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Geophysical Monograph Series

 

Keywords

  • palynology
  • meltwater
  • North Atlantic
  • Holocene
  • foraminifera
  • reconstructions

Index Terms

  • 4901 Paleoceanography: Abrupt/rapid climate change
  • 4952 Paleoceanography: Palynology
  • 4954 Paleoceanography: Sea surface temperature
  • 0459 Biogeosciences: Macro- and micropaleontology

Article

GEOPHYSICAL MONOGRAPH SERIES, VOL. 193, PP. 139-159, 2011

The Impact of the Final Lake Agassiz Flood Recorded in Northeast Newfoundland and Northern Scotian Shelves Based on Century-Scale Palynological Data

Elisabeth Levac

Environmental Studies and Geography, Bishop's University, Sherbrooke, Quebec, Canada


C. F. M. Lewis

Geological Survey of Canada-Atlantic, Natural Resources Canada, Dartmouth, Nova Scotia, Canada


A. A. L. Miller

marine g.e.o.s., Wolfville, Nova Scotia, Canada


Two high-resolution century-scale palynological records from the eastern Canadian margin were analyzed to estimate the impact of Lake Agassiz's final drainage at circa 8.3 ka on sea surface conditions and to track the path of the meltwater plume. Core HU87033-19 from Notre Dame Channel on Northeast Newfoundland Shelf contains four distinct detrital carbonate (DC) beds, known to be sediment transported from Hudson Strait and Hudson Bay, and one layer is coeval with the drainage of Lake Agassiz. Within that DC layer, significant changes in dinoflagellate cyst assemblages indicate lower sea surface temperatures and salinity. The drop in salinity is a doublet, suggesting two episodes of meltwater drainage. Core HU84011-12, from St. Anne's Basin, on the northern Scotian Shelf contains similar changes in dinoflagellate cyst assemblages at the time of the drainage, indicating sea surface cooling accompanied by a slight decrease in salinity. The impact of the meltwater was greater in the Notre Dame Channel. This suggests that most of the meltwater from the final drainages of Lake Agassiz flowed south over the Labrador and Northeast Newfoundland shelves and was not dispersed directly into the Labrador Sea. Instead, it was possibly dispersed into the slope water system and subsequently into the North Atlantic after flowing initially over the continental shelf. This is the first paper describing paleoecological data indicating the presence of the Agassiz meltwater along the eastern Canadian margin.

Citation: Levac, E., C. F. M. Lewis, and A. A. L. Miller (2011), The impact of the final Lake Agassiz flood recorded in northeast Newfoundland and northern Scotian shelves based on century-scale palynological data, in Abrupt Climate Change: Mechanisms, Patterns, and Impacts, Geophys. Monogr. Ser., vol. 193, edited by H. Rashid, L. Polyak and E. Mosley-Thompson, pp. 139–159, AGU, Washington, D. C., doi:10.1029/2010GM001051.

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