Mountains graphic with white diamonds on itGeoscience and Exploration

The Fury and Hecla Geoscience Project 2019: A summary of Precambrian bedrock mapping, northwestern Baffin Island, Nunavut

Tuesday, November 19, 2019 - 3:40pm to 4:00pm Theatre One


L.E. Lebeau (Presenting)
Canada-Nunavut Geoscience Office
M. Russer
Indigenous Relations and Northern Affairs Canada
I. Therriault
University of British Columbia
P.J. Bovingdon
Laurentian University

The Fury and Hecla Geoscience project is a multiyear initiative by the Canada-Nunavut Geoscience Office (CNGO) in collaboration with Canadian universities and Crown-Indigenous Relations and Northern Affairs Canada (CIRNAC). The goals of this project are to collect geological data from an area of Baffin Island that remains largely unmapped. Specifically, aeromagnetic geophysical data, bedrock, and surficial data was collected in order to constrain crystallisation ages and metamorphic events, to characterise sedimentary deposition, to record glacial dynamics, and to assess economic potential.

Field observations and preliminary interpretations from the 2019 bedrock mapping program are presented here. The project area is located north of the Fury and Hecla Strait between the communities of Igloolik and Arctic Bay. The study area comprises nine 1:250 000 National Topographic System (NTS) map sheets (37C, F, 47C-H and 48A), which covers an area of approximately 300 x 300 km.

Bedrock in this area is part of the ca. 3.0-2.5 Ga Committee Bay Fold belt, part of the northern Rae Domain, comprising Archean to Palaeoproterozoic orthogneiss and greenschist- to upper amphibolite-facies supracrustal belts. In the 2019 Fury and Hecla field area specifically, bedrock is composed of orthogneiss basement with remnants of supracrustal assemblages and minor ultramafic intrusions. Late syenogranite dykes, sills, and plutons; mafic dykes; and syenogranitic pegmatite dykes are also pervasive throughout the area. The orthogneiss basement is granodioritic to monzogranitic in composition with sporadic and deformed mafic enclaves. Structurally, it has a range of fabrics from weakly foliated, to gneissic with well-defined bands, to highly deformed (folded, boudinaged, faulted). The basement has a low magnetic signature containing sporadic mineralisation of pyrite, and a single occurence of molybdenite, and malachite-chrysocolla. In the eastern portion of the study area porphyritic- to porphyroclastic, locally megacrystic, monzogranite is present. Supracrustal panels are uncommon and include banded iron formation (BIF), and quartzite. In the central portion of the map area, a 15 x 3 km magnetic anomaly outlined from the geophysical survey is identified as a tightly folded BIF. The exposed BIF includes sections of crenulated and folded quartz-magnetite layers with horizons of coarse-grained specularite, sections with massive and coarse magnetite, and sulphide-rich gossans. Ultramafic intrusions are uncommon, including local showings of serpentinised peridotite that may potentially be used as carving stone. Late NW-SE trending gabbroic dykes related to the ca. 723 Ma Franklin igneous event crosscut the entire field area and are easily observable on the geophysical survey. Syenogranite pegmatites crosscut all rock-units with preferred orientation. These pegmatites are commonly zoned and can display graphic and perthitic textures.

Future work will include the submission and interpretation of geochemical, geochronological, and assay analyses by the CNGO and graduate students. All field data from 2018 and 2019 will be compiled for research purposes and the creation of Precambrian bedrock maps.