Specificity of Ore Generation (Tin, Pegmatites, Gems) in Trans-Porphyry Deposits
Bibliographic record
Abstract
During the magmatic stage, base and rarer metals segregate from silicate melts to form ore deposits. The usual case is the porphyry (PD) type (Cu, Mo, W) above subduction zones. The metal grade increases from some ppb or ppm up to percent levels. A new type of trans-porphyry (TPD) deposits (Sn, Ta, Nb, gems) results from large-scale shear between cratons within continental plates, internal decoupling and vertical motion. The bulk ore generation process develops along three stages, from magma generation; emplacement; and formation of an immiscible magmatic phase (MIP), fluids and melt. However, in TPD, metals segregate from the crust during melting below 800 °C, breakdown of biotites, and the melt remains below the critical point (731 °C). Fluids advection competes with chemical diffusion yielding the required enrichment. The subcritical MIP splits into a silicate-rich and an aqueous rich phase, both incompatible with each other. Granite, pegmatites and greisen coexist in the magma chamber. Their respective extraction from a composite mush involves electrons exchanges between charges, or orbitals, yielding metal oxides through chemical diffusion. In contrast, metals (Nb, Ta) observed in pegmatites, and also in gems, electrons rearrange their electronic cloud through its polarizability. At last, gems independently grow under the influence of the extremely hard fluids (Li, Be, B). Magma generation, involving the lower crust (garnet, pyroxene) result in melts that form the two observed pegmatites groups (NYF, LCT)., each being associated with alkaline (A-type) or continental (S-type) granitic melts.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| 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 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".