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Structure of Lardeau group rockes, Albert Canyon, British Columbia.

University of British Columbia

At the north end of the Kootenay Arc, isolated patches of gritty quartzite of the upper Lardeau Broadview Formation (Ord.?) lie in the core of a northwesterly trend-in structure, the Illecilleweat Synform. These rocks overlie, in tectonic contact, black, carbonaceous phyllite of the lower Lardeau Index Formation (lower to middle Ord.). The contact is enclosed in a zone of highly sheared and recrystallized rocks designated here as a phyllonite zone. The Broadview rocks were thrust into juxtaposition with the Index during an early phase of isoclinal, recumbent folding which correlates with the development of nappe structures during deformation along the Kootenay Arc. Interstratal formations of the middle Lardeau were sheared out. The phase was accompanied by regional metamorphism of greenschist grade which aided recrystallization and reoientation of quartz and mica. Similar folding, nearly co-axial with Phase 1 and accompanied by waning metamorphism, folded, tightened, and reactivated earlier-formed structures. This resulted in transposition of lithology and the asymmetric Illecillewaet Synform. The relative age of the Broadview, which is very similar lithologically to Horsethief Creek elastics of Windermere age, has not been established from this study.

Text

2011-05-12

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http://hdl.handle.net/2429/34495

Geological Sciences

University of British Columbia

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