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Sediment Routing Analysis of the Early Cretaceous McMurray Formation in East Alberta, Canada

Abstract

New detrital zircon data from the Early Cretaceous McMurray Formation in east Alberta, Canada is analyzed in the current study using the U-Pb method in order to develop a better understanding for sediment routing of the named unit. The objective of this study is to develop a detailed paleodrainage model for a fluvial depositional system by leveraging high-resolution, geochronological characterization of detrital zircon grains preserved in named fluvial deposits. Previous studies described sediment routing patterns in different parts of the Western Canadian Foreland Basin (WCFB), with results indicating lateral variability between multiple fluvial paleodrainage systems trending south-to-north, generally divided by regional paleo-highs. The limited amount of data and resolution in this region, however, seem to have prohibited detailed longitudinal connections to other parts of the continent in the landward direction. McMurray Formation outcrop and subsurface core detrital zircon samples from eastern Alberta, Canada reveal a uniform age-population distribution with subtle spatial and stratigraphic variabilities. Detrital zircon samples collected from the overlaying Wabasaca Formation show a distinctly-different age-population distribution. The comparison of results from the two formations has substantive implications on terrestrial to marine transitions in the environment of deposition by using geochronological data. Purposely biased detrital zircon sampling to determine the maximum depositional age (MDA) of the McMurray Formation at different stratigraphic positions yields identical age-population distribution when compared to random sampling with no emphasis on younger-depositional ages. Numerical methods including multidimensional scaling (MDS), are utilized to identify nearest-kin provenance-source contributors in the paleodrainage area in order to visualize patterns of the paleo-river systems in North America. Geochronological results from the McMurray Formation are compared to Early Cretaceous (and older) successions in North America to better constrain continental-scale sediment routing models and paleo-flow directions. Results will contribute to the overall understanding of paleo-river system evolution from bed-rock river valleys into alluvial river valleys.