SEDIMENTARY AND PHYSIOGRAPHIC CONSTRAINTS ON PINGO DISTRIBUTION, TUKTOYAKTUK PENINSULA REGION, NORTHWEST TERRITORIES, CANADA

The physical basis for the widespread distribution of pingos in the Tuktoyaktuk Peninsula region has long intrigued scientists. Early mapping identified ~1400 of these ice-cored permafrost hills on the modern Mackenzie Delta and Pleistocene deposits to the east, occupying drained lake basins, depressions, and floodplains (Mackay 1962), but was limited by the resolution of monochromatic aerial photographs and precise georeferencing.

We developed a comprehensive dataset of pingos in this region using an ArcticDEM basemap and high resolution (1 m or better) colour satellite imagery on ArcGIS Earth and Google Earth platforms. Pingo-like features were identified and those that met both topographic and optical criteria were confirmed as pingos. We mapped nearly 2820 pingo-like features, confirmed over 2350 pingos, and noted about 5% in a state of collapse. Pingos occur in an area of about 18,500 km² at elevations from 60 m asl to sea level.

Only ~5% of the mapped pingos were in the outer delta. According to Mackay (1979), most pingos occur on Pleistocene interglacial sands and silts, veneered with glacial and postglacial sediments. We attribute these pingos to Pleistocene alluvial sediments, specifically the Kidluit Formation distributed by the paleo-Peel and paleo-Porcupine rivers. Pingos are absent on the Caribou Hills and Anderson Plain, and west of Nicholson Point, which provides constraints on the extent of the Kidluit deposits. Pingos are least abundant on the Toker Point Moraine, Kittigazuit Low Hills, and Husky Lakes Pitted Terrain physiographic units, suggesting additional glacial and postglacial controls on pingo distribution. Pingos are most concentrated within the Low Involuted Hills, Kugmallit Plain, and Tununuk Low Hills, where Holocene thermokarst lacustrine basins are most abundant.

The georeferenced database improves the geological context for pingos in the Tuktoyaktuk Peninsula region. The catalogue of collapsed forms and other pingo-like forms provides a means to assess associated morphologies, and to assess pingo-like features elsewhere on Earth and Mars.

Mackay, J. R. (1962). Pingos of the Pleistocene Mackenzie Delta Area. Geographical Bulletin, 18: 21-63.