The late (2.61 billion-year-old) Cheechoo tonalite is interpreted to be a mushroom shaped intrusion with a 450 to 500 m thick, roughly tabular top having a shallow to moderate dip to the south along its southern contact and a moderate dip to the west along its western contact (JT Prospect area). The Contact Trend is interpreted to represent a decompression stockwork zone close to the top of the intrusion. This mineralized zone may extend downwards, parallel to, and below, the contact with the overlying metasedimentary country rocks.
Numerous indicators suggest this tonalite-hosted corridor corresponds to a large-scale late-magmatic hydrothermal system. These include the presence of local hydrothermal breccia, sheeted veins, extensive and significant intervals of pervasive silicification and albite alteration. Variable amounts of biotite, albite and actinolite alteration along with low levels of disseminated pyrite (py), pyrrhotite (po) and arsenopyrite (aspy) are also present. This type of alteration and sulphide mineralization correlate to results reported by Sirios nearby in the Cheechoo tonalite. Gold commonly occurs as small discrete visible gold grains.