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TitleEvidence for meltwater drainage via the St. Lawrence River Valley in marine cores from the Laurentian Channel at the time of the Younger Dryas
AuthorLevac, E; Lewis, MORCID logo; Stretch, V; Dufresne, K; Neulieb, T
SourceGlobal and Planetary Change vol. 130, 2015 p. 47-65,
Alt SeriesEarth Sciences Sector, Contribution Series 20160015
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf
ProvinceEastern offshore region
NTS1; 2; 10; 11; 12; 20I; 20J; 20O; 20P; 21A; 21B; 21G; 21H; 21I; 21J; 21O; 21P; 22A; 22B; 22G; 22H; 22I; 22J; 22O; 22P
AreaSt. Lawrence River Valley; Gulf of St. Lawrence; St. Lawrence estuary; Scotian Shelf; Sable Island Bank; St. Pierre Bank; Green Bank; Atlantic Ocean; Cabot Strait; Joe's Pond; Woody Hill Brook Pond; Gaspé Peninsula; Grand Bank; Northeast Newfoundland Shelf
Lat/Long WENS -68.0000 -48.0000 52.0000 42.0000
Lat/Long WENS -64.0000 -60.0000 50.0000 48.0000
Subjectssurficial geology/geomorphology; marine geology; paleontology; geochronology; stratigraphy; sedimentology; geochemistry; Nature and Environment; glaciology; glacial history; deglaciation; postglacial deposits; glaciomarine deposits; glacial lakes; drainage systems; meltwater channels; marine sediment cores; surface waters; palynology; palynological analysis; palynomorphs; pollen analysis; microfossils; salinity; water temperature; sea ice; radiocarbon dating; carbon-14 dates; climate; chronostratigraphy; fossil assemblages; diatoms; Laurentian Channel; Laurentian Fan; Goldthwait Sea; LaHave Basin; Emerald Basin; Banqureau; Halibut Channel; Glacial Lake Agassiz; Laurentian Great Lakes; Laurentide Ice Sheet; Dinoflagellates; Lycopodium; Foraminifera; Molluscs; Phanerozoic; Cenozoic; Quaternary
Illustrationssketch maps; location maps; tables; graphs; models; diagrams; profiles
ProgramOffshore Geoscience
ProgramGSC Atlantic Division
ProgramNSERC Natural Sciences and Engineering Research Council of Canada
ProgramBishops' Univeristy, Senate Research Grant
AbstractDebate is ongoing about the source(s) and paths of meltwater that drained into the North Atlantic Ocean at the time of the Younger Dryas (YD), especially the eastern route from glacial Lake Agassiz and predecessor lakes of the Laurentian Great Lakes located along the southeastern edge of the Laurentide Ice Sheet. Here, evidence is presented for meltwater drainage via the St. Lawrence valley from five new sediment cores from Cabot Strait, Laurentian Channel and Scotian Shelf at the time of the YD. Palynological analyses are used to reconstruct sea surface conditions based on dinoflagellate cyst records, and pollen data are used for additional correlation. The reconstructions show distinct drops in salinity, temperature and increased sea ice cover duration within the YD period. In addition to these new records, we present a re-examination of original data and paleoceanographic interpretation of surface waters based on a new analysis of dinoflagellate cyst zonation in combination with an updated chronology supported by new radiocarbon dates and refined calibrations. The results clearly define the YD core intervals which contain strong evidence of lowered salinity, thereby re-establishing the St. Lawrence drainage system as a significant route for inflow of YD meltwater to the North Atlantic. This inflow does not exclude the possibility for another source of freshwater, as suggested by geographical differences in the duration of cold, low salinity conditions west and east of Laurentian Channel associated with the YD climatic event.
Summary(Plain Language Summary, not published)
Dinoflagellate cysts in dated sediment cores from Cabot Strait, Laurentian Channel, and the Scotian Shelf were analysed to determine trends in sea surface temperature, salinity, and seasonal duration of sea ice during the Younger Dryas (YD) climatic cold period 12,900 to 11,700 years ago. Such knowledge is important in understanding sensitivity of the ocean for triggering future rapid changes as meltwater inflows increase from the Greenland and other glaciers during the present period of global warming.

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