Investigation of a possible impact structure on Victoria Island, NWT

Regions: Inuvialuit Settlement Region

Tags: physical sciences, sediment, fossils, paleoenvironment, stratigraphy, meteoritics

Principal Investigator: Osinski, Gordon (3)
Licence Number: 15083
Organization: University of Western Ontario
Licensed Year(s): 2015 2012
Issued: Jun 27, 2012
Project Team: Dr. Gordon Osinski (Professor, University of Western Ontario), Jeremy Hansen (Astronaut, Canadian Space Agency), Cassandra Marion (PhD Student, University of Western Ontario), Raymond Francis (PhD Student, University of Western Ontario), Salma Abou-Aly (BSc Student, University of Western Ontario), Field Assistant (BSc Student, University of Western Ontario)

Objective(s): To confirm the meteorite impact origin for the Collinson Inlet structure; to investigate the tectonics of complex impact crater formation; to investigate intra-crater lake sediments; and to search for possible impact-induced hydrothermal alteration.

Project Description: The objectives of this research are to:
(1) Confirm of a meteorite impact origin for the Collinson Inlet structure. In order to confirm the meteorite impact origin of this structure, unequivocal shock metamorphic criteria need to be documented.

Shatter cones are the only diagnostic shock effect visible to the naked eye (French and Koeberl 2010). The research team will seek out the potential shatter cones documented and confirm their origin through a comparative study with shatter cones from the nearby Haughton impact structure, which formed in similar Paleozoic strata. Samples will also be collected throughout the structure for follow-up microscopic laboratory work, where the research team will look for other signs of shock (French and Koeberl 2010), including planar deformation features (PDFs) in quartz and high pressure polymorphs.

(2) Investigate the tectonics of complex impact crater formation. The structural geology of large multi-km diameter impact craters are poorly constrained. In this project, the research team will create a 3D geological map of the river section, which cuts through the centre of this crater.

Detailed geological mapping will be conducted aided by 3D scanning lidar. Faults and fracture surfaces will be mapped and orientations collected. This data will be synthesized with remote sensing imagery in ArcGIS software. There will also be a ground magnetic and ground penetrating radar survey conducted of the surrounding terrain in order to build up a more complete 3D image of this site.

(3) Investigate the intra-crater lake sediments. Following most impact events on Earth it is likely that impact crater lake(s) will form, at least temporarily (Cockell and Lee 2002). Reconnaissance mapping of this region suggests that lacustrine sediments may fill this structure (K. Dewing pers. comm. 2010). The goal is to confirm their presence and to explore for any possible relationships with similar sediments within the Haughton impact structure, where researchers have made some recent impressive discoveries (e.g., in 2007–2009 a research team led by N. Rybczynski discovered fossil fish, rabbits and two new fossil mammal taxa, including a morphologically primitive (“missing link”) pinniped (Rybczynski et al. 2009)).

Surface prospecting for fossils will be conducted. Stratigraphic sections will be measured at key outcrops. Samples will be collected for paleoenvironmental reconstruction (e.g., paleolake salinity, pollen composition). Indurated horizons will also be sought out and sampled for C and O stable isotope analysis.

(4) Search for possible impact-induced hydrothermal alteration. The heat generated by impact events typically produces a hydrothermal system immediately following the impact event. These hydrothermal deposits can be of economic value and also provide habitats for life (Osinski et al., 2005a). Given the size of the Collinson structure, hydrothermal activity should have been generated.

The research team will search for evidence for this activity in the form of vugs and veins of secondary minerals. Given the similar rocks to the Haughton impact structure, this mineralogy is likely to be sulfides, carbonates, and sulfates. Rocks will be analyzed in the field using a portable X-Ray Fluorescence spectrometer and also collected for follow-on laboratory work.

If this site proves to be a meteorite impact crater, the research team would plan to create a virtual tour, rock kits, and activities that we would provide to "local" schools on Victoria Island. Regardless, team members will be happy to run a public outreach event to talk to the community about our research via the internet.

This research will be published in scientific journals and presented at conferences. Copies of these papers will be distributed to interested northern communities and research organizations.

The fieldwork for this study will be conducted from July 1, 2012 to July 14, 2012.