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TitleU-Pb zircon ages of volcanic ashes integrated with ammonite biostratigraphy, Fernie Formation (Jurassic), Western Canada: supplementary data files
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorPana, D I; Poulton, T P; Heaman, L M
SourceGeological Survey of Canada, Open File 8472, 2018, 2 pages, Open Access logo Open Access
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedThis publication accompanies U-Pb zircon ages of volcanic ashes integrated with ammonite biostratigraphy, Fernie Formation (Jurassic), western Canada, with implications for Cordilleran-Foreland Basin connections and comments on the Jurassic time scale
File formatreadme
File formatpdf (Adobe® Reader®); rtf; xlsx (Microsoft® Excel®); xls (Microsoft® Excel®); dbf (ESRI® ArcExplorer(TM) and ArcReader(TM)); shp (ESRI® ArcExplorer(TM) and ArcReader(TM)); csv
ProvinceAlberta; British Columbia
NTS82F; 82J; 82N; 82O; 83B; 83C
AreaRocky Mountains; Cadomin; Nordegg; Fernie
Lat/Long WENS-118.0000 -114.0000 53.0000 49.0000
Subjectsgeochronology; stratigraphy; paleontology; tectonics; radiometric dating; uranium lead dating; zircon dates; mass spectrometer analysis; biostratigraphy; fossils; bedrock geology; lithology; volcanic rocks; volcanic ash; intrusive rocks; sedimentary rocks; shales; limestones; sandstones; bentonite; basin evolution; tectonic history; magmatism; volcanism; source areas; Fernie Formation; Nordegg Member; Ammonites; Western Canada Sedimentary Basin; Rocky Mountain Fold-and-thrust Belt; Omineca Belt; Quesnellia Terrane; Phanerozoic; Mesozoic; Jurassic
ProgramGEM2: Geo-mapping for Energy and Minerals TransGEM
Released2018 11 27
AbstractThe Jurassic system of the Western Canada Sedimentary Basin records the transition in its tectonic setting from a "passive" back-arc platformal basin to a foreland basin at the western margin of ancient North America. In the accompanying report (Pana et al., 2018), we report new U-Pb zircon ages from bentonite layers and from probable volcanic ash components of clastic detritus in other strata of the Fernie Formation, which encompasses most of the Jurassic in the western portions of the basin and which is now deformed in the Rocky Mountain fold-and-thrust belt. The bentonite ages come from the lower Nordegg Member (Pliensbachian) and an equivalent ash layer in the Lower Fernie phosphatic shale. Detrital zircon spectra from the Bathonian Gryphaea Bed silty limestone and the zircon ages from the mainly Oxfordian Green Beds glauconitic sandstone also are likely indicative of contemporaneous ash-falls. The presence of multiple volcanic ashes throughout the Jurassic system in the Western Canada Sedimentary Basin supports tectonostratigraphic models with relatively nearby western magmatic activity. The southeastern Omineca crystalline belt and Quesnellia terrane contain magmatic rocks with ages that could account for all of the Fernie ashes, and are closest to the depositional basin, but source terranes farther afield cannot be ruled out.
Summary(Plain Language Summary, not published)
The dating of volcanic ashes in the Jurassic strata of the Western Canadian Sedimentary Basin by radioactive decay allows correlation of their ages with more westerly volcanic events in the Cordillera. This contributes to interpretations of their accretionary history to the North American continent. These ashes occur within strata that contain fossils, so that they contribute to our calibration of the "absolute" time scale (millions of years) with respect to the "relative" biostratigraphic scale based on the succession of fossils. Our data fill a gap of about 50 million years in the time scale which is not yet reliably dated anywhere, and calls into question some of the "best guesses" that are incorporated into the current time scale.

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