NWT RESEARCH DATABASE

Regions: Dehcho Region, South Slave Region

Tags: fossils, paleontology, rock outcrops

Objective(s): The Upper Devonian age marine deposits & fossils in the Hay River region of the Northwest Territories accumulated in ancient continental shelf environments in the tropical equatorial ocean. The Hay River region has been selected by our group for detailed study because it features a very thick, well preserved, fossil rich and structurally undisturbed Upper Devonian (Frasnian-Famennian age) succession of ancient inner continental shelf deposits. Devonian rocks in the Hay and upper Mackenzie River valleys are easily accessibly by paved roads and small boats. Easy access to complete outcrop succession in this region provides ideal conditions for the successful and timely completion of a detailed faunal investigation of the Upper Devonian rocks in the area. The initial field sampling phase of the project will begin in 1997, and we anticipate conducting additional sampling during 3-4 week periods during the summer of 1998 and 1999. Study of changes in composition, diversity and abundance of environmentally sensitive fossil groups in these rocks will allow us to establish the timing & nature of faunal radiations and extinctions to determine if they coincide to environmental changes related to changes in sea level, climate & ancient oceanic chemistry & structure.

Project Description: The Hay River region features a complete well preserved Upper Devonian deposits that accumulated over a span of time when known or suspected major species extinctions, sea level & climate changes have been detected in other sites in North America, Europe & Asia. Goals of the project are to: 1) collect new detailed fossil data to allow for more accurate age estimates of Upper Devonian deposits in the Hay River region and adjacent areas of western Canada & 2) study & document sea level & climate changes during the Late Devonian time interval (approx. 8 million years in duration), & 3) study rates & possible causes of species extinctions in the tropical ocean recorded by rocks and fossil sequence in the region. All sites to be visited are readily accessible by road (Mackenzie highway) or by small boats along the banks of the Hay River. We will operate from bases set up in local hotels or camp grounds in or near communities of Hay River, Enterprise and Kakisa. In June, study involves site location, description & sampling of selected outcrops or roadcut exposures for rock types & fossils at sites between Grumbler Rapids (near Alexandra Falls) and the Town of Hay River along the Mackenzie Highway southwest of Enterprise on Highway 1. If time permits, visits to additional sites along the Mackenzie Highway between Kakisa Lake and Trout River. In early August will visit additional sites along the Hay River, and Kakisa river. Sampling will be done with rock hammers. Measurement of rocks at sites is done with portable hand-held compasses-transits and ruled tapes and stadia rods. All sites will be documented photographically. All sites located with GIS instruments and topographic maps. Rock sample size varies depending on if for 1)microfossils, 2) larger animal fossils, 3) chemical & physical studies of rock textures & chemistry. After analysis, description & photographic documentation, all fossil specimens will be permanently placed at the Institute of Sedimentary & Petroleum Geology at Geological Survey of Canada in Calgary.