BC75 44, upper Tindir Creek (Tonian of Canada)

Where: Yukon, Canada (65.3° N, 141.0° W: paleocoordinates 0.0° N, 0.0° E)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Fifteenmile Group, Tonian (1000.0 - 850.0 Ma)

• Originally assigned to "Unit 5" of the upper Tindir Group, and thought to be either latest Neoproterozoic or earliest Cambrian. Stratigraphic revisions by Macdonald et al. (2010) determined that the unit is the upper part of the Fifteenmile Group and U/Pb radiometric ages constrained the fossiliferous units to between 811.5 and 717.4 Ma.

• bed-level stratigraphic resolution

Environment/lithology: deep subtidal ramp; lithified, gray, cherty/siliceous lime mudstone

• We have located no evidence of mud cracks, evaporite minerals or other indications of subaerial exposure, or of herring-bone cross-bedding suggestive of littoral conditions, or of ripple marks implying wave influence, and hence conclude that the fossiliferous limestones represent subtidal accumulation below wave base. The abundant and diverse benthic cyanobacteria indicate accumulation within the photic zone. More persistent fragmentation and slight disarrangement of chert layers toward the suggest higher-energy conditions for the uppermost part of the section. There were energetic pulses that ripped up previously deposited material including microfossiliferous chert, likely from the centimeter-scale channeling and possibly storms.
• Dark gray to black, thin-bedded, platy limestone with chert nodules.

Size class: microfossils

Preservation: concretion, permineralized, original phosphate, original carbon

Collected by Bruce Clardy in 1975

Collection methods: chemical, peel or thin section

• Repository: University of Alaska Museum

Primary reference: C. W. Allison and S. M. Awramik. 1989. Organic-walled microfossils from earliest Cambrian or latest Proterozoic Tindir Group rocks, northwest Canada. Precambrian Research 43:253-294 [P. Cohen/M. Hernandez/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 227536: authorized by Matthew Clapham, entered by Matthew Clapham on 15.10.2022

Creative Commons license: CC BY (attribution)

Taxonomic list

Biocatenoides
  -
Biocatenoides sp. Schopf 1968
Microagglomeratus borealis
  -
 Life -
Fusilabellum brevistriatum n. sp. Awramik 1989
Tindiromacula hofmanni n. sp. Allison 1989
Hyalocyrillium clardyi Allison 1989
Archeomyces dimakeloides
  -
Archeomyces dimakeloides n. sp. Allison 1989
Coccogoneae
 Pleurocapsales - Pleurocapsaceae
 Chroococcales - Chroococcaceae
Eosynechococcus sp. Hofmann 1976
Sphaerophycus parvum Schopf 1968
Tetraphycus major Oehler 1978
Hormogoneae
  -
Siphonophycus sp., "Eomycetopsis robusta" = Siphonophycus robustum
Siphonophycus sp. Schopf 1968
"Eomycetopsis robusta" = Siphonophycus robustum Schopf 1968
 Oscillatoriales - Oscillatoriaceae
Heliconema bulbosa n. sp. Allison 1989
Palaeolyngbya minor Schopf and Blacic 1971
Calyptothrix annulata Schopf 1968
Halythrix cf. nodosa Schopf 1968
  -
Veteronostocale cf. amoenum Schopf and Blacic 1971
 Nostocales - Rivulariaceae
Caudiculophycus sp. Schopf 1968
Myxococcoides minor
  -
Myxococcoides
  -
 Life -