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 5

(a) Example of channel-forming travertine at CPS. Photo taken May 2018; channel bounded by snow. (b) Double-polished thin section of channel travertine overhang showing laminated fabric. (c) SEM-BSD micrograph of area shown in (b). (d) SEM-BSD micrograph of area shown in (c). (e, f) SEM-BSD micrographs of areas shown in (d) showing two types of micritic fabrics: (e) microcrystalline grains embedded within calcite (circle) and (f) abrupt boundary layers (arrows). (g) SEM-BSD micrograph of area shown in (d). Dashed square shows area milled in (h) with thick bar showing milled face. (h) SEM in-lens micrograph of FIB-milled face shown in (g). (i) SEM in-lens micrograph of area shown in (h). (j) SEM-SE micrograph of area shown in (i). Note trapped gas inclusions (asterisks) and microcrystalline grains (arrow) within the calcite matrix. (k) SEM in-lens micrograph of aggregates of microcrystalline FeS grains intermixed with surficial sediments from a CPS outflow. (l) TEM micrograph of microcrystalline FeS aggregates from a CPS outflow. Note morphological similarities to microcrystalline grains in (j).

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