A study of the sedimentology, geochemistry, and stratigraphic organization of the Lower Cretaceous Horsefly (Basal Quartz) Valley (Taber-Cutbank), southern Alberta and northern Montana

The Basal Quartz unit (Early Cretaceous) consists of all deposits from the sub-Cretaceous unconformity upon which it sits to the base of the Ostracode Zone. In southern Alberta and northern Montana is a complex unit composed of four mineralogically distinct units (A-sands, Horsefly, BAT, and Ellerslie Formation) consisting of quartz-rich sandstones and mudstones of fluvial and fluvial-estuarine origin. These units comprise at least four different incised-valley systems (i.e., four different depositional sequences). In the study area (Townships 1-7, Ranges 15-18W4 in Alberta, and Townships 31-37N, Ranges 4-6W in Montana; from 48.5{dollar}spcirc{dollar} to 49.5{dollar}spcirc{dollar}N latitude and 112{dollar}spcirc{dollar} to 113{dollar}spcirc{dollar}W longitude), the fill of the second valley (the Horsefly unit; Taber-Cutbank equivalent) is composed of only fluvial sediments with no marine influence. The purpose of the study is to determine how changes in the rates of creation of accommodation space are reflected in the fluvial architecture (channel stacking patterns). This was done using subsurface oil-industry data such as petrophysical well-logs (270 wells on 20 cross-sections, plus wells off-section) and drill cores (60). (Abstract shortened by UMI.)...