LOW-Al TOURMALINES OF THE SCHORL-DRAVITE - POVONDRAITE SERIES IN REDEPOSITED TOURMALINITES FROM THE WESTERN CARPATHIANS, SLOVAKIA
Bibliographic record
Abstract
Tourmalines of the schorl–dravite – povondraite series were studied in three samples of tourmalinite pebbles from Lower Triassic Lužna Formation in the Tatric Unit (Bratislava, Devinska Kobyla hill) and the Upper Cretaceous Upohlav conglomerates of the Pieniny Klippen Belt (Orlove), in the western Carpathians, Slovakia. A combination of analytical techniques was used to analyze for major elements (electron microprobe), Fe 3+ and Fe 2+ (Mossbauer spectroscopy). The tourmaline-group minerals studied belong to the schorl–dravite subgroup; they attain the composition of povondraite by virtue of an obvious dravite–schorl – povondraite trend, partially overlapped by a schorl – feruvite trend. A significant amount of Fe 3+ in the tourmaline was determined directly by Mossbauer spectroscopy (at least 59.1% of iron is Fe 3+ ) and indirectly by the cation charge-deficiency (Fe 3+ up to 3.7 apfu ). The Al 3+ content is less than 5.0 apfu , locally reaching below 3.0 (2.86) apfu in sample TQ6. A decreasing Al 3+ content can be charge-balanced by two different mechanisms of substitution: (1) feruvite–uvite substitution [CaMg(NaAl) −1 ], and (2) povondraite substitution (Fe 3+ Al −1 ). The feruvite–uvite substitution saturates the X site with Ca 2+ and the octahedral sites with Mg 2+ to balance Al 3+ below 6.0 apfu . Subsequent decreases in Al content below 5.0 apfu cannot be compensated by the input of divalent cations, but by Fe 3+ using a povondraite substitution. Enlargement of the tourmaline structure in Al-poor povondraitic tourmaline due to Fe 3+ Al −1 substitution allows introduction of K into the X site (up to 0.03 apfu ). The genetic environment of the tourmalines studied remains obscure, but their high Fe 3+ contents and K-enrichment suggest highly oxidized conditions in association with evaporitic processes.
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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 | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 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".