Sequence stratigraphic, lithostratigraphic and stable isotope analysis of the Minto Inlet Formation and Kilian Formation of the Shaler Supergroup, Northwest Territories

The Minto Inlet Formation is sub-divided into three regionally extensive members: the lower evaporite, carbonate and upper evaporite members. The Kilian Formation is sub-divided into 4 third-order depositional sequences and their respective systems tracts. Both formations reflect deposition on a subtidal to supratidal ramp, influenced by siliciclastic supply, arid climate and tectono-eustasy. Sulphate samples from the Minto Inlet Formation are characterized by low δ34S (~17‰) with little secular variability, whereas samples from the Kilian Formation show high average δ34S (~26‰) and high secular variability. Biogeochemical models indicate an initial decrease in the pyrite burial fraction (ƒp) from ~1 to ~0.3, was initiated prior to the deposition of the Minto Inlet Formation, and a return of ƒp values near 1 (recorded in the Kilian Formation). These changes are interpreted to be the result of basin-scale evaporite deposition during the middle Neoproterozoic, driven by the migration of Rodinia across arid climate belts.