What does the ichnological content of the Middle McMurray Formation tell us?

Shchepetkina, Alina; Gingras, Murray K.; Pemberton, S. George; MacEachern, James A.

doi:10.2113/gscpgbull.64.1.24

Cited by 24 publications

(11 citation statements)

References 65 publications

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“…The majority of published studies on the upper McMurray Formation occur to the east or north-east of the GPV in the bitumen-hosting channel successions along the Main Fairway of the MSB (Mossop & Flach, 1983;Flach & Mossop, 1985;Muwais & Smith, 1990;Crerar & Arnott, 2007b;Smith et al, 2009Smith et al, , 2011Hubbard et al, 2011;Labrecque et al, 2011;Fustic et al, 2012;Musial et al, 2012;Nardin et al, 2012;Dolby et al, 2013;Hein et al, 2013;Jablonski & Dalrymple, 2016;Shchepetkina et al, 2016).…”

Section: Geological Overviewmentioning

confidence: 99%

“…Pemberton et al (1982) were the first to document brackish ichnofossil suites within channel deposits of the McMurray Formation that were likely affected by a proximal marine source. Since this pivotal paper was published, numerous other papers regarding brackish-water associated ichnofossil suites in conjunction with IHS observed in the middle to upper McMurray Formation have interpreted such deposits as estuarine point bars with controversially varying degrees of marine versus fluvial influence (Smith, 1988;Ranger & Pemberton, 1997;Wightman & Pemberton, 1997;Crerar & Arnott, 2007a;Hubbard et al, 2011;Musial et al, 2012;Barton, 2016;Jablonski & Dalrymple, 2016;Shchepetkina et al, 2016;Shchepetkina et al, 2017).…”

Section: The Application Of Ichnology In Distinguishing Parasequence mentioning

confidence: 99%

“…The majority of published studies on the upper McMurray Formation occur to the east or north‐east of the GPV in the bitumen‐hosting channel successions along the Main Fairway of the MSB (Mossop & Flach, ; Flach & Mossop, ; Muwais & Smith, ; Crerar & Arnott, 2007b; Smith et al ., , ; Hubbard et al ., ; Labrecque et al ., ; Fustic et al ., ; Musial et al ., ; Nardin et al ., ; Dolby et al ., ; Hein et al ., ; Jablonski & Dalrymple, ; Shchepetkina et al ., ). More local studies of the GPV have focused on bitumen reservoirs at the northern end of the GPV (Brekke et al ., ; Martinius et al ., ), and only a few studies describe the regional stratigraphy and present a stratigraphic framework for the McMurray Formation in the GPV (Carrigy, ; Ranger & Pemberton, ; Hein et al ., ); these are described in more detail below.…”

Section: Introductionmentioning

confidence: 98%

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Evolution of an ancient (Lower Cretaceous) marginal‐marine system from tide‐dominated to wave‐dominated deposition, McMurray Formation

Weleschuk

Dashtgard

2019

Sedimentology

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Regionally extensive parasequences in the upper McMurray Formation, Grouse Paleovalley, north‐east Alberta, Canada, preserve a shift in depositional processes in a paralic environment from tide domination, with notable fluvial influence, through to wave domination. Three stacked parasequences form the upper McMurray Formation and are separated by allogenic flooding surfaces. Sediments within the three parasequences are grouped into three facies associations: wave‐dominated/storm‐dominated deltas, storm‐affected shorefaces to sheltered bay‐margin and fluvio‐tidal brackish‐water channels. The two oldest parasequences comprise dominantly tide‐dominated, wave‐influenced/fluvial‐influenced, shoreface to bay‐margin deposits bisected by penecontemporaneous brackish‐water channels. Brackish‐water channels trend approximately north‐west/south‐east, which is perpendicular to the interpreted shoreline trend; this implies that the basinward and progradational direction was towards the north‐west during deposition of the upper McMurray Formation in Grouse Paleovalley. The youngest parasequence is interpreted as amalgamated wave‐dominated/storm‐dominated delta lobes. The transition from tide‐dominated deposition in the oldest two parasequences to wave‐dominated deposition in the youngest is attributed mainly to drowning of carbonate highlands to the north and north‐west of the study area, and potentially to relative changes in accommodation space and deposition rate. The sedimentological, ichnological and regional distribution of the three facies associations within each parasequence are compared to modern and Holocene analogues that have experienced similar shifts in process dominance. Through this comparison it is possible to consider how shifts in depositional processes are expressed in the rock record. In particular, this study provides one of few ancient examples of preservation of depositional process shifts and showcases how topography impacts the character and architecture of marginal‐marine systems.

