic stage (dated by 40Ar/39Ar laser probe on brown amphibole
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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 | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 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) | 0.001 | 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".