Stream catchment areas digitized from existing regional stream sediment sample locations are assessed for quality and confidence of sample site location, catchment surface area (used as a proxy for downstream dilution), surface material type, slope angle and slope aspect. Rankings for each of these attributes are combined into quality indices to give an overall impression of reliability for each catchment that can be incorporated into mineral exploration targeting criteria and design of further sampling programs. Data from quality control samples included with each sample batch during a recent re-analysis program are also assessed for some key elements. Standard reference materials included in two separate re-analysis campaigns show slight shifts in bias even though the same analytical method was used in both instances. Some elements, particularly Au, show an unacceptable amount of scatter in repeat analyses of the standard reference materials indicative of a non-homogenous distribution of Au in the materials for the small sample mass (0.5 g) used for analysis. Data precision is assessed using field and blind duplicate analyses for selected elements. The Au analyses show the poorest precisions, with data from Cu giving the best precision and data for As yielding intermediate precisions.

Multi-element stream sediment reconnaissance in the Hess River region of the Eastern Yukon has outlined an extensive area characterized by anomalously high molybdenum values. An accessible region in the Hess Mountains, within the high molybdenum zone, was selected for detailed study of trace element levels in stream sediment, rock, soil and vegetation. In view of the frequently observed relationship between high forage molybdenum concentrations and the incidence of copper deficiency in cattle, molybdenum concentrations in plant species likely to be consumed by caribou and moose were of particular interest. High sediment molybdenum values are characteristic of catchments underlain by dark shales and less commonly dark limestone. These rocks and associated soils are rich in molybdenum. Concentrations in vegetation growing on anomalous shaly soils are characteristically low, while most plants growing on soils derived predominantly from limestone are molybdenum-rich. The Mo-Cu status of vegetation on limey soils is typically within the range associated with molybdenum induced hypocuprosis in cattle. Low molybdenum uptake by plants on soils derived from shales likely reflects the unavailability of the molybdate anion, resulting from its adsorption onto clay minerals and sesquioxides under acidic conditions prevalent in these soils. In neutral to mildly basic environments, typical of dark limestone soils, molybdenum adsorption is greatly decreased, and therefore molybdenum is relatively available to plants. In the detailed study area soil pH values are typically similar to pH levels in associated stream water. Therefore by combining stream sediment molybdenum concentrations with stream pH data, catchments likely to contain molybdenum-rich vegetation can be predicted. Unfortunately stream pH values were not obtained in the regional survey. In view of the apparent rarity of dark limestone throughout the Eastern Yukon, however, molybdenum-rich vegetation is not likely to be particularily widespread. Wildlife in this area, therefore, is probably not significantly affected by molybdenum induced copper deficiency.

This project involved the collection of moss mat samples from sites throughout Yukon. Sites included: Laura Creek, which drains Brewery Creek gold deposit; Logjam Creek, draining the Logtung tungsten and molybdenum occurrence; Williams Creek which drains the Williams Creek copper deposit; the Vancouver Creek placer drainage; and Eldorado Creek in the Klondike goldfields.

The MacMillan Pass district (map sheet 105O) located in east Yukon contains several sedimenthosted Ba ± Zn ± Pb deposits including the Tom and Jason deposits, as well as a multitude of 'barren' sediment-hosted barite occurrences. A classic sedimentary-exhalative (SEDEX) model has been postulated for these occurrences in which the barite horizons represent distal expressions of a hydrothermal vent system. Fieldwork was completed at the Walt and Tyrala barite occurrences that occur within the MacMillan Pass district in order to examine the deposit-scale geology and to sample undeformed barite horizons for subsequent geochemical analysis. Samples were also collected from drill core from the Hess barite occurrence. Barium mineralization occurs in both the Devonian Portrait Lake Formation (Lower Earn Group) and in underlying Ordovician-Silurian limestone of the Road River Group. A variety of textures were encountered that were indicative of both synsedimentary deposition of barite, as well as diagenetic to epigenetic barite mineralization. Base metal sulphides that are interpreted to post-date the barite mineralization were encountered at depth in drill core and are primarily hosted by Road River Group carbonates.

A stream sediment and water survey was carried out in the Coal River area of southeastern Yukon during the summer of 2005. This survey was carried out under a Joint Research Agreement between the Yukon Government (Oil & Gas and Mineral Resources Division of the Department of Energy, Mines and Resources) and the Federal Government, acting through the Earth Science Sector's Metals in the Environment Program. Analytical data accompany this document for 50 elements in stream sediments and 60 variables in waters from a total of 174 sites sampled in 2005. National Geochemical Reconnaissance protocol was used for the collection, preparation and analysis of waters and silts. Samples were collected in the Yukon Territory portion of NTS map sheet 95E, west of the height of land that marks the boundary between Yukon and Northwest Territories and separates the Coal River and Flat River drainage basins.

Mineralized zones on the Jason property are stratifrom, sediment hosed Pb-Zn-barite deposits that occur in a Late Devonian age marine carbonaceous shale and turbidite sequence. The Jason Property is located 400 km northeast of Whitehorse near Macmillan Pass on the Canol Road. Since the discovery of mineralization in 1975, eighty-nine diamond drill holes have delineated three mineral deposits. In order of their discovery, they are known as the Main, South and End zones. Geological reserves indicated and inferred for the three zones total 14.1 million tonnes averaging 7.1% Pb, 6.6% Zn and 79.9 g/t Ag. The following questions are the focus of the study:: 1) What is the stratigraphic position and setting of the South zone? 2) What is the geological relationship of the South zone to the Main zone? 3) What is the geometry of the South zone? 4) How can the mineralization in the South zone be described in terms of mineralogical and textural facies? 5) What constraints on the processes of ore formation can be demonstrated by utilizing the above studies?

NGR surveys were originally conducted in the McQuesten map area in 1987 and 1988. Stream sediment and water samples were collected from a total of 841 sample sites. A total of 841 original samples were selected for reanalysis. Representative 2 gram splits were successfully recovered from 840 samples. Samples were analysed by an ultra-trace aqua-regia digestion ICP-MS package for 53 elements.

Stream sediment and water geochemistry for the Stewart River map area. The following stream sediments were analyzed: Ag, As, Au, Ba, Cd, Co, Cu, F, Fe, Hg, Loss-on-ignition, Mn, Mo, Ni, Pb, Sb, Sn, U, V, W, ,Zn. Stream waters were analyzed for pH, uranium, and fluoride.

The Macmillan Pass area is underlain by Hadrynian to Middle Devonian fine grained sedimentary strata and volcanic rocks of Selwyn Basin. Widespread occurrences of Upper Devonian debris flows and turbidites record uplift and erosion of older rocks to the west or northwest. Deposition of overlying, locally derived coarse clastic assemblages are related to subsequent formation of a graben-like, fault-bounded trough in the study area. Stratiform barite-lead-zinc mineralization on the Tom claims is contained in two tabular zones separated by a fault. Both zones occur at the transition between Upper Devonian locally derived coarse clastic rocks and overlying basinal shales. Ore textures vary from massive quantities of poorly bedded galena, sphalerite and pyrite to finely laminated barite and cherty argil lite with disseminated sulphide minerals. A mineralized and altered breccia body underlies the stratiform massive sulphide mineralization. A copy of this thesis is available at the EMR library – QE195 C38. This thesis is available online at http://hdl.handle.net/2429/21561.