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Analytical data sets provided for mineral exploration borehole samples from the McCreedy W mine and other orebodies along the N Range of the Sudbury igneous complex have been examined in a series of atomic ratio diagrams designed to elucidate the mass transfer processes involved in their genesis. The compositions of ores from the McCreedy W mine display a strongly bimodal distribution. 1) A Cu-poor population largely located along the footwall contact displays trends consistent with fractionation dominated by pyrrhotite (monosulphide solid solution) crystallization. 2) A Cu-rich population location within the footwall vein system, displays trends consistent with fractionation dominated by chalcopyrite (intermediate solid solution) crystallization. What appears to be a shared trend between the two populations suggests that they are related by derivation from a cognate pair of immiscible sulphide liquids. The same ore composition is found in the Levack embayment on the N Range. Compositional relationships displayed by these deposits are consistent with the separation of an immiscible, Cu-rich melt during cooling and fractionation of monosulphide solid solution from a less Cu-rich, parental sulphide liquid. The spatial relationships of the two ore populations at McCreedy W and within the Levack embayment suggest that density relations and volume changes associated with the unmixing and crystallization processes have played a major role in the emplacement of footwall orebodies. Spatial relationships of the two ore populations suggest that the various orebodies within the Levack embayment were all emplaced when the basal contact of the Sudbury igneous complex was essentially horizontal.

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GeoRef, Copyright 2018, American Geological Institute.<br/>2003-014842<br/>Coleman Deposit<br/>Levack Embayment<br/>McCreedy East Mine<br/>McCreedy West Mine<br/>North Range<br/>Victor Deposit