Abstract: 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.

Authors: Bond, J.D.

NTS Mapsheet(s): 105K02, 105K03, 105K05, 105K06, 105K07

Citation: Bond, J.D., 2001. Quaternary Geology and Till Geochemistry of the Anvil District (Parts of 105K/2, 3, 5, 6 and 7), central Yukon Territory. Exploration and Geologial Services Division, Yukon, Indian and Northern Affairs Canada, Bulletin 11, 39 p.

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