Abstract

Seven discrete faunal zones comprise the late Upper Devonian, Famennian succession in western Canada. These, in descending order are:

DFM 7 Zone of Crurithyris youngstownensis

DFM 6 Zone of Gastrodetoechia u. utahensis

DFM 5 Zone of Cyrtiopsis normandvillana

DFM 4 Zone of Cyrtiopsis nahanniensis

DFM 3 Zone of Cyrtiopsis prepta

DFM 2 Zone of Cyrtiopsis mimetes

DFM 1 Zone of Eoparaphorhynchus walcotti

Stratigraphically the beds divide into a lower, Clastic Succession (DFM 1 to 3) and an upper, Carbonate Succession (DFM 4 to 7). However, in parts of the region carbonate units pass laterally to argillaceous units, notably in the case of the Big Valley Limestone and Shale to the euxinic Lower Exshaw Black Shale.

Faunal assemblages show a high degree of difference between the “Northern Province” (District of Mackenzie plus northeastern British Columbia) and the “Southern Province” (Rocky Mountains of Alberta and British Columbia, plus contiguous plains eastward as far as Saskatchewan). The two faunal provinces are separated by the “Peace River High”.

Determination of equivalent conodont zones serves to place the regional brachiopod zonation in the broader context of the World Standard Succession. Conodont control confirms the fact that in western Canada, non-sequences exist:

1) between the Sassenach Formation and Morro Member of the Palliser Formation;

2) between the Morro and Costigan members of the Palliser Formation;

3) between the Costigan Member and Lower Black Shale Member of the Exshaw Formation;

4) between the Lower and Upper members of the Exshaw.

Under the plains, the relationship between the Stettler and Big Valley Formations likewise is hiatal.