Emplacement of sulfide-rich quartz-diorite melts in the Whistle-Parkin Dike of the Sudbury Igneous Complex, Canada

A field-based structural study including surface mapping, construction of geological profiles, drill core logging complemented by petrographic and microstructural analyses was conducted on the Whistle-Parkin Offset Dike and its Paleoproterozoic host rocks. The study was aimed at elucidating the cause for the variation in the dike's sulfide content and, thus, to contribute to process-oriented exploration strategies of sulfide and PGE mineralisations at Sudbury. Logging of drill cores provided by Wallbridge Mining indicates that the dike displays variable orientation and was emplaced into impact-induced polymict breccia bodies decorating lithological interfaces. Stuctural mapping revealed that the deviation from the overall NE-SW strike and subvertical orientation of the dike is primary, i. e. intrusive in origin. This segment of the Whistle-Parkin dike is enriched in sulfide minerals such as pyrrhotite, pyrite and chalcopyrite. Post-impact, large-scale orogenic folding modified the orientation of the Whistle-Parkin dike, thereby tilting the moderately inclined dike segment from the horizontal toward the SW by about 40°. Gravity-driven emplacement of sulfide-rich quartz-diorite phases prior to folding can account for the concentration of sulfide minerals in this dike segment as well as for their lack in subvertical segments of the Whistle-Parkin Offset Dike.