PGE-Rich Ni-Cu Sulfide Mineralization in the Flin Flon Greenstone Belt, Manitoba, Canada: Implications for Hydrothermal Remobilization of Platinum Group Elements in Basic-Ultrabasic Sequences
Notice bibliographique
Résumé
The Flin Flon greenstone belt is best known for its world-class volcanogenic massive sulfide deposits. However, the recent discovery of the McBratney platinum group element (PGE)-Au occurrence and other PGE occurrences has drawn attention to the potential for Ni-Cu-PGE (Au) deposits in this belt. The McBratney occurrence contains some of the highest PGE and Au grades found in this type of deposit in North America (up to 207 g/t Pd, 34 g/t Pt, 2.6 g/t Rh, and 75 g/t Au). It is hosted in chlorite-actinolite and chlorite schists of the Bear Lake magmatic unit in the Bear Lake block of the Flin Flon greenstone belt. The metamorphosed host rocks are komatiitic and tholeiitic in composition. The mineralization is hydrothermal and postdates the regional, retrograde metamorphic event. It occurs as sulfide-rich veins and surrounding disseminated zones controlled by faults, as well as isolated disseminated zones within chlorite-actinolite and chlorite schists. Platinum group minerals (PGM) and gold are spatially and temporally associated with pyrrhotite, chalcopyrite, carbonate, second generation chlorite, chamosite and, locally, stilpnomelane. In the disseminated zones, these phases replace the metamorphic actinolite-chlorite assemblage in both types of host rocks. Locally the veins are layered with pyrrhotite-rich zones and chalcopyrite-rich zones. The PGM include, in order of abundance, Te-rich sudburyite, borovskite, sperrylite, sudburyite, an unknown Pd-Te-Sb mineral, temagamite, and merenskyite, which occur mainly as inclusions in the sulfides. Minor amounts of PGE also occur within chlorite, carbonate, and stilpnomelane, and Au-Ag alloy is observed locally included in Fe sulfides in association with sphalerite. The mantle-normalized metal distribution shows that the McBratney mineralization is enriched in Bi, As, Au, Pd, Cu, Pt, Rh, Os, Ru, Zn, Re, and Ag; the mineralization is both enriched and depleted in Ir and Cr, and it is depleted in Ni in all analyzed samples when compared with typical komatiitic magmatic ore. The mineral assemblage suggests that the hydrothermal fluids were reduced (pyrrhotite-pyrite stable), neutral to alkaline, and CO 2 bearing (carbonate-chlorite stable). Chlorite geothemometry indicates that the hydrothermal assemblage formed at temperatures ranging from 250° to 350°C. Under these conditions, PGE may have been transported mainly as bisulfide complexes and their precipitation likely occurred due to reactions of the hydrothermal fluids with the Fe-rich host rocks, which led to the formation of Fe sulfides, reduction of the activity of the bisulfide, and formation of PGM. Palladium precipitated mainly as tellurides and antimonides; however, Pt formed an arsenide. The abundant As, Te, and Sb may have been crucial in forming high-grade PGE ore. Sulfur isotope data indicate that magmatic rocks or fluids were likely the sources of sulfur, which may include the metamorphosed basic-ultrabasic sequence, hidden magmatic Ni-Cu sulfide mineralization, or fluids derived directly from postmetamorphic magmatic rocks.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
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