The Middle–Upper Devonian Canol Formation is the focus of a new study by the Yukon Geological Survey in north Yukon. Fieldwork in summer 2013 involved locating, measuring, and sampling Canol Formation strata in the Richardson and northern Ogilvie mountains. In June, 229 m of Canol Formation strata were measured on the Trail River, eastern Richardson Mountains (NTS 106L/6). The Canol Formation at this location is entirely exposed, except for ~2 m at its upper contact with the overlying Imperial Formation. On Trail River, the Canol Formation is a resistant, silica-rich unit that is characterized by rhythmically bedded siliceous shale and chert comprising four lithofacies: 1) siliceous shale; 2) chert; 3) siliceous shale (>50%) and chert (10-50%); and 4) chert (>70%) and siliceous shale (10-30%). Siliceous shale is fissile, finely laminated in beds up to 10 cm thick, and may be either soft and recessive or hard and resistant. Chert exhibits conchoidal fracture and occurs in beds up to 16 cm thick. Both shale and chert are black in color on fresh surfaces, and weather grey to black, olive grey, brown with a distinct yellowish orange, dark red, and/or very minor apple-green weathering residue. The lower contact of the Canol Formation with Road River Group calcareous shale is sharp, and marked by a concretionary bed overlain by a thin (<1 m) weathered mineralized zone. This mineralized zone may be in-part correlative with the Ni-Zn-PGE “Nick” horizon observed in the region. A marked lithology change occurs from the Canol to the Imperial formation which consists of weathered mudstones with a significantly lower silica content. Concretions up to 2.5 m long were observed in the Canol Formation but possible fossils were only observed at two locations where unidentified impressions on a bedding surface could be biological (or mineralogical). Fine-grained pyrite occurs throughout the formation, either as disseminated grains, in thin laminations (mm-scale), and rarely in concretionary horizons. The sampling program involved spectral gamma-radiation readings at one-metre intervals, and chip samples through two-metre intervals for Rock-Eval/total organic carbon (RE/TOC) and inductively coupled plasma-emissions/mass spectroscopy lithogeochemistry (ICP-ES/MS). Targeted samples for microfossil biostratigraphy, vitrinite reflectance, and XRD mineralogy were also collected. Laboratory results are anticipated in 2014.

for a copy of this paper please contact the Yukon Geological Survey; geology@gov.yk.ca.

Includes geological cross sections, mineral occurrences, fossil localities, and marginal notes on physiography and stratigraphy.

Stratigraphic and structural relationships within Stikinia, and overlap assemblages of the Whitehorse trough, are investigated in the Teslin Mountain area, southern Yukon. The Middle Triassic Joe Mountain Formation is dominated by a thick sequence of aphyric basalt produced by subaqueous volcanism. The Upper Triassic Lewes River Group displays complex lateral and vertical lithological and facies changes. It illustrates synvolcanic terrane exhumation, with erosion of the volcanic upland leading to deposition of thick volcaniclastic sequences, in parallel with ongoing clastic and carbonate sedimentation in marginal basins. Unravelling the Lewes River Group stratigraphy is critical in understanding the latest stages of Stikinia arc volcanism and the onset of Whitehorse trough marine sedimentation in the Early-Middle Jurassic. Further mapping and analytical work will focus at characterizing the Joe Mountain Formation and Lewes River Group, to determine how Stikinia evolved prior to final amalgamation of the Intermontane terranes with North America.

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Regional bedrock mapping has revised structural and stratigraphic relationships in the northeastern corner of the Glenlyon map area (NTS 105L). Three structural panels, separated by south and southwest dipping thrust faults, subdivide the area. Cambrian (?) to Ordovician metasedimentary and volcanic rocks underlie the southwestern panel and include all exposures southwest of the Duo fault. Ordovician to Silurian (?) siliciclastic and carbonate strata and phyllite units that are intruded by Late Devonian porphyritic rocks underlie the central panel. Silurian (?) to Triassic siliciclastic and carbonate strata in the northern panel occur to the north, and in the footwall of, the Twopete fault. Mid-Cretaceous granitic rocks that crop out near Kalzas Mountain and occur below the surface near Dromedary Mountain intrude the central and northern panels. Northeast-verging folds and thrust faults deform layered rocks in the northeastern Glenlyon area and are offset by north-south oriented, steeply dipping structures with both normal and strike-slip motion. Upper Devonian Earn Group strata host layered sulphide bodies and polymetallic veins that contain lead, zinc and silver. This mineralization occurs in the footwall of the Twopete fault, a regional structure that originally developed as a Late Devonian synsedimentary fault. Ordovician and Silurian (?) quartz-rich clastic rocks are unlike coeval basinal facies rocks mapped elsewhere within the Selwyn basin in Yukon. These rocks represent slope facies deposits that mark a transition from basin to platform that is the northern extension of the McEvoy platform–Selwyn basin boundary.

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