| Title | U-Pb zircon ages of volcanic ashes integrated with ammonite biostratigraphy, Fernie Formation (Jurassic), Western Canada: supplementary data files |
| Download | Downloads |
| |
| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Pana, D I; Poulton, T P; Heaman, L M |
| Source | Geological Survey of Canada, Open File 8472, 2018, 2 pages, https://doi.org/10.4095/313116  Open Access |
| Year | 2018 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| Related | This 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 format | readme
|
| File format | pdf (Adobe® Reader®); rtf; xlsx (Microsoft® Excel®); xls (Microsoft® Excel®); dbf (ESRI® ArcExplorer(TM) and ArcReader(TM)); shp (ESRI® ArcExplorer(TM) and ArcReader(TM)); csv |
| Province | Alberta; British Columbia |
| NTS | 82F; 82J; 82N; 82O; 83B; 83C |
| Area | Rocky Mountains; Cadomin; Nordegg; Fernie |
| Lat/Long WENS | -118.0000 -114.0000 53.0000 49.0000 |
| Subjects | geochronology; 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 |
| Program | GEM2:
Geo-mapping for Energy and Minerals TransGEM |
| Released | 2018 11 27 |
| Abstract | The 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. |
| GEOSCAN ID | 313116 |
|
|