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Geology of Vaseaux Lake area

University of British Columbia

A local structural lithplogic succession comprised of 5 map-units totalling more than 4,000 feet in present thickness has been established in the Vaseaux Formation (Bostock, 1940). Units 1-5 are comprised of high grade metamorphic rocks derived from possible greywacke suite sediments and volcanics that have undergone a complex 5-phase history of deformation, metamorphism and igneous intrusion. Phases 1, 2 and 3 each gave rise to large scale recumbent fold sets along respective northerly, northwesterly and westerly trends. Each in turn brought about tightening and re-folding of earlier formed structures. Associated metamorphism reached upper greenschist facies during' phase 1 and culminated in middle amphibolite facies at the time of emplacement of a synkinematic, granitic pluton during phase 2. Metamorphism again reached at least lower amphibolite facies during phase 3, possibly at a time of re-activation of earlier formed phase 3 structures during the Upper Jurassic. Phases 1, 2 and 3 are all of pre-late Mississippian age but their exact ages are not known. They are believed to be all related in time to the lower Mississippian Caribooan Orogeny. Phases 4 and 5 of deformation gave rise to respective northerly and northwesterly open, flexural-slip folds. Phase 4 is associated in time with early Tertiary volcanism and hydrothermal alteration and has been K/Ar dated at 44 m.y.B.P. (Ross and Barnes 1972). Phase 5 folding, pre-Miocene in age is associated , with extensive fracturing and faulting in the district.

Text

2011-03-02

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http://hdl.handle.net/2429/31927

Geological Sciences

University of British Columbia

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