District of Mackenzie, Sunblood Mountain Isotelus Biofacies (A-190) (Ordovician of Canada)

Also known as A 190

Where: Northwest Territories, Canada (61.6° N, 125.8° W: paleocoordinates 6.8° N, 58.0° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Esbataottine Formation, Blackriveran (457.3 - 449.6 Ma)

• formation-level stratigraphic resolution

Environment/lithology: deep subtidal; argillaceous, silty limestone

• "[H]omogeneous, probably soft bottom, carbonate and mud substrate, deposited under quiet water conditions on a wide shelf ranging from the littoral to, possibly, deep sub-littoral zones."
• "[H]omogeneous sequence of micrites and microbiosparites, commonly silty and argillaceous. The bedding is regular to nodular and generally thin (3-8 cm) to medium (8-20 cm), rarely thickly bedded. Sand-size components are absent and more common biotic contributors to skeletal sands (pelmatozoans, heavy-shelled brachiopods, algae, corals, or stromatoporioids) are rare or absent."

Size classes: macrofossils, microfossils

Preservation: replaced with silica

Collection methods: Also includes leperditellid and oepikellid ostracods and bryozoans.

Primary reference: B. D. E. Chatterton and R. Ludvigsen. 1976. Silicified Middle Ordovician trilobites from the South Nahanni River Area, District of Mackenzie, Canada. Palaeontographica Abteilung A 154(1-3):1-106 [S. Holland/T. Hanson/T. Hanson]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 25930: authorized by Steven Holland, entered by Tori Hanson on 28.09.2002

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Trilobita
 Asaphida - Asaphidae
Nahannia sp., Isotelus sp.
Nahannia sp. Chatterton and Ludvigsen 1976 trilobite
Isotelus sp. Dekay 1824 trilobite
 Corynexochida - Illaenidae
Bumastoides sp., Nanillaenus sp.
Bumastoides sp. Whittington 1954 trilobite
Nanillaenus sp. Jaanusson 1954 trilobite
Strophomenata
 Strophomenida - Strophomenidae
Strophomena sp.
Strophomena sp. Rafinesque and De Blainville 1824