The Evolution and Structural Modification of the Supergiant Mitchell Au-Cu Porphyry, Northwestern British Columbia
Bibliographic record
Abstract
The calc-alkalic Mitchell Au-Cu-Ag-Mo porphyry deposit, hosted in intrusive rocks of the Stikine volcanic arc terrane of northwestern British Columbia, is the largest undeveloped gold resource in Canada, with 40.72 Moz of contained gold. It lies within the KSM trend, a 12-km-long linear porphyry array in the Sulphurets district. It is genetically related to Early Jurassic Sulphurets stocks: phase 1 diorite to monzodiorite hosts Cu-Au mineralization in potassic assemblages (stage 1), a phase 2 granodiorite plug cores a molybdenum halo (190.3 ± 0.8 Ma, 191.3 ± 0.7 Ma; Re-Os, molybdenite) that is accompanied by phyllic alteration (stage 2), and a poorly mineralized phase 3 diorite plug temporally overlaps with quartz-pyrophyllite alteration at shallow levels (stage 3). Two deformation events (D1 and D2), attributed to orogen-scale mid-Cretaceous transpression, structurally modified Mitchell. D1 deformation, expressed as steep E-striking pressure solution cleavage (S1) and related W-plunging folded veins (F1), is heterogeneously developed as a function of alteration type. D2 is divided into two progressive events: D2a, defined by N-plunging, folded veins (F2a), and D2b, defined by E-vergent thrust faults, including the Mitchell thrust fault, which offsets the updip continuation of Mitchell (the Snowfield deposit, 192.0 ± 1.0 Ma, 191.1 ± 0.8 Ma; Re-Os, molybdenite) ~1,600 m to the east-southeast. Host structures for the KSM trend may have been long-lived, N-striking basement lineaments that provided transcrustal magma and fluid pathways. East-trending intrusions, hydrothermal veins, alteration and metal distribution at Mitchell are attributed to subsidiary E-striking cross faults. These original anisotropies in turn influenced the geometry of Cretaceous faults and flattening domains within the deposit.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".