The Keno Hill-Galena Hill area is underlain by Yukon Group metasedimentary rocks which form the southern flank of the McQuesten anticline in the area. A series of faults, striking northeast and dipping steeply southeast, host the silver-lead-zinc lode deposits. In excess of 65 ore deposits and prospects have been identified within the district. The principal lode deposits occur within the Central Quartzite in areas where brittle failure of the competent quartzite has allowed open areas conducive to ore deposition. Ore zones are also known to occur in the Lower Schist where a competent unit, such as greenstone lense, forms one or two of the walls of the vein fault. The Husky Mine, located near the base of Galena Hill, is currently the main underground producer. Ore production from Husky to December 31, 1984 has totalled 359,450 tonnes (396,230 tons) grading 1450 g/t Ag (42.32 oz/ton). The lead and zinc content within Husky Deposit averages 3.96% and 0.27% Zn. The 10.7:1 silver to lead ratio (ounces silver to percent lead) in the Husky Deposit is the third highest among the district's major silver producers. The low zinc content is also unusual in light of the fact that the Husky Deposit exhibits very little evidence of oxidation. The Husky S.W. Deposit is located 1400 m southwest of the Husky shaft. The Husky S.W. Vein zone is a highly fractured breccia structure with a quartz-rich gangue. Mineralization occurs as native silver with some argentite (acanthite) and stephanite within fracture veinlets with a pyrite/graphite matrix. The ore is completely non-visual. The amount of lead and zinc within the deposit is very low (0.2% Pb aand 0.03% Zn). The silver to lead ratio of 195:1 in this deposit is an order of magnitude higher than in any deposit ever mined in the area (district average is 6:1).

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.

Silver has been won from narrow vein faults in the Keno Hill district for nearly 70 years. During this period, 3.9 million tonnes (4.3 million tons) of ore have yielded 5754 million grams (185 million ounces) of silver. All of this production has come from sub-cropping ore shoots; supergene enrichment is not an important factor in most deposits. Parallelsim of the ore zone with the present surface has been seen in other Cordilleran vein camps, but despite considerable effort, operators in these camps have met with little success in their search for blind ore shoots. The potential for blind ore in the Keno Hill district is examined from the perspective of metal-ratio zonation. An approximate reconstruction of the original fracture pattern in the district and the metal-ratio definition of a hydrothermal system acting within these fractures suggest that some ore shoots have been eroded, some are exposed at the present surface, and others remain preserved at depth.

The Logan (MINFILE 105B 099) and YP (MINFILE 105B 001) zinc-lead-silver deposits are located in the Rancheria District, Yukon Territory. These deposits and numerous other occurrences occur in veins and breccia zones which cut clastic sedimentary rocks of Proterozoic and Palaeozoic age, along fracture zones cross-cutting Cretaceous granites and Eocene volcanic dykes of mafic and felsic composition, and form replacement bodies in Palaeozoic carbonates. At the Logan and YP deposits, four phases of mineralization can be distinguished. The main sulphide minerals are sphalerite, galena, pyrrhotite, pyrite, chalcopyrite and arsenopyrite. Silver is mostly confined to galena, but also occurs in tennantite-freibergite group minerals, stannite, Pb-Ag-Bi-sulphosalts of the matildite-galena series and lillianite homologues. Arsenopyrite geothermometry using the method of Kretschmar and Scott (1976) returned maximum formation temperatures of 465° - 490° C at YP and 335° - 385°C at Logan. Microthermometric investigations of fluid inclusions in quartz associated with the YP mineralization showed formation pressures corresponding to a depth of 2500 m. Fluid inclusion data from quartz suggest that mineralization at YP and Logan is caused by a mixture of magmatic and metamorphic fluids. The fluid inclusions have low salinities of 34 weight per cent NaCl equivalent, an unusally low value for fluids which have separated from acid magmas. The metamorphic fuids may have been derived from metamorphic dewatering of Palaeozoic sediments.

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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.

