COEXISTING Ba-FELDSPAR AND MELILITE IN A MELAFOIDITE LAVA AT MT. VULTURE, ITALY: ROLE OF VOLATILES AND ALKALINE EARTHS IN BRIDGING A PETROLOGICAL INCOMPATIBILITY
Bibliographic record
Abstract
A Ba-rich alkali feldspar (hyalophane to almost pure celsian) coexists with melilite in the groundmass of the S. Caterina melafoidite lava, Mt. Vulture, Italy. The accompanying phases are a very Al- and Ti-rich clinopyroxene, magnetite, hauyne–sodalite, Ca-rich nepheline, leucite, apatite–britholite and accessory phases (mainly pyrochlore). This mineral assemblage is considered to be the result of the crystallization of a highly silica-undersaturated, alkali-rich magma, in an environment that stabilized S–Cl-rich minerals and inhibited the crystallization of minerals such as phlogopite, owing to the lack of sufficient amounts of volatile species (F, OH) promoting mica crystallization. As a result, the concentration of Ba in the residual liquids, due to its broadly incompatible behavior with respect to the early-crystallized phases, forced crystallization of an increasingly Ba-rich feldspar, along with melilite and volatile-poor feldspathoids such as nepheline and leucite. This apparently incompatible mineral assemblage may occur where interstitial liquid compositions (and thus the eventual crystallizing feldspar) are very rich in Ba or Sr or both, as noted in other rare occurrences worldwide. The final liquid composition crystallized in an assemblage made up of clinopyroxene + feldspathoids + melilite + hyalophane or celsian; it was thus far more undersaturated in silica than a phonolite.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 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 teacher head, 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".