Sulfur Isotopes as a Record of Complex Sulfide Saturation Histories in Conduit-Type Ni-Cu-PGE Deposits: An Example from the Eastern Gabbro, Coldwell Complex, Canada
Bibliographic record
Abstract
Abstract Copper-platinum-group element (PGE) mineralization in the Eastern Gabbro Suite is restricted to the Marathon Series. The mineralization occurs in the Marathon deposit and the Sally deposit, as well as Four Dams, Boyer, and Redstone occurrences, which are to the north of Marathon (i.e., the northern deposits). The northern deposits must have formed by distinct processes because they are characterized by Cu/Pd and S/Se ratios that are higher and lower than mantle values, respectively. Base-metal sulfides in the northern deposits exhibit a range of δ34S (–0.7 to 3.78‰) and Δ33S (–0.44 to 0.34‰) values. The nonmantle values imply that externally derived S was added to the northern deposit magmas, with the sources of S likely having been Archean in age. The variability toward mantle values likely resulted from destruction of the contaminant signatures by interaction of the sulfide liquids with multiple uncontaminated pulses of magma. This interpretation can also explain the systematically low S/Se ratios of the northern deposits because, unlike S isotopes that equilibrate to mantle values at high R factors, S/Se ratios equilibrate to values lower than mantle at equivalent R factors. Taken together, it is evident that, compared to Marathon, the northern deposits experienced more complex sulfide saturation histories, which were characterized by multiple sulfide segregation events—some of which depleted the melts in PGE—and derivation of S from Archean reservoirs containing elemental S and S produced by sulfate reduction.
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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 | 0.000 | 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.010 | 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".