The Tan occurrence is located in the Tan mineral claims, 900 metres south of Hidden Valley Creek, 7.5 kilometres northwest of its confluence with Major Hart River, in the mountainous Kechika Ranges (Assessment Report 6840).
The area is immediately southwest of the northwest-trending Burnt Rose Fault, and consists of lower to middle Paleozoic sedimentary rocks of the Cassiar terrane (Geological Survey of Canada Maps 46-1962, 1712A, 1713A). The Tan claims themselves are underlain by the lower Cambrian Atan Group and the Cambro-Ordovician Kechika Group (Assessment Report 6840). All units dip moderately to steeply southwest. The Atan Group comprises slate and phyllite which are overlain by massive to thinly laminated limestone; this sequence is repeated by a thrust fault. Another fault separates the Atan Group from calcareous phyllites of the Kechika Group to the southwest.
Mineralization appears to be restricted to the Atan Group limestone (Assessment Report 6840). It consists of disseminations and small pods of sphalerite, galena, hydrozincite and pyrite in thinly laminated limestone in the upper part of the unit. Sphalerite is red-brown, and hydrozincite is very common on rock surfaces. Less commonly, sphalerite occurs in veinlets and small patches in irregularly dolomitized limestone.
The Tan occurrence is centred on Zone 1 in the Tan 2 claim, where the mineralization is locally high grade but pinches out along strike. One grab sample (8507) assayed 21.2 per cent zinc, 3.42 per cent lead, and 3.8 grams per tonne silver (Assessment Report 6840). Other samples are considerably lower, similar to those from Zone 2 in the Tan 1 claim, 2 kilometres to the southeast, where a chip sample (8659) assayed 2.32 per cent zinc and 1.62 per cent lead over 9 metres (Assessment Report 6840). Zone 2 also contains weakly mineralized carbonate-barite material. Although lower grade, Zone 2 mineralization is thicker and more laterally persistent than Zone 1.
Work History
In 1978, Amoco Canada Petroleum Company Ltd. completed a program of rock and soil sampling on the area as the Tan claims of the Deadwood Lake property.
