GENESIS OF THE PTARMIGAN GOLD DEPOSIT, YELLOWKNIFE, N.W.T. CANADA

The Ptarmigan, as well as nearby Tom and Cassidy Point mines, are unique among metasedimentary-rock-hosted mesothermal gold deposits in the Slave Province because they are not associated with an iron formation (IF). Lithogeochemical analysis of wallrock samples (collected at <80 m intervals from drill core and surface outcrops) indicate that alteration occurs proximal to the veins, but that wallrock sulfidation characteristic of IF-hosted deposits, is absent.

An alternative explanation for formation of the Ptarmigan and Tom veins is that structure played a role in their formation. Vein width and grade for ~500 samples collected in the Ptarmigan stopes were used to construct long sections. These contoured plots of vein width and grade indicate a close correlation between high gold values and narrow vein widths. This correlation is consistent with free gold occurring in thinly-sheeted quartz veins exposed in the Tom vein and suggests that there is a genetic link between vein width and grade.