SMA 413, upper Tindir Creek (Tonian of Canada)

Where: Yukon, Canada (65.3° N, 140.9° W: paleocoordinates 0.0° N, 0.0° E)

• coordinate estimated from map

• small collection-level geographic resolution

When: Craggy Dolomite Formation (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: permineralized, original carbon, replaced with silica

Collection methods: peel or thin section

• Repository: Canadian National Collection; University of California, Santa Barbara

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 227534: authorized by Matthew Clapham, entered by Matthew Clapham on 15.10.2022

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Myxococcoides
  -
Myxococcoides cantabrigiensis
Chlorococcaceae
  - Chlorococcaceae
Palaeoanacystis vulgaris