Geology of the Kobau Group Between Oliver and Cawston, BC
BCMEMPR Open File 1989-02
View Open File (PDF, 2.58 MB)
Open File 1989-02 describes the geology and structure of the Kobau Group between Oliver and Cawston (82E/4E). The geology map is at approximately 1:6667 scale and contains a legend, cross sections and descriptive notes. The Open File is a contribution to the Canada/British Columbia Mineral Development Agreement 1985-1990.
The Kobau Group consists of banded, foliated quartzite lithologies with minor intercalated mafic schists, and mafic schists with intercalated quartzite. Minor meta-carbonates and meta-volcanic flows occur within the quartzites and schists.
Pre-Early Jurassic dacite dikes are weakly to distinctly foliated. Two Jurassic intrusions cut the Kobau Group: the Fairview Granodiorite and the Oliver Granite. Other Jurassic intrusions include aplite dikes, small granitic, dioritic and mafic stocks; there are also Tertiary mafic dikes. The Oliver pluton is heterogeneous, varying from diorite to granite, quartz monzonite and syenite. The Fairview intrusion is more homogeneous.
The main deformation is pre-Jurassic and syn-kinematic metamorphism reached greenschist grade. At least three discrete folding events are recorded in the Kobau Group. The earliest are isoclinal, mesoscopic folds. The second phase produced tight to isoclinal folds and occurs on all scales. The third phase formed megascopic open buckle folds. A series of north-south, steeply inclined sinistral faults offset the lithology.
Quartz veins are ubiquitous in the metasedimentary rocks. Veins adjacent to the Fairview Granodiorite contact are auriferous. The Stemwinder gold mine exploited this kind of veining.
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