The basement of Quesnellia in southern British Columbia consists of several diverse lithotectonic assemblages, including the Harper Ranch Group, Apex Mountain complex, and Knob Hill complex, as well as the Anarchist, Kobau, Attwood and Chapperon assemblages. Scarce fossil ages and rare U-Pb zircon ages from some of these assemblages range from Devonian to Permian. However, there are major lithological differences between the various assemblages. The Harper Ranch group is considered to be of calc-alkaline arc affinity, whereas the Knob Hill and Apex Mountain complexes are more oceanic (ophiolitic) in character. The paleotectonic affinity of the other assemblages is largely unknown at this point.
This project was a regional study of the Paleozoic basement components of southern Quesnellia, utilizing U-Pb dating of volcanic units and detrital zircons, together with micropaleontology (radiolarian and conodonts) and lithogeochemical analysis of volcanic rocks. Results of the study provide a much-improved understanding of the age, nature and paleotectonic setting of the various basement components, and the possible relationships between them. This information can help identify possible previously unrecognized exploration targets within southern Quesnellia.