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Structural relations between the Shuswap Terrane and the Cache Creek Group in Southern British Columbia.

University of British Columbia

The rocks of the Shuswap terrane have been the subject of controversy for more than 65 years. Jones (1959) recently presented evidence that in the Vernon map-area the original rocks and the superimposed metamorphism are all pre-Permian in age and probably pre-Cambrian. Jones also described (1959, pp. 47-4-9 and pp. 28-29) five different localities where unconformities separate Shuswap rocks of the Monashee and Chapperon groups from rocks of the Cache Creek group of Permian age. The present writer mapped in detail three of these localities, near Lavington, at B.X. Creek and at Salmon River. Near Lavington the contact described by Jones as an unconformity is considered to be a fault. However, the relations between metamorphic and non-metamorphic rocks are compatible with the existence of an unconformity which, if it exists, is not exposed. At B.X. Creek, the arcuate path described by Jones as marking an unconformity was found to follow a nearly-straight line in a northerly direction and to coincide with two parallel, steeply-dipping and north-trending faults which truncate the non-metamorphic rocks. At Salmon River the evidence for an unconformity is strong. The rocks below the unconformity are chloritic and argillaceous schists of the Chapperon group and strike northeast with steep dips to the southeast and northwest. The rocks above the unconformity are calcarenites, feld-spathic volcanic wackes and tuffs grading upward into argillites, and have been described by Jones as part of the Cache Creek group; they strike north or slightly east of north and dip gently to the west or west-northwest.

Text

2011-10-04

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http://hdl.handle.net/2429/37780

Geological Sciences

University of British Columbia

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