Tectono-depositional characterization and sedimentary provenance of the Mesoproterozoic Fury and Hecla Basin, Nunavut, Canada

Abstract

Understanding the original depositional environments, architecture, and sediment sources of intracratonic basins is integral to terrane analysis in Precambrian cratons. Proterozoic intracratonic basins are widespread throughout Arctic North America, yet their inception and evolution are poorly understood. The late Mesoproterozoic amalgamation of the supercontinent Rodinia represents, specifically, an exemplary time to investigate intracratonic basin development due to many basins being formed. Four basins in eastern arctic Canada and Greenland, known as the Bylot basins, are thought to be genetically linked due to broadly similar lithologies, age, and geographic proximity. Southernmost in this basin system is the Fury and Hecla Basin, which straddles the homonymous strait and is exposed on Baffin Island and Melville Peninsula. Establishing a correlative framework between the Fury and Hecla Basin and the better characterized Borden Basin is key to a refined understanding of the broader Bylot basins. The late Mesoproterozoic strata filling the Fury and Hecla basin, cumulatively known as the Fury and Hecla Group, comprise six formations: Nyeboe, Sikosak Bay, Hansen, Agu Bay, Whyte Inlet, and Autridge; of these, three (the Nyeboe, Sikosak Bay, and Whyte Inlet formations) are sandstone-dominated. Facies analysis indicates that the lowermost Nyeboe Formation records a range of depositional environments including terrestrial, backshore eolian, marine intertidal, wave-dominated marine shelf, and marine-offshore transitional. The Sikosak Bay and Whyte Inlet formations were largely deposited in a wave-dominated marine-shelf realm and show evidence of large sandwave buildup due to prolonged longshore drift. Seven sandstone samples were analyzed for detrital zircon U-Pb geochronology from the Fury and Hecla Group, and yielded grains with ages ranging from ~3350 to ~1695 Ma. Altogether, detrital zircon grains show a bimodal age distribution with peaks at ~2.7 Ga and ~1.9 Ga. Notably, the Archean age peak is more prominent in the lower stratigraphy, whereas the Paleoproterozoic peak is more significant in the upper stratigraphy.

Facies and provenance analyses suggest that the Fury and Hecla Basin opened in a half- graben setting, with its master fault located on the present-day northern side of the basin. Initially,

sediment was likely derived from erosion of local basement rocks. Facies mapping suggests that the basin expanded its catchment area with time. This trend was accompanied by increasing recycling of older siliciclastic successions from nearby basins – a provenance pattern that dominated over local sediment sourcing in the upper strata. As such, despite broadly similar lithologies and age, the Fury and Hecla Basin shows different depositional environments and a unique evolution, when compared to the known data, from the other Bylot basins.