| Title | Earthquakes and faults of the Charlevoix Impact Structure, Quebec |
| Download | Downloads |
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| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Nadeau, L; Lamontagne, M; Brouillette, P; Locat, J; Castonguay, S ; Morin, A |
| Source | Geological Survey of Canada, Open File 8432, 2020, 49 pages (1 sheet), https://doi.org/10.4095/315675  Open Access |
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| Year | 2020 |
| Publisher | Natural Resources Canada |
| Meeting | Eastern Section of the Seismological Society of America (ES-SSA) 2013 Annual Meeting; La Malbaie, QC; CA; October 6-8, 2013 |
| Document | open file |
| Lang. | English; French |
| Maps | Publication contains 1 map |
| Map Info. | geological, bedrock geology, 1:200,000 |
| Media | on-line; digital |
| Related | This publication is a translation of Tremblements de terre
et failles de l'astroblème de Charlevoix (Québec) |
| File format | pdf (Adobe® Reader®) |
| Province | Quebec |
| NTS | 21M/07; 21M/08; 21M/09; 21M/10; 21M/15; 21M/16 |
| Area | Malbaie; Clermont; Saint-Urbain; Baie-Saint-Paul; Mont-des-Éboulements; Les Éboulements; Saint-Hilarion; Saint-Joseph-de-la-Rive; Pointe-au-Pic; St. Lawrence River; L'Isle-aux-Coudres |
| Lat/Long WENS | -70.7500 -70.0000 47.8333 47.3333 |
| Subjects | geophysics; structural geology; geochronology; Science and Technology; Nature and Environment; seismology; earthquakes; seismicity; earthquake magnitudes; landslides; bedrock geology; basement geology;
structural features; meteorite craters; faults; fault zones; lithology; sedimentary rocks; limestones; quartzites; metamorphic rocks; gneisses; breccias; igneous rocks; intrusive rocks; granites; metamorphism, shock; shatter cones; brecciation;
dykes; sills; fracturing; radiometric dating; argon argon dating; uranium lead dating; Upper Ordovician; field relations; tectonic history; plate margins; rifting; faulting; deformation; tectonic elements; remote sensing; satellite imagery;
structural interpretations; crustal structure; geophysical interpretations; magnetic interpretations; magnetic anomalies; gravity interpretations; gravity anomalies; bouguer gravity; Charlevoix Seismic Zone; Charlevoix Impact Structure; Iapetus
Ocean; Logan's Line; Appalachian Orogen; St. Lawrence Platform; Canadian Shield; Grenville Province; 1663 M ~7 Earthquake; 1791 M ~6 Earthquake; 1860 M ~6 Earthquake; 1870 M ~6.5 Earthquake; 1925 magnitude MS 6.2 ± 0.3 Earthquake; Laurentian Margin;
St. Lawrence Rift System; St-Laurent Fault; Gouffre Fault; February 5, 1663 Saint Joseph-de-la-Rive Landslide; Canadian National Seismograph Network; Phanerozoic; Paleozoic; Ordovician; Cambrian; Precambrian; Proterozoic |
| Illustrations | geoscientific sketch maps; location maps; block diagrams; tables; digital elevation models; satellite images; cross-sections; schematic cross-sections; stratigraphic columns; photographs; 3-D
images |
| Program | Public Safety Geoscience Eastern Canada Geohazards Assessment Project |
| Released | 2020 01 27 |
| Abstract | This field guide was first written for the meeting of the Eastern Section of the Seismological Society of America (ES-SSA), held in La Malbaie in 2013. It has been slightly modified, mostly with new
figures.
The Charlevoix Seismic Zone is the locus of the highest seismic hazard in continental eastern Canada. At the heart of this zone is the ~54 km diameter Charlevoix impact structure. This structure, located less than 125 km east of Quebec
City, is one of the most accessible large meteorite impact structures in eastern North America. The Charlevoix impact structure is singled out as it overprints Iapetus rift faults and the Logan's Line marking the edge of the Appalachian
Orogen.
The Charlevoix impact structure gives the region its singular landscape. The ~5 km wide peripheral ring trough forms a prominent open valley extending from St. Lawrence River (sea level) to a threshold at ~250 m altitude. The highest point
in the valley is nearly 850 m below the ~1100 m mean elevation of the external Laurentian plateau. The highest point is also 550 m below the central uplift, 'Mont-des-Éboulements,' which stands 780 m above sea level. The overall morphology of the
Charlevoix impact structure matches that of a complex impact crater. Shatter cones, mylolisthenite injections and shock-induced planar deformation microstructures in quartz and feldspar are widespread providing compelling evidence for the extent of
shock metamorphism. The age of the impact is poorly constrained. Recently acquired 40Ar/39Ar and U-Pb data from impact melt rock and pseudotachylite give a late-Ordovician age, which appears to be in better agreement with field relationships than the
previously reported K-Ar Devonian-age.
Based on historical and current earthquake rate, the Charlevoix Seismic Zone is a region of high seismic hazard. Since the arrivals of the first Europeans in the early 1600s, it has been subject to five
earthquakes of magnitude 6 or larger: in 1663 (M~7); 1791 (M ~6); 1860 (M ~6); 1870 (M ~6 ½); and 1925 (magnitude MS 6.2 ± 0.3). Recently, the magnitude of the 1663 earthquake was estimated to be as large as M 7.2 to 7.9!
The field trip provides
an opportunity to enjoy the panoramic view of the peripheral trough and ring structure and of the central uplift, and to visit key outcrops featuring shock-related features, including shatter cones, impact breccias, and related fault zones. The focus
of the field trip is on the region's long fault reactivation history, dating back to the Iapetus Ocean rifting. The field trip also includes visiting outcrops of the St. Lawrence Platform Cambro-Ordovician sedimentary cover, allowing observation of
the structural relationships with the Logan's Line marking the edge of the Appalachian Orogen. Field research in the Charlevoix region is also important because, paired with seismic hazard, the area is known for its landslide sensitivity; stops at
St. Joseph-de-la-Rive feature a major landslide caused by the February 5th 1663 earthquake. |
| Summary | (Plain Language Summary, not published)
This Open File provides an overview of some geological and seismological aspects of the Charlevoix region. |
| GEOSCAN ID | 315675 |
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