A regional till geochemistry project was completed in conjunction with bedrock mapping across rocks of Yukon-Tanana Terrane and North American affinity in central Yukon. The high mineral potential of the area is based on recent discoveries in the Finlayson Lake area to the southeast, an area thought to juxtapose the Glenlyon area prior to displacement on the Tintina Fault. The study area lies at the limit of the Late Wisconsinan McConnell glaciation. Ice flow was largely directed by topography. Soil profiles reveal a veneer of White River ash and loess over most till deposits. Geochemical results from 285 till samples highlight new anomalies in gold, gold/arsenic (intrusive- and fault-related), copper (veins), copper/nickel (ultramafic rocks) and zinc (sedimentary-exhalative (SEDEX) and epithermal). An orientation survey was completed at the Clear Lake SEDEX deposit to evaluate the extent of glacial dispersion down-ice from mineralization.

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.

Includes a geological cross section, mineral occurrences and isotopic age dates.

Geological map (1:1,000,000 scale) of the Yukon Territory, including the following inset maps: terrane map; physiographic regions map; glacial limits map; aeromagnetic image map; and NTS index map.

The Finlayson Lake fault zone forms the boundary between autochthonous North American rocks and rocks of the innermost accreted Slide Mountain and Yukon-Tanana terranes in southeastern Yukon. Geological mapping at 1::50 000 scale in a well exposed area of the Campbell Range, southeastern Yukon, was undertaken to examine the kinematics of the Finlayson Lake fault zone and rock types of the Slide Mountain terrane. Five units were identified: (1) chloritic schist and phyllite, (2) laminated metachert and carbonaceous black slate, (3) tan weathering metachert and maroon siliceous and argillaceous metasiltstone, (4) greenstone and associated breccia, gabbro, metagreywacke, metachert and maroon metasiltstone and (5) serpentinite. Unit 2 is structurally interleaved with submap-scale bodies or layers of serpentinite, hornblende-plagioclase porphyry, plagioclase-potassium fledspar porphyry, quartz-eye muscovite-chlorite phyllite or schist, chloritic schist and minor grey, calcareous metacarbonate. Serpentinite is also exposed in unit 4 and as small slivers along the thrust contact between units 3 and 4. Lithologically, units 4 and 5 are similar to the upper division of the Slide Mountain terrane in east-central and north-central British Columbia. Unit 2 has similarities with the lowest division of the Sylvester allochthon and is tentatively correlated with the Slide Mountain terrane. Maroon metasiltstone in unit 3 is indistinguishable lithologically from metasiltstone in the overlying greenstone unit suggesting that the eastern thrust fault juxxtaposes parts of the same depositional sequence, ie. The Slide Mountain terrane. Regional correlation of unit 1 is unclear. Unit 2 is inferred to be bounded to the east and west by northwest-striking faults and to the south, by an east-striking, steeply dipping, normal (north-side down) fault. The northern boundary of unit 2 is unconstrained. Greenstone (unit 4) is thrust towards the southwest over unit 1 in the western part of the map area along a northwest-striking, gently northeast-dipping thrust fault. In the eastern part of the map area, greenstone is thrust towards the northeast over unit 3 along a northwest-striking, moderately southwest-dipping thrust fault. Outcrop data and topographic patterns suggest that the eastern thrust fault is truncated by a northwest-striking, steeply dipping fault and that the normal fault truncates the westernmost northwest-striking fault. The northwest-striking faults are poorly exposed and their kinematics have yet to be determined. However, if they are steep faults, they are likely dextral strike-slip faults. Field data indicate that the Finlayson Lake fault zone consists of diverging thrust faults and subparallel strike-slip(?) faults. These structures are consistent with the interpretation of the Finlayson Lake fault zone as a transpressive fault zone. More constraints on the relative timing of faulting and the kinematics of the steep faults are required to test this hypothesis,

Interpretive geology of the Jakes Corner geophysical survey, southern Yukon, (NTS 105C/5 and 105D/8,9) including one 1:50,000-scale map and an interpretive report. The accompanying geological map is designed to be overlain upon the 1:50,000 geophysical maps of Open File 1994-10(G). It incorporates published geological information which has been modified to accord with constraints provided by the geophysical data as well as from publicly available assessment reports and limited field checking. The map is highly interpretive, except for the eastern portions which benefit from mapping by Gordey and Stevens (1994b). Elsewhere, mapping concentrated on defining blocks with a uniform geophysical expression which could represent a particular rock unit. Sharp magnetic gradients between units are considered to represent faults, or where applicable, intrusive contacts. Structural relations between units are generally interpretive and may not be consistent throughout the map area. This report describes the rock units that occur in the survey area and elaborates on the mineral deposit types that might occur there.

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This map accompanies paper: Johnston, S.T. and Shives, R.B.K., 1995. Interpretation of an airborne multiparameter geophysical survey of the northern Dawson Range, central Yukon: A progress report. In: Yukon Exploration and Geology, 1994. Exploration and Geological Services Division, Yukon, Indian and Northern Affairs Canada, p. 105-111.