Deglaciation ages and meltwater routing in the Fort McMurray region, northeastern Alberta and northwestern Saskatchewan, Canada

Evidence for meltwater drainage via the St. Lawrence River Valley in marine cores from the Laurentian Channel at the time of the Younger Dryas

“…The meltwater would have then reached the Arctic Ocean rather than the North Atlantic (Teller, 2012). Fisher et al (2009) and Murton et al (2010) also believe that water from Lake Agassiz discharged to the north, via the Mackenzie River system, based on radiocarbon dates of a boulder terrace near Fort McMurray attributed to a large flood, and an unconformity in the sediments of Richards Island, Beaufort Sea. Modelling by Tarasov and Peltier (2005) shows that it is possible to trigger a cold event with freshwater discharge via the Arctic Ocean.…”

“…Despite the evidence for freshwater drainage to the Arctic Ocean at the time of the YD, some researchers have argued that the Fort McMurray area was deglaciated only after the start of the Younger Dryas (Fisher and Lowell, 2006;Fisher et al, 2009). In his review of the literature about Lake Agassiz, Teller (2013) concluded that the question as to which path the Lake Agassiz floodwaters took has not been resolved yet.…”

“…In North America, southerly (Manabe and Stouffer, 1997), easterly (Broecker et al, 1989;Licciardi et al, 1999;Clark et al, 2001) and northerly (Tarasov and Peltier, 2005;Teller et al, 2005;Fisher et al, 2009;Murton et al, 2010) routes ( Fig. 1) from glacial lakes and rapidly melting ice margins, in addition to non-North American sources, have all been considered for the rapid introduction of meltwater to the North Atlantic for the initiation and maintenance of the Younger Dryas cold event, as described in more detail in the subsequent '2.…”

Ice sheet sources of sea level rise and freshwater discharge during the last deglaciation

“…Such routing events do not necessarily cause changes in sea level and may have caused other deglacial AMOC reductions [ Clark et al , 2001; Obbink et al , 2010; Thornalley et al , 2010]. This routing hypothesis with respect to the Younger Dryas (and other cold events as well) has been questioned based on interpretations of St. Lawrence salinity proxies [ de Vernal et al , 1996; Keigwin and Jones , 1995], the southern LIS margin chronology [ Fisher et al , 2009; Lowell et al , 2009], and ice sheet model simulations [ Tarasov and Peltier , 2005], posing a fundamental problem of what caused deglacial AMOC reductions if not MWPs or routing events [ Broecker , 2006; Steig , 2006].…”

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

“…As a result, the history of the lakes is recorded by a complex sequence of shorelines that shows an overall lowering (regression) of the lake levels, which was marked by abrupt drops that were generally followed by rises (transgressions). This evolution is particularly well documented in the Lake Agassiz basin where over a century of research has identified several lake stages, along with the position of outlets and the occurrence routing events (Upham, 1895;Johnston, 1946;Elson, 1967;Teller et al, 1983;Smith and Fisher, 1993;Lewis et al, 1994Lewis et al, , 2005Thorleifson, 1996;Teller and Leverington, 2004;Fisher et al, 2009). Reconstructions of Agassiz lake levels are based for the most part on a series of extensive shorelines that spread over large areas of the flat-laying prairie terrain that was covered by the lake.…”