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Section: Geological Overviewmentioning

confidence: 99%

Section: The Application Of Ichnology In Distinguishing Parasequence mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

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Evolution of an ancient (Lower Cretaceous) marginal‐marine system from tide‐dominated to wave‐dominated deposition, McMurray Formation

Weleschuk

Dashtgard

2019

Sedimentology

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“…The development of IHS is most prominent in meandering channels of estuaries (Thomas et al ., ) where deposition is influenced by fluvial and tidal processes in varying proportions and the overall hydraulic energy is at a minimum (Dalrymple et al ., ). The IHS deposits of the McMurray Formation have been variably ascribed to deltas (Carrigy, ; Nelson & Glaister, ), fluvially dominated point bars (Mossop, ; Mossop & Flach, ; Flach & Mossop, ; Smith et al .,; Hubbard et al ., ; Labrecque et al ., ; Durkin et al ., ) and tidally influenced (estuarine) point bars (Stewart & MacCallum, ; Pemberton et al ., ; Wightman et al ., ; Smith, ; Smith, ; Beynon et al ., ; Keith et al ., ; Ranger & Pemberton, 1988; Ranger & Pemberton, ; Wightman & Pemberton, ; Langenberg et al ., ; Crerar & Arnott, ; Musial et al ., ; Gingras et al ., ; Shchepetkina et al ., ,b).…”

Section: Introductionmentioning

confidence: 99%

“…In addition, IHS can form with elements of downstream accretion and counter point‐bars (Smith et al ., ). Based on the examination of both modern (de Mowbray, ; Smith, ; Allen, ; Choi et al ., ; Choi, ; Sisulak & Dashtgard, ; La Croix & Dashtgard, ; Shchepetkina et al ., 2016a) and ancient settings (Rahmani, ; Ranger & Pemberton, ; Räsänen et al ., ; Eberth, ; Falcon‐Lang, ; Gingras et al ., ; Rebata et al ., ; Shchepetkina et al ., 2016b), the majority of reported IHS has been attributed to the deposition of tidally influenced point bars. The development of IHS is most prominent in meandering channels of estuaries (Thomas et al ., ) where deposition is influenced by fluvial and tidal processes in varying proportions and the overall hydraulic energy is at a minimum (Dalrymple et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Using ichnological relationships to interpret heterolithic fabrics in fluvio‐tidal settings

Melnyk¹,

Gingras

2019

Sedimentology

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In fluvio-tidal settings, the sediment is dominantly derived from the river systems. However, the importance of landward tidal transport of sediment in tidally influenced sedimentary environments is difficult to assess, particularly in the rock record. This problem is addressed using two intervals within the Lower Cretaceous McMurray Formation, each representing a distinct inclined heterolithic stratification motif. The ichnological variation between the heterolithic intervals is analyzed to determine which lithosomes are associated with brackish-water (tidally influenced) colonization windows. From this, the relative fluvial influence responsible for the deposition of the fine and coarse members can be determined. Both of the inclined heterolithic stratification fabrics studied record the deposition of fluvio-tidal point bars wherein the heterolithic bedding represents variations in river discharge. The first fabric comprises inclined heterolithic stratification in which bioturbation only occurs in mudstone beds. This fabric indicates that deposition occurred in more proximal positions within a fluvio-tidal system (i.e. the outermost inner to middle estuary or distributary channels). In this example sand deposition is interpreted to represent high-energy, freshwater dune migration within a fluvial-dominated setting, whereas mud beds reflect brackish-water suspension deposition during times of low river discharge. The second fabric, which is interpreted to have developed in more distal depositional positions (i.e. the middle estuary or seaward of the turbidity maximum in deltas), consists of inclined heterolithic stratification with laminated mudstone and bioturbated sandstone. In these inclined heterolithic stratification successions the mudstone beds were deposited under the influence of freshwater and heightened sedimentation rates, whereas bioturbated sandstone was colonized under brackish-water conditions and in the presence of tidally facilitated sediment transport. In both examples, the bioturbated lithosomes are related to colonization windows that indicate the predominance at that time of marine or tidally influenced processes over fluvial processes.

