Evidence of late glacial paleoseismicity from submarine landslide deposits within Lac Dasserat, northwestern Quebec, Canada. Issue 2 (September 2016)

• Record Type: Journal Article
• Authors: Brooks, Gregory R.
• Is Part Of: Quaternary research. Volume 86:Issue 2(2016)
• Page Start: 184
• Page End: 199
• Publication Date: 2016-09
• Subjects: Paleoearthquakes, -- Seismo-stratigraphy, -- Chrono-stratigraphy, -- Submarine landslide deposits, -- Varves, -- Glacial Lake Ojibway, -- Intracratonic, -- Deglaciation, -- Eastern Canada; Geology, Stratigraphic -- Quaternary -- Periodicals; Glacial epoch -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; Époque glaciaire -- Périodiques; Geology, Stratigraphic; Glacial epoch; Quaternary Geologic Period; Electronic journals; Periodicals; 551.79
• DOI: 10.1016/j.yqres.2016.06.005
• Languages: English
• ISSNs: 0033-5894

Abstract

Abstract: An integrated seismo- and chronostratigraphic investigation at Lac Dasserat, northwestern Quebec, identified 74 separate failures within eight event horizons. Horizons E and B, and H and G have strong or moderately-strong multi-landslide signatures, respectively, composed of 11-23 failures, while horizons F, D, C, and A have minor landslide signatures consisting of a single or pair of deposit(s). Cores collected at six sites recovered glacial Lake Ojibway varve deposits that are interbedded with the event horizons. The correlation of the varves to the regional Timiskaming varve series allowed varve ages or ranges of varve ages to be determined for the event horizons. Horizons H, G, E, and B are interpreted to be evidence of paleoearthquakes with differing levels of interpretative confidence, based on the relative strength of the multi-landslide signatures, the correlation to other disturbed deposits of similar age in the region, and the lack or possibility of alternative aseismic mechanisms. The four interpreted paleoearthquakes occurred between 9770 ± 200 and 8470 ± 200 cal yr BP, when glacial Lake Ojibway was impounded behind the Laurentide Ice Sheet during deglaciation. They probably represent an elevated period of seismicity at deglaciation that was driven by crustal unloading.