The Blende zinc-lead-silver deposit, 60 km northeast of Keno City, Yukon Territory, is spatially associated with a mid-Proterozoic fault zone that crosscuts stromatolitic dolostones of the Middle Proterozoic, upper Gillespie Lake Group. It is the largest known strata-bound, carbonate-hosted, zinc-lead deposit in the Yukon Territory. Mineralization, largely epigenetic, consists of sphalerite and galena, with lesser pyrite and chalcopyrite, and trace friebergite in quartz-carbonate veins and veinlets. Veining is zoned from copper- and silver-rich mineralization at the base of the deposit, through lead- and zinc-rich, to zinc-dominated at the top. Detailed cross-section mapping indicates that controls on the deposit are both stratigraphic and structural. Many of the stromatolite beds are mineralized and are especially rich in lead and zinc close to normal faults. Fluid inclusion studies indicate that mineralizing fluids were about 285 degrees C during main-stage mineralization. Sulfur isotope analyses of unmineralized whole-rock samples cluster tightly around an average delta 34 S value of 23.6 + or - 0.4 per mil. The source of sulfur is apparently seawater sulfate, probably from minor anhydrite in the host dolostone. Sulfide sulfur isotope ratios define three populations. Local blebs of pyrite associated with stromatolites have markedly negative ratios (- 15.1%) that are probably bacteriogenic in origin. Vein sulfides in tight dololutites have ratios between 19.0 and 26.3 per mil, with an average delta 34 S value of 23.2 PM 0.9 per mil. This is virtually identical to the whole-rock sulfur isotope ratio. Veins that crosscut stromatolitic beds have sulfur isotope ratios between 18.3 and 7.4 per mil with a mean of 15.0 + or - 1.2 per mil. Intermediate sulfur isotope ratios apparently reflect a mixed sulfur source of both whole-rock sulfate and biogenic sulfide. Carbon and oxygen isotopes in host rocks and ore-stage dolomite spar are related genetically; both are related to ancient seawater. The calculated isotopes for mineralizing fluids are characteristic of basinal brines...

Sphalerite and tetrahedrite occur with arsenopyrite and minor chalcopyrite and galena in a tabular, fault-bounded body which cuts granitic rocks of the Cassiar batholith. Diamond drilling between 1986 and 1988 outlined a deposit 1100 m long and 50-100 m wide containing geological reserves of 12.3 million tonnes grading 6.17% Zn and 26 g/t Ag. These reserves are amenable to open pit mining and the deposit is open to depth.

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 McMillan deposit contains 1.1 million tonnes grading 8.3% Zn, 4.1% Pb and 62 g/t Ag in a manto-like replacement deposit in the Proterozoic/Lower Cambrian Hyland Group at the sheared contact between carbonate rocks and underlying shale. A smaller deposit to the south contains a further 0.4 million tonnes grading 9.3% Pb, 1.7% Zn and 214 g/t Ag. These deposits appear to lie in the footwall of a southward-dipping thrust fault which extends eastward toward the Hyland Gold property.

Massive black sphalerite occurs with pyrrhotite and magnetite in up to 3 irregular but roughly concordant layers at the contact between massive white marble and hard green and white-banded meta-tuff. The mineralization is believed to have replaced brecciated marble in the footwall of a south-dipping thrust fault which passes through the DAN prospect and extends through the Crescent Lake area 5.8 km to the east.

The Brown McDade Mine is a gold-silver discovery in Yukon, halfway between Whitehorse and Dawson. It lies in the area unglaciated during the Pleistocene Period. Diamond drilling and stripping in 1946 indicated commercial values across a width of 10 feet and over a length of 1000 ft. The geologic structure is that of a Late Tertiary, dike-like body of quartz feldspar porphyry cutting quartz diorite of Jurassic or later age. This body has a Northwest strike and dips steeply west. The ore zone lies in the porphyry and is believed genetically related to it. The mineralization consists of a cherry-like fine grained blue quartz, with disseminated sulphides comprising less than 5% of the mass. Metallic minerals are pyrite, arsenopyrite, and sphalerite, with lesser amounts of galena, chalcopyrite, tetrahedrite, stibnite, bournonite, jamesonite and gold. The gold is associated with the pyrite in fine particles, the majority less than 150 microns in size. The gold-silver ratio is about one to ten. Sericitization and carbonatization are the chief forms of hydrothermal alteration, while considerable limonite, and around the ore zone, jarosite, have been produced by weathering. On the basis of comparisons with known deposits, the Brown McDade is considered to belong to the deeper epithermal type. It should continue to reasonable depths although the ore shoots are likely to be erratic. The area south of the main ore zone, underlain by schistose rocks will probably be unfavorable for the occurrence of ore. A copy of this thesis is available at the EMR library – QE376.5.Y8 L35. This thesis is available online at https://open.library.ubc.ca/cIRcle/collections/ubctheses/831/items/1.0053530.

The Keno Hill-Galena Hill mining district of central Yukon has been a prolific silver-lead-zinc producer since the early part of the century. Typical orebodies are extensive vein systems with a mineralogy consisting of siderite, quartz, pyrite, galena, sphalerite, and freibergite in varying combinations. The veins are restricted to steep SE-dipping fault zones principally contained within a brittle graphitic quartzite unit and some concordant greenstone bodies. The main silver lodes form a narrow east-west belt, 25 km long, and have been assigned a mid-Cretaceous age as have nearby granitic bodies and their associated tin and tungsten mineralization. This study of the vein minerals indicates that groups of adjacent deposits have characteristic mineral assemblages distinguishing them from other groups; these form zones along the entire length of the belt. The following summarizes the principal mineralogical zones from west to east:: 1) pyrargyrite in quartz-siderite veins with some native silver, polybasite, stephanite, and acanthite are mainly in the west; 2) siderite, galena, sphalerite, and freibergite occur in most deposits but are found without the other index minerals on top of Galena Hill; 3) pyrrhotite and arsenopyrite are in deep vein exposures in the valley between Galena Hill and Keno Hill; 4) calcite is also in the deep veins along the eastern flank of Galena Hill but extends to the east onto Keno Hill; and 5) boulangerite-jamesonite and abundant quartz-arsenopyrite rich fractions of veins at the eastern end of the district overlap with the calcite zone. Higher gold values are recorded in zones 1, 2, and 5. The changing mineralogical facies record an evolving environment of deposition in a continuous, 25 km long hydrothermal vein system. The western deposits are thought to be higher level, or laterally "downstream" equivalents of the eastern deposits. This zoning sequence is typical and is well established in other regions of the world. Such systems are known to progress further downwards, into gold-quartz veins before attaining tin and tungsten mineralization and associated granitic bodies.

A copy of this thesis is available at the EMR library – QE195 F56.

A placer mining and exploration compilation of NTS map sheet 105E, southern Yukon Territory, Canada. This compilation includes the location, history and previous work, description of bedrock geology, surficial geology and mineralization. Accompanying this report is one 1:250,000-scale map (NTS 105E) which displays the locations of the placer occurrences discussed in the report.

The Mel deposit consists of a concordant, folded lens of barite and coarse recrystallized galena and sphalerite at the contact between Cambro-Ordovician limestone and shaly limestone. Based on diamond drilling since 1972, the deposit contains geological reserves of 6,200,000 tons grading 6.77% Zn, 1.92% Pb and 49.6% barite to a depth of 457 m. The mineralization is open to depth and the higher grade part of the deposit lies below 305 m.