Quartz dioritic magmas and Cu-(Ni)-PGE mineralization, Podolsky Deposit, Whistle Offset Structure, Sudbury, Ontario
Bibliographic record
Abstract
The Whistle Offset, emanating from the northeastern corner of the 1.85 Ga Sudbury Igneous Complex (NTS 41-I/15), is atypical, as it contains three intrusive phases of 'quartz dioritic' magma that occur as pods instead of a continuous dyke. Lithogeochemical analyses reveal compositional similarities between the quartz dioritic phases and the footwall breccia, but expose a subdivision that supports the hypothesis that the leucocratic quartz diorite is earlier than the quartz diorite and inclusion quartz diorite, and is derived from the same rock types as the footwall breccia. Mineral, chemical, and textural features within the quartz dioritic phases include stellate amphibole, granophyric intergrowths, and elongate fluorapatite with axial melt inclusions and irregular rare earth element zoning, which suggest disequilibrium conditions during crystallization. This is interpreted to indicate rapid crystallization induced by volatile loss through pressure decrease during readjustment of the crater. Leucocratic quartz diorite is interpreted as the original composition of the undifferentiated melt sheet in the Whistle offset area. Inclusion quartz diorite represents an early phase of the melt sheet, where silicate differentiation, assimilation, and gravitational segregation had initiated. Readjustment of the crater caused rapid crystallization of the leucocratic quartz diorite, and injected a pulse of inclusion quartz diorite into the structure. The quartz diorite is believed to have developed in the offset structure directly from the inclusion quartz diorite melt. High temperatures would have produced convective cells in the inclusion quartz diorite melt, and the circulatory movement induced by these cells would cause clastic material to concentrate in low velocity areas, essentially creating inclusion-free pods of quartz diorite. Mineralization ranges from disseminated to blebby Ni-Cu sulphides to vein-style Cu-(Ni)-PGE-rich sulphides rimmed by epidote and/or chlorite. The association with hydrous silicate alteration minerals, together with irregular vein morphology, implies that the Cu-PGE-rich mineralization was concentrated by a fluid and precipitated when the fluid flow was choked.
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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 | 0.001 |
| Science and technology studies | 0.002 | 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) | 0.005 | 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".