Abstract: Unconsolidated sediments in the Mount Nansen area can be subdivided into eight clastic facies: 1)clay-rich diamicton; 2) massive/stratified silt/clay; 3) massive/disorganized pebbly sand/sand; 4) stratified pebbly sand/sand; 5) disorganized muddy gravel; 6) massive/stratified sandy gravel; 7) disorganized gravel; and 8) massive to crudely stratified gravel. Diamicton is interpreted as glacial till; other facies are fluvial/glaciofluvial in origin.
Sediments have a number of geomorphic setting, including: 1) Holocene colluvium, alluvial fans and stream deposits; 2)Reid periglacial alluvial fans; and 3) pre-Reid glacial and glaciofluvial deposits.
Previous workers suggested that significant placer gold concentrations occur only in alluvium that lies either upon bedrock or glacial till. New data from this study suggest that significant amounts of placer gold also occur in the diamicton, primarily at the diamicton/bedrock contact. Gold concentration in the diamicton is likely due to glacial erosion and incorporation of a supergene- enriched bedrock mantle and pre-existing auriferous alluvium.

Authors: LeBarge, W.P.

Map Scale: 1 : 0

NTS Mapsheet(s): 115I

Citation: LeBarge, W.P., 1995. Sedimentology of Placer Gravels Near Mt. Nansen, Central Yukon Territory (115 I). Indian and Northern Affairs Canada, Exploration and Geological Services Division, Yukon Region, Bulletin 4, 115 p.

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