The Anvil Mining District contains the most westerly exposures of the off-shelf basinal facies (Selwyn Basin) of the Cordilleran miogeocline, a prism of sedimentary rocks of Precambrian to Jurassic age deposited along the relatively stable, passive continental margin of western North America. Anvil District is immediately northeast of the Slide Mountain and Yukon-Tanana Terranes, the most easterly of the allochthonous suspect terranes which were amalgamated with North America starting in Jurassic time. The total interpreted stratigraphic thickness of the metasedimentary rocks of North American affinity is greater than 7400 m, ranging in age from latest Precambrian or earliest Cambrian through Devonian. These metasedimentary rocks consist predominantly of fine clastic sediments deposited in an off-shelf marine basin with local occurrence of euxinic carbonaceous shales and coarser sandstones and conglomerates. Extensive Ordovician within-plate basaltic submarine volcanic rocks and associated epiclastic breccias are indicative of localized rifting along the continental margin.

The integration of till geochemistry and glacial geology into Yukon mineral exploration has been largely underused. In the Anvil district, thick glacial deposits have consistently hampered exploration. From the time of the initial discovery made in Vangorda Creek, it took an additional 20 years before the Grum deposit was discovered only 2 km to the northwest. This work examines the utility of till geochemistry as a method to trace mineralized soil/till samples back to their source rocks in the Anvil district. The Anvil district was last glaciated during the McConnell glaciation, which had a significant impact on the local terrain. The relatively swift-flowing Cordilleran ice sheet deposited thick sequences of till in low-lying areas and eroded southeast-facing slopes and hill summits in the Swim basin and Vangorda plateau. This type of glacial history is conducive for till geochemical exploration. Evidence for a late glacial Cordilleran re-advance is discussed and has implications on prospecting in the district. A 12-km2 till grid was sampled northwest of the Faro deposit to map the glacial dispersion of mineralized sediment. The till geochemistry on the -230 mesh fraction (silt and clay) indicated a broad dispersion plume for lead, zinc and copper extending more than 5 km west of the Faro Pb/Zn deposit. A section of the dispersion train may have a palimpsest origin. The soil geochemistry on the -80 mesh fraction, from 1964 data, indicated a much narrower dispersion plume extending directly from the Faro deposit. The geochemical changes at depth in the till stratigraphy were examined at the Vangorda mine. Results showed that anomalous lead concentrations, unlike zinc concentrations, were found throughout the 20-m till column. Regional till sampling was carried out in three areas peripheral to the known massive sulphide deposits. Results from these sampling programs highlighted anomalies in lead, zinc and copper. Overall, the application of till geochemistry proved to be successful in the Anvil district. Applying similar techniques to drift-covered terrain elsewhere in the northern Cordillera would be beneficial.

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.

Till geochemistry and glacial geology have rarely been integrated into Yukon mineral exploration. In the Anvil District, thick glacial deposits have consistently hampered exploration. From the initial (massive sulphide) discovery in Vangorda Creek, twenty years elapsed before the Grum deposit was discovered only two kilometres to the northwest. This work examines the utility of till geochemistry as a method to trace mineralized soil/till samples back to their source rocks in the Anvil District. The Anvil District was last glaciated during the McConnell glaciation, which had a significant impact on the local terrain. The relatively swift-flowing Cordilleran ice sheet deposited thick sequences of till in low-lying areas and eroded southeast-facing slopes and hill summits in the Swim Basin and Vangorda Plateau. This type of glacial history is conducive for till geochemical exploration. A 12 km 2 till grid was sampled northwest of the Faro deposit to map the glacial dispersion train. The till geochemistry on the -230 mesh fraction (silt and clay) indicated a broad dispersion plume for lead, zinc, and copper, extending more than 5 km west of the Faro Pb/Zn deposit. A section of the dispersion train may have a palimpsest origin. The soil geochemistry on the -80 mesh fraction, from 1964 data, indicated a much narrower dispersion plume extending directly from the Faro deposit. Till geochemistry, particularly on the fine fraction, has applications to similar drift-covered terrain, such as the Finlayson Lake massive sulphide district to the southeast.

Geochemical anomalies in soils over zones of lead mineralization were studied, both in known mineralized areas and in areas of suspected mineralization. The anomalies were readily detected and outlined by using a dithizone technique on acid extracts of soil samples collected from grid systems. By assuming the principles of mechanical mixing of the mineralized rock with other material during soil formation, and of downhill migration of soils, the anomalies were correlated with the zones of their origin: the asymmetric anomalies discovered are typical of such conditions. Applied to areas of suspected mineralization the geochemical prospecting was responsible for the discovery of two new bands of lead mineralization and several large lead and copper anomalies. The method proved to be extremely useful for indicating the most favourable areas for more detailed prospecting such as diamond or churn drilling and geophysical methods.

Includes a geological cross section, mineral occurrences, isotopic age dates and fossil samples.

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A detailed methodology has been devised and tested for establishing metal zoning patterns in and about oreshoots within the plane of Ag-Pb-Zn veins of the Keno Hill - Galena Hill mining camp, Yukon, using whole rock vein geochemistry of run-of-mine samples. These ideal metal distribution patterns are easily interpretable in more classical zoning terms as mineral distribution patterns. To establish a zoning model samples that span a wide range of grades are rearranged in order of decreasing silver contents. The resulting "rearranged" profiles for other elements are then evaluated relative to silver. Computer-based curve fitting methods are useful means of generalizing these "rearranged" metal profiles. The foregoing procedure has been used to develop a general model for the Keno Hill - Galena Hill camp based on analytical results from 3 main deposits (Keno, Husky, No Cash) including 6 veins. Essential character of the model is embodied in analyses of Ag, Pb, Zn, and Ca and the Zn/Ag ratio. Additional but in cases ambiguous detail is added to the model by Hg, and Co and/or Ni analyses. These elements allow vein mineralogy to be monitored in a quantitative manner and provide a practical zoning model that can be used as an exploration, tool in evaluating underground workings for proximity to oreshoots in the more than 60 deposits known in the camp. A companion study involving whole rock K-Ar age determinations of small stockwork zones adjacent to Ag-Pb-Zn veins indicated an age of mineralization of about 87±2 Ma. for the Ag-Pb-Zn veins.

This thesis is available from the EMR library – QE195 M67.

Soil morphology and geochemistry were studied at three mineral properties (gold; lead-zinc; copper-gold) in the unglaciated terrain of west-central Yukon. The purpose of this work was to describe soil and parent material properties, and to assess the effects of soil development and slope processes on element distribution in soils derived primarily from colluvium and weathered bedrock. At each property, soils were examined on slopes with opposing aspects. These results provide baseline pedological and soil-geomorphological descriptions for the Klondike Plateau, which will assist future biophysical mapping and contribute to our understanding of landscape evolution. Results pertaining to soil geochemistry provide landscape related guidelines for mineral exploration. For example, the stratigraphic distribution of loess within soil profiles is described according to slope aspect. This allows the explorationist to design sampling procedures that are more likely to detect geochemical anomalies in the underlying bedrock. Soil geochemical variations in colluvium are shown to reflect upslope variations in bedrock lithology. Results of the soil particle size fraction geochemistry indicate that for base metal elements such as copper, lead and zinc, the -80 mesh component was generally the most responsive in either the B or C horizon. For gold, the -80 mesh fraction worked well in the B horizon, whereas the -230 mesh contained the highest concentration in the C horizon.