In the area southwest of Tatsamenie Lake, pre-Upper Triassic tuffs, phyllites, siltstones and limestones are underlain by Permian limestones of the Stikinia Terrane. These rocks are intruded by plutonic rocks associated with three separate igneous events. These consist of foliated diorite of Triassic age, unfoliated albitite and quartz monzonite of Jurassic and Late Cretaceous ages, respectively, and feldspar porphyry basaltic dykes of the Sloko Group of Eocene age. The volcanics and sediments have undergone two phases of folding, a tight isoclinal fold with a horizontal fold axis and an upright more open fold. The early isoclinal phase of folding is associated with thrust faulting, which places Upper Carboniferous felsic phyllites on Permian limestone.

The Permian limestones consists of a massive, white, thick bedded, grey weathering, recrystallized limestone unit overlain by a dark grey, thin bedded, grey weathering carbonaceous limestone unit. The upper unit contains quartz veins, up to one metre wide, with disseminated pyrite, arsenopyrite, malachite, azurite and minor tetrahedrite and chalcopyrite.

The Tut zone occurs within a 900 metre long belt of dolomitized and silicified Permian limestone, approximately 100 to 150 metres wide, between strong east-northeast trending faults, the southern fault acting to truncate the LCZ zone at its north end (Figure 7 and Appendix I). Surface samples from the Tut zone have yielded values of up to 1.6 grams per tonne gold (Assessment Report 16726) from within silicified limestones and up to 3900 ppb gold over 1.1 metres (Trench #2, sample KB4T 1-325) from trenched dolomitized limestone located near the north bounding fault (Assessment Report 13068). The trenched zone is open to the north and west. The intensity of dolomitization increases in the direction of the bounding faults. Stockwork veinlets of silica are common. Traces of tetrahedrite occur in fractures in the dolomitized limestone. In 1987, Chevron drilled a single hole (R-37) through the south bounding east-northeast trending fault, which contains abundant scorodite and silica. Drillhole R-37 yielded assays up to 275 ppb over 0.95 metre from a 10.0-metre intersection of silicified limestone Assessment Report 16528). The core was also reported to be mineralized with fine arsenopyrite.

Refer to the LCZ occurrence (104K 080) for further details of area geology and a common work history.