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Salt dissolution tectonism and origin of lacustrine carbonate beds: Mn‐Fe‐calcite and Mn‐siderite micro‐spherulite fabrics of the Lower Cretaceous McMurray Formation, Athabasca Oil Sands deposit, western Canada

Broughton

2022

The Depositional Record

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Several lacustrine carbonate beds, each a metre-thick interval of densely packed Mn-rich sideritic micro-spherulites or Mn-rich ferroan calcite micro-spherulites, are recorded for the first time within strata of the Lower Cretaceous McMurray Formation of the northern Athabasca Oil Sands deposit, western Canada. A lower McMurray lacustrine carbonate deposit is characterised by a metre-thick bed fabric of Mn-rich siderite micro-spherulites. The middle and upper interval McMurray beds developed fabrics of Mn 2+ -rich ferroan calcite micro-spherulites. These carbonate beds represent saline lacustrine depositional environments that resulted from the lake bottom sediments ingressed from below by Mn 2+ -Fe 2+ -rich carbonate-saturated brines. These up-section migrations of Devonian formation water were sourced from dissolution trends developed in limestone and haliteanhydrite beds of the underlying Devonian Prairie Evaporite during Cordilleran deformation of the Alberta Basin foreland. These brines ascended to the overlying McMurray Formation sediments along dissolution-collapse structures such as breccia pipes, sinkholes and margins of differentially subsided Upper Devonian fault blocks. The up-section migration of a sulphate-saturated Fe 2+ and Mn 2+ -rich brine resulted in the ingress of a lower McMurray lacustrine bottom sediment at a site associated with the development of a peat mire terrain. Microbial redox of the lake bottom sediment resulted in a carbonate bed of micro-spherulitic fabrics of Mn-rich siderite interwoven with pyrite laminae. Subsequent salt dissolution events and up-section migrations of Devonian brine during deposition of the middle and upper McMurray intervals resulted in similar carbonate-saturated but sulphate-poor chemistry. These saline flows also ingressed lacustrine bottom sediments below, and resulted in limestone beds of densely packed spherulitic fabrics of Mn-ferroan calcite, not siderite. These deposits provide insight into largely unknown dispositions of voluminous brine resulting from salt dissolution trends | 657 BROUGHTON How to cite this article: Broughton, P.L. (2022) Salt dissolution tectonism and origin of lacustrine carbonate beds: Mn-Fe-calcite and Mn-siderite micro-spherulite fabrics of the Lower Cretaceous McMurray Formation,

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What does the ichnological content of the Middle McMurray Formation tell us?

Cited by 24 publications

References 65 publications

Evolution of an ancient (Lower Cretaceous) marginal‐marine system from tide‐dominated to wave‐dominated deposition, McMurray Formation

Evolution of an ancient (Lower Cretaceous) marginal‐marine system from tide‐dominated to wave‐dominated deposition, McMurray Formation

Using ichnological relationships to interpret heterolithic fabrics in fluvio‐tidal settings

Salt dissolution tectonism and origin of lacustrine carbonate beds: Mn‐Fe‐calcite and Mn‐siderite micro‐spherulite fabrics of the Lower Cretaceous McMurray Formation, Athabasca Oil Sands deposit, western Canada

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