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A thick late Pleistocene sequence comprising multiple beds of massive diamict facies resting on outwash gravels, occurs along the Bow River, near Banff, Alberta. Diamicts have a simple sheet-like geometry which dip downvalley at between 5° and 10°, with largely conformable bedding contacts. The sediments are strongly bimodal in texture, consisting of clasts supported by a silty sand matrix. Prolate clasts show a weak a-axis alignment parallel and transverse to the trend of the Bow Valley with a weak imbrication. Clasts of soft sediment are common. The diamict sequence has a maximum thickness of 30 m, infills the valley floor over an area of approximately 12 km[SUP2] and buries a channeled topography cut on the surface of underlying outwash gravels. Abandoned braided channels, veneered by windblown sand containing volcanic tephra dated at 6600 yr BP, occur on the infill surface. Diamict facies were emplaced as subaerial debris flows derived by the mixing and remobilization of large volumes of outwash and glaciolacustrine sediment. Orientation data from clasts and a few basal grooves indicate that debris was derived upvalley and from adjacent valleyside slopes. A major episode of debris flow sedimentation may have been triggered by the abrupt drainage of lakes in tributary valleys as the Bow Valley glacier retreated. Downslope resedimentation of large volumes of sediment resulted in braided river aggradation downstream along the Bow River and can be dated to between 12 000 and 10 000 yr BP. Similar conditions probably occurred during deglaciation throughout the Canadian Cordillera and many other alpine areas, where poorly-sorted late glacial debris-flow facies have been mistaken for tills deposited directly by glaciers. The late glacial setting identified in this paper provides a basis of comparison with ancient continental glacial facies preserved in area of active tectonism and high relief. [ABSTRACT FROM AUTHOR]

High‐frequency incised valley systems and subaerial exposure surfaces are prevalent in Aptian‐aged units, having been documented in numerous basins around the world. In light of a growing body of palynological, geochemical and sedimentological evidence, a glacio‐eustatic mechanism for their generation has been suggested, driven by the waxing and waning of polar ice caps. The densely‐penetrated McMurray Formation of north‐eastern Alberta, Canada, provides a unique opportunity to test for an Aptian glacio‐eustatic signal within the Western Canadian Foreland Basin. This study combines detailed drill core description with wireline log‐based stratigraphic analysis to map and evaluate a series of drainage networks located along the cratonic edge of the Western Canadian Foreland Basin. Four stratigraphically distinct composite channel‐form bodies are documented across an area >14 000 km2. Composite channel‐form bodies are up to 50 km wide and locally exceed 70 m thick, subtending from upward‐coarsening parasequence sets 2 to 12 m thick; bounding marine flooding surfaces are mappable over distances exceeding 280 km along the north–south trending basin. Detailed internal fill characterization of the four composite channel‐form bodies suggests that three represent tidal–fluvial incised valley networks, and one represents a deltaic distributary system. At least six cycles of transgression and regression are apparent within the McMurray Formation stratigraphy. Recent biostratigraphic assessment has constrained deposition of the McMurray Formation between ca 125 Ma and 118 Ma, and periods on the order of 0·7 to 1·7 Ma are estimated for the mapped transgressive–regressive cycles. The high frequency nature of these Aptian sequences suggests that the sea‐level oscillations recorded in McMurray Formation strata are consistent with a glacio‐eustatic driver. Linking the internal stratigraphic architecture of the McMurray Formation with interpreted global cooling events and sea‐level drops provides the first evidence of glacio‐eustasy within Early Cretaceous strata of western Canada. [ABSTRACT FROM AUTHOR]

In south-eastern Alberta, the Oxfordian Swift Formation comprises two unconformity-bounded sequences. Sequence 1 consists of the shale member. It unconformably overlies Bathonian calcareous shale of the Rierdon Formation and consists dominantly of shale with uncommon hum- mocky cross-stratified siltstone. The shale member comprises up to four parasequences that show a subtle upward-fining stacking pattern, suggesting overall deepening in a storm-dominated fully marine basin. Deposition of the shale member was terminated by a fall in relative sea-level, which in turn initiated sequence 2. During lowstand, a network of north-east- to south-west-trending meandering channels incised the top of sequence 1. Despite the preserved morphology of these channels, observations in core suggest that lowstand deposits are absent. These strata were most likely thoroughly reworked by ravinement processes associated with the ensuing transgression and are recorded only by a thin chert pebble lag. Also associated with transgression were significant changes in the physical and ecological conditions in the local Swift basin. These changes were related to modifications in basin configuration and the development of a low-energy strait, which probably formed as a result of uplift of the Sweetgrass Arch. Within this newly configured basin, brackish-water conditions prevailed, and sedimentation was dominated by suspension deposition of mud. Bed-load sediment, composed mostly of very fine and fine sand, made up only a small part of the total sediment flux into the area and was transported principally by low-energy combined flows with variable-speed microtidal currents and a low-energy oscillatory component related to storm waves. Sand was generally deposited in the form of small, discontinuous sand ridges that developed locally throughout the study area – it is these features that form the principal hydrocarbon reservoir bodies in the Swift Formation in the study area. After... [ABSTRACT FROM AUTHOR]

