The 3 Aces Property, in the southeast corner of Yukon Territory, is sited along the edge of the ancient North American continental shelf. This large land holding is on the eastern margin of the Selwyn Basin, a long, narrow belt that extends across much of the south-eastern and central portions of the Yukon. The sedimentary rock record preserved in the Selwyn Basin chronicles the progressive infilling of Proterozoic through Paleozoic rift basins that formed along the margin of Ancient North America. These sedimentary rocks were deformed and metamorphosed during Cretaceous time by the intrusion of numerous granitic bodies.
Hyland Group sedimentary rocks underlay the 3 Aces claims, these rocks representing the bottom of the Selwyn Basin near the terrain boundary with the older North American continent. These sedimentary rocks consist of medium to coarse grained clastic beds intercalated with shale. Deformation at this older continental margin has produced a folded package of rocks with intense faulting at the contact between shale and sandstones/conglomerates. Gold-bearing quartz veins fill these faults at the contacts between sedimentary units.
An orogenic gold model best fits the occurrences at 3 Aces, where contact metamorphic features and metal zonation are absent. Massive quartz veins, hosted in structural zones at contacts, commonly contain exceptionally high gold grades (often exceeding 1,000 g/t gold). The coarser-grained sedimentary units are frequently quartz-flooded, forming haloes around the massive veins with lower grade gold mineralization (ranging from 0.5 g/t to about 6.0 g/t gold). Veins hosted in the fine-grained sedimentary rocks are narrow but often contain high grade gold. These sulfide-poor quartz veins and surrounding quartz flooding contain gold, arsenopyrite and pyrite with trace amounts of pyrrhotite, chalcopyrite and galena.