The Giant Mascot Ni-Cu-PGE Deposit, British Columbia: Mineralized Conduits in a Convergent Margin Tectonic Setting
Bibliographic record
Abstract
The Giant Mascot Ni-Cu-PGE deposit is the only past-producing nickel mine (1958–1974) in the Canadian Cordillera of British Columbia, Canada, with ~4.2 Mt of ore grading 0.77% Ni and 0.34% Cu (Ni/Cu = 2.3). The deposit is part of an emerging class of convergent margin Ni-Cu-PGE sulfide deposits where the host rocks are characterized by abundant orthopyroxene and magmatic hornblende. The Giant Mascot intrusion is a crudely elliptical, 3- × 2-km plug composed of ultramafic arc cumulates (olivine-orthopyroxene, hornblende-clinopyroxene) that intruded the Late Cretaceous Spuzzum dioritic pluton. The ores are contained within subvertical pipe-like, lensoid, and tabular bodies ( n = 28), interpreted to represent mineralized conduits and consist of pyrrhotite, pentlandite (+argentopentlandite), chalcopyrite, minor pyrite, troilite, and Pt-Pd-Ni bismuthotellurides. The sulfides have moderate tenors (3–14 wt % Ni, 0.1–17.1 wt % Cu, 84 ppb to 5 ppm total PGE), and variations in PGE concentrations distinguish two geographic mineralized zones (western and eastern). Sulfur isotopes for sulfides span a restricted range of δ 34 S values (−3.4 to −1.3‰) and overlap with analyses from locally pyritiferous Settler schist (−5.4 to −1.2‰). Olivine chemistry reveals a wide range of both Fo (80–89 mol %) and Ni contents (336–3,859 ppm) and provides evidence that Ni contents of olivine were locally upgraded during equilibration with sulfide liquid. Sulfide saturation in the Giant Mascot parental magma(s) was triggered in response to (1) reduction of an oxidized, mantle-derived arc magma, producing ores that formed at an oxidation state of ~ ΔQFM +1; (2) addition of external sulfur and silica by assimilation of Settler schist and Spuzzum diorites; and (3) fractional crystallization of olivine ± orthopyroxene. The presence of high-tenor sulfides in the Giant Mascot deposit indicates that orthomagmatic Ni-Cu-PGE deposits in convergent margin tectonic settings may be of significance to future global exploration.
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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 | 0.002 | 0.003 |
| 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".