Affinity and Petrogenesis of the Huzyk Creek Metal-Enriched Graphite Deposit: A Metamorphosed Metalliferous Black Shale in the Trans-Hudson Orogen Of Manitoba, Canada

Abstract

ABSTRACT The Huzyk Creek area is situated along the boundary between the Reindeer Zone and the Superior Boundary Zone of the Paleoproterozoic Trans-Hudson Orogen, where the Precambrian rocks are overlain by Phanerozoic cover. Two drill holes intersect graphite schist that is enriched in V, as well as U, Zn, Mo, and Cu, and is hosted by a metamorphosed wacke-mudstone sequence interleaved with variably altered mafic rocks. Whole-rock lithogeochemistry and Sm-Nd isotope chemistry suggest that the wacke-mudstone package is related to the turbidite-derived Burntwood Group of the Kisseynew Domain and was likely deposited relatively proximal to the Flin Flon arc-collage. A model is proposed in which redox-sensitive metals were leached from rocks of the Flin Flon arc-collage during weathering under oxidizing conditions. The metals were transported in oxygenated surface run-off draining the arc-collage and discharged into the Kisseynew Basin. Shallow waters of the Kisseynew Basin were likely oxygenated and biologically productive; however, the basin was likely euxinic at mid-depths. The mixing of the metal-enriched, oxygenated water with organic matter and euxinic water resulted in the reduction of the redox-sensitive metals and the formation of insoluble organometallic complexes and particles. A highstand, or period of tectonic quiescence, likely halted turbidite deposition and allowed for the settling organic and metal-rich particles to create relatively thick deposits. Burial and metamorphism resulted in the organic-rich material being transformed into graphite, while Mo, Cu, and Zn were partitioned into sulfides. The mineral hosts of V and U are not known at this time. The model calls for the fractionation of redox-sensitive metals from the water column shortly after discharge into the Kisseynew Basin and implies that graphitic horizons in relatively close proximity to the Flin Flon arc-collage have a greater potential for metal enrichment than graphite deposits farther removed from the arc. This model could apply to basins of similar metamorphic grade, age, and tectonic setting around the globe.