AAPG Foundation 2019 Grants-in-Aid Projects

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High-resolution sedimentological analysis of matrix-rich sandstone in the Windermere turbidite system and comparison with equivalent deposits from the middle Ordovician Cloridorme Formation of eastern Quebec, Canada.

Abstract

Deep-marine sandstones with significant (>20%) detrital mud and silt matrix content have been variously termed slurry beds, transitional flow deposits and hybrid-event beds, however, details about the spatial and temporal evolution of these enigmatic rocks remain poorly understood. This research will provide a high-resolution sedimentological characterization and depositional interpretation of matrix-rich sandstone strata from two different study areas in Canada: Neoproterozoic Windermere Supergroup in the southern Canadian Cordillera, and the Middle Ordovician Cloridorme Formation of eastern Quebec. In both areas, these strata form a horizontal depositional continuum of increasing matrix-content from matrix-poor sandstone (<20%) to clayey sandstone (20-50%) to bipartite bed with a basal sandy (20-60%) part overlain sharply by a planar- to irregular-based muddier portion (40-80%) to sandy claystone (50-80%) over a distance of few to several 100s m. Vertically, similar facies preferentially overlie one another and form packages 2-10 beds thick. In addition to the outcrop-based observations, qualitative and quantitative petrographic facies analysis will be used to assess their microscopic textures and composition including grain size, structure, fabric, sorting, and mud (silt vs. clay) content. The results of this project will be vital for understanding the depositional origin, architecture, and stratigraphic distribution of matrix-rich strata. The depositional model proposed from this study can be directly applied as analogue for other deep-water systems such as Gulf of Mexico, offshore West Africa etc. with the intent to minimize risk and devise efficient hydrocarbon recovery strategy.