FLUID EVOLUTION IN THE ZONED RARE-ELEMENT PEGMATITE FIELD AT CAP DE CREUS, CATALONIA, SPAIN
Bibliographic record
Abstract
The Cap de Creus LCT granitic pegmatites, in Catalonia, northeastern Spain, belong to the beryl – columbite and beryl – columbite – phosphate subtypes and to the albite type. Fluid inclusions have been studied in all these types of pegmatite to determine the nature of the fluids involved in their formation. Beryl – columbite pegmatites are zoned; border, wall, intermediate zones and a quartz core and albite-dominant replacement bodies are distinguished. Beryl – columbite – phosphate pegmatites, in addition, feature veins of albite and quartz–muscovite. In the albite pegmatites, phosphate and albite–chlorite veins also occur. Five types of fluid inclusions have been identified: hypersaline aqueous–carbonic fluid inclusions (type A), low-salinity aqueous– carbonic inclusions (type B), carbonic inclusions (type C), multiphase aqueous fluid inclusions (type D), and late multiphase aqueous–carbonic fluid inclusions (type E). In the early stages of crystallization, a hypersaline fluid exsolved from the melt. It is CO 2 -rich, 41–46 wt.% NaCl eq., in beryl – columbite – phosphate pegmatites, and the aqueous fluid contains 23–38 wt.% NaCl eq. in albite pegmatites. A second immiscibility process occurred in the last stages of the crystallization of the intermediate zones; the fluid unmixed into two fluids: one CO 2 -rich, salt-poor (3–5% NaCl eq.) and the other hypersaline (up to 35% NaCl eq.) and CO 2 -poor. The CO 2 -rich fluid is related to the formation of the quartz core, and the second fluid formed albite veins and circulated throughout the pegmatite, owing to the development of a network of fractures, which produced a Na-metasomatic alteration of the previously formed units. These processes took place at 415–450°C and 2.2–2.7 kbar. Later, quartz–muscovite veins developed at 2.4 kbar and 400°C. The fluid that formed these veins (36–39 wt.% NaCl eq.) produced a K-rich alteration that affected the previously formed pegmatite units. In addition, in albite pegmatites, late albite–chlorite veins formed at pressures lower than 700 bars and more than 340°C.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".