High-sulphidation epithermal Au-Ag-Cu mineralization at the McKay Hill property — a revised deposit model

The past-producing McKay Hill property on NTS map sheet 106D/6 (Nash Creek) has previously been described as polymetallic Ag-Pb-Zn ± Au-style mineralization. During the 2009 YMIP-funded exploration program the central claims on the property were mapped and numerous distinct differences from the proposed polymetallic model became apparent. Unlike Keno Hill, veins on the McKay Hill property lack siderite gangue and are not present as vein-faults. Propylitic alteration halos surrounding vertically zoned ore shoots (high-level Au-Cu and deeper level Ag-Cu-Pb) were observed within consistently north-northwest-striking, near vertical, siliciclastic and hypabyssal-volcanic rocks. The Ag-Pb-Zn veins in the Keno Hill Camp were emplaced in discrete dilational fault structures within polydeformed clastic metasediments and are not associated with extensive alteration. Host rock competency in both areas is vital in controlling mineralization. Re-evaluating the regional framework could potentially illustrate the area’s metallogenic potential for different types of mineral occurrences.