Skip to main content

Skip to navigation

The access keys for this page are:

Ministry of Energy Mines and Responsible for Core Review

Geology of the Stuart - Pinchi Lakes Area, Central British Columbia
(NTS 93K - parts of 7,8,9,10 and 11)

BCMEMPR Open File 1993-09


by C. Ash, R.W.J. MacDonald and I.A. Paterson


View Open File (PDF, 5.05 MB)


Open File 1993-09 describes the geology and mineral occurrences of the Stuart and Pinchi Lakes area (parts of 93K/7, 8, 10, 11) in central British Columbia. The map has geology at 1:100 000 scale, a legend, references, and tables of mineral occurrences, Regional Geochemical Survey results, and rock sample elemental analyses.

The study area covers late Paleozoic and early Mesozoic oceanic rocks of the Cache Creek terrane. The terrane in this area forms a northwest trending belt that is bounded by faults. The belt consists of tectonically intercalated pelagic sediments, limestones and subordinate oceanic metavolcanic and plutonic ultramafic rocks.

Late Paleozoic to early Mesozoic (?) rocks of the Cache Creek complex are dominantly argillite, phyllitic argillite and siliceous limestone with lesser ribbon chert. Limestone frequently occurs as massive blocks in tectonized argillite. Younger rocks of the Takla Group and Uslika Formation were not mapped in detail during this study because it focused on gold related to ophiolitic rocks.

Several large ultramafic-bearing bodies were tectonically emplaced, presumably as klippe. They consist of oceanic crust metabasalt and metagabbro, and upper mantle-derived harzburgites, minor dunites and serpentinized equivalents. Locally the ultramafic rocks are carbonatized and associated with mineralized quartz veins.

The Shass Mountain pluton, which is the largest intrusive body in the area, is of Middle Jurassic age. Other similar-looking but undated intrusions also occur.

Subparallel major faults control the fabric of the mapsheet. Folding and an associated foliation fabric reflect the structural grain of the area.

The most significant occurrence in the area is the Snowbird gold-stibnite deposit. It is a shear-hosted quartz-carbonate vein that is within the Sowchea shear zone. Associated is quartz-carbonate-mariposite alteration of ultramafic or volcanic rocks.


All print publications of the BC Geological Survey are available digitally, free of charge, from this website.


For questions or more information on geology and minerals in British Columbia contact BCGS Mailbox or call toll free (BC Residents only).