Variation in vein mineralogy and mineral chemistry around the Marathon Cu-Pd deposit, Ontario: insights into the development of an exploration tool
Bibliographic record
Abstract
The Marathon Cu-Pd deposit (125 Mt at 0.26% Cu, 0.72 ppm Pd, 0.25 ppm Pt, and 0.08 ppm Au) is hosted within the Two Duck Lake Intrusion (TDLI), a late-stage phase of the Eastern Gabbro in the Coldwell Complex. Late-stage chlorite±calcite veins are present in and around the Marathon deposit, indicating subsolidus movement of fluids throughout mineralized and barren rocks. The hypothesis to be tested is did fluids migrating upwards through mineralized rock mobilize metals into overlying barren rock and was this movement recorded in the chemistry of vein minerals? Chlorite- and calcite-bearing veins were collected from drillholes throughout the deposit. The drill-core samples contain veins hosted in variably mineralized and barren host rocks. Chlorite, the dominant phase, occurs as very fine-grained, bladed crystals in massive, radiating, or aligned aggregates. The veins also contain minor saponite, talc, serpentine, and/or amphibole. Mineral chemistry data from energy- and wavelength-dispersive spectroscopy indicate that the Fe/Mg ratio in chlorite (chamosite to clinochlore) is highly variable, and varies as a function of host-rock type. Laser ablation ICP-MS analyses were carried out on 52 chlorite samples collected throughout the deposit and barren host rocks. Transition metals were detected in all chlorite veins, whereas metalloids were only detected in a subset of samples. Titanium, Cr, Mn, Zn, and metalloid concentrations do not correlate with host-rock type. Transition metal concentrations in vein chlorite that crosscuts plagioclase, pyroxene, and pyrrhotite are comparable; however, chlorite in veins that occur in magnetite, altered olivine, and chalcopyrite have distinctive transition metal signatures (e.g. significantly higher Ti and V concentrations in veins hosted by magnetite), indicating that chlorite chemistry was controlled on a very local scale. Cobalt, Ni, and Cu concentrations are greater above mineralization than within mineralization. The Mn concentrations in chlorite increase linearly towards mineralization, whereas Co, Ni, and Zn decrease. When employing chlorite chemistry as a vector to mineralization, grain-scale variations in chlorite must be considered. Our results show that when these small-scale controls on chlorite composition are recognized, the chemistry of chlorite can be a successful exploration tool.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.001 | 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".