The Platinum-Group Minerals of the River Ko Watershed, Sisim Placer Zone, Eastern Sayans, Russia, and the Differentiation of Multicomponent Melts
Bibliographic record
Abstract
Abstract The textures and chemical compositions (based on the results of over 1000 analyses) of a suite of platinum-group minerals obtained from concentrates collected along the River Ko watershed in the Sisim placer zone, Eastern Sayans, Russia, have been analyzed and described. Detrital grains of Ir–Os alloy, considered to have been derived from the Lysanskiy layered ultrabasic complex, are interpreted to be domains of melt in the interstices of olivine–chromian spinel cumulates. This melt fractionated before crystallization of the alloys; some domains show a core-to-rim enrichment in Ir. The incompatible behavior of lithophile elements, base metals, S, semimetals, and H2O in the melt now represented by the alloy led to the crystallization of a broad range of ore minerals in multicomponent globules of residual melt. In this way, laurite and cuproiridsite developed in the melt and now are in a symplectitic intergrowth with the alloy. A spherule of laurite with a core of anthophyllite-rich amphibole and a mantle of irarsite shows that H2O and lithophile components were also present in the PGE-rich melt. Rhodium-rich pentlandite-related minerals, likely including oberthürite, postdate the crystallization of laurite; these may be Ru-enriched and may contain lamellar grains of torryweiserite or ferrotorryweiserite, both of which may represent exsolution products. These two species, and the related kuvaevite, which locally replace the Rh-rich pentlandite-related minerals, appear to be paragenetically later. The new data provide valuable insight on the evolution of late, multicomponent melts in basic–ultrabasic complexes.
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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) | 0.000 | 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".