CONODONT BIOSTRATIGRAPHY OF THE DONNELLY LAKE SECTION OF THE MT. KINDLE FORMATION, NORTHWEST TERRITORIES, CANADA

The Mt. Kindle Formation in the Northwest Territories of Canada has been broadly categorized as Middle Ordovician to Silurian in age. It is underlain by the Cambrian – Middle Ordovician Franklin Mountain Formation and overlain in most areas by the Devonian Bear Rock Formation. This report focuses on preliminary conodont biostratigraphy from a section near Donnelly Lake, Northwest Territories, Canada. Samples were collected at approximately 10-meter intervals through the Mt. Kindle Formation, and one sample each was collected from the (subjacent) uppermost Franklin Mountain Formation and from the (superjacent) lowermost Bear Rock Formation at Donnelly Lake. The uppermost Franklin Mountain Formation contains a conodont fauna consisting of Drepanodus sp., Eucharodus parallelus, Oneotodus simplex, Colaptoconus sp. cf. C. quadraplicatus and Variabiloconus sp. This fauna is interpreted as upper Floian (upper Ibexian, upper part of the Lower Ordovician). Samples from the lowermost Mt. Kindle Formation contain a conodont fauna that includes Pseudobelodina sp. cf. P. inclinata, Drepanoistodus suberectus, and Panderodus sp. This fauna is interpreted as middle to upper Katian (Cincinnatian, upper part of the Upper Ordovician). Our results indicate that the Middle Ordovician and part of the Upper Ordovician probably are not preserved at the Donnelly Lake section. The Ordovician-Silurian boundary tentatively is placed within a 20-meter interval in the upper part of the Mt. Kindle Formation. Poor preservation and poor recovery of conodonts hinder a more precise location of the boundary. The highest sample containing conodonts of definite Ordovician age, at 65m above the base of the section, contains Drepanoistodus suberectus and Panderodus sp. A sample at the top of the Mt. Kindle Formation, at approximately 85 meters above the formation base, has the first appearance of a fauna of Silurian aspect, consisting of Ozarkodina hassi and Oulodus sp. Samples between 65m and 85m were barren, as was the sample from the lowermost Bear Rock Formation.