MIDDLE-EARLY UPPER DEVONIAN BRACHIOPOD SEQUENCE IN THE KAKWA PROVINCIAL PARK AREA OF EASTERN BRITISH COLUMBIA, WESTERN CANADA

The Devonian brachiopod sequence in Kakwa Park area of eastern B.C. indicate an initial marine flooding of the Peace River Arch and West Alberta Arch as early as the upper Middle varcus Zone, much earlier than the oldest Devonian rocks in the Alberta Rocky Mountains. The lowest marine brachiopod fauna of the lower Flume consists of the oldest element of the Tecnocyrtina brachiopod lineage (T. aff. T. missouriensis). Above this initial assemblage, brachiopod-bearing Flume highstand deposits yield Desquamatia (D.) with Athyris. A second significant marine flooding established middle shelf conditions introducing a diverse Upper Givetian brachiopod fauna including Desquamatia (D.), D. (Seratrypa), Spinatrypa (S.) aff. bellula, Tecnocyrtina missouriensis raaschi, Cyrtina, Nervostrophia sp., and Hypothyridina cf. cameroni, capped by prograding stromatoporoid bank carbonates with lagoonal and reef flat assemblages of Desquamatia (D.), and Cyrtina. The occurrence of H. cf. cameroni suggests an age no younger than the hermanni Zone or lower part of the disparilis Zone. Upper Flume lagoonal and reef flat facies with conodonts of the Icriodus subterminus Fauna include Desquamatia. Very late Givetian marine flooding of the first “Waterways cycle” introduced deeper shelf faunas with elements of the Tecnocyrtina billingsi Zone fauna, including: T. billingsi, Schizophoria lata, Athyris sp. aff. parvula, species of D. (Independatrypa), and Pseudoatrypa. These are succeeded up-section by early Frasnian assemblages with Ladogioides asmenista, Eleutherokomma cf. killeri, Pseudoatrypa aff. P. lineatea, overlain by deposits with E. cf. E. jasperensis, Schizophoria athabascensis, Platyterorhynchus russeli, Strophodonta (S.) calumetensis, and S. (S.) cf. clearwaterensis. Small patch reef deposits in the upper part of the first “Waterways” cycle yield Pseudoatrypa cf. missouriensis, Spinatrypina (Exatrypa) cf. albertensis, and Ladogioides cf. L. pax. A second “Waterways” deepening is marked by the introduction of offshore faunas that include Radiatrypa aff. R. multicostellata, Spinatrypa, and Ladogioides kakwawaensis, with the latter also known from the Maligne Formation of western Alberta indicating a correlation within early Frasnian Montagne Noire conodont Zone 4.