Paleo-Hydrothermal Predecessor to Perennial Spring Activity in Thick Permafrost in the Canadian High Arctic, and Its Relation to Deep Salt Structures: Expedition Fiord, Axel Heiberg Island, Nunavut

Figure 4

(a) Plot of Apatite Fission Track Age vs. Mean Track Length for samples in the Expedition Fiord area. Note the extreme position in the plot of samples FT-59 and FT-66, from within the area of PSS (see Figure 2). (b, c) Monte Carlo inverse thermal history models for Sverdrup Basin AFT samples using AFTINV [82, 83]. The internally consistent models are compatible with the interpretation that whereas rocks now at the surface in the Princess Margaret Range (60 km to the northeast of Expedition Fiord) cooled rapidly after the Eurekan Orogeny (62 to 33 Ma), rocks in the area of the PSS maintained temperatures of up to 75°C until the Miocene. Note: all models were done using the annealing model of [48]. The middle panels show the upper and lower bounds of time-temperature solution space explored by the 250-300 acceptable model solutions (defined by a K-S goodness of fit statistic) as well as the exponential mean solution, or preferred model (thicker line). The lower panels show the measured length histograms and the exponential mean probability distributions, as well as the upper and lower bounds of the model distributions in the solution set (note that the upper and lower bounds themselves are not solutions). 5 My time steps were used, with new populations of unannealed tracks introduced at 1 My intervals. See text for discussion. Data summary in Table 1.

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