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TitleProbable Early Callovian ammonite horizons from northwestern British Columbia, Canada
AuthorPoulton, T P; Hall, R L
SourceJournal of South American Earth Sciences vol. 95, 102214, 2019 p. 1-15,
Alt SeriesNatural Resources Canada, Contribution Series 20180070
PublisherPergamon-Elsevier Science Ltd
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia
Lat/Long WENS-130.0000 -129.5000 57.7500 57.5000
SubjectsScience and Technology; sedimentology; paleontology; Nature and Environment; Callovian; sedimentary basins; faunal studies; Bower Basin; Phanerozoic; Mesozoic; Jurassic
Illustrationslocation maps; cross-sections; Landsat images; stratigraphic sections; photographs; sections
ProgramGEM: Geo-mapping for Energy and Minerals GSC Science Laboratory Network
Released2019 06 21
AbstractThis report describes and illustrates probably Early Callovian ammonites from the Todagin and Tsatia mountains area, at the northern margin of the Bowser sedimentary basin, northwestern British Columbia, western Canada. They include East Pacific eurycephalatinid species Lilloettia lilloetensis Crickmay, Xenocephalites bearpawensis Imlay, and Iniskinites cepoides (Whiteaves), as well as a new East Pacific pseudoperisphinctinid species, Homoeoplanulites todaginensis n. sp., and Chaffatia. These ammonites comprise the next two recognizable faunal associations below a previously reported, probably late Early or early Middle Callovian, fauna on the south flank of nearby Tsatia Mountain containing Cadoceras with Indosphinctes. If their determination as Early Callovian is correct, based on the close similarities of H. todaginensis with European forms, it involves an extension of the range of North American Iniskinites above its currently supposed Late Bathonian upper limit. It remains possible that the pseudoperisphinctids represent an endemic East Pacific group older than their European homeomorphs, and perhaps as old Late Bathonian, which would not be inconsistent with the associated Eurycephalitinae.
Summary(Plain Language Summary, not published)
This report presents results from a deceased university colleague who had continued working on materials from the Legacy FGP Bowser Basin project, NW B.C. Ammonites are the most precise tool for understanding the age of their enclosing strata during the Jurassic period and are critical for understanding relationships among tectonic events in the Cordillera (Jurassic rocks are mineral-rich), the Western Canada Sedimentary Basin (WCSB; hydrocarbons), and global events. It contributes data and a partial solution for a time interval which remains one of the most difficult for regional and global correlations because of nearly mutually exclusive fossil faunas between the eastern Pacific area and other parts of the world. It affects correlations within and beyond the WCSB.

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