The drainage of Lake Ojibway in glaciolacustrine sediments of northern Ontario and Quebec, Canada

Abstract

Physical evidence for the drainage of glacial lakes remains relatively rare in depositional records, giving rise to much debate on the location of outlets and discharge pathways, as well as on the climate impact of the attendant meltwater forcing. Lake Ojibway developed following the withdrawal of the Laurentide Ice Sheet in northern Ontario and Quebec, Canada. The late-stage evolution of this large ice-dammed lake was influenced by the complex dynamics of the retreating ice margin, which highly complicates the identification of the termination of Lake Ojibway in glaciolacustrine sediment records. Here, we document the composition of sections of rhythmites that contain in their upper part an anomalously thick and whitish bed (10-15 cm) that is in turn overlain by ∼1 m of faintly bedded rhythmites. Grain-size analyses showed that the thick whitish bed consists primarily of fine to coarse silt (2-63 μm), contrasting with the lower and upper rhythmites that are largely dominated by clay (<2 μm). The detrital carbonate content of the thick silt bed is characterized by consistently high values (2.5 to 2.8%), whereas the bounding rhythmites show lower and highly variable values. Oxygen isotope measurements further show a marked change going from typical glacial meltwater values (∼ −29.6 to −27.7‰; VSMOW) for the lower rhythmites and the silt bed to modern-like meteoric values (−18.4 to −14.6‰) for the uppermost rhythmites. These data suggest that this marker bed may be associated with a major drawdown event that possibly corresponds to the final drainage of Lake Ojibway. AMS radiocarbon dating of ostracods extracted from the drainage bed also documents an important hardwater effect within the Ojibway basin.

Late-stage phases of glacial Lake Ojibway in the central Abitibi region, eastern Canada

“…Prest (1970) subsequently presented a reconstruction of glacial lake phases that included late-stage migrations of the southern shoreline of Lake Ojibway across the region encompassing Lake Abitibi. The existence of a paleolake Abitibi in postglacial time is also supported by the presence of an extensive and faintly bedded clay containing ostracods yielding δ 18 O values clearly unrelated to glacial meltwaters, and that is found above a thick silt bed marking the end of Ojibway sedimentation in the area (Daubois et al, 2014). This is the first time that a sequence of low-elevation shorelines associated with late-stage phases are identified for Lake Ojibway.…”

“…yr BP (Hardy, 1982;Barber et al, 1999;Roy et al, 2011). Although these Cochrane readvances left a distinct imprint on the geomorphology of the region, their number and timing remains a subject of debate (e.g., Roy et al, 2011;Breckenridge et al, 2012;Daubois et al, 2014). The demise of Lake Agassiz-Ojibway has been traditionally attributed to the collapse of the disintegrating ice dam in Hudson Bay (e.g., Dyke and Prest, 1987), but recent glaciological modeling and geomorphological data indicate that the lake may have, in part at least, drained subglacially (Clarke et al, 2003(Clarke et al, , 2004Lajeunesse and St-Onge, 2008).…”

A Multi-Proxy Reconstruction of Environmental Change in the Vicinity of the North Bay Outlet of Pro-Glacial Lake Algonquin

“…The use of multiple lines of independent proxy evidence has become central to reconstructing early postglacial lacustrine environments and to accurately tracking changing conditions within them (e.g., Daubois et al 2015;Hu et al 1999;Liu 1990;Lutz et al 2007;Teller et al 2008;Wolfe et al 1996;Yu 1994Yu , 2003. Seven lab-based proxies were applied to our analysis of the Balsam Creek record.…”

Deglacial record of palaeoearthquakes interpreted from mass transport deposits at three lakes near Rouyn‐Noranda, north‐western Quebec, Canada

“…This lake, known at different stages as lakes Barlow, Barlow–Ojibway or Ojibway, formed within the isostatically‐depressed landscape between roughly 11·0 and 8·4 ka cal year bp (Vincent & Hardy, ; Veillette, ; Dyke, ; Breckenridge et al ., ; Stroup et al ., ; Roy et al ., ). The succession of lake stages ended when glacial Lake Ojibway, which existed in the area north of the modern Hudson Bay–Ottawa River drainage divide, drained northward into the James and Hudson basins through a breach in or beneath the impounding Laurentide Ice Sheet (Hardy, ; Barber et al ., ; Roy et al ., ; Daubois et al ., ). Modern lakes, such as Duparquet, Dufresnoy and Dasserat, are present within low‐lying areas that were formerly sub‐basins within the large glacial lake.…”