From mine-face to micron-scale investigation of the Cretaceous McMurray Formation at Kearl Mine, northeastern Alberta, Canada
Date
2024-08-27
Authors
Ferens, Trevin
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Abstract
River meander-belt morphodynamics are critical to understanding fluvial sedimentology, however, the process-to-product relationships are highly complex. To improve understanding of meander belt heterogeneity and depositional processes this thesis investigates the Lower Cretaceous McMurray Formation at Kearl mine, northeastern Alberta. The research objectives are to i) utilize extensive mine-face exposures by integrating them with related borehole data to reconstruct the local paleoenvironment, ultimately interpreting the paleochannel morphodynamic evolution through time; and ii) investigate fluvial mudstone microstructure of point-bar mudstones from Kearl mine using scanning electron microscopy (SEM).
The area of interest at Kearl mine is a 1.9 x 1.1 km area where mine-faces were excavated while on-site geologists documented notable geologic features. A focus of the study is the atypical channel-belt deposit trends observed in one of the documented point bars. The atypical point-bar deposits comprise inclined heterolithic stratification (IHS) that was interspersed with mudstone clast breccias and mudstone-lined trough cross-bedded sandstone. The deposits were localized in a segment of the point bar that did not conform to upward- nor downstream-fining trends in typical point-bar models. To better understand these peculiar deposits, this research produces and utilizes a planform reconstruction to investigate the fluvial processes that occurred during the atypical deposition, noting that the upstream cutbank material was mudstone-rich and may have influenced the atypical point-bar heterogeneity. Furthermore, a mudstone sampled downstream from the atypical deposits is analyzed with SEM to observe microstructure characteristics, which reveals evidence of sub-mm-sized mudstone aggregates. The presence of these micron-scale mudstone aggregates implies that a broader range of hydrodynamic conditions should be considered for fluvial mudstone deposition, particularly the mudstone component of point-bar IHS.
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Keywords
Geology, Fluvial, Sedimentology, Stratigraphy, McMurray Formation, Sedimentary geology, Mudstone, Mudstone microstructure, IHS, Point bar, Channel belt, Oil sands, Petroleum geology, Hydrocarbons, geomorphology, planform reconstruction, Cretaceous, McMurray Formation, mudstone aggregate, mudstone clast, breccia, inclined heterolithic stratification