Abstract

A sequence of three phases of recumbent folding has been established within some western-most exposures of gneiss of the Shuswap Complex, near Vaseaux Lake, in the southern Okanagan Valley of British Columbia. These three structural events comprise large northerly trending recumbent folds (Phase 1) that have been refolded, first about northeasterly dipping axial surfaces (Phase 2) and secondly about southerly dipping axial surfaces (Phase 3).Much of the ductile strain visible in these rocks appears associated with Phase 2. Strain analysis of plastically deformed garnets, originally synkinematically developed during early stages of Phase 2, indicates that the growth of Phase 2 recumbent folds was associated with extreme flattening strain across their axial surfaces, accompanied by intense constriction subparallel with their hinge lines. A similar but less intense mode of strain appears associated with Phase 3 folds. No useful strain markers are associated with Phase 1 and perhaps this was a translational phase of strain.The Phase 3 event probably is an early part of the Columbian Orogeny, with Phases 1 and 2 being formed either during or earlier than the Permo-Triassic.Early Tertiary events have gently warped and fractured these three early main structures.

You do not currently have access to this article.