The Coffee Project comprises numerous gold occurrences, including the structurally-controlled gold-only Coffee deposit, which is hosted in poly-deformed Paleozoic basement rocks of the Yukon-Tanana terrane and Mesozoic plutons situated in the northern Canadian Cordillera, west-central Yukon. The deposit has been interpreted as having characteristics of numerous deposit types over the project’s history including epithermal, reduced intrusion-related, Carlin-type, and orogenic gold, as well as combinations of deposit types. Recent mapping efforts and new geochronology highlight a previously unknown secondary phase of the Permian Sulphur Creek suite and led to the relocation of the Coffee Creek fault which is interpreted as a primary controlling structure of the Coffee deposit. A new structural analysis builds on previous depth estimates and suggests that the deposit formed at a relatively shallow depth of 1–3 km and together with the new map has outlined the structural history of the deposit in greater detail. New dike geochemistry suggests some mineralized Coffee dikes may be related to the Carmacks group volcanics or Prospector Mountain suite intrusives, which implies a Late Cretaceous age of formation. Field relationships and timing of regional faulting together corroborate a minimum age of formation of ~57 Ma. Available multi-element geochemistry highlights a subtle Au-As-Sb ± Ag-Pb-Te-W-Zn-K metal association that suggests a possible magmatic component to the mineralizing fluids at Coffee. Newly drilled shallow mafic intrusions adjacent to the Coffee Creek pluton serve as a potential source and may be coeval with movement on the Coffee Creek and Big Creek fault systems.

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Auriferous sheeted quartz veins and silicified shear zones occur along the margins and within adjacent hornfels zones of mid-Cretaceous Tombstone intrusions near the head of Clear Creek in the central Yukon. The lodes are the source for more than 120,000 ounces of downstream placer gold production. These lodes contain variable amounts pyrrhotite, pyrite, and arsenopyrite, with less abundant scheelite - alkali-feldspar, muscovite, biotite and tourmaline are common gangue phases. Grab samples of mineralization often contain gold grades in excess of 1 ounce per ton. Gold-to-silver ratios vary most commonly from 1:1 to 5:1. Gold-rich quartz veins cut all stocks, adjacent hornfels and associated lamprophyre dykes commonly contain greater than 1% arsenic. Bismuth, and less consistently tungsten and stibnite, characterize many of the most highly mineralized veins within and surrounding the stocks. Quartz veins along the intrusive-metasedimentary rock contact around the Pukelman stock are also enriched in lead and silver. R-mode factor analysis of multi-element geochemical data for 111 gold- and sulphide-bearing rock samples indicates that there are two geochemically distinct metal suites in the Clear Creek occurrences. The first is characterized by As-Au-Bi ± Sb, Te ore-related mineral association, which is typical of many intrusion-related deposits in the Tombstone gold belt. Less consistently, anomalous concentrations of Ag, Co, Cu, Fe, and Mo occur within these auriferous rocks. The second metal factor is defined by Ag-Bi-Pb ± As, Au and Te. It characterizes metalliferous vein samples that have uncommonly low Au: Ag ratios and may represent a second hydrothermal episode. Tungsten shows little consistent correlation with the metalliferous veins in either element suite.

The Sugar gold prospect, located 20 km southeast of the Coffee gold deposits in Yukon, is hosted in the mid-Cretaceous Dawson Range batholith, of which three mappable sub-units are recognized: a biotite hornblende quartz monzodiorite; a K-feldspar phyric hornblende biotite syenogranite; and a biotite hornblende diorite. Plutonic rocks are cut by steep, west to northwest-striking andesite dikes of uncertain age. Alteration and mineralized zones coincide with fault-fracture zones that are parallel and proximal to dikes and their margins. Alteration is characterized by an early phase of calc-sodic (albite-amphibole) and potassic (pervasive biotite and fracture-controlled K-feldspar) alteration and a later phase of silica flooding and sericite alteration. Gold mineralization is associated with disseminated sulphides in zones of silica flooding and with variably sheared veins of quartz-carbonate-arsenopyrite ± pyrite ± freibergite ± stibnite ± sphalerite. Late chalcedonic quartz-carbonate and ferroan carbonate veins mark the collapse of the hydrothermal system.

Gold-bearing, arsenic-rich pyrite in association with enriched As, Sb and minor Ag is found in two separate mineralization styles at Kaminak Gold Corp.’s Coffee Gold Project, Yukon. Arsenian pyrite replaces primary metamorphic mica by sulphidizing Fe in the host, while pervasive dolomite-illite alteration destroys the host and eventually consumes early mineralized pyrite. Silicification of host rocks is observed with associated arsenian pyrite deposition due to cooling. Brecciation of silicified intervals by coarse grained hydrothermal quartz occurs later with additional pyrite deposition. Mineralized intervals are oxidized by late, meteoric fluids which consume Au-bearing pyrite and release micron-scale free gold from the pyrite crystal lattice into the remnant oxides. Sulphidized biotite within the 98 Ma Coffee Creek Granite constrains mineralization to <98 Ma. Similar metal associations (Au-As-Sb vs. Au-As-Sb-Pb-Zn-Cu) suggest Coffee potentially represents the shallower, epizonal extension of the mesozonal orogenic Boulevard gold deposit, with a late epithermal overprint.

