Detrital carbonate peaks on the Labrador shelf, a 13-7 ka template for freshwater forcing from the Hudson Strait outlet of the Laurentide Ice Sheet into the subpolar gyre

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  • Anne Jennings, Univ Boulder Colorado, University of Colorado Boulder, University of Colorado System, Inst Arct & Alpine Res INSTAAR, United States
  • John Andrews, Univ Boulder Colorado, University of Colorado Boulder, University of Colorado System, Inst Arct & Alpine Res INSTAAR, United States
  • Christof Pearce
  • Lindsay Wilson, Akvaplan Niva AS, Fram Ctr, Unknown
  • Saedis Olfasdotttir, Univ Bergen, University of Bergen, Dept Earth Sci, Unknown

The Laurentide Ice Sheet (LIS) was a large, dynamic ice sheet in the early Holocene. The glacial events through Hudson Strait leading to its eventual demise are recorded in the well-dated Labrador shelf core, MD99-2236 from the Cartwright Saddle. We develop a detailed history of the timing of ice-sheet discharge events from the Hudson Strait outlet of the LIS during the Holocene using high-resolution detrital carbonate, ice rafted detritus (IRD), delta O-18, and sediment color data. Eight detrital carbonate peaks (DCPs) associated with IRD peaks and light oxygen isotope events punctuate the MD99-2236 record between 11.5 and 8.0 ka. We use the stratigraphy of the DCPs developed from MD99-2236 to select the appropriate Delta R to calibrate the ages of recorded glacial events in Hudson Bay and Hudson Strait such that they match the DCPs in MD99-2236. We associate the eight DCPs with H0, Gold Cove advance, Noble Inlet advance, initial retreat of the Hudson Strait ice stream (HSIS) from Hudson Strait, opening of the Tyrrell Sea, and drainage of glacial lakes Agassiz and Ojibway. The opening of Foxe Channel and retreat of glacial ice from Foxe Basin are represented by a shoulder in the carbonate data. Delta R of 350 years applied to the radiocarbon ages constraining glacial events H0 through the opening of the Tyrell Sea provided the best match with the MD99-2236 DCPs; Delta R values and ages from the literature are used for the younger events. A very close age match was achieved between the 8.2 ka cold event in the Greenland ice cores, DCP7 (8.15 ka BP), and the drainage of glacial lakes Agassiz and Ojibway. Our stratigraphic comparison between the DCPs in MD99-2236 and the calibrated ages of Hudson Strait/Bay deglacial events shows that the retreat of the HSIS, the opening of the Tyrell Sea, and the catastrophic drainage of glacial lakes Agassiz and Ojibway at 8.2 ka are separate events that have been combined in previous estimates of the timing of the 8.2 ka event from marine records. SW Iceland shelf core MD99-2256 documents freshwater entrainment into the subpolar gyre from the Hudson Strait outlet via the Labrador, North Atlantic, and Irminger currents. The timing of freshwater release from the LIS Hudson Strait outlet in MD99-2236 matches evidence for freshwater forcing and LIS icebergs carrying foreign minerals to the SW Iceland shelf between 11.5 and 8.2 ka. The congruency of these records supports the conclusion of the entrainment of freshwater from the retreat of the LIS through Hudson Strait into the subpolar gyre and provides specific time periods when pulses of LIS freshwater were present to influence climate. (C) 2014 Elsevier Ltd. All rights reserved.

Original languageEnglish
JournalQuaternary Science Reviews
Volume107
Pages (from-to)62-80
Number of pages19
ISSN0277-3791
DOIs
Publication statusPublished - 1 Jan 2015

    Research areas

  • Laurentide Ice Sheet, Hudson Strait outlet, Detrital carbonate peaks, Glacial events, Holocene deglaciation, Freshwater forcing, Subpolar gyre, ABRUPT CLIMATE-CHANGE, GLACIAL LAKE AGASSIZ, C-14 YR BP, NORTH-ATLANTIC, HEINRICH EVENTS, COLD EVENT, HOLOCENE DEGLACIATION, CATASTROPHIC DRAINAGE, CARTWRIGHT SADDLE, SUBGLACIAL ORIGIN

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