In the area northwest of Tatsamenie Lake, pre-Upper Triassic tuffs, phyllites, siltstones and limestones are underlain by Permian limestones of the Stikine Terrane. These rocks are intruded by three igneous events, which include foliated diorite of Triassic age, unfoliated albitite and quartz monzonites 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 are a dark grey, thin bedded, grey weathering carbonaceous unit. The overlying Upper Carboniferous phyllites contain interbedded siliceous siltstone and buff weathering limestone. These are overlain by intermediate to mafic volcanics. The siltstones are pervasively silicified and commonly quartz veined.
Mineralization consisting of pyrite, chalcopyrite, stibnite and scorodite occurs near a north trending fault. A 2.42 metre sample from a trench across a shear zone assayed 3.4 grams per tonne gold (Assessment Report 13068). A sample of chalcopyrite stringers cutting phyllite assayed 0.3 per cent copper (Assessment Report 11779). A drill hole across the zone intersected 3.81 grams per tonne gold over 2.26 metres and an arsenic value of 1.0 per cent over 0.76 metres (Assessment Report 16528).
Tetrahedrite, stibnite, malachite and azurite also occur in veins within phyllites and dolomitic limestone. A sample, 500 metres northwest of the trench, assayed 93.0 grams per tonne silver and over 0.1 per cent antimony (Assessment Report 11779).
Solomon Resources Ltd staked the Tatsa claims in early 2004. Work in 2004 included geological mapping, prospecting and reconnaissance soil and silt geochemical surveys. A total of 49 rock (34 grab, 4 chip and 11 float samples), 571 soil and 13 stream silt samples were collected and submitted for geochemical analysis. Tetrahedrite vein material was collected from near the top of the ridge north above the TOT occurrence. The samples were reported to have been taken from a quartz- carbonate vein with blue copper staining. One grab yielded a high of 0.18 per cent copper (Assessment Report 27775). No work or sampling was undertaken on the Tatsa #6, #7 claims to the west due to glaciers. Soil samples were collected along the southernmost boundaries of the Tatsa 8 and 9 claims.
Please refer to LCZ (104K 080) for details of a common geology and work history prior to 2004.