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Title58 million and 25 years in the making: stratigraphy, fauna, age, and correlation of the Paleocene/Eocene sedimentary strata at Oyster Bay and adjacent areas, southeast Vancouver Island, British Columbia
AuthorHaggart, J W; Cockburn, T; McNeil, D ORCID logo; Mahoney, J B
Source12th British Columbia Paleontological Symposium, 2018, Courtenay, abstracts; 2018 p. 28-30
Year2018
Alt SeriesNatural Resources Canada, Contribution Series 20180158
PublisherBritish Columbia Paleontological Alliance
Meeting12th British Columbia Paleontology Symposium; Courtenay, British Columbia; CA; August 17-20, 2018
Documentbook
Lang.English
Mediapaper; digital
File formatpdf
ProvinceBritish Columbia
NTS92A; 92B; 92E; 92F; 92G/04; 92K/03; 92K/04; 92K/05; 92L; 102I
AreaVancouver Island; Oyster Bay; Campbell River; Shelter Point
Lat/Long WENS-128.5000 -123.0000 51.0000 48.2500
Subjectsstratigraphy; paleontology; Eocene; Paleocene; Upper Cretaceous; Campanian; biostratigraphy; stratigraphic correlations; fossils; macrofossils; microfossils; faunas; fossil assemblages; fossil zones; bedrock geology; lithology; sedimentary rocks; clastics; sandstones; stratigraphic analyses; lithostratigraphy; radiometric dating; zircon dates; Nanaimo Group; Spray Formation; Martinez Formation; Keasey Formation; Lodo Formation; Gastropods; Ammonites; Bivalves; Inoceramids; Molluscs; Foraminifera, Benthic; Appian Way Beds; Phanerozoic; Cenozoic; Tertiary; Mesozoic; Cretaceous
Illustrationsphotographs; photomicrographs
ProgramGSC Pacific Division, Canadian Crustal Deformation Service
Released2018 08 01
AbstractClastic strata exposed in the intertidal platform of Oyster Bay, approximately 10 km south of Campbell River, Vancouver Island, as well as along lower Oyster River, an additional 4 km still farther south, have preoccupied paleontologists substantially over the past 25 years. No pre-glacial strata were recognized in this area by Muller and Jeletzky (1970). Richards (1975) described an abundant fauna in the beds at Shelter Point, approximately 2 km north of the Oyster Bay exposures, including the crab Longusorbis and associated ammonites and inoceramid bivalves, and he assigned these beds to the Spray Formation of the Nanaimo Group. This information, combined with the very low dip of the Oyster Bay strata and their general lithological similarity with the coarse clastic strata found commonly in the Nanaimo Group, suggested a Late Cretaceous (Campanian) age of the Oyster Bay strata.
Beginning in the 1980s, amateur collectors from Vancouver Island began amassing significant collections of fossils from the strata of southern Oyster Bay that are found several hundred metres southeast of the local road called "Appian Way," thus providing the informal moniker "Appian Way Beds" for these localized exposures. While these collections included a great diversity of gastropod, bivalve, nautiloid, scaphopod, echinoderm, and coral specimens, as well as impressive collections of plant materials, much previously undescribed, no taxa found commonly in Campanian strata of the Nanaimo Group were noted in these collections; particularly lacking were ammonites and inoceramid bivalves. For this reason, the hypothesis began to emerge that the "Appian Way Beds" of Oyster Bay were of younger, post-Cretaceous, age than thought previously. Just how young, however, has been a source of some controversy, with different parties continuing to favour the traditional Campanian age (based on lithostratigraphy), others a Paleocene age, and still others an Eocene age (based on plant macrofossils).
We have studied the foraminiferal and marine mollusk faunas of the Appian Way Beds of Oyster Bay, and we have also collected sandstone samples from the strata for detrital zircon analysis. The youngest detrital zircons present in our samples indicate the strata have a Maximum Depositional Age of 63.1┬▒1.0 million years, or early Paleocene (Danian); the strata have to be younger than this and we can thus rule out a Cretaceous age for them. The gastropod assemblage present in the beds is particularly diverse. Several of the gastropods found in the Appian Way Beds are found in the Martinez Formation of California, which was originally described as Eocene (Dickerson, 1914), but is now considered to be late Paleocene in age (Squires, 2003). Important taxa of gastropod mollusks present in the assemblage include Eocypraea aff. martini (Dickerson 1914), Leptomaria aff. vacavillensis (Hickman 1976), ?Serratocerithium usanium Compton 1944, Drepanocheilus aff. exilis (Gabb 1864), and Pseudoperissolax blakei (Conrad 1855), collectively suggesting a late Paleocene to Eocene age.
Based on foraminifers, we can also rule out late Eocene and younger as a possible age for the Appian Way strata as late Eocene assemblages are well described from Vancouver Island, Washington, and Oregon, including the Keasey Formation of Oregon, and are not comparable to that from Appian Way. There is no single foraminiferal assemblage in the literature that is identical to that seen in the Appian Way samples, but the closest is from the "Lodo Formation" of California, dated as latest Paleocene (Prothero, 2001). Silicosigmoilina californica Cushman & Church 1927 is the most abundant foraminifer at Appian Way. Mallory (1959) established a S. californica Zone from the Ynezian (Paleocene) Lodo Formation at Media Agua Creek, Kern County, California, but this species is not confined to that zone, and probably has a total range of Coniacian to Eocene. Several other species in the Appian Way collection appear similar to Lodo Formation foraminifers. Collectively, the faunal data from the Appian Way Beds suggest the strata are earliest Eocene or possibly latest Paleocene in age.
Summary(Plain Language Summary, not published)
This is an abstract of a paper to be presented at a scientific meeting. The authors have studied local rock exposures on southeast Vancouver Island and determined their likely age based on their fossil content. This is the first time rocks of this age have been found in this region of British Columbia. The authors discuss the fossil gastropods (snails) and foraminifers (single-celled marine forms) found in the rocks and the value of these fossils in providing correlation with similar age rocks in other areas of western North America.
GEOSCAN ID308471

 
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