The Corossol structure: A possible impact crater on the seafloor of the northwestern Gulf of St. Lawrence,Eastern Canada |
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| Authors: | Patrick Lajeunesse Guillaume St‐Onge Jacques Locat Mathieu J Duchesne Michael D Higgins Richard Sanfaçon Joseph Ortiz |
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| Institution: | 1. Centre d'études nordiques and Département de géographie, Université Laval, , Québec City, Québec, G1V 0A6 Canada;2. Canada Research Chair in Marine Geology, Institut des sciences de la mer de Rimouski and GEOTOP, Université du Québec à Rimouski, , Rimouski, Québec, G5L 3A1 Canada;3. Département de géologie et de génie géologique, Université Laval, , Québec City, Québec, G1K 7P4 Canada;4. Natural Resources Canada, Geological Survey of Canada, , Québec City, Québec, G1K 9A9 Canada;5. Sciences de la Terre, Université du Québec à Chicoutimi, , Saguenay, Québec, G7H 2B1 Canada;6. Canadian Hydrographic Service, Institut Maurice‐Lamontagne, , Mont‐Joli, Québec, G5H 3Z4 Canada;7. Department of Geology, Kent State University, , Kent, Ohio, 44242 USA |
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| Abstract: | We report on a 4.1 (±0.2) km diameter and 185 m deep circular submarine structure exposed on the seabed in >40 m water depths in the northwestern Gulf of St. Lawrence (Eastern Canada) from the analysis of high‐resolution multibeam bathymetric and seismic data. The presence of a circular form characterized by a central uplift and concentric rings resembles the morphology and geometry of complex meteorite impact structures. Also, other origins, such as kimberlites, intrusions, karsts, or diapirs, can be eliminated on geological criteria. A single 4 cm long breccia fragment recovered from the central uplift has numerous glassy droplets of fluorapatite composition, assumed to be impact melts, and a single quartz grain with planar intersection features thought to be shock‐induced planar deformation features (PDFs). The absolute age of this possible impact structure is unknown, but its geological setting indicates that it was formed long after the Mid‐Ordovician and before regional pre‐Quaternary sea‐level lowstands. Present results outline the need for further examination to confirm an impact origin and to precisely date the formation of the structure. |
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