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Yukon Geological Survey

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Reference Number
Geology of Spencer Creek (105B/1) and Daughney Lake (105B/2) Map Areas, Rancheria District, Southeastern Yukon
Reference Type
Indian & Northern Affairs Canada/Department of Indian & Northern Development: Exploration & Geological Services Division
Document Type
Open File (Geological - Bedrock)

General Information

Abstract: Twelve lithostratigraphic units, including ten autochthonous and two allochthonous units, are recognized, and most of these are divided into 27 subunits. They range from Cambrian to Quaternary in age and include a wide range of sedimentary, igneous and metamorphic rock types. Lower Cambrian siliciclastic and carbonate rocks of the Cassiar Batholith predominate.

Three phases of structures are identified. First phase structures include bedding and slaty cleavage, of which the latter is attributed to late stage diagenetic recrystallization. Second phase structures trend northwest and include crenulation cleavage and related folds and lineations. They are attributed to northeast-southwest compression resulting from accretion and obduction of allochthonous rocks during arc-continent collision in Late Jurassic-Early Cretaceous time. Third phase structures are approximately 90° to the second phase structures and trend northeast. They include joints and related folds and lineations and are attributed to dextral transcurrent movement on Tintina, Kechika and Cassiar faults.

Precious and base metal mineralization is found mostly within Paleozoic sedimentary rocks and Cretaceous plutonic rocks and forms predominantly veins and replacement lenses. The dominant sulphides include galena, sphalerite, pyrite and chalcopyrite. Arsenopyrite, freibergite, tetrahedrite, pyrrhotite, wolframite, cassiterite, stannite, fluorite and lepidolite are also present. Common gangue minerals include quartz, siderite and iron and manganese oxides. Mineralization appears to be structurally controlled by the northeast-southwest jointing and, to a lesser extent, lithologically controlled by limestone-phyllite contacts. It is attributed to hydrothermal solutions migrating along the joints and was probably deposited approximately 50 Ma ago. The most useful exploration guide to finding additional mineralization is iron and manganese gossans.
Authors: Lowey, G.W. and Lowey, J.F.
Map Scale: 1 : 50000
NTS Mapsheet(s): 105B01, 105B02
Citation: Lowey, G.W. and Lowey, J.F., 1986. Geology of Spencer Creek (105B/1) and Daughney Lake (105B/2) Map Areas, Rancheria District, Southeastern Yukon. Yukon Geological Survey, Open File 1986-1.


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Report File is 5.25 MB Download PDF

Location Map

NTS Mapsheet(s): 105B01, 105B02

Related Occurrences

Name Number Type Status
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Kerns 105B 018 Hard-rock Showing

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