Revised Regional Frasnian Sequence Stratigraphic Framework, Alberta Outcrop and Subsurface

Wong, Pak K.; Weissenberger, John A.W.; Gilhooly, Murray G.

doi:10.2110/sepmsp.107.05

Cited by 4 publications

(8 citation statements)

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“…() is slightly different from that of Wong et al . (); their third‐order sequence 7 is a combination of Woodbend Sequence 4 and Winterburn Sequence 1 and includes the Mount Hawk Formation containing the two mud‐mounds.…”

Section: Geological Settingmentioning

confidence: 99%

“…It is subdivided into reef facies comprising the Zeta Lake Member, and off-reef facies, the Lobstick, Bigoray, Cynthia and Wolf Lake members in ascending order (Chevron Exploration Staff, 1979). The Nisku Formation comprises Winterburn Sequence 1 (Wong et al, 2016). This interval contains so-called 'pinnacle reefs' along the south-eastern side of the Winterburn Basin (Chevron Exploration Staff, 1979).…”

Section: Geological Settingmentioning

confidence: 99%

“…The latter interpretation seems more likely, due to the backstepping nature in the upper Lobstick to Bigoray interval (Switzer et al, 1994;Wendte et al, 1995). The sequence stratigraphic scheme of Whalen et al (2008) is slightly different from that of Wong et al (2016); their third-order sequence 7 is a combination of Woodbend Sequence 4 and Winterburn Sequence 1 and includes the Mount Hawk Formation containing the two mud-mounds.…”

Section: Geological Settingmentioning

confidence: 99%

“…The Lobstick Member was interpreted as the lowstand systems tract of the Winterburn Sequence 1 (Potma et al., ; Wong et al., ). Alternatively, the lower part of Lobstick Member consists of regression deposits, whereas the rest was deposited during transgression (Switzer et al., ; Villéger, ).…”

Section: Geological Settingmentioning

confidence: 99%

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Composition and origin of stromatactis‐bearing mud‐mounds (Upper Devonian, Frasnian), southern Rocky Mountains, western Canada

Zhou

Pratt

2019

Sedimentology

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Stromatactis‐bearing mud‐mounds remain an enigmatic reef type despite being common in Palaeozoic ramp settings. Two well preserved Upper Devonian (Frasnian) mud‐mounds in the Mount Hawk Formation crop out side by side in the southern Rocky Mountains of west‐central Alberta and provide an opportunity to develop a new case study that can be compared with the other coeval examples, such as those well‐known ones in southern Belgium, as well as evaluate competing hypotheses for mud‐mound formation. The southern mud‐mound is 46·2 m thick and 38·6 m wide at the base, whilst the northern one is 53·3 m thick and 72·2 m wide at the base, and they exhibit three or four growth stages indicated by interfingering and onlapping geometries with flanking strata. The biota is diverse, but fossils only occupy 10·7% by volume, among which sponge spicules, echinoderms, ostracods, brachiopods and calcimicrobes belonging to Girvanella and Rothpletzella are the most common. Five microfacies are discriminated in the mud‐mounds: biomicrite, clotted micrite, spiculite, stromatolite and laminite, with clotted micrite comprising the largest proportion. There is no internal vertical or lateral palaeoecological zonation, and the presence of calcimicrobes and calcareous algae throughout indicates accretion entirely within the photic zone, in a deeper ramp setting seaward of a large carbonate platform to the east. Stromatactis is abundant and the cavities were mostly due to excavation by currents rather than physical collapse of spiculate siliceous sponges. Formation of lime mud involved a combination of multiple organisms, mechanisms and processes. Cyanobacteria were integral to mud‐mound frame‐building and accretion because they stabilized the surface, often permineralized to form Girvanella and provided organic matter that was decomposed by bacteria. This induced precipitation of micrite, forming early indurated rigid masses, evidenced by the presence of intraclasts, stromatactis cavities, isopachous marine cements, absence of bioturbation and rare synsedimentary brittle deformation. The same microbial components, invertebrate biota and clotted micrite occur in underlying strata, suggesting that there was a protracted period of potential mud‐mound initiation before the exact conditions arose to trigger it. The ramp setting, antecedent sea floor topography and relative sea‐level likely contributed together to control this. This study indicates that mud‐mound formation was controlled by a combination of processes, but they are essentially a microbial buildup.

