The Fyre Lake volcanogenic massive sulphide (VMS) copper-cobalt-gold property is situated 160 kilometres northwest of Watson Lake in the Finlayson Lake area of the Yukon-Tanana Terrane. Columbia Gold Mines Ltd. conducted an integrated exploration program there between late June and early October, 1996. The Fyre Lake property is underlain by a sequence of metamorphosed sedimentary and volcanic rocks known as the Layered Metamorphic Sequence (LMS). Copper-cobalt-gold VMS mineralization within the Kona Creek cirque area is hosted by deformed and metamorphosed chlorite-actinolite-quartz schist of the middle unit of the LMS which is interpreted to be a succession of basic to possibly intermediate flows with intercalated volcaniclastics and volcanically-derived fine-grained sedimentary rocks. These rocks are structurally overlain by a thick sequence of phyllitic metasedimentary rocks with a basal unit of micaceous quartz-chlorite-mica schist. The copper-cobalt-gold (± zinc, silver) VMS mineralization within the central portion of the Kona deposit occurs in three distinct horizons of massive to semi-massive sulphide and magnetite mineralization over a combined thickness of 70 to 80 metres, a continuous strike length of more than 1,000 metres and widths in excess of 100 metres. The geological setting and mineralogy of the copper-cobalt-gold VMS mineralization within the Kona zone is that of a mafic, volcanic-hosted Besshi-type VMS deposit. The Fyre Lake contains copper-cobalt-gold mineralization with significant thickness, grade and continuity.

The Fyre Lake sulphide-magnetite deposit is located in the Finlayson Lake massive sulphide district in the Yukon-Tanana terrane, southeastern Yukon. It is hosted by quartz-chlorite-actinolite schist derived from (probable) Devono-Mississippian-aged mafic volcanic rocks. Overlying the deposit are intercalated metasedimentary and metavolcanic rocks. This mixed sequence is, in turn, overlain by a thick sequence of graphitic phyllite. The deposit consists of three northwest-trending stratiform lenses comprising massive and semi-massive sulphide and magnetite iron formation. Pyrite is the dominant sulphide mineral in the deposit, with lesser amounts of pyrrhotite, chalcopyrite, and locally, sphalerite. The sulphide mineralization is copper and cobalt-rich and locally contains significant concentrations of zinc and gold. It has low to trace amounts of lead, barium, arsenic, antimony, tin and selenium. Lithogeochemical results indicate that the host mafic metavolcanic rocks are strongly depleted of light rare-earth elements (LREE) and high field strength elements (HFSE), and contain elevated levels of MgO, Ni and Cr. SiO2 in the host rocks ranges from 53 to 58%. Chemically, the mafic metavolcanic rocks are similar to boninitic rocks found in some suprasubduction zone ophiolites such as those at Cyprus. The primitive boninitic chemistry of the host metavolcanic rocks implies that they originated as melts from a depleted mantle in a rifted setting. The presence of felsic metasedimentary rocks below, within and overlying the host metavolcanic rocks suggests that the Fyre Lake deposit was formed in or near a mature tectonic setting, possibly a continental arc or an evolved island arc. The host mafic metavolcanic rocks are chemically distinct from other mafic and intermediate metavolcanic rocks that outcrop on the Fyre Lake property. A clastic metavolcanic rock unit lies stratigraphically below the deposit. It consists of fragmental LREE and HFSE-enriched transitional subalkaline basalts. Other discontinuous bodies of metavolcaniclastic and metaflow rocks occur stratigraphically above and peripheral to the Fyre Lake deposit. These are enriched in LREE and Th, and relatively depleted in Nb, Ta and Ti, and generally display the chemical features of transitional basalts and andesites erupted in a continental arc or evolved island arc setting.

The Fyre Lake volcanic-hosted massive sulphide (VMS) deposit is located about 160 km northwest of Watson Lake in the Finlayson Lake district of southeastern Yukon. The deposit is hosted by Devonian (?) and Mississippian rocks of the Yukon-Tanana Terrane and occurs close to the contact between chlorite schist and overlying carbonaceous phyllite. Copper-cobalt-gold mineralization occurs in two parallel zones: West Kona and East Kona. The chemical composition and rare earth element (REE) pattern of chlorite schist which hosts the Kona zones is unique in the Fire Lake area. The data indicate that the protolith of these meta-volcanic rocks has a boninitic affinity and was likely derived from a depleted source region. Mafic meta-volcanic rocks (chlorite schist) elsewhere in this area are tholeiitic and may have developed in an arc or rift-related setting. Analyses of psammitic schists in the hanging wall of the West Kona zone indicate the rocks are felsic in composition and were likely deposited in a mature arc or continental-margin setting.

not_specified

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.

The Hunker Creek area is located 30 km southeast of Dawson City, Yukon. Gold and sulphide-bearing quartz veins (MINFILE 115O 067, 068) crosscut metamorphic rocks of the Klondike Schist. The veins are enclosed by envelopes of sericitic (inner) and propylitic (outer) alteration. Locally, carbonatization occurs between propylitized and sericitized rocks. Three stages of vein mineralization can be distinguished:: (1) quartz, carbonates, gold, arsenopyrite, pyrite, pyrrhotite, chalcopyrite, and galena; (II) quartz, carbonates, chalcopyrite, sphalerite, tetrahedrite, freibergite, polybasite, 'polyargyrite', argentite, pyrostilbnite and galena; (III) quartz and gold. Fluid inclusion data indicate that stage I minerals precipitated from hydrothermal solutions containing CO2. Homogenization temperatures range from 260° to 390°C. Stage II aqueous fluid inclusions homogenize between 190° and 260°C. Stage III inclusions homogenize between 120° and 210°C. Salinities of the three stages range from 0 to 7.2 wt-% NaCl equiv. and show no significant changes with time. It is suggested that stage I mineralization was initiated by unmixing of an original single-phase H2O and CO2 bearing fluid, and that subsequent hydrothermal evolution was controlled mainly by decreasing temperature.

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.

The Brewery Creek gold mine (13.3 Mt @ 1.44 g/t Au) is a bulk tonnage, heap leach operation located 57 km east of Dawson City, Yukon. The deposit lies on the northeastern side of the Tintina Fault and within Selwyn Basin. Gold mineralization is hosted by intrusions of the mid-Cretaceous Tombstone Plutonic Suite (TPS), and Silurian to Carboniferous clastic metasedimentary rocks of the Steel Formation and Earn Group. The sedimentary rocks are faulted and variably folded, however they display poor cleavage development. The TPS intrusions are also faulted and contain rafts of argillaceous sedimentary rock. No regional ductile fabrics were observed to crosscut the intrusions. Five phases of intrusion have been recognized; these are `raft monzonite, feldspar porphyry (FP1), biotite monzonite, a second phase of feldspar porphyry (FP2), and a pyroxenite. The most important feature at Brewery Creek is a linear zone of monzonite intrusions, faulting and mineralization termed the Reserve trend. This zone trends west-northwest and has a moderate dip to the south. A number of stages and orientations of faulting have been identified along the Reserve trend; lithological relationships suggest a substantial amount of vertical movement occurred post-TPS emplacement and pre- to syn-mineralization.

not_specified