Structural geology and basement-cover relations in the southeastern Cape Breton Highlands, Nova Scotia
LE3 .A278 2003
Bachelor of Science
Earth & Environmental Sciences
The southeastern Cape Breton Highlands consist of various pre-Carboniferous plutonic, volcanic and metamorphosed basement rocks of the Bras d'Or Terrane, with Carboniferous sedimentary material in the adjacent valley and coastal regions. Field investigations in the past have shown that the older basement rocks outcrop at equal, if not higher, topographic elevations than the nearby Carboniferous sedimentary units in the southeastern Highlands. Detailed mapping of the contact, structural analyses, thin section petrography and geophysical map interpretations show that the basement rocks have been ernplaced by a thrust fault that extends from the Baddeck River area, through the Christopher Macleod and Big Glen Brook valleys, east into the St. Anns area where it follows topographic contours northwards into the North River area. The thrust fault transported a slab of pre-Carboniferous basement rocks at least 100 metres thick and over 200 km2 in area over Carboniferous Horton and Windsor group rocks for a cumulative distance of at least 9 km. The timing of the thrust fault movement was likely during the Alleghanian Orogeny in Late Carboniferous to Permian times based on the observation elsewhere on Cape Breton Island that rocks of the Mabou Group are deformed and overlain by undeformed rocks of the younger Cumberland Group, which are the oldest rocks that postdate the Alleghanian Orogeny.
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