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Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

See 2 more Smart Citations

Composition and origin of stromatactis‐bearing mud‐mounds (Upper Devonian, Frasnian), southern Rocky Mountains, western Canada

Zhou

Pratt

2019

Sedimentology

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“…The Duvernay Formation shales are organic-rich, calcareous to argillaceous/siliceous shales that were deposited during the Frasnian-age (382–372 Ma) Woodbend Group (Fig. 1 ), when the WCSB was a passive margin on the western passive margin of the North American craton 31 . The most up to date conodont stratigraphy from the WCSB places the lower portion of the Duvernay in the punctata conodont zone (Montagne Noire (MN) 5/6) and the upper Duvernay mostly in the hassi conodont zone (MN7-10) 31 .…”

Section: Introductionmentioning

confidence: 99%

Mapping amorphous SiO2 in Devonian shales and the possible link to marine productivity during incipient forest diversification

Corlett

Feng

Playter

et al. 2023

Sci Rep

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Silica cycling in the world’s oceans is not straightforward to evaluate on a geological time scale. With the rise of radiolarians and sponges from the early Cambrian onward, silica can have two depositional origins, continental weathering, and biogenic silica. It is critical to have a reliable method of differentiating amorphous silica and crystalline silica to truly understand biogeochemical and inorganic silica cycling. In this study, opal-A is mapped across the Western Canada Sedimentary Basin in the Late Devonian Duvernay Formation shales using longwave hyperspectral imaging alongside geochemical proxies that differentiate between crystalline and amorphous SiO2, during the expansion of the world’s early forests. Signaled by several carbon isotope excursions in the Frasnian, the punctata Event corresponds to the expansion of forests when vascular land plants develop seeds and deeper root networks, likely resulting in increased pedogenesis. Nutrients from thicker soil horizons entering the marine realm are linked to higher levels of primary productivity in oceans and subsequent oxygen starvation in deeper waters at this time. The results of this study reveal, for the first time, the spatial distribution of amorphous SiO2 across a sedimentary basin during this major shift in the terrestrial realm when forests expand and develop deeper root networks.

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Upper Devonian (Frasnian) stromatactis-bearing mud mounds, western Alberta, Canada: reef framework dominated by peloidal microcrystalline calcite

Zhou

Pratt

2019

Journal of Sedimentary Research

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Two well-preserved mud mounds, approximately 50 m thick, in the Mount Hawk Formation (Upper Devonian, Frasnian) in western Alberta provide an unparalleled opportunity to study the microstructure of this reef type in detail for this time interval. This reveals that they are composed dominantly of peloidal sediments—more than a quarter of mud mound volume—along with dense micrite, particulate micrite, bioclasts, and stromatactis cavities. Five types of peloids are differentiated: bacterial, cyanobacterial, bioclastic, intraclastic, and pseudo-peloids. Bacterial peloids were generated by bacterial metabolic activities with possibly some contribution from organomineralization in areas within spicular networks. Three subtypes of cyanobacterial peloids are distinguished based on whether they are physically reworked calcified filaments, aggregates of calcified coccoids, or precipitated within stromatolite-forming cyanobacterial mats or biofilms. Bioclastic peloids are fully micritized fragments of skeletons and shells. Intraclastic peloids are eroded fragments of early-lithified matrix. Pseudo-peloids represent artifacts of poorly preserved sponge spicular networks reflecting the interplay between dissolution of spicules and organomineralization. The distribution of the various peloid types shows specificity in different microfacies. They prove to be valuable paleoecological indicators, and taken together suggest that the mud mounds accreted within the photic zone above storm wave base but below the fair-weather wave base, during deposition of a transgressive and perhaps highstand systems tracts. They are the products reflecting a dynamic balance between constructional versus destructive processes. Bacterial peloids combined with dense micrite constitute the framework, which in turn makes up close to 40% of the mud mounds. This indicates that microbial activities are responsible for the early-indurated framework. The onset of bacterial peloid formation in the bedded sediment immediately underlying the mud mounds further demonstrates that it may have been a necessary precursor to mud-mound initiation. Bacterial peloids appear to characterize most Paleozoic and Mesozoic reefal mud mounds as an essential framework element.

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Revised Regional Frasnian Sequence Stratigraphic Framework, Alberta Outcrop and Subsurface

Cited by 4 publications

References 0 publications

Composition and origin of stromatactis‐bearing mud‐mounds (Upper Devonian, Frasnian), southern Rocky Mountains, western Canada

Composition and origin of stromatactis‐bearing mud‐mounds (Upper Devonian, Frasnian), southern Rocky Mountains, western Canada

Mapping amorphous SiO2 in Devonian shales and the possible link to marine productivity during incipient forest diversification

Upper Devonian (Frasnian) stromatactis-bearing mud mounds, western Alberta, Canada: reef framework dominated by peloidal microcrystalline calcite

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