The partly dolomitized Swan Hills Formation (Middle-Upper Devonian) in the Simonette oil field of west-central Alberta underwent a complex diagenetic history, which occurred in environments ranging from near surface to deep (>2500 m) burial. Five petrographically and geochemically distinct dolomites that include both cementing and replacive varieties post-date stylolites in limestones (depths >500 m). These include early planar varieties and later saddle dolomites. Fluid inclusion data from saddle dolomite cements (Th=137–190 °C) suggest that some precipitated at burial temperatures higher than the temperatures indicated by reflectance data (Tpeak=160 °C). Thus, at least some dolomitizing fluids were ‘hydrothermal’. Fluorescence microscopy identified three populations of primary hydrocarbon-bearing fluid inclusions and confirms that saddle dolomitization overlapped with Upper Cretaceous oil migration. The source of early dolomitizing fluids probably was Devonian or Mississippian seawater that was mixed with a more 87Sr-rich fluid. Fabric-destructive and fabric-preserving dolostones are over 35 m thick in the Swan Hills buildup and basal platform adjacent to faults, thinning to less than 10 cm thick in the buildup between 5 and 8 km away from the faults. This ‘plume-like’ geometry suggests that early and late dolomitization events were fault controlled. Late diagenetic fluids were, in part, derived from the crystalline basement or Palaeozoic siliciclastic aquifers, based on 87Sr/86Sr values up to 0·7370 from saddle dolomite, calcite and sphalerite cements, and 206Pb/204Pb of 22·86 from galena samples. Flow of dolomitizing and mineralizing fluids occurred during burial greater than 500 m, both vertically along reactivated faults and laterally in the buildup along units that retained primary and/or secondary porosity. [ABSTRACT FROM AUTHOR]

Examines the anatomy and evolution of a Lower Cretaceous alluvial plain in the upper Blairmore Group in Alberta, Canada. Recognition of five types of palaeosols in the upper Blairmore Group based on lithology, the presence of pedogenic features and degree of horizonization; Regional distribution of various types of palaeosols.

The dynamic behaviour of sediment-laden underflows was examined in Peyto Lake, Alberta, Canada, which contains a midlake sill 7 m high. Sediment-laden underflows are driven by the downslope component of negative buoyant gravity multiplied by the current's thickness. Our measurements of wind, lake currents and water properties indicate that underflows pass over the sill due, to the active storage of turbid suspension near the bottom in the deepest proximal region. Sill overflows occurred only when a hydrological threshold of the inflowing river was exceeded, causing quasicontinuous underflow and associated sedimentation in the distal region of the lake basin. [ABSTRACT FROM AUTHOR]

Seven mud-filled incised valleys (MFIVs) in the paralic facies of the Dinosaur Park and Horseshoe Canyon formations (Upper Cretaceous) of southern Alberta were studied to better understand their morphology, geometry and depositional histories in an estuarine context. Two preservational geometries occur: simple, U-shaped forms; and internally complex forms. Both types of MFIV record deposition in the central zone of low energy (turbidity) in an estuarine setting. Simple, U-shaped MFIVs have sharp basal erosional surfaces and consist of mudstone-dominated heterolithic fills of channel-wide, concave-up laminae. Associated fossil assemblages are marine to brackish. Each simple MFIV records a cut-and-fill history associated with a cycle of relative sea-level drop and rise. Low-energy depositional settings, loss of channel form during infilling, and associated shoreface deposits, as well as the absence of clear tidal indicators suggest a coastal plain estuarine setting, along a wave-dominated, barred coastline. Complex MFIVs are rarer, and consist of imbricated, wedge-shaped sets of inclined-to-horizontal heterolithic strata. Tidal deposits and/or nonmarine-tomarine macrofossils occur locally. Complex MFIVs were infilled in meandering reachers of the central zone of low energy in tide-dominated estuaries. Their rarity compared to simple MFIVs and their freshwater palaeontological content suggest that they were contiguous landward with extensive fluvial channels. A complex MFIV near Onefonr comprises three in-channel depositional cycles. Each cycle consists of an erosional surface overlain by lateral accretion bedding and a conformable transition to vertically aggraded strata. Each cycle reflects a cut-and-fill event under the control of changes in relative sea-level that culminated in overbank All MFIVs formed in low-gradient settings (≤ 0.03%) where estnarine zones were stretched out over many tens of kilometres. Tide-dominated estuaries apparently exhibited... [ABSTRACT FROM AUTHOR]