The AurMac property, located 35 km north of Mayo in central Yukon, includes two metasedimentary rock-hosted gold deposits: the 6158 koz Au Powerline deposit and the 845 koz Au Airstrip deposit. Mineralization at the Powerline and Airstrip deposits is characterized by gold in sheeted quartz veins and mineralized skarn horizons, respectively. The AurMac deposits straddle the Robert Service thrust fault whereby the Powerline deposit is hosted in the Late Proterozoic to Cambrian Hyland Group hanging wall, and the Airstrip deposit is hosted in the Mississippian Sourdough Hill Member of the Keno Hill Quartzite footwall. Host rocks comprise siliciclastic metasedimentary rocks, variably calc-silicate–altered calcareous metasedimentary rocks and magmatic rocks. Magmatic rocks in the Powerline zone consist of foliated mafic horizons that are geochemically similar to Cambro-Ordovician magmatic rocks found in Hyland Group metasedimentary rocks in the McQuesten, Mayo, Clark Lakes and Hart River map areas. In the Airstrip zone, magmatic rocks include a steeply south-dipping, unfoliated, aplite dike. Evidence for intrusion-related gold mineralization at AurMac includes sheeted vein and skarn mineralization similar to the intrusionhosted, intrusion-related gold deposits at Dublin Gulch, as well as the presence of metamorphic porphyroblast assemblages that suggest contact metamorphism. These findings suggest potential for further discovery of mineralized intrusion-hosted zones on the AurMac property and sedimenthosted, intrusion-related gold deposits elsewhere in the region.

The Livingstone Creek area is located 100 km northeast of Whitehorse, Yukon Territory, Canada. Hydrothermal gold-sulphide mineralization (MINFILE 105E 001) occurs in quartz-carbonate veins and veinlets which cut Paleozoic metamorphic rocks of the Teslin Suture Zone. The metamorphic rocks are also cut by Cretaceous(?) feldspar-porphyry dykes with an average thickness of 2 m. The mineralization appears to be structurally controlled by NNE-striking faults and a set of NNW-trending joints. The vein minerals consist of gold, pyrite, chalcopyrite, galena, hessite/stuetzite, tetradymite, Au-Ag tellurides, tennantite, hematite, pyrrhotite, quartz, and carbonate. Gold occurs as: 1) "free gold" in cracks and interstices of quartz gangue, 2) inclusions in galena, usually rimmed by hessite, 3) minute grains associated with chalcopyrite and galena in aggregates of coarse-grained pyrite and 4) individual grains or fracture fillings in iron hydroxides. The coarse-grained gold in Livingstone Creek appears to be derived from gold-quartz veins in the metamorphic bedrock. This is indicated by: 1) similar silver and mercury contents in primary and placer gold 2) identical trace element composition of galena from gold-quartz veins and galena inclusions in placer gold, 3) similar telluride mineral assemblages in both gold-quartz veins and placer gold grains and 4) similar homogenization temperatures and salinities in fluid inclusions from both gold-quartz veins and placer nuggets. A limited amount of gold appears to have formed by supergene leaching and precipitation. This kind of gold occurs as irregular-shapd grains in the stream placers and in iron hydroxide along fractures in quartz veins. Relative to the pirmary gold it is enriched in silver and mercury.

The Boulevard gold prospect, located in the Independence Creek area of the Dawson Range, comprises sheeted, auriferous quartz-sulphide-carbonate veins and fault breccia, hosted mainly by mafic schist. The nearby Toni Tiger molybdenum showing is characterized by quartz-molybdenite veins cutting Late Permian meta-aplite and garnet-pyroxene skarn of uncertain age. We present geochronological evidence that gold and molybdenum were deposited at 96-95 Ma, approximately 3 m.y. after intrusion of the Dawson Range batholith and Coffee Creek granite. Fluid inclusions from mineralized quartz veins suggests that gold at Boulevard and molybdenite at Toni Tiger were formed from similar H2O-CO2-NaCl type fluids between 279 and 310°C and >1 kbar. We conclude that both are part of the same mineralizing system, and that structurally-hosted gold at the nearby Coffee deposit and in the Moosehorn Range of western Yukon may be broadly related, post-arc orogenic systems developed during exhumation of the Dawson Range in mid-Cretaceous time.

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