| Title | New occurrences of Oldhamia in eastern Yukon, Canada: stratigraphic context and implications for Cambrian deep-marine biostratigraphy |
| Author | MacNaughton, R B; Moynihan, D P; Roots, C F; Crowley, J L |
| Source | Ichnos: An International Journal For Plant and Animal Traces vol. 23, no. 1-2, 2016, 33-52 pages, https://doi.org/10.1080/10420940.2015.1127232 |
| Year | 2016 |
| Alt Series | Earth Sciences Sector, Contribution Series 20150359 |
| Publisher | Taylor-Francis |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Yukon |
| NTS | 105O; 105J |
| Area | Selwyn Basin |
| Lat/Long WENS | -132.0000 -130.0000 64.0000 62.0000 |
| Subjects | geochronology; marine geology; paleontology; regional geology; stratigraphy; chronostratigraphy; index fossils; paleobiology; invertebrates; fossil distribution, strata; marine deposits;
biostratigraphy; Selwyn Basin; Cambrian |
| Illustrations | location maps; geologic maps; stratigraphic cross-sections; photographs; graphs; tables |
| |
| Program | Mackenzie Corridor, Shield to Selwyn, GEM2: Geo-mapping for Energy and Minerals |
| Abstract | For over a century, the ichnogenus Oldhamia has been used as an index fossil for Cambrian deep-marine siliciclastic successions. New specimens from the Cambrian of Selwyn Basin, eastern Yukon, Canada,
provide an opportunity to constrain the chronostratigraphic range of Oldhamia and test its potential for more detailed biozonation. The upper part of Narchilla Formation (Arrowhead Lake Member) yields O. antiqua, O. curvata, O. flabellata, and O.
radiata. The overlying Gull Lake Formation yields a less diverse assemblage of O. antiqua, O. curvata, and O. flabellata. The upward disappearance of O. radiata is consistent with models that infer increasing complexity of Oldhamia ichnospecies
through time but may also be a function of limited sampling. Regional stratigraphic correlations suggest Oldhamia appeared in Arrowhead Lake Member during Cambrian Stage 3. Archaeocyathans and trilobites from Gull Lake Formation confirm that Oldhamia
was present during Cambrian Stages 3 to 4. A younger age limit on Oldhamia in Selwyn Basin is provided by synvolcanic detrital zircons recovered from the base of the overlying Old Cabin Formation, which yield an age of 499.89 § 0.14 Ma (earliest
Guzhangian). Oldhamia appears to be a reliable index fossil for Cambrian Series 2 and Series 3 in Selwyn Basin. |
| Summary | (Plain Language Summary, not published)
Manuscript reports new occurrences of fossilized burrow networks from ancient rocks in eastern Yukon that were deposited in a deep-marine basin. The
burrow networks are collectively referred to by the name "Oldhamia". Oldhamia has long been known to to indicate that rocks containing it probably were deposited during the Cambrian Period of Earth history (485-542 million years ago), but the time
range of Oldhamia within the Cambrian is more controversial. We are able to show that Oldhamia first appeared more than 20 million years after the start of the Cambrian and had disappeared after another 20 million years. As a result, Oldhamia can now
be used as a well-constrained "index fossil" for dating deep-water Cambrian rocks in NW Canada. |
| GEOSCAN ID | 297448 |
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