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TitleVariation in Lower Cretaceous coastline morphology and resultant depositional conditions along the Scotian Margin, Canada
AuthorDafoe, L TORCID logo; MacRae, R A; Correia, VORCID logo; Fensome, R A
Source36th International Meeting of Sedimentology, abstracts book; 2023 p. 356
Alt SeriesNatural Resources Canada, Contribution Series 20220580
PublisherInternational Association of Sedimentologists
Meeting36th International Meeting of Sedimentology; Dubrovnik; HR; June 12-16, 2023
Mediapaper; digital; on-line
File formatpdf
ProvinceEastern offshore region
Lat/Long WENS -64.0000 -57.0000 45.0000 43.0000
Subjectssurficial geology/geomorphology; Lower Cretaceous; coastal studies; morphology; depositional analyses; depositional environment
ProgramEnergy Geoscience Offshore Geoscience Collaboration
Released2023 06 12
AbstractThe onset of North Atlantic rifting along the Scotian Margin, offshore eastern Canada, began in the Middle Triassic, with eventual breakup taking place in the Early-Middle Jurassic. Resultant basins include a predominantly siliciclastic passive margin succession. In particular, the Lower Cretaceous interval is characterized by strata reported from a variety of marine, shallow marine, and fluvial settings. In concert with ongoing palynological and other analyses, the present study aims to contribute to an event stratigraphic scheme by focussing on paleoenvironmental and eventual sequence stratigraphic interpretations. Ichnological and sedimentological analyses of conventional cores from two wells were used to build a facies model, with an initial focus on a 170 m-thick, relatively continuous succession of the Barremian to (?)Aptian Upper Member of the Missisauga Formation. Wave-dominated marine conditions initially prevailed with oolitic sandy limestones and local distal Skolithos Ichnofacies assemblages. Successive restricted bay and possible deltaic deposits show an upward decrease in wave-dominance, with impoverished archetypal Cruziana Ichnofacies suites suggesting deposition within a wave-influenced estuary. Overlying sandstone bodies are mostly trough cross-bedded, but contain herringbone cross-stratification, cyclical bedding, wood with Teredolites borings, and locally highly impoverished Skolithos Ichnofacies suites and are interpreted as tidal channels. The concurrence of tidal channel, tidal flat, barrier shoreface, and restricted bay facies, however, indicates deposition within a mixed wave- and tide-influenced estuarine setting. Deposition then shifted to the outer estuary, with barrier shoreface, tidal flat, and restricted bay deposits dominating the succession and characterized by impoverished Cruziana and local Skolithos Ichnofacies assemblages. The top of the Missisauga Formation shows a return to marine conditions with storm influence indicated by hummocky cross-stratification, weakly stressed Cruziana Ichnofacies suites, and more diverse marine macrofauna. Evidently, depositional conditions varied in the Early Cretaceous as a function of varying coastline morphology that can be linked to overall transgressive and regressive events.
Summary(Plain Language Summary, not published)
Offshore of Nova Scotia is a thick package of sedimentary rocks that accumulated during the opening of the North Atlantic Ocean. These rocks have been studied over the last few decades, but our focus is specifically on the Lower Cretaceous part of the sedimentary package. We aim to develop an event stratigraphy, with this part of the study detailing the environments that the rocks were originally deposited in, including shallow marine and more normal marine settings. In future, this will be combined with age information to produce a comprehensive assessment of the Lower Cretaceous interval along the margin, supporting resource development in the region.

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