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

Glacial limits and ice-flow map (1:250,000 scale) of Mayo area, central Yukon (parts of NTS 115P northeast, 116A southeast, 105M northwest and 106D southwest).

The Anvil district contains the most westerly off-shelf basinal facies of the Cordilleran miogeocline, a prism of sedimentary rocks of Precambrian to Jurassic age deposited along the relatively stable continental margin of western North America. The district is part of Selwyn basin, a large area of central Yukon in which deep water clastic rocks, chert, and minor carbonate accumulated along the ancient North American continental margin during Neoproterozoic and early Paleozoic time (Gabrielse, 1967).

The integration of till geochemistry and glacial geology into Yukon mineral exploration has been largely underused. In the Anvil district, thick glacial deposits have consistently hampered exploration. From the time of the initial discovery made in Vangorda Creek, it took an additional 20 years before the Grum deposit was discovered only 2 km to the northwest. This work examines the utility of till geochemistry as a method to trace mineralized soil/till samples back to their source rocks in the Anvil district. The Anvil district was last glaciated during the McConnell glaciation, which had a significant impact on the local terrain. The relatively swift-flowing Cordilleran ice sheet deposited thick sequences of till in low-lying areas and eroded southeast-facing slopes and hill summits in the Swim basin and Vangorda plateau. This type of glacial history is conducive for till geochemical exploration. Evidence for a late glacial Cordilleran re-advance is discussed and has implications on prospecting in the district. A 12-km2 till grid was sampled northwest of the Faro deposit to map the glacial dispersion of mineralized sediment. The till geochemistry on the -230 mesh fraction (silt and clay) indicated a broad dispersion plume for lead, zinc and copper extending more than 5 km west of the Faro Pb/Zn deposit. A section of the dispersion train may have a palimpsest origin. The soil geochemistry on the -80 mesh fraction, from 1964 data, indicated a much narrower dispersion plume extending directly from the Faro deposit. The geochemical changes at depth in the till stratigraphy were examined at the Vangorda mine. Results showed that anomalous lead concentrations, unlike zinc concentrations, were found throughout the 20-m till column. Regional till sampling was carried out in three areas peripheral to the known massive sulphide deposits. Results from these sampling programs highlighted anomalies in lead, zinc and copper. Overall, the application of till geochemistry proved to be successful in the Anvil district. Applying similar techniques to drift-covered terrain elsewhere in the northern Cordillera would be beneficial.

Includes glacial limits and ice-flow direction, inset maps of the Mayo and Dawson areas and descriptive notes on Yukon placer deposits.

Surficial geological map (1:50,000 scale) of North McQuesten River area, central Yukon (NTS 116A/1) including marginal notes on physiography, glacial history, placer gold potential and terrain hazards.

The Anvil Mining District contains the most westerly exposures of the off-shelf basinal facies (Selwyn Basin) of the Cordilleran miogeocline, a prism of sedimentary rocks of Precambrian to Jurassic age deposited along the relatively stable, passive continental margin of western North America. Anvil District is immediately northeast of the Slide Mountain and Yukon-Tanana Terranes, the most easterly of the allochthonous suspect terranes which were amalgamated with North America starting in Jurassic time. The total interpreted stratigraphic thickness of the metasedimentary rocks of North American affinity is greater than 7400 m, ranging in age from latest Precambrian or earliest Cambrian through Devonian. These metasedimentary rocks consist predominantly of fine clastic sediments deposited in an off-shelf marine basin with local occurrence of euxinic carbonaceous shales and coarser sandstones and conglomerates. Extensive Ordovician within-plate basaltic submarine volcanic rocks and associated epiclastic breccias are indicative of localized rifting along the continental margin.

The Anvil Lake area consists of mostly contact-metamorphosed siltstone and sandstone having lesser interbedded volcanic and carbonate units that belong to the Early Paleozoic Selwyn basin, thrust northward over the Devono-Mississippian Earn Group and Carboniferous to Triassic formations. These are intruded by the mid-Cretaceous Anvil batholith. The mapped area surrounds the Keg, a disseminated silver-base metal deposit of current interest; new bedrock information will increase the efficiency of exploration of silver bearing veins noted along stratigraphic and structural contacts regionally. It is the first season of an investigation aiming to provide more detailed revision of regional maps, with further paleontology, geochronology, and structural analysis.

Includes glacial limits, glacial deposits, ice-flow direction and descriptive notes on placer gold and glaciation in the Dawson area.