Structural geology of the Pend d'Oreille area and tectonic evolution of the southern Kootenay Arc
Structural and stratigraphic boundaries between late Paleozoic and early Mesozoic oceanic assemblages, the early Paleozoic North American outer continental margin, and the late Proterozoic to early Paleozoic North American miogeocline are preserved in the southern Kootenay Arc of southeastern British Columbia, in the Pend d'Oreille River area. This dissertation provides the first detailed interpretation of the structural and tectonic evolution of the southern Kootenay Arc. In the Pend d'Oreille River area the oceanic and outer continental margin assemblages are condensed against the North American miogeocline by the Waneta, Tillicum Creek and Argillite faults. All of these faults are margin-ward verging thrust faults, which are overturned at high structural levels. Mapping conducted during this study suggests that some of the Cambrian metasedimentary rocks in the hangingwall of the Argillite fault, previously mapped as Laib Formation, are laterally continuous, and correlative, to the Index Formation of the Lardeau Group. The recognition of Index Formation rocks within the study area provides the basis for the first regional structural interpretation of the southern Kootenay Arc. In addition, an erosional unconformity at the top of the Index Formation was identified during this study, indicating that a pre-Mississippian deformational event affected the North American outer continental margin in the Pend d' Oreille River area. The Argillite fault is herein interpreted to be a segment of a thrust fault that extends the length of the southern Kootenay Arc. The complete structure is described in this dissertation, and is referred to as the Kootenay Thrust. The Kootenay Thrust is a craton-ward verging thrust fault, overturned at high structural levels, that carried an island arc assemblage, marginal basin assemblages, and the lower Paleozoic outer continental margin assemblage in its hangingwall over lower to middle Paleozoic miogeoclinal stratigraphy in its footwall. This dissertation provides the first whole-rock major, trace, rare earth element, and Rb/Sr analyses of two Cretaceous stocks, and the first whole-rock major and trace element analyses of Paleozoic metabasite rocks in the Pend d' Oreille River area.
Bibliography: p. 161-171.
Einarsen, J. M. (1994). Structural geology of the Pend d'Oreille area and tectonic evolution of the southern Kootenay Arc (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/18333