STRATIGRAPHY OF THE MACKENZIE RIVER DELTA, NORTHWEST TERRITORIES, CANADA

摘要

An investigation was carried out in April 1961 to determine the distribution of permafrost under and adjacent to a small lake in the Mackenzie River delta near the new townsite of Inuvik, Northwest Territories, Canada. Using drilling methods, deposits were sampled to bedrock at a depth of about 230 feet, and it is believed that this is the first study in which a complete section of the deltaic deposits has been obtained. Perennially frozen ground was not found in the hole bored under the center of the lake but was found in the total thickness of deposits in each of three holes drilled adjacent (within 500 feet) to the lake. About 180 feet of stratified silts, fine sand, and organic material overlie 50 feet of dense silty clay deposited on bedrock. Results of laboratory tests on the sediments sampled suggest that the lower portion of the dense silty-clay layer, which contains pebbles, is probably till deposited by the ice sheet that covered the area during the Wisconsin. The upper portion of the silty-clay layer, containing no pebbles, was possibly deposited under glaciomarine or estuarine conditions. The sediments overlying the clay layer are of deltaic origin and were deposited by the present Mackenzie River and its postglacial predecessors.