Characterizing alluvial architecture of point bars within the McMurray Formation, Alberta, Canada, for improved bitumen resource prediction and recovery

Alluvial architecture of mid‐channel fluvial–tidal barforms: The mesotidal Lower Columbia River, Oregon/Washington, USA

“…and lateral-accretion sets of modern sand-bed, large-river braid-bars (Bristow, 1993;Best et al, 2003;Reesink et al, 2014), modern and ancient counter point-bar accretion-sets (Smith et al, 2009(Smith et al, , 2011Durkin et al, 2015), and downstream most point-bar lateral-accretion successions (Thomas et al, 1987;Hubbard et al, 2011;Durkin et al, 2015;Moreton & Carter, 2015).…”

“…1) in several key ways. First, fluvial to fluvial-tidal point-bar IHS tends to have dip-angles ≥5°t o ≤35°(more commonly ca 5 to 15°) that do not vary spatially across a point-bar since their dipangles are set by the transverse point-bar slope (Thomas et al, 1987;Smith et al, 2009;Durkin et al, 2015;Moreton & Carter, 2015;Jablonski & Dalrymple, 2016). Furthermore, their finegrained components of IHS are nearly always interpreted to reflect the hydraulic-sedimentation response of tidal processes (for example, tidal slackwater or turbidity-maximum enhanced deposition of fines) in conjunction with increased salinity-levels and brackish water ichnofacies (cf.…”

“…Fine-grained interbeds form via suspended-sediment fallout, and subsequent reworking, into current-ripples within the low-velocity bartail recirculation-cell produced by flow-separation around bars during a single, or multiple, high-river stage event(s) (cf. Leeder & Bridges, 1975;Nanson & Page, 1983;Smith et al, 2009Smith et al, , 2011Moreton & Carter, 2015).…”

“…Firstly, its foundation rests upon a small number of modern studies (Smith, , 1989Choi et al, 2004;Dalrymple & Choi, 2007;Dalrymple et al, 2012;Johnson & Dashtgard, 2014), whilst relying heavily on observations from ancient fluvial-tidal settings (Hubbard et al, 2011;Fustic et al, 2012;Feldman & Demko, 2015;Martinius et al, 2015;Jablonski & Dalrymple, 2016), where the planform geometry, and hydraulic initial and boundary conditions, are not well-constrained. Secondly, it implies that IHS is strongly related to tidal-processes, and de-emphasizes the potential importance of fluvial and wind-wave processes (Smith et al, 2009(Smith et al, , 2011Durkin et al, 2015;Moreton & Carter, 2015) in producing IHS. Thirdly, it is conditioned upon single-thread FTTs with pointbars, and thus it is unknown whether the IHS model applies to multi-channelled FTTs with mid-channel bars.…”

“…For example, the Cretaceous bitumen-rich McMurray Formation, Alberta, Canada (Hein, 2015), is commonly interpreted as being constructed from FTT barform strata (Smith, 1988(Smith, , 1989Wightman & Pemberton, 1997;Hubbard et al, 2011;Fustic et al, 2012;Feldman & Demko, 2015;Martinius et al, 2015;Jablonski & Dalrymple, 2016), but fully-fluvial McMurray Formation barform depositional models have also been proposed (cf. Moreton & Carter, 2015). Modern FTT barforms have thus received a lot of recent attention (Smith, , 1989Smith et al, 2009;Choi, 2010;Sisulak & Dashtgard, 2012;Choi et al, 2013;Johnson & Dashtgard, 2014;Carling et al, 2015;Prokocki et al, 2015;Leuven et al, 2016) in order to establish how fluvial-tidal processes alter their morphology and alluvial architecture.…”