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TitlePaleoseismic assessment of multi-mass transport deposit signatures preserved within the deposits of glacial Lake Ojibway, northwestern Quebec, Canada
AuthorBrooks, G RORCID logo
SourceProceedings of the 7th International INQUA Workshop on Paleoseismology, Active Tectonics and Archaeoseismology ('PATA Days'); by McCalpin, J P (ed.); Gruetzner, C (ed.); 2016 p. 46-49 Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20150436
PublisherCrestone Science Center (Crestone, CO, USA)
Meeting7th International INQUA Workshop on Paleoseismology, Active Tectonics and Archaeoseismology ('PATA Days'); Crestone, CO; US; May 30-June 3, 2016
Mediaon-line; digital
File formatpdf; html
AreaLac Dasserat; Rouyn-Noranda
Subjectssedimentology; sediment transport; glaciolacustrine deposits; rhythmites; varves; sedimentation; deposition; Ojibway Lake
Illustrationslocation maps
ProgramPublic Safety Geoscience Western Canada Geohazards Project
Released2016 05 01
AbstractEight event horizons, consisting of 74 mass transport deposits (MTDs), were mapped using high-density sub-bottom profiles surveyed at Lac Dasserat, northwestern Quebec, Canada. Five of the event horizons (H-D) are intercalated within glaciolacustrine deposits of glacial Lake Ojibway, the other three (C-A) are at the interface of the glaciolacustrine-lacustrine deposits. Event horizons H, G and E exhibit are interpreted to be the products of paleoearthquakes, respectively, based on the relative strength of the multi-MTD signatures, the lack of likely alternative aseismic interpretations, and the occurrences of similarly-aged disturbed deposits regionally in NW Quebec-NE Ontario.
Summary(Plain Language Summary, not published)
Mapping at Lac Dasserat, Quebec, revealed that the deposits of a large number of ancient landslides are buried at multiple levels within the lake bed. All of the mapped landslide deposits occur within the glaciolacustrine deposits or at the interface between the glaciolacustrine deposits and overlying lacustrine deposits. This indicates that the landslide deposits are old, and were deposited when or immediately after a large glacial lake (known as glacial Lake Ojibway) occupied the region over 8000 years ago. Most of the landslides occur within one of four distinct levels within the lake bed, which implies that the landslides within each group happened synchronously and by a common trigger. It is interpreted that each group of landslides was triggered by shaking from an ancient earthquake. These earthquakes likely represent a period of elevated seismic activity that was caused by rapid regional crustal uplift which occurred as the Laurentide Ice Sheet retreated from the area.

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