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 9

Petrographic characteristics of carbonate-quartz veins (WGVA). (a) Complete vein cross section (hand sample) showing early brown, comb-textured (acicular, hexagonal) carbonate lining vein wall (cal1), later white, massive, sparry carbonate and quartz (cal2 + qtz), and sulfide-mineralized wallrock. (b) Enlarged view of the contact between cal1 and cal2 generations where euhedral crystals of cal1 contact cal2. (c) Banded (“zebra”) texture showing alternating layers consisting of sulfide-mineralized wall rock laminae and cal2. (d) Thin-section photomicrograph (transmitted light) showing the paragenetic sequence of early pyrite (py) surrounded in zoned, euhedral brown carbonate (cal1), followed by massive white-orange carbonate (cal2) infilling and late galena infilling fractures and pits in cal2. (e-h) Transmitted light (ppl) photomicrographs (at 20°C) showing large primary (“P”) two-phase () inclusions and planes of much smaller secondary (“S”) two-phase () inclusions in cal2. Images (f) and (h) show more highly magnified areas of the central parts of images (e) and (g), respectively. (i) Transmitted light (ppl) photomicrograph (at 20°C) of a long, rectangular primary two-phase () inclusion in cal2. (j) Transmitted light (ppl) photomicrograph (at 20°C) of a planar trail of secondary inclusions cross-cutting cal2 cleavage planes. (k-l) Secondary fluid inclusions in cal2 containing two phases () at 20°C. (m) Transmitted light (ppl) photomicrograph (at 20°C) of an irregularly shaped secondary two-phase inclusion () in cal1. (n) Transmitted light (ppl) photomicrograph (at 20°C) shows two types of secondary inclusion morphologies in cal2: rectangular to irregular two-phase inclusions (“S”) and later (“S2”) rectangular two-phase inclusions with rounded edges. The latter inclusions tend to show lower values (see text for description).