Occurrences of Slawsonite In Rocks of the Teschenite Association In the Podbeskydí Piedmont Area (Czech Republic) and Their Petrological Significance
Bibliographic record
Abstract
Slawsonite is an extremely scarce natural member of the Feldspar Group, occurring in less than 10 known localities worldwide. We report three new slawsonite occurrences (in Certak, Krmelin, and Repiste.) in rocks of the Cretaceous teschenite association in the Czech Republic. At Certak, a tabular sill of "teschenite'' (in fact analcime syenite, based on its mineral composition) is one of the most alkaline examples of the teschenite association rocks. It shows differentiation to a coarser-grained core enriched in amphiboles, with diffuse transition to the outer zones. Rare thin leucocratic "aplite'' dikes contain slawsonite, celsian, microcline, natrolite, prehnite, analcime, and thomsonite-Ca. Slawsonite forms aggregates exhibiting symplectite-like microstructures up to 2 mm long and is associated with euhedral zoned celsian micrograins up to 100 mu m in size. Wavelength dispersive X-ray analyses indicate that the chemical composition of slawsonite ranges from Sl(90.4)Cn(3.4)An(1.7)Ab(3.1)Or(1.4) to Sl(60.3)Cn(8.7)An(6.9)Ab(18.3)Or(5.8); the composition of celsian ranges from Cn(95.8)An(0.4)Ab(1.0)Or(2.3)Sl(0.5) to Cn(70.1)An(0.5)Ab(2.2)Or(6.3)Sl(20.9); and the Na-rich microcline exhibits a composition of Or(58.3)An(2.8)Ab(29.4)Cn(6.4)Sl(3.1). Slawsonite from Krmelin and Repiste occurs in a similar geological setting, as aggregates up to 0.3 mm in size that are confined to leucocratic dikes at the endo-contacts of teschenite sills or lava pods. We suggest that slawsonite forms pseudomorphs after nepheline or possibly after plagioclase. Whole-rock geochemistry shows that local teschenites have an affinity for alkali basaltoid rocks typical of MORBs, but are significantly enriched in incompatible elements such as Rb, Ba, Th, U, Ta, Nb, and Sr. With regard to the obvious presence of autometamorphic hydrothermal alteration, we propose that bodies of teschenite association rocks should not be described as dikes; instead, a model of lava pods should be applied.
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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 | 0.003 | 0.002 |
| 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".