Sedimentology, depositional environments, and high-resolution sequence stratigraphy of the Horsefly, BAT, and Ellerslie (Basal Quartz) incised valleys, south-central Alberta, Canada

This study describes the sequence stratigraphy of the Basal Quartz (BQ) in southern Alberta (Townships 7-18, Ranges 11-25W4) and provides a detailed description of the deposits, including an examination of the controls on sedimentation and representative depositional models.; Twelve facies and five facies associations are recognized in the study interval. These deposits occur within six sequences representing two compound incised-valley fills and one simple incised-valley fill. The two oldest valley fills, the sheet-distributed Horsefly sequences, are composed of braided-fluvial sandstones and overbank mudstones. The overlying BAT compound valley system is composed of three narrow, deeply-incised sequences, which contain meandering-fluvial sandstones overlain by tidal-fluvial sandstones, and estuarine mudstones. The youngest and most widespread valley system is the Ellerslie sequence, which is comprised of ribbon sandstones, overlain by tidal-fluvial channels, prodelta, central-basin, and distal flood-tidal delta deposits. Each of the sequences shows a generally upward change from basal conglomerates/sandstones to mudstones containing localised ribbon sandbodies marking a change from a lowstand to transgressive systems tract.; Vertical changes in the depositional environment occur at two scales. (Abstract shortened by UMI.)...