Geology and Mineralization of the Mount Skelly Pluton,
Kootenay Lake, Southeastern British Columbia
(NTS 82F/7E)

BCMEMPR Open File 2000-08

by J. Logan and R. Manns

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Describes the geology and mineral occurrences of the Mount Skelly pluton (82F/7E) near Kootenay Lake in southeastern British Columbia. The 1:50 000 scale coloured geological map includes a legend, references, photographs with rock types and mineralization, and tables with modal analyses, selected chemical analyses, and mineral occurrences.

The oldest rocks in the map area are from the Helikian Purcell Supergroup. Middle Aldridge siltite and fine quartzite with argillite interbeds, are overlain by Upper Aldridge argillite, silty argillite with characteristic white siltite laminae. Lower Creston Group rock units consist of siltite and thinly interbedded siltite and argillite; middle Creston rocks are siltite, fine quartzite, black to purple argillite and white quartzite. The Coppery Creek Group has a gray carbonate member; a lower unit with dolomite, dolomitic siltstone, argillite, siltite and quartzite; a middle unit of thinly laminated argillite and siltstone; and an upper unit of dolomite interbedded with quartzite. The Moyie intrusions are mainly metadiorite and metaquartz diorite. The lower unit of the La France Group consists of thinly bedded argillite and siltite; the upper unit is interbedded siltite and argillite. Mt. Nelson Formation units are dominated by: quartzite; dolomite, dolomitic siltstone, and argillite; thinly interbedded argillite and siltstone; and dolomite. Rocks of the Hadrynian Windermere Supergroup are represented by the Toby Formation and the Horsethief Creek Group. Toby Formation is composed of polymictic conglomerate, quartzite and grit, and phyllite. Horsethief Creek Group units are phyllite, siltite and carbonate; quartzite and pebbly quartzite; cobble conglomerate; pebble conglomerate; grey limestone, marble and dolomite; and phyllite and schist with interbedded quartzite, conglomerate and marble. Argillite, silty argillite, siltstone, and silty limestone comprise the Cambrian, Eager Formation.

Intrusive rocks of the Cretaceous Bayonne suite include the Sanca stock, which is biotite granodiorite, and the Mount Skelly pluton, which consists mainly of granodiorite and biotite monzogranite.

Mineral deposit types with potential in the area include low-sulphide quartz veins with elevated arsenic and values in lead, silver, gold, and tungsten; greisen veins with molybdenum and tungsten values (some also carry copper minerals); quartz veins with values in copper, silver and gold; and polymetallic quartz veins with values in silver, lead, zinc and sometimes gold. Four of the occurrences have past production. Most of the occurrences are either in Horsethief Creek strata or Cretaceous intrusive rocks.

Last updated November 16, 2007