MICROLITE AND TANTALITE IN THE LCT GRANITIC PEGMATITES OF LA CANALITA, NAVASFRIAS Sn-W DISTRICT, SALAMANCA, SPAIN
Bibliographic record
Abstract
The La Canalita pegmatites in the Navasfrias Sn–W district, in Spain, are a group of Li-rich LCT rare-element pegmatites hosted by metamorphic rocks. It consists of several dikes up to 1 m thick, 16 m in length and of unknown depth that were mined during the 40s and 50s for tin. Here, we document the Ta-rich oxide minerals, such as those of the columbite–tantalite group, tapiolite-(Fe) and microlite. It is possible to distinguish a primary assemblage, formed of extremely Mn-rich columbite and tantalite, and microlite, the latter forming the host of columbite-(Mn) exsolution lamellae in the intermediate parts of the dikes. The influence of metasomatic fluids led to the formation of a lepidolite–albite late unit and the crystallization of a secondary assemblage consisting of tantalite-(Fe), tantalite-(Mn) and tapiolite-(Fe). Uranium-rich microlite (up to 6% wt. UO 2 ) is present in this assemblage, replacing tantalite. Subsequently, the entrance of hydrothermal fluids, probably mixed with metamorphic fluids, caused a partial greisen-like alteration of the pegmatite bodies and formed a second generation of microlite replacing tapiolite, with high Ca and Ta and low F contents. The lack of a chemically suitable protolith in the surrounding metamorphic rocks, combined with the mineralogical paragenesis containing U-rich microlite, together with the composition of the Sn, Nb and Ta oxide minerals of the pegmatite dikes, suggest that the Cadalso – Casillas de Flores batholith is the most probable source of the melts forming the La Canalita pegmatite dikes.
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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 | 0.001 |
| 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".