Northwest Territories Geological Survey

The multi-disciplinary Fury and Hecla Geoscience Project is led by the Canada-Nunavut Geoscience Office in partnership with McGill University, Laurentian University, and the Université du Québec à Montréal. Through 2017–2020, the project aims to generate new geoscience knowledge in the under-explored areas of northern Baffin Island and Melville Peninsula around the Fury and Hecla Strait. These areas are underlain by Archean to Paleoproterozoic rocks of the Rae Craton basement, Meso- to Neoproterozoic sedimentary rocks of the Fury and Hecla Group, and (sub-)volcanic products tentatively related to 1.27 Ga Mackenzie and 723 Ma Franklin igneous events. Specifically, the project aims to improve the mapping resolution and tectono-thermal history of the basement rocks; provide a solid framework for the sedimentology, stratigraphy, micro-paleontology, and sedimentary provenance of the hitherto poorly detailed Fury and Hecla Group; constrain the timing, duration and paleomagnetic signature of (sub-)volcanic magmatic events; and explore the potential for economic mineral and carving stone deposits in the study area.

Here we highlight the field observations and preliminary interpretations from the 2018 field season. Most basement rocks comprise variably deformed granodioritic–monzogranitic orthogneiss with pods and lenses of ultramafic, mafic and supracrustal rocks at amphibolite facies, which are cut by monzo- to syenogranite dykes, sills and small plutons. Foliated K-feldspar-phyric monzodiorite predominates in the east, while mafic, ultramafic, siliciclastic and iron-rich supracrustal rocks (possibly correlative with the 2.72 Ga Mary River Group) were found in the western part of the study area. Large, deformed mafic–ultramafic intrusions are associated with magnetic anomalies; their potential for mineralization is being evaluated.

Sedimentologic and stratigraphic work in the Fury and Hecla Group focused on sandstones, shales, and minor carbonates found in the Nyeboe, Sikosak Bay, Agu Bay, Whyte Inlet, and Autridge formations. The Nyeboe Formation preserves evidence of a remarkable variety of sub-aerial to shallow-marine depositional environments. Black shale samples from the Agu Bay and Autridge formations represent prospective targets for Rhenium-Osmium geochronology and host well-preserved assemblages of microfossils. Basaltic flows and gabbro dykes and sills across the study area were systematically sampled to constrain their age and paleomagnetic records, and test correlations with the Mackenzie and Franklin igneous events through geochemistry. The Hansen Formation, previously interpreted as a set of sub-aerial lava flows in the Fury and Hecla Group, has been tentatively reappraised as a sill that cuts the basin stratigraphy. Potential for uranium mineralization is demonstrated where the nonconformity between the Rae Craton basement and Fury and Hecla Group is displaced by fault zones that are cored by quartz stock-work.