Kyle Fry's Honours Thesis Abstract

Three granitic dike swarms of peraluminous composition within the southern North Caribou Terrane display both compositional and textural zoning.  Two distinct mineralogical phases can be recognized within each swarm: a granodiorite and tonalite phase at 6k Ridge and Lake 282 drill core, and a monzogranite and granodiorite phase at Cigar Lake.  In addition to mineralogical zoning, textual zoning is also present within the dikes at each of the locations.  A fine-grained border zone next to the contact with the host rock consists predominantly of albite and quartz.  Secondly a medium-grained wall zone with albite, quartz, microcline ± tourmaline that extends inward from the border zone and into the dike.  Finally, a coarse-grained quartz, albite, microcline, muscovite ± biotite ± garnet zone extends inward from the wall zone into the core of the dikes.  Structures such as internal foliation parallel to the adjacent host rock, as well as pinch and swell structures, suggest that the dikes and host rocks were still ductile when they were emplaced and that timing of emplacement was syn-orogenic.  Trace element geochemistry shows significant alteration within the dikes, as well minor assimilation of the adjacent host rock.  ɛNd values of -0.9 to -6.0 suggest enrichment of the magma from a crustal source through partial melting prior to emplacement.