The Maturi Cu-Ni-PGE deposit occurs along the basal zone of the SKI where it is in contact with granitic rocks of the Archean Giants Range Batholith (GRB) composed of plagioclase rich monzonite to monozodiorite. Generally Cu-Ni-PGE-enriched sulfides are disseminated throughout a 50-150m-thick basal mineralized zone (BMZ) and locally may be semi-massive to massive sulfide. Several researchers have noted significant sulfide disseminated to massive sulfide mineralization resultant from S originating from the BMZ. The mechanism of mineralization was unconfirmed. The goal of this study is to determine the mechanism of mineralization using petrography, traditional lithogeochemical analysis, and isocon geochemical modeling. Petrographic observations are consistent with pyroxene hornfels metamorphism by the presence of charnokites and partial melted indicated by the presence of quartz-feldspar aggregates, mortar texture, lattice dislocations in feldspars, and sieve texture in feldspars. Often those characteristics of partial melting are closely associated with magmatic sulfides. Isocon modeling indicates that incompatible elements were lost from the system which is often coincident with the gain in sulfide components based on a best-fit isocon of Mg-Mn-Cr. Petrographic and geochemical lines of evidence are interpreted to result from the dense sulfide liquid displacing the less dense partial melt from the GRB thereby penetrating into the footwall and resulting in the mineralization of below the Maturi Deposit.
University of Minnesota Master of Science thesis. October 2014. Major: Geological Sciences. Advisor: James Mille. 1 computer file (PDF); v, 205 pages + 11 supplementary files (zipped)
Steiner, Ronald Alexander.
Genesis of sulfide mineralization within the granite footwall of the maturi deposit of the South Kawishiwi intrusion, Duluth complex, NE Minnesota.
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