Surficial geological mapping in the central Kluane Ranges was undertaken to better understand the distribution and character of surficial materials. Upland surficial materials in the area are dominated by near-source bedrock derivatives. Valley bottom settings, including Shakwak trench and Duke River valley, are characterized by broad open valleys with thick deposits of Quaternary sediment. Permafrost is discontinuous in the study area and its character is affected by slope and aspect, topography and material texture. Mass wasting processes in the study area include rock fall and avalanches, debris flows and avalanches and active layer detachment slides. The distribution and character of surficial materials has significance for soil geochemical sampling programs and infrastructure and implications for mineral exploration and developments are addressed.

Much of west-central Yukon escaped glaciation and is underlain by leached and oxidized, deeply weathered bedrock. Background and anomalous metal values in these soils are presumed to be lower than normal and therefore increase the challenge of interpreting soil geochemical surveys. It is suspected that the geochemical contrast between background and anomalous values can be maximized by sampling a particular soil horizon or analysing a specific size fraction. One hundred and sixteen samples were collected from soil profiles at ten sites above four porphyry-style mineral deposits - Antoniuk, Revenue, Nucleus and Casino in the Dawson Range of the Yukon-Tanana Terrane. B-horizon soils are locally clay-rich, thin and poorly developed. C-horizon soils are unconsolidated and very coarse grained. Bedrock samples from each site were crushed and analysed for comparison. All samples were analysed using the Au plus 32 (FA-AA and ICP) package which is a popular and economical method currently employed in most exploration programs. The results are generally consistent within the few samples taken at each deposit, but vary considerably overall, and probably reflect the variable physio-chemical conditions between the deposits. Gold and copper are emphasized in the evaluation of the data, but gold data from the fine-grained fraction are incomplete due to insufficient material from the generally coarse-grained soils. Although statistical accuracy cannot be confirmed with such a small sample set, the following trends are recognized: - the highest gold values typically occur in the lowest soil horizon (C2) and in the -200 mesh fraction; - the highest copper values were found in both the -35+80 and -200 mesh fractions (deposit dependent) but were consistently richer in the C2 horizon; - metal values are commonly depleted in the highest B-horizon (B1), particularly in the +35-80 fraction; - metal values are most commonly enriched in the B2 and C2 horizons; - metal depletion is most pronounced in the -35+80 fraction; - there is a strong positive correlation between gold, copper and molybdenum; - in addition, As, Bi, P, and to a lesser extent, Sb and Sr have a strong positive correlation with gold, As, Sb, Sr and to a lesser extent Ba and Pb have a strong positive correlation with copper.

not_specified

not_specified

not_specified

Kalzas, in central Yukon, is a porphyry-style stockwork and sheeted-vein wolframite deposit. Alteration includes a potassic core, a quartz-tourmaline-sericite zone and an outer quartz-sericite-pyrite zone, the latter in excess of 2 km in diameter. Wolframite is confined to the inner two zones, in an oval area 1500 m by 800 m. The wolframite is disseminated within the quartz-tourmaline stockwork and also occurs as coarse crystals in sheeted veins. Mineralization occurs within Neoproterozoic to Early Cambrian Hyland Group quartzites and phyllites, which are likely intruded at depth by a pluton, possibly of the Cretaceous Tombstone Suite. From 1981 to 1984, Union Carbide carried out mapping, soil and rock geochemistry, an airborne magnetometer survey, road building, trenching and drilling of two diamond drill holes. Results from Copper Ridge's 2001 sample program range from 0.3% WO3 to 0.5% WO3 over widths up to 70 m. They demonstrate the potential to define a signifi cant resource of surface-mineable tungsten mineralization at a grade of 0.4% WO3 or better. Drilling is required to confirm grade continuity at depth and along strike.

not_specified

Geological map (1:50,000 scale) of the West Klondike area, central Yukon (NTS 115O/14,15 and 116B/2,3) including marginal notes on mineral occurrences.

Surficial geological mapping in the central Kluane Ranges was undertaken to better understand the distribution and character of surficial materials. Upland surficial materials in the area are dominated by near-source bedrock derivatives. Valley bottom settings, including Shakwak trench and Duke River valley, are characterized by broad open valleys with thick deposits of Quaternary sediment. Permafrost is discontinuous in the study area and its character is affected by slope and aspect, topography and material texture. Mass wasting processes in the study area include rockfall and avalanches, debris flows, debris avalanches and active layer detachment slides. The distribution and character of surficial materials are significant for soil geochemical sampling programs, mineral exploration, infrastructure and development.