Preliminary Map No. 43: Geology of the Eastern Margin of Shuswap Complex(082M)
View Map (PDF, 3.1 MB), (1:100 000)
Preliminary Map 43 describes the geology of the eastern margin of the Shuswap complex in the Frenchman Cap area northwest of Revelstoke, British Columbia. The 1:100 000 scale geology map includes a legend, references, and a series of geologic cross sections.
The Aphebian (?) core gneiss complex consists of a unit of dominantly granitic orthogneiss and paragneiss, and a unit of mixed paragneiss and orthogneiss, biotite-hornblende gneiss, amphibolite and minor calc-silicate gneiss, micaceous schist and quartzite. The age of the autochthonous Monashee complex cover is unknown. Five units in the cover succession are: basal quartzite with minor conglomeratic quartzite, schist and calc-silicate gneiss; calc-silicate gneiss, sillimanite and kyanite-bearing schist, quartzite, hornblende gneiss and marble with local carbonatite layers; quartzite, schist, quartzofeldspathic grit and gneiss with local amphibolite interbeds; micaceous schist, hornblende gneiss, calc-silicate gneiss, marble and quartzite; and nepheline syenite gneiss and syenite gneiss. Allochthonous Hadrynian (?) cover rocks consist of pegmatite-laced quartz-biotite-feldspar paragneiss, amphibolite, hornblende gneiss, and calc-silicate gneiss. Apparently younger porphyritic granite gneiss has also been mapped.
The area is structurally complex. Early deformation produced isoclinal folds that are subsequently refolded during later events. The complex is bounded to the east by the east-dipping Columbia River fault and the contact of the allochthonous cover is marked by a shallow west-dipping fault. Moderately inclined west-dipping faults cut the rocks of the complex and younger high angle faults are normal and reverse.
The area has a known stratabound lead-zinc-silver deposit south of Hiren Creek and a former producing molybdenum mine at Mount Copeland. The stratabound base metal deposit is in the calc-silicate gneiss, marble and micaceous schist unit. They are interpreted to be of Broken Hill or Sedimentary Exhalative type. The molybdenite mineralization is associated with syenite and nepheline syenite. The nepheline syenite may also have industrial mineral potential.
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