Jura-Cretaceous Back-Arc Basin Evolution and Collisional Tectonics of West-Central British Columbia

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A basin analysis of the Skeena group of west-central British Columbia will be undertaken to evaluate Early Cretaceous tectonics and mechanics of terrane collision. The model to be tested is that initial terrane collision resulted in the mergence of two subduction zones and uplift of the Late Jurassic to earlier Cretaceous Skeena Arch. Progressive collision led to the expansion of the arch behind an active arc to the west. The arch subsided in the Early Cretaceous and the Skeena Group were deposited in the back-arc basin. The two hypotheses that this study will address are (1) back arc subsidence was the result of extension or transtension, or (2) subsidence was due to shortening, tectonic loading and lithospheric flexure. Distinguishing criteria will include sediment provenance, facies analysis, subsidence history, paleocurrent analysis, diagenetic history, and trace element geochemistry of interbedded volcanics. The results of this study will have important implications for the evolution of the Jurassic- Cretaceous Pacific basin and the Farallon plate.