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TitleLower Triassic river-dominated deltaic successions from the Sverdrup Basin, Canadian Arctic
AuthorMidwinter, D; Hadlari, T; Dewing, K
SourcePalaeogeography, Palaeoclimatology, Palaeoecology vol 476, (2017), 2017 p. 55-67, https://doi.org/10.1016/j.palaeo.2017.03.017
Year2017
Alt SeriesEarth Sciences Sector, Contribution Series 20160435
PublisherElsevier
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthwest Territories; Nunavut
NTS120; 28; 29; 340; 38; 39; 48; 49; 540; 58; 59; 68; 69; 78; 79; 88; 89; 98; 99
Lat/Long WENS-128.0000 -64.0000 84.0000 72.0000
Subjectssedimentology; stratigraphy; deltas; deltaic deposits; braided channels; basins; depositional environment; vegetation; sandstones; sedimentation rates; Permian Mass Extinction
Illustrationslocation maps; stratigraphic columns; tables; photographs; photomicrographs; ternary diagrams
ProgramWestern Arctic Sverdrup Basin, GEM2: Geo-mapping for Energy and Minerals
AbstractSedimentary facies analysis of Lower Triassic deltaic deposits tests a hypothesis that the Latest Permian Mass Extinction influenced sedimentation in the Sverdrup Basin. The pre-existing stratigraphic framework sub-divides the coeval Blind Fiord and Bjorne formations into three T-R sequences and component braid-deltaic successions, with the Latest Permian Mass Extinction at the base of the first. As described here, river-dominated deltaic facies of the first sequence are indicative of high-magnitude flood flows resulting in a predominance of upper flow regime sedimentary structures. River-dominated deltaic facies of the second sequence contain fewer upper flow regime structures recording lower energy flows that generated mostly 3D and 2D dunes. The third sequence marks the furthest progradation of the braid-delta into the basin.

Beyond the gross braided stream characteristics of the three river-dominated deltaic successions, the lower two provide a compelling comparison of depositional environments because they formed in the same basin within only a few millions years and thereby were probably subject to similar boundary conditions. We propose that the lower, Induan, sequence is dominated by upper-flow regime plane beds due to the effect of the Latest Permian Mass Extinction on vegetative cover, whereas the middle sequence is dominated by dune-scale cross-stratification formed by lower magnitude, less flood-type flows during the Olenekian.
Summary(Plain Language Summary, not published)
We studied delta deposits that had formed shortly after one of Earth's greatest mass extinctions at the Permo-Triassic boundary. We found that the sedimentary signature was much like landscapes before the evolution of land plants, and concluded that the mass extinction probably affected vegetation.
GEOSCAN ID299875