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TitleDeglaciation and ice shelf development at the northeast margin of the Laurentide Ice Sheet during the Younger Dryas chronozone
AuthorFurze, M F A; Pienkowski, A J; McNeely, M A; Bennett, R; Cage, A G
SourceBoreas 2017, 26 pages,
Alt SeriesEarth Sciences Sector, Contribution Series 20160266
PublisherJohn Wiley & Sons Ltd.
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthern offshore region; Nunavut
NTS48C; 48D; 48E; 48F
AreaLancaster Sound; Baffin Island
Lat/Long WENS -90.0000 -75.0000 75.0000 72.0000
Subjectsglaciation; deglaciation; ice rafting; biostratigraphy; lithofacies; mass wasting; Laurentide Ice Sheet (LIS); ice shelves; ice streams; deglacial behavior
Illustrationslocation maps; geological sketch maps; lithologic logs; tables; graphs; schematic diagrams
ProgramMarine Geohazards, Public Safety Geoscience
AbstractCore 2011804-0010 from the intersection of Lancaster Sound and Baffin Bay provides important insights into deglacial timing and style at the marine margin of the NE Laurentide Ice Sheet. Spanning 13.0-10.7 cal ka BP and investigated for ice-rafted debris (IRD), calcareous microfossils, and biogeochemistry (biogenic silica, total organic carbon), the record shows a lithofacies progression from proximal
grounding line to distal calving margin sub-ice shelf environments to open glacimarine deposition; a sequence consistent with records described from Antarctic ice shelves. IRD initially reflects input from northern Baffin Island via an Admiralty Inlet trunk glacier to eastward-streaming ice in Lancaster Sound. This is succeeded by the increasing importance of Bylot Island sources following ice shelf break-up.
Foraminiferal faunas are dominated by characteristic ice-proximal glacimarine benthics (Cassidulina reniforme, Elphidium excavatum f. clavata), complemented by advected Atlantic water (Cassidulina neoteretis, Neogloboquadrina pachyderma) and enhanced current indicators (Lobatula lobatula). The biostratigraphy, coupled with biogeochemistry, further supports the ice shelf model, with advection of sparse faunas beneath the ice shelf, followed by increased productivity under open glacimarine conditions.
Results imply the existence of grounded ice in eastern Lancaster Sound at and following the Last Glacial Maximum, and consequently along northern Bylot Island. Initial float-off of grounded ice occurred >13.0 cal ka BP, followed by a persistent extensive glacial ice shelf stabilizing the retreating margin of the Laurentide Ice Sheet in eastern Lancaster Sound until ~12.2 cal ka BP. Absent Holocene deposits and the site's proximity to tidewater glacial sediment sources and 20th century earthquake foci 23 suggest loss of the upper record due to mass sediment transport, potentially due to Holocene seismic activity. Collectively, this study represents the first marine evidence for deglacial ice shelves in the eastern Northwest Passage, with implications for deglacial dynamics, ice sheet stability, and ice-ocean interactions in this complex archipelago setting.
Summary(Plain Language Summary, not published)
This paper discusses new interpretations of deglacial processes and timing in eastern Lancaster Sound and Baffin Bay. Slope instability is interpreted to have caused the lack of recent sediments (<10,000 years old) observed in the core sample analyzed for this paper.