| Title | Evidence of early postglacial paleoearthquakes from mass transport deposits buried within glaciolaustrine sediments in northeastern Ontario-western Quebec, Canada |
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| Author | Brooks, G R |
| Source | GAC®-MAC 2021, London, Canada: Exploring Geosciences Through Time and Space/GAC®-MAC 2021, London, Canada : Explorer les géosciences à travers le temps et l'espace; Geological Association of
Canada-Mineralogical Association of Canada, Joint Annual Meeting, Programs with Abstracts vol. 44, 2021 p. 53  Open Access |
| Links | Online - En
ligne (complete volume - volume complet, PDF, 2.45 MB)
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| Image |  |
| Year | 2021 |
| Alt Series | Natural Resources Canada, Contribution Series 20210480 |
| Publisher | Geological Association of Canada |
| Meeting | GAC-MAC 2021: Geological Association of Canada-Mineralogical Association of Canada Joint Annual Meeting 2021; London, ON; CA; November 1-5, 2021 |
| Document | serial |
| Lang. | English |
| Media | digital; on-line |
| File format | pdf |
| Province | Ontario; Quebec |
| NTS | 31M/06; 31M/07; 31M/08; 31M/09; 31M/10; 31M/11; 31M/15; 31M/16; 31N/05; 31N/12; 31N/13; 32C/04; 32C/05; 32C/12; 32C/13; 32D; 41O/08; 41O/09; 41O/16; 41P/05; 41P/06; 41P/07; 41P/08; 41P/09; 41P/10; 41P/11;
41P/12; 41P/13; 41P/14; 41P/15; 41P/16; 42A; 42B/01; 42B/08; 42B/09; 42B/16 |
| Area | Kirkland Lake; Rouyn-Noranda; Dasserat Lake; Dufresnoy Lake; Duparquet Lake; Chassignolle Lake; Malartic Lake |
| Lat/Long WENS | -82.4167 -77.8333 49.0000 47.2500 |
| Subjects | surficial geology/geomorphology; stratigraphy; Nature and Environment; Science and Technology; landslides; mass wasting; landslide deposits; earthquakes; seismicity; glacial history; deglaciation;
glacial lakes; isostatic rebound; sedimentation rates; lake sediments; varves; stratigraphic analyses; Glacial Lake Ojibway; glaciolacustrine sediments; Phanerozoic; Cenozoic; Quaternary |
| Program | Public Safety Geoscience Assessing Earthquake Geohazards |
| Released | 2021 11 01 |
| Abstract | Eastern Canada is a large region of recently glaciated terrain where evidence of early postglacial, glacially-induced seismic activity should be abundant, but there are no confirmed examples of early
postglacial seismogenic faults. Nevertheless, research within the basin of Glacial Lake Ojibway, which persisted between 10.57-8.47 ka cal BP in northeastern Ontario-western Quebec, revealed mass transport deposits (MTDs) buried at differing
stratigraphic levels within the glaciolacustrine sediments throughout the region. Detailed mapping of the sub-bottom deposits at Dasserat, Duparquet, and Dufresnoy lakes, located 24 to 38 km apart, near Rouyn-Noranda, Quebec, identified 26 MTD event
horizons of which 15 contain three or more MTDs. High-resolution, relative dating control using varves indicates: that the event horizons span a period of about 450 varve years (between 9.4-8.95 ka cal BP); that one set of identically-aged event
horizons is common to each lake; and another set is common to two lakes. The 15 event horizons containing three or more MTDs are interpreted to be evidence of 11 paleoearthquakes of Mw5 or larger. The confidence of each interpretation is weighted
from low to high, reflecting the relative strength of the MTD signature in each event horizon (moderate (three to five MTDs) or strong (more than six MTDs)), and evidence of common- or similar-aged MTD signatures at two or more distinctly separate
locations. The event horizon with the most numerous and widespread MTDs in each lake formed in the identical varve year 1483 (about 9.1 ka cal BP). These occurrences are part of a regional MTD signature present in other lakes and in subaerial
exposures that enclose an area of about 14,600 km2 in northeastern Ontario and western Quebec. This signature is best explained by a strong paleoearthquake of about Mw 7.3. The interpreted paleoearthquakes occurred when early postglacial uplift had
diminished moderately, but was still high, compared to mid-Holocene and late Holocene rates. This record, thus, is likely representative of a period of elevated, early postglacial seismicity associated with rapid crustal unloading from the waning of
the Laurentide Ice Sheet. |
| Summary | (Plain Language Summary, not published)
This abstract summarizes evidence of a period of elevated earthquake activity that occurred at the time of the retreat of the ice sheet from the most
recent glaciation. The evidence is based on mapping ancient landslides buried in the bottom of modern lakes. Evidence of such elevated earthquake activity is important for the design of critical infrastructure, such as nuclear waste
repositories. |
| GEOSCAN ID | 329344 |
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