The Ketza River polymetallic mineral deposits are situated in the Pelly Mountains, Central Yukon Territory. The deposits were mined for gold from 1988 to 1990, producing 400 tomes of oxide ore per day over that period. The Ketza River deposits are hosted by lower Paleozoic sedimentary strata of the parautochthonous Cassiar Terrane. The main host to economic mineralisation is a lower Cambrian, massive, areheocyathid-bearing limestone, which outcrops over much of the Ketza River area. Four styles of mineralisation are recognised within the Ketza River deposits. Type I mineralisation occurs in the centre of the area and consists of argillite-hosted, Au- quartz-sulphide veins. Sulphide mineralogy is mainly arsenopyrite and pyrite. Type II mineralisation consists of limestone-hosted, massive sulphide mantos and chimneys. The principal sulphide mineralogy of the mantos is pyrrhotite-arsenopyrite-pyrite-chalcopyrite, with quartz and calcite gangue. Gold is present within the arsenopyrite and pyrite. Type III mineralisation consists of limestone-hosted, quartz-sulphide veins and mantos. Mineralogy is similar to the Type II mineralisation, but contains a higher proportion of gangue. Type IV mineralisation consists of Ag-Pb veins. These veins are hosted by a variety of lithologies and represent the outermost extent of Ketza River mineralisation. Sulphide mineralogy is galena-sphalerite-pyrite, with siderite, calcite and quartz gangue. Oxidation of sulphides in parts of the Ketza River area is deep and pervasive. Areas of oxidation show increased gold grade and were the focus for mining. Oxidation occurs in the heavily fractured central area of the mineralisation, and along the Peel Fault, which extends from the centre of mineralisation towards the east. Light stable isotope studies indicate that the main mineralising fluid was of meteoric origin (delta (18)Ofluid = 10 per mil, delta Dfluid = -165 per mil). This fluid had evolved in delta (18)O by interaction with Cassiar Terrane rocks before mineralisation occured. Fluid flow in the limestones was pervasive, and produced a large, approximately 75km(2), (18)O depletion halo around the deposits. The later oxidising fluid was also of meteoric origin (delta (18)Ofluid = 18 per mil) but shows no evidence of interaction with the sedimentary pile. Fluid inclusion microthermometry suggests that the temperature of formation of the deposit was around 325 degrees C, at pressures above 600 bars. The mineralising fluid contained approximately 11 mole% CO2+ or -CH4, and 5 equivalent weight% NaCI.

This report was prepared to provide published information on the lode and placer mining industries in the Yukon during an important part of its history: mining and milling of Elsa and Keno Hill silver-lead ores had begun; significant nickel, copper, lead and zinc deposits were discovered in the White River, Vangorda Creek, and Macmillan Pass areas; and asbestos deposits were discovered. Placer mining activity continued, although pressures in the form of rising costs, and stable gold prices were forcing the industry into decline. Both the lode and placer mining industries were affected during the war years by shortages of men and equipment, although there was a great deal of attention paid to sources of tungsten, a strategic mineral. Records are not complete. Government office changes, lack of storage space and a warehouse fire may be some of the contributing factors..

The Stewart River map area (115 O&N) is the most important historic and current placer gold producing region in the Yukon. Unfortunately, the historic placer-gold deposits are becoming depleted, and more efficient mining of existing deposits and exploration for new deposits must be encouraged. Although placer deposits in the Klondike district are well described and their origin is quite well understood, placer deposits in the remaining part of the Stewart River map area have not been so well documented. The purpose of the Stewart River placer project is to describe and document the geology of known placer deposits, to interpret the formation of the placer deposits, and to relate the geology of the placer deposits to the regional surficial and bedrock geology. The objectives of the project are to aid in the exploration and mining of placer deposits by providing a comprehensive and up-to-date placer geoscience database. The utility of the placer database is that it can be used to construct placer deposit models (general summaries of given placer settings). These models then serve as predictors for future placer exploration and mining. Fieldwork for the project began in 1998 and will be completed in 2001; results of the project will be published in a final report and a resource appraisal map for placer gold.

Keno Hill is located 330 km north of Whitehorse in one of the world's highest-grade silver mineralized districts. Stops include host rock stratigraphy, mine sites in the district and the historic community of Keno City.