Marine heat flow observations on the Canadian Arctic continental shelf and slope

Abstract

We present 36 new heat flow measurements, grouped within five separate sites on the Canadian Arctic continental shelf and slope, between 95°–115°W and 80°–82°N. Observations consist of temperature gradients and in-situ thermal conductivity using a modified, marine-type, multiple-penetration probe with a length of 4–6 m. Repeat measurements from nearby locations at different times of the year indicate that, for depths deeper than 200 m, the bottom water remains sufficiently stable to allow shallow measurements to characterize the deeper, geothermal flux. In this respect, the cold, ice-covered, deep-water Arctic margin is unique among the world's passive continental margins. Using these data, we construct a preliminary geothermal transect between the continental Sverdrup Basin to the south and the oceanic Canada Basin to the north. Values of 35–45 mW m −2 exist on the Axel Heiberg headland, Nansen Channel and on the continental slope, and indicate a broad-scale reduction from higher values of 55–60 mW m −2 within the Canadian Basin to values of 40–50 mW m −2 within the Sverdrup Basin. In contrast, there is a zone of high heat flow, with well-constrained values of 80 mW m −2 within Peary Channel. Low values in the northeastern sector of the margin suggest that the early Tertiary, Eurekean Orogen near Ellesmere Island has not thermally affected the margin. Based on calculations for pure-shear extension, the 15 mW m −2 reduction across the continental margin suggests that the Canada Basin proper may not have opened until Late Cretaceous, unless the pre-existing continental crust contains an extremely low amount of radiogenic material. Lithospheric models cannot account for the high values in Peary Channel which may indicate water movement within the sedimentary basin.