Argues that diamict exposures around Banff, Alberta are not basal tills. Explanation of the observed textural variability within the diamict sequences; Indication on positive forms of the surface of the diamict; Explanation of valley fill sedimentation assemblage of variable sediment types.

Discusses description and interpretation of the diamicton facies of the Bow Valley near Banff, Canadian Rocky Mountains. Availability of detailed facies of valley-fill treatments; Explanation of properties indicating subglacial deposition; Evidences for glacial interpretation.

Glacigenic sediments exposed in pits around Villeneuve, near Edmonton, Alberta, are subdivided into facies based on grain size, sedimentary structure, glacially-induced deformation and faulting, and groove marks. Two diamicton facies are recognised , one of which is interpreted as a primary till, deposited directly from glacier ice, and the other as a product of mass-movement. The diamicton facies are closely associated with current bedded facies interpreted as fluvioglacial deposits. The stratigraphic sedimentological and tectonic aspects of these fluvial deposits suggest subglacial deposition in channels and cavities. At any one place the glacier appears to have alternated between being attached to the bed, causing thrusting and sole marking, and being separated from the bed by a cavity in which fluvial and mass-movement sediments accumulated. The net result is a highly complex and laterally variable stratigraphy produced by a single glacial advance. The correct interpretation of such sequences is essential if lithostratigraphy is to be used to establish glacial history. In addition, the interpretations presented here have implications regarding the formation of soft zones in 'till'. They indicate that the soft zones are beds of sorted sediment redeposited by mass-movement. [ABSTRACT FROM AUTHOR]

In the region of the Athabasca Oil Sands, Alberta, the Lower Cretaceous McMurray Formation comprises 50-8O m of uncemented quartz sand and associated shale, saturated throughout by bitumen. The sediments are dominantly of continental origin, except in the uppermost parts of the formation where sedimentation was influenced by the encroaching boreal sea. In most outcrop and mine face exposures of the McMurray Formation, a sequence of three facies is recognized. In ascending order these are (1) an erosionally based thick-bedded sand facies, 2-20 m thick, dominated by large-scale trough cross-beds, (2) an epsilon cross-stratified facies with solitary sets up to 25 m in thickness, consisting of decimetre to metre thick couplets of sand/mud, with depositional slopes of 8 -12° and palaeocurrent indications parallel to the strike of the epsilon cross-set, and (3) a horizontally bedded argillaceous sand facies up to a few metres thick The three-fold sequence is interpreted as a single upward-fining cycle of channel sedimentation, the trough cross-bedded sands resulting from channel bottom deposition, the epsilon cross-strata accumulating by lateral accretion of channel point bars, and the upper argillaceous sand representing floodplain sedimentation. Where the McMurray Formation is relatively thin (less than 50 m), virtually the entire formation is commonly composed of a single upwards fining channel deposit. Details of the size and physiographic setting of the channels are somewhat uncertain, but the present evidence suggests that the epsilon-dominated McMurray Formation sequence in the Athabasca Deposit region represents the coastal plain culmination of a very large fluvial drainage system. [ABSTRACT FROM AUTHOR]

A small mound, 4 × 23 m in size, on the fore-reef slope of the Ancient Wall reef complex at Mount Haultain, Alberta, consists of fenestral, renalcid micrite and wackestone. Stromatoporoids are the most abundant skeletal component but do not form an organic framework. Renalcids, together with early micrite cementation, performed a supporting and stabilizing role but only rarely directly encrusted skeletal material. Many of the primary shelter voids, interparticle voids and fenestrae were filled with internal sediments and submarine micrite cements. A considerable proportion of the micrite matrix appears to be cement. The location and development of the bioherm was controlled by a local hard substrate and suitable environmental conditions. The mound developed on and around a large block within an underlying megabreccia bed soon after it was deposited in a debris flow on the fore-reef slope, it formed near wave base in about 30–50 m water depth and was subject to gentle current action. Laminar stromatoporoids grew on the flanks and top of the mound, and fenestral, renalcid micrite and wackestone accumulated in the central part. Deepening water and increased rates of mud accumulation terminated further build-up of the bioherm and it was buried by basin mud. Fenestral, renalcid micrite occurs in a number of Devonian and Lower Palaeozoic organic mounds. This study suggests that early, submarine cementation was a significant factor in the development and preservation of this distinctive lithotype. [ABSTRACT FROM AUTHOR]

Nineteen shales from the continental Belly River Formation and sixteen shales from the marine Wapiabi Formation were studied by X-ray diffraction and fluorescence methods. The diffraction data indicate that dolomite and lilite are present in significant amounts only in the Wapiabi. Feldspar and 12 Å and 14 Å clays are more abundant in the continental shales. The marine shales are enriched in K, Ca, Rb and Zr. The continental shales are higher than marine shales in Sr and Mn. The Rb/K is higher in the marine shales, the Sr/Ca is lower than in the continental shales. [ABSTRACT FROM AUTHOR]

The upper Cretaceous Belly River Formation of the southern Foothills of Alberta is a unit 2,000–2,500 ft. thick composed mainly of mudstone interbedded with lenticular, fine- to medium-grained sandstones in units 5–100 ft. thick. Thin intraformational mudstone-pebble conglomerates, nodular limestones, coal seams, bentonites, magnetite-sandstone, and pelecypod beds make up the remaining, minor part of the lithology. The sandstones are composed of about one-half quartz (and quartzite), one-third rock fragments (including chert), and one-fifth feldspars. They are mostly lithic sandstones in the cIassification scheme adopted. The quartz rock fragments and feldspars are separable into compositional and genetic groups. Variatal minerals are carbonates, chlorites, red and brown biotide, and two types of glauconite. The principal accessory minerals are allanite, apatite, collophane, almandine garnet, tourmaline, and zircon. Albitization of intermediate plagioclase suggest the grade of diagenetic aIteration has neared the laumontite-albite stage. Quantitative clay analysis of nine mudstones, shales and bentonites shows illite and montmorillionite to be the dominant minerals (with considerable mixed layering). Illite is detrital, montmorillonite and mixed-layer clays are diagenetic.

In the Muskeg Trough of northcentral Alberta the Gilwood Member contains widespread carbonate deposits that formed within terrigenous mudstone and sandstone hosts. Stratigraphic, depositional and petrographic relationships indicate that these carbonates represent calcretes and dolocretes. Calcretes, observed best with cathodoluminescence, display microcrystalline alpha fabrics, circumgranular cracks, root networks, displacive growth fabrics, elongate channel voids and rare coloform growths with flower spar. Similarly, dolocretes have microcrystalline alpha fabrics, brecciation, gradational contacts with host mudstones, extensive layered nodular horizons and are associated with anhydrite and pyrite. δ[sup 13]C values range between -7‰ to +1‰ and –6‰ to +3‰ for calcretes and dolocretes, respectively. Oxygen isotopes are more variable and differ with host lithologies. δ[sup 18]O of calcretes ranges between -11‰ to -8‰ for sandstones and -8‰ to -3‰ for mudstones, whereas δ[sup 18]O of dolocretes ranges between -3‰ to 1‰ for marine mudstones and -6‰ to -2‰ for pedogenic mudstones. Regional mapping indicates that calcretes thicken towards the deepest parts of the Muskeg Trough. Widespread dolocretes extend beyond the eastern and western limits of Muskeg Trough and are useful marker intervals for regional correlations. Dolocretes of restricted lateral extent are found within gleyed palaeosol mudstones next to calcretized channel sandstones. Calcrete isotopic values are interpreted as indicative of carbonate precipitation from waters with meteoric water input. However, the higher δ[sup 18]O values in dolocretes are indicative of a contribution from an isotopically heavier source such as seawater. Stratigraphically, calcretes are most common along the western and northern edges of Muskeg Trough; thus, calcrete accumulation was further controlled by meteori... [ABSTRACT FROM AUTHOR]