FINAL STAGES IN THE COLLAPSE OF THE LAURENTIDE ICE-SHEET, HUDSON STRAIT, CANADA, NWT - C-14 AMS DATES, SEISMIC STRATIGRAPHY, AND MAGNETIC-SUSCEPTIBILITY LOGS

Hudson Strait is a key element in the history of ice sheet/ocean inter actions during the deglaciation of the Laurentide Ice Sheet. Data from over 30 giant piston cores, supplemented by ca. 40 C-14 AMS dates on foraminifers and shells from sites within and adjacent to Hudson Strai t, are used to describe the timing and sediment processes associated w ith the final,complex phases of deglaciation in Hudson Strait. Each co re is placed in a regional seismic architectural context through exami nation of deep-tow Huntec profiles. Most cores sample a thin postglaci al unit and extend several meters into glacial marine sediment (mainly silty clays). C-14 dates on cores from the adjacent shelf indicate th at deglaciation occurred by greater than or equal to 13 ka. We have no t been unable to confirm that Hudson Strait was ice-free by 11-12 ka, although this is a probable scenario. Whole core, magnetic susceptibil ity (WCMS) data are used as the primary signature of changes in the st yle of sedimentation and provenance, and to correlate between cores. W CMS indicates that there is a regional differentiation in the MS signa l associated with bedrock provenance, changes in contribution of detri tal carbonate, and style of sedimentation. One low WCMS event is prese nt in cores from both the Western and Eastern Basins; it dates from 8. 0 +/- ka and provides an important re ion al stratigraphic marker, pro bably associated with the final deglaciation of Hudson Bay and Hudson Strait. Sediment from a southerly source (Ungava Bay), continued to be contributed into the 900 m deep Eastern Basin of Hudson Strait <8 and greater than or equal to 7 ka, and thick postglacial sequences were p iled within Ungava Bay between 6 and